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Heat soak? Issues when when temps are 80+ out.
06-25-2012, 06:47 AM
#31
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Year: 2000
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Engine: 4.0
I believe the "Heat Soak" issue was a TSB not a recall. And yes the heat shield just addresses the symptom. Solving the root cause issue would have required significant redesign of the exhaust/emission system components. The reason it applies to "later" 4.0l is because emission regulations required the changes.
And I have a theory that this heat cycle issue goes beyond the misfire in injectors 3 or 4 and may also contribute (or cause) the 0331 head cracking in the same area. Coincidence, may be. But I believe in cause and effect not coincidences.
And I have a theory that this heat cycle issue goes beyond the misfire in injectors 3 or 4 and may also contribute (or cause) the 0331 head cracking in the same area. Coincidence, may be. But I believe in cause and effect not coincidences.
06-25-2012, 07:24 AM
#32
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Year: 2000
Model: Cherokee
Engine: 4.0
80 degrees is not really hot.
Federally mandated recalls are for safety reasons. Voluntary recalls are when the mfgr feels a recall would be cheaper than lots of lawsuits and a bad reputation. Voluntary recalls are things like drivability, comfort, and cosmetic complaints.
If he'd actually ever been in the automotive repair business he'd know that.
If you can fix it with candy wrappers and chewing gum, go ahead.
The problem is still there and it will only get worse.
Mickey Mouse repairs like that are the reason the automotive repair business has such a bad reputation.
Using intelligence and logic is a thing of the past. Doing a simple task like measuring fuel pressure is beyond the capability of most "code reader ""mechanics."""
Remember - "basic physics does not apply to Jeeps"
Federally mandated recalls are for safety reasons. Voluntary recalls are when the mfgr feels a recall would be cheaper than lots of lawsuits and a bad reputation. Voluntary recalls are things like drivability, comfort, and cosmetic complaints.
If he'd actually ever been in the automotive repair business he'd know that.
If you can fix it with candy wrappers and chewing gum, go ahead.
The problem is still there and it will only get worse.
Mickey Mouse repairs like that are the reason the automotive repair business has such a bad reputation.
Using intelligence and logic is a thing of the past. Doing a simple task like measuring fuel pressure is beyond the capability of most "code reader ""mechanics."""
Remember - "basic physics does not apply to Jeeps"
2. The heat soak Technical Service Bulletin was a Technical Service Bulletin, NOT A RECALL. That means that if a customer brought their Jeep in for that symptom, you referred to the TSB on how to fix it. IT WAS NOT A RECALL.
I work at a dealership. I can bring BOTH of the TSB's related to this issue up on Alldata all day long. OR you could just look back in this thread where someone posted it for you to read.
3. The PROBLEM is still there - you're right. Poor design of the intake/exhaust manifolds lead to heat soak problems where the fuel inside the injectors boils into vapor and the engine idles roughly when you restart it after a 10 to 20 minutes hot soak.
YOU say it's the fuel pressure regulator or the fuel lines. YOU are wrong.
Ever owned an old car with a carbureted engine?
There was this phenomenon called "Vapor Lock" where the fuel would boil from the heat of the engine, and the engine would be difficult to restart.
On the newer 4.0's, the part of the fuel system that gets the hottest ARE THE FUEL INJECTORS THEMSELVES.
But, you know what, go ahead and continue to argue. Go ahead and be Mr. Know-It-All. The rest of us will continue to laugh at your foil-hat wearing ignorance.
4. Measuring fuel pressure during this symptom will not yield an accurate result. If the fuel is vapor, you're not going to get an accurate reading. That could be related to the fuel pump, fuel lines, injectors, computer, ANYTHING that controls or has to do with fuel pressure.
But, thankfully, someone has already traced the problem to the root cause - THE INJECTORS GET TOO HOT. WOW! WHAT A THOUGHT! Someone has already figured it out! There's already a "fix" for it! You're NOT the first person to attempt to diagnose the problem! AMAZING!
