Engine "stutter" problem
#31
The ticking purge valve just means it is working to pull a vacuum on the fuel evap purge system to check for leaks in a self test mode.
If a large leak is detected anywhere in the system it will set the po455 code.
It could be a leak anywhere in the fuel vapor containment system......OR, this may sound weird, but you may have accidently trashed your charcoal canister by overfilling the fuel tank at one point by topping off too much.
Most fuel filler necks have a vacuum line that goes into the side of the fuel filler neck that is part of the fuel evap purge system under vacuum test.
Check for any vacuum lines at the filler neck, and try to remember if you ever overfilled your tank prior to that check engine light coming on.
If you over saturate the filler neck there is a chance liquid fuel can go into the vacuum line and trash that charcoal canister which will result in a permanent check engine light/po455 code that will only go away once the charcoal canister is replaced.
I am not positive your Jeep has this line in the filler neck but i can tell you that I have seen this before on numerous other model vehicles.
Check all rubber lines and seals to the purge valve and the charcoal canister, intake area or anywhere else those lines can go.
I have also seen charcoal canister shut off valves leak due to a weak rubber internal diaphragm.
The dealership can turn you charcoal canister shut off valve on/off using diagnostic tools in conjunction with a vacuum gauge to see if the evap purge system is holding a specific amount of vacuum within a certain time frame to determine if you have a leak.
Sometime the shut off valve seal will trick you and not act up, but in most cases if it's bad, it will not hold vacuum.
If it holds vacuum well, I would suspect a contaminated charcoal canister with raw fuel.
If a large leak is detected anywhere in the system it will set the po455 code.
It could be a leak anywhere in the fuel vapor containment system......OR, this may sound weird, but you may have accidently trashed your charcoal canister by overfilling the fuel tank at one point by topping off too much.
Most fuel filler necks have a vacuum line that goes into the side of the fuel filler neck that is part of the fuel evap purge system under vacuum test.
Check for any vacuum lines at the filler neck, and try to remember if you ever overfilled your tank prior to that check engine light coming on.
If you over saturate the filler neck there is a chance liquid fuel can go into the vacuum line and trash that charcoal canister which will result in a permanent check engine light/po455 code that will only go away once the charcoal canister is replaced.
I am not positive your Jeep has this line in the filler neck but i can tell you that I have seen this before on numerous other model vehicles.
Check all rubber lines and seals to the purge valve and the charcoal canister, intake area or anywhere else those lines can go.
I have also seen charcoal canister shut off valves leak due to a weak rubber internal diaphragm.
The dealership can turn you charcoal canister shut off valve on/off using diagnostic tools in conjunction with a vacuum gauge to see if the evap purge system is holding a specific amount of vacuum within a certain time frame to determine if you have a leak.
Sometime the shut off valve seal will trick you and not act up, but in most cases if it's bad, it will not hold vacuum.
If it holds vacuum well, I would suspect a contaminated charcoal canister with raw fuel.
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#32
Senior Member
Joined: Jun 2009
Posts: 670
Likes: 0
From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
My 99 XJ has just under 100k on it. In the last couple weeks I have been experiencing occasional engine "stutters," or at least that is what it feels like. It only seems to happen when I am casually on the pedal cruising at a consistent speed (and even then, it is seldom, but it has been happening more frequently lately). It has happened on both level roads and inclines but never while going down hill. It has happened on backroads while cruising around 45-50mph and on the highway in the 60-70mph range. When it happens, it feels like the engine just missed a beat for a split second, kinda like the feeling of hitting a quick small bump. It runs fine otherwise although my wife recently had trouble starting it (it took her 3 tries to get it started at a convenience store last week but I drive it daily and have never had a problem starting it) and it kind of feels a bit low on power lately. Other than that, I have the P0455 code which I have had for a long time but don't know if that is related. My gut is leaning towards a fuel system issue but I'm not sure. Any insight or suggestions would be greatly appreciated. Thanks in advance!!
#33
Junior Member
Joined: Mar 2015
Posts: 41
Likes: 0
From: Eastern CT
Year: 98
Model: Cherokee
Engine: 2.5
I wanted to re-up this thread, because I'm having a very similar problem and I'm quite stumped. Engine stutters intermittently, usually when I'm on the highway and it's under heavy load (75 MPH+). I have no tachometer in my jeep, which is a 98, 2.5l, and stickshift.