Last edited by 77olds; 06-25-2012 at 07:27 AM.
06-25-2012, 08:19 AM
#33
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Originally Posted by rrich
80 degrees is not really hot.
Federally mandated recalls are for safety reasons. Voluntary recalls are when the mfgr feels a recall would be cheaper than lots of lawsuits and a bad reputation. Voluntary recalls are things like drivability, comfort, and cosmetic complaints.
If he'd actually ever been in the automotive repair business he'd know that.
If you can fix it with candy wrappers and chewing gum, go ahead.
The problem is still there and it will only get worse.
Mickey Mouse repairs like that are the reason the automotive repair business has such a bad reputation.
Using intelligence and logic is a thing of the past. Doing a simple task like measuring fuel pressure is beyond the capability of most "code reader ""mechanics."""
Remember - "basic physics does not apply to Jeeps"
Federally mandated recalls are for safety reasons. Voluntary recalls are when the mfgr feels a recall would be cheaper than lots of lawsuits and a bad reputation. Voluntary recalls are things like drivability, comfort, and cosmetic complaints.
If he'd actually ever been in the automotive repair business he'd know that.
If you can fix it with candy wrappers and chewing gum, go ahead.
The problem is still there and it will only get worse.
Mickey Mouse repairs like that are the reason the automotive repair business has such a bad reputation.
Using intelligence and logic is a thing of the past. Doing a simple task like measuring fuel pressure is beyond the capability of most "code reader ""mechanics."""
Remember - "basic physics does not apply to Jeeps"
The injector sleeves are the fix. they never come back with the same problem after the repair.
And on any of the missfire codes relating to this the normal test have always come out fine. Fuel pressure, pw, duel sync, ect.
Its a design flaw, simple as that. Sleeves or hood vents will keep it from happening again.
But if you do find some magic cure, be sure to let us know
Last edited by N20jeep; 06-25-2012 at 08:25 AM.
06-25-2012, 11:13 AM
#35
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Engine: 4.0
Carburetor Vapor Lock was caused by the liquid fuel turning to vapor - then the pump could not pump liquid into the carb. When the pump tried to create pressure, the vapor just compressed without liquid fuel flowing.
The chewing gum and candy wrapper advocates used to put clothes pins on the fuel lines.
The actual mfgr's solution was 2 things:
It was redesigned with a pressure regulator that recycled the excess fuel - causing the fuel to be constantly recycled back to the tank, keeping it cooler instead of standing in the lines where it got hot.
And the pump was relocated to the tank - that allowed the entire fuel line to be presurized instead of the engine mounted punp trying to "suck" the fuel all the way from the tank.
Some longer vehicles, like motor homes and trucks used 2 pumps, one at the tank, one midway.
Even though some don't believe in physics, it's harder for fuel to vaporize under pressure than under vacuum.
FI systems still use the recycling idea - fuel constantly being returned to the tank.
And FI systems the pump is located back by the tank. The major change is the pump pressure is much higher now.
Now think about it - sure - candy wrappers will shield the heat from the injectors - it's just insulation.
But it's a double edged sword - when you shut the engine off the heat still creeps through - especially now that air can no longer circulate to keep the injectors cool.
Now the insulation HOLDS THE HEAT IN.
Look at your house - insulation is used to keep heat out when it's hot AND to keep heat in when it's cold! (On no -- physics again!)
Using a fuel pressure gauge when it's hot and acting up will show the rail pressure is down when it's trying to pump against vapor.
But it's not always the fault of the regulator. Pressure from the pump itself can be low causing it.
I don't know why so many people would rather use candy wrappers rather than use simple test equipment and fix it right.
MANY late model vehicles have the exhaust manifold and cats right under the intake - especially on front wheel drives. It's done on purpose - the hot manifold - hot air - helps vaporize the fuel in the cylinders - for better mileage, more power.
WHY don't they have a problem? They don't use candy wrappers!
(But they do use higher pump pressures.)
Next thing ya know he'll claim there's TSB'S to use duct tape to repair windshields!
But it's your choice - it's your rig.
The chewing gum and candy wrapper advocates used to put clothes pins on the fuel lines.
The actual mfgr's solution was 2 things:
It was redesigned with a pressure regulator that recycled the excess fuel - causing the fuel to be constantly recycled back to the tank, keeping it cooler instead of standing in the lines where it got hot.
And the pump was relocated to the tank - that allowed the entire fuel line to be presurized instead of the engine mounted punp trying to "suck" the fuel all the way from the tank.
Some longer vehicles, like motor homes and trucks used 2 pumps, one at the tank, one midway.
Even though some don't believe in physics, it's harder for fuel to vaporize under pressure than under vacuum.
FI systems still use the recycling idea - fuel constantly being returned to the tank.
And FI systems the pump is located back by the tank. The major change is the pump pressure is much higher now.
Now think about it - sure - candy wrappers will shield the heat from the injectors - it's just insulation.
But it's a double edged sword - when you shut the engine off the heat still creeps through - especially now that air can no longer circulate to keep the injectors cool.
Now the insulation HOLDS THE HEAT IN.
Look at your house - insulation is used to keep heat out when it's hot AND to keep heat in when it's cold! (On no -- physics again!)
Using a fuel pressure gauge when it's hot and acting up will show the rail pressure is down when it's trying to pump against vapor.
But it's not always the fault of the regulator. Pressure from the pump itself can be low causing it.
I don't know why so many people would rather use candy wrappers rather than use simple test equipment and fix it right.
MANY late model vehicles have the exhaust manifold and cats right under the intake - especially on front wheel drives. It's done on purpose - the hot manifold - hot air - helps vaporize the fuel in the cylinders - for better mileage, more power.
WHY don't they have a problem? They don't use candy wrappers!
(But they do use higher pump pressures.)
Next thing ya know he'll claim there's TSB'S to use duct tape to repair windshields!
But it's your choice - it's your rig.
Last edited by rrich; 06-25-2012 at 11:18 AM.
06-25-2012, 11:16 AM
#36
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Year: 2001
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Guys. Thanks for the suggestions. I'm not new to working on my own cars so I'm willin to try and look at all options if necessary. To me it seems like I is the heat soak issue as per the TSB. I don't believe the throttle sensor error is directly related but more of a fluke. Possibly from me being hard on the accelerator trying to keep the jeep running when heat soaked. This has only happened a couple times as we are not in the heat of summer yet. If I remember correctly both time I had been running the a/c.
No need to argue between everyone, I'm open to all suggestions. I will try the post cost options first and work my way through the list.
Thanks
No need to argue between everyone, I'm open to all suggestions. I will try the post cost options first and work my way through the list.
Thanks
06-25-2012, 12:10 PM
#38
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
We've had several FWD inline motor vehicles and none have had the exhaust/cats under the intake.....they've all had the intake on one side of the head and exhaust/cats on the other side. How fuel vaporized in the cylinders, or they got great mpg, or they had any kind of power with that kind of engine design (intake opposite of exhaust) is beyond me.
06-25-2012, 01:11 PM
#39
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Year: 2000
Model: Cherokee
Engine: 4.0
Carburetor Vapor Lock was caused by the liquid fuel turning to vapor - then the pump could not pump liquid into the carb. When the pump tried to create pressure, the vapor just compressed without liquid fuel flowing.
The chewing gum and candy wrapper advocates used to put clothes pins on the fuel lines.
The actual mfgr's solution was 2 things:
It was redesigned with a pressure regulator that recycled the excess fuel - causing the fuel to be constantly recycled back to the tank, keeping it cooler instead of standing in the lines where it got hot.
And the pump was relocated to the tank - that allowed the entire fuel line to be presurized instead of the engine mounted punp trying to "suck" the fuel all the way from the tank.