As far as the trouble shooting, I've put in new plugs, wires, cap, rotor, battery, and clutch in the jeep within the last year, since I bought it. I've tested the fuel pressure, which reads a steady 45 while idling and also while neutral and the foot down on the gas.
I've never had a problem starting it, and it doesn't idle rough, but this engine stuttering comes and goes and it seems like it's getting worse lately. I figured it either has to be a fuel or spark issue, but both systems seem to test out perfectly fine.
The trashed charcoal canister and the evap canister sound like useful troubleshooting ideas. I'll check them out tomorrow morning, and see if I can get anywhere with that.
As far as the trouble shooting, I've put in new plugs, wires, cap, rotor, battery, and clutch in the jeep within the last year, since I bought it. I've tested the fuel pressure, which reads a steady 45 while idling and also while neutral and the foot down on the gas.
I've never had a problem starting it, and it doesn't idle rough, but this engine stuttering comes and goes and it seems like it's getting worse lately. I figured it either has to be a fuel or spark issue, but both systems seem to test out perfectly fine.
The trashed charcoal canister and the evap canister sound like useful troubleshooting ideas. I'll check them out tomorrow morning, and see if I can get anywhere with that.
#34
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Have you changed/back-flushed the fuel filter? It might maintain pressure under low flow, but crap when asked for high flow. Regular maintenance anyway, maybe take that question out of the equation.
#35
Junior Member
Joined: Mar 2015
Posts: 41
Likes: 0
From: Eastern CT
Year: 98
Model: Cherokee
Engine: 2.5
Upon investigating the other day, I decided to take out and check my ignition coil. It was pretty corroded with rust. I tried to look up some tests for it, but I couldnt find any information on it in my Haynes manual or online anywhere. I decided i should replace it regardless, and I took it on a spirited drive. The jeep only stuttered once, and it wasn't even that bad. I'll keep watch over it the next few days and update the news on here
#38
Junior Member
Joined: Mar 2015
Posts: 41
Likes: 0
From: Eastern CT
Year: 98
Model: Cherokee
Engine: 2.5
Ignition coils been changed out, and I've been driving it for a few days. The stutter is still happening. Now I'm trying to think of what else it could be.
Couldn't be the clutch, its only 8 months old.
The 02 sensors upstream and downstream were replaced a few months ago to clear a code for emissions.
Could be the fuel filter, but on a 98 its not a serviceable part, since its built in the pump inside the tank.
I don't think its a fuel issue, as those are more gradual declines in power over periods of time, where this is just a really sharp jab, like i just gave the brakes a quick pump, and then its done.
It's usually at higher loads, but I think that's just because the engine RPM is higher, giving it more chances to stutter. Any other ideas?
Couldn't be the clutch, its only 8 months old.
The 02 sensors upstream and downstream were replaced a few months ago to clear a code for emissions.
Could be the fuel filter, but on a 98 its not a serviceable part, since its built in the pump inside the tank.
I don't think its a fuel issue, as those are more gradual declines in power over periods of time, where this is just a really sharp jab, like i just gave the brakes a quick pump, and then its done.
It's usually at higher loads, but I think that's just because the engine RPM is higher, giving it more chances to stutter. Any other ideas?
#40
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
For one, higher compression under load makes the voltage needed for the spark to jump the gap go up.
Last edited by DFlintstone; 08-27-2016 at 03:02 PM.
#41
Junior Member
Joined: Mar 2015
Posts: 41
Likes: 0
From: Eastern CT
Year: 98
Model: Cherokee
Engine: 2.5
No point starting a new thread when there's a similar one already. But nevertheless, the problem still isn't solved. it's still doing it, so no celebrations yet.
as for the plugs and wires, they're only about 6 months old. same goes with cap and rotor.
as for the plugs and wires, they're only about 6 months old. same goes with cap and rotor.
#42
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
#43
My girlfriends jeep is doing the same thing stutters on backboard at 40-45 and on the highway over 60 we replaced cap and rotor plugs cool wire both fuel filters and problem persists hers is an 86 and you can hear a vacuum leak but that has been there since she bought it a few months ago I also pulled the cat off to see if that's the problem and it didn't seem to help I'm leaning towards maybe a carb issue or something but not sure anyone have any clue on these older jeep cherokees
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