Some longer vehicles, like motor homes and trucks used 2 pumps, one at the tank, one midway.
Even though some don't believe in physics, it's harder for fuel to vaporize under pressure than under vacuum.
FI systems still use the recycling idea - fuel constantly being returned to the tank.
And FI systems the pump is located back by the tank. The major change is the pump pressure is much higher now.
Now think about it - sure - candy wrappers will shield the heat from the injectors - it's just insulation.
But it's a double edged sword - when you shut the engine off the heat still creeps through - especially now that air can no longer circulate to keep the injectors cool.
Now the insulation HOLDS THE HEAT IN.
Look at your house - insulation is used to keep heat out when it's hot AND to keep heat in when it's cold! (On no -- physics again!)
Using a fuel pressure gauge when it's hot and acting up will show the rail pressure is down when it's trying to pump against vapor.
But it's not always the fault of the regulator. Pressure from the pump itself can be low causing it.
I don't know why so many people would rather use candy wrappers rather than use simple test equipment and fix it right.
MANY late model vehicles have the exhaust manifold and cats right under the intake - especially on front wheel drives. It's done on purpose - the hot manifold - hot air - helps vaporize the fuel in the cylinders - for better mileage, more power.
WHY don't they have a problem? They don't use candy wrappers!
(But they do use higher pump pressures.)
Next thing ya know he'll claim there's TSB'S to use duct tape to repair windshields!
But it's your choice - it's your rig.
The chewing gum and candy wrapper advocates used to put clothes pins on the fuel lines.
The actual mfgr's solution was 2 things:
It was redesigned with a pressure regulator that recycled the excess fuel - causing the fuel to be constantly recycled back to the tank, keeping it cooler instead of standing in the lines where it got hot.
And the pump was relocated to the tank - that allowed the entire fuel line to be presurized instead of the engine mounted punp trying to "suck" the fuel all the way from the tank.
Some longer vehicles, like motor homes and trucks used 2 pumps, one at the tank, one midway.
Even though some don't believe in physics, it's harder for fuel to vaporize under pressure than under vacuum.
FI systems still use the recycling idea - fuel constantly being returned to the tank.
And FI systems the pump is located back by the tank. The major change is the pump pressure is much higher now.
Now think about it - sure - candy wrappers will shield the heat from the injectors - it's just insulation.
But it's a double edged sword - when you shut the engine off the heat still creeps through - especially now that air can no longer circulate to keep the injectors cool.
Now the insulation HOLDS THE HEAT IN.
Look at your house - insulation is used to keep heat out when it's hot AND to keep heat in when it's cold! (On no -- physics again!)
Using a fuel pressure gauge when it's hot and acting up will show the rail pressure is down when it's trying to pump against vapor.
But it's not always the fault of the regulator. Pressure from the pump itself can be low causing it.
I don't know why so many people would rather use candy wrappers rather than use simple test equipment and fix it right.
MANY late model vehicles have the exhaust manifold and cats right under the intake - especially on front wheel drives. It's done on purpose - the hot manifold - hot air - helps vaporize the fuel in the cylinders - for better mileage, more power.
WHY don't they have a problem? They don't use candy wrappers!
(But they do use higher pump pressures.)
Next thing ya know he'll claim there's TSB'S to use duct tape to repair windshields!
But it's your choice - it's your rig.
You're building a straw man argument. That is all you're doing.
The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.
This causes the fuel within the injectors to percolate, which causes erratic ignition when it's injected into the cylinders.
THIS IS THE PROBLEM. GET THAT THROUGH YOUR HEAD.
The fix? Shield the injectors from the heat source.
It's NOT the pump. It's NOT the regulator. Tell me, if that's all it is, why does the condition worsen as UNDER-HOOD TEMPERATURES RISE? If I remember correctly, the pump is way back there in the tank, sitting in nice cold gasoline.
Yet the problem only occurs with a hot engine bay... hmmmmm MUST BE PHYSICS
While you choose to insult the intelligence of everyone, we're all sitting back and laughing at the ridiculous lengths you're going to in order to save face when you MUST know you're wrong.
You know how I know you're wrong? First you say that the injectors are not the problem, then you carefully explain why insulating the injectors holds the heat in therefore doesn't fix the problem.
You contradicted yourself.
You're wrong. Get over it and do the rest of us a favor - stop posting.
Last edited by 77olds; 06-25-2012 at 01:13 PM.
06-25-2012, 01:36 PM
#40
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Another thing that might help is to change the spark plugs, whenever my 01 xj would have a rough idle after driving then sitting for a short period of time and when it threw P0303 cylinder 3 misfire, I replaced the spark plugs and it fixed the problem. You may want to try that seeing as you got misfire codes. Simple less than $20 fix. Make sure you gap them to .035
06-25-2012, 03:35 PM
#41
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Intelligence?
77 said “”””The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.””””
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the “armchair experts” seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
77 said “”””The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.””””
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the “armchair experts” seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
06-25-2012, 03:41 PM
#42
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Join Date: Apr 2011
Location: Lansing, MI
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Year: 2000
Model: Cherokee
Engine: 4.0
Intelligence?
77 said “”””The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.””””
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the “armchair experts” seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
77 said “”””The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.””””
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the “armchair experts” seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
It's not the fuel pump. IT IS NOT THE FUEL PUMP.
Here are more people who say you're wrong:
http://www.quadratecforum.com/archiv.../t-107253.html
http://www.cherokeetalk.com/forum/f6...fire-fix-9124/
http://bleepmicro.livejournal.com/57852.html
http://www.jeepforum.com/forum/f11/r...-soak-1152025/
http://www.cherokeetalk.com/forum/f2...i-think-18134/
http://midsouthjeeps.com/forum/index...-xj-heat-soak/
http://www.justanswer.com/jeep/6kzsu...g-problem.html
Chrysler Technical Service Bulletin:
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02,
DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM
YOUR FILES. THIS IS A COMPLETE REVISION AND NO ASTERISKS
HAVE BEEN USED TO HIGHLIGHT REVISIONS.
SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak
OVERVIEW:
This bulletin involves the installation of a fuel injector insulator sleeve.
MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)
NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)
SYMPTOM/CONDITION:
Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked
engine. This condition may be most noticeable when the engine is restarted following a
prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF)
or higher. This condition may be consistent with short city stop-and-go driving trips and
can be aggravated by the use of fuel with a high ethanol content. Depending upon
various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.
This condition may be caused by heat from the exhaust manifold that following engine
shut down migrates to the area around injector #3 and causes fuel vapor to form
within the injector. This in turn may cause a momentary misfire of cylinder #3 until
the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3
temperature to a point below which the fuel will not normally vaporize.
DIAGNOSIS:
1. If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following
a 10 to 20 minute hot soak, perform the Repair Procedure.
18-031-03 -2-
PARTS REQUIRED:
Qty. Part No. Description
1 56028371AA Ignition Wire Shield
REPAIR PROCEDURE:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves
about 25-30 mm (1 in.) in length.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the
injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o’clock
position (from driver’s side of vehicle).
Fig. 1 SLEEVE INSTALLATION
1 - # X INJECTOR
2 - INSTALLED SLEEVE
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
Labor Operation
No:
Description Amount
14-30-20-97 Install Heat Insulator to #3 Fuel Injector 0.2 Hrs.
-3- 18-031-03
FAILURE CODE:
AM Authorized Modification
Let me point out the important part.
"This condition may be caused by heat from the exhaust manifold that following engine
shut down migrates to the area around injector #3 and causes fuel vapor to form
within the injector. This in turn may cause a momentary misfire of cylinder #3 until
the fuel vapor is cleared of injector #3."
"This condition may be caused by heat from the exhaust manifold that following engine
shut down migrates to the area around injector #3 and causes fuel vapor to form
within the injector. This in turn may cause a momentary misfire of cylinder #3 until
the fuel vapor is cleared of injector #3."
"This condition may be caused by heat from the exhaust manifold that following engine
shut down migrates to the area around injector #3 and causes fuel vapor to form
within the injector. This in turn may cause a momentary misfire of cylinder #3 until
the fuel vapor is cleared of injector #3."
This condition may be caused by heat from the exhaust manifold that following engine
shut down migrates to the area around injector #3 and causes fuel vapor to form
within the injector. This in turn may cause a momentary misfire of cylinder #3 until
the fuel vapor is cleared of injector #3.
Well rrick, I guess since you know more that Chrysler, you'd better give them a call and tell them you've figured out the problem once and for all. I'm sure they'll be glad to hear from you.
Last edited by 77olds; 06-25-2012 at 03:56 PM.
06-25-2012, 04:41 PM
#43
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Join Date: Mar 2010
Location: Jacksonville, FL
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Year: 92
Model: Cherokee
Engine: 4.0
Originally Posted by rrich
Intelligence?
77 said """"The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.""""
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the "armchair experts" seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
77 said """"The issue at hand is this: The placement of the fuel injectors on the 97+ Jeep 4.0 inline 6 exposes them to high temperatures following shut down after a long period of driving.""""
The injectors are still in the same location as other years - how has that changed?
The newer heads may be slightly thinner there causing other types of problems, that may contribute to the problem - if so, the heat is coming up from within. How is a gum wrapper on the outside going to stop that?
Think - if the pump is weak, the entire system pressure will be weak. Even though the pump is located far away from the hot engine bay it still can be weak. Do a search on here - there are lots of cases where a weak pump caused problems - starting, running etc. I'd have to guess, but it seems ALL of them the pump was in the rear where it's cooler.
BUT - The Fuel Pressure Regulator is in the engine bay where it's hot and heat can certainly affect it. So the question arises as to which, the pump or regulator - is the culprit. A simple 3 minute pressure test will determine which.
Funny how simple testing is way beyond the ability of so many.
There's no question that it's a vapor problem - but it's not the injector's fault. It's the fact that the pressure in the rail is lower than it should be. The low pressure is not able to force liquid fuel past the vapor. Measuring pressure will show that - fast and easy!
If there was sufficient pressure behind it, all the vapor would instantly spit out as soon as the injector opened during the first crank. The 2nd time it opened (2nd cranking rotation) liquid would come out. The vapor may cause a stumble on initial starting for the first firing rotation or two, but it would clear up almost instantly.
Insulating may even exacerbate the problem by holding heat in.
I've never contradicted myself on here - but several readers have misinterpreted what I said and misquoted.
Then of course - why are there so few 4.0's with that problem?
But it's OK - if folks wish to use gum wrappers, duct tape, nail polish, grape juice, snake oil, or whatever it's fine. It only increases the value of the rest of ours that haven't been intentionally destroyed by their owners.
Some owners come on here to seek genuine advice - some of the "armchair experts" seem to enjoy posting misleading information, often costly - some even detrimental or dangerous.
Funny - during this entire thread over days NOBODY HAS TRIED TESTING THE PRESSURE. Too difficult? Too complicated? Too logical? Too obvious?
I hace never had one test out of spec for this issue.
This even has a damn TSB about this problem and fix. Why is this so difficult for you
Edit': and ill add, out of the dozen or so I've sleeved ZERO have returned with an issue
Last edited by N20jeep; 06-25-2012 at 04:51 PM.
06-25-2012, 05:17 PM
#45
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Join Date: Jan 2011
Location: Modesto, CA
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Year: 1989
Model: Cherokee
Engine: 4.0
I'm curious what would happen if you could put a higher pressure than stock fuel pump on an xj that was having this problem. Would be interesting to say the least