Idle-Timing issue
#1
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
Idle-Timing issue
Just recently put a crate 4.0 in my jeep and am having a couple of issues. From my understanding the 4.0 timing is not adjustable. It only has one setting. Well at idle I am having a sort of miss. It feels like the motor is pulsating. When I accelerate or decelerate it is fine. Going down the road it's fine. I am just wondering if I could have my timing set very close but it is still a little advanced or retarded. My vacuum connections are all good. It idles around 750. New plugs, wires, distributor, cap, rotor, all the goodies. It also takes a decent amount of time to crank over and start. Not sure if that's tied into the timing or not. I would assume so, just hoping someone has some advice for me before I go through the procedure of setting the timing. Thanks!
#3
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Joined: Feb 2014
Posts: 172
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From: north of the Rio Grande, south of the Red, east of the Pecos, west of the Sabine
Year: 1990
Model: Comanche
Engine: 4.0
Timing's not adjustable, but you can index the distributor (not convinced that's your problem, but indexing sure smooothed out my old Renix)... Cruiser's tip #13. I'm not sure if it can be done for the HO (which I assume is the crate engine you bought), but is good on the Renix.
Last edited by Bobolink; 08-28-2014 at 12:15 AM.
#4
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
You do know the books and diagrams are wrong? #1 is at 5:00 as viewed from the side, 153624 clockwise.
Like Bob mentioned, indexing the dizzy can be tricky. Cruisers tips are right on top if you click on my sig. You want the rotor tip to land ahead, almost leaving the electrode, so when the puter advances the timing the spark can still reach.
Btw, the "key trick" might work on your 94. The codes are explained in "info threads" at the top of this forum.
OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.
Like Bob mentioned, indexing the dizzy can be tricky. Cruisers tips are right on top if you click on my sig. You want the rotor tip to land ahead, almost leaving the electrode, so when the puter advances the timing the spark can still reach.
Btw, the "key trick" might work on your 94. The codes are explained in "info threads" at the top of this forum.
OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.
Last edited by DFlintstone; 08-28-2014 at 12:38 AM.
#5
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
When I dropped the rotor down it was pointed towards cylinder one wire. No clock for me I just know when the motor is top dead center on the compression stroke that's where it should be. I was just wondering can it be advanced or retarded and still runs. Just wasn't sure if it's retarded a little but still runs. Causing a choppy idle and prolonged start.
#6
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,565
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Setting Your 4.0 at #1 TDC
With #1 spark plug removed, turn the engine over clockwise using the 3/4" front crankshaft bolt. You will see the degree marks on your front cover. Mark the 0 with chalk or white-out.You will see the timing mark on the balancer. Mark it with chalk or white-out. While turning the engine over, put your finger/thumb over #1 spark plug hole. As the mark on the balancer approaches the marks on the front cover, if you are coming up on #1 TDC, pressure in the cylinder will push on your finger. If there's no pressure, you're at #6 TDC and need to crank the engine over until you see the marks coming together and you get pressure. Set the mark on the balancer to the 0 mark on the front cover.
With #1 spark plug removed, turn the engine over clockwise using the 3/4" front crankshaft bolt. You will see the degree marks on your front cover. Mark the 0 with chalk or white-out.You will see the timing mark on the balancer. Mark it with chalk or white-out. While turning the engine over, put your finger/thumb over #1 spark plug hole. As the mark on the balancer approaches the marks on the front cover, if you are coming up on #1 TDC, pressure in the cylinder will push on your finger. If there's no pressure, you're at #6 TDC and need to crank the engine over until you see the marks coming together and you get pressure. Set the mark on the balancer to the 0 mark on the front cover.
#7
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
Setting Your 4.0 at #1 TDC With #1 spark plug removed, turn the engine over clockwise using the 3/4" front crankshaft bolt. You will see the degree marks on your front cover. Mark the 0 with chalk or white-out.You will see the timing mark on the balancer. Mark it with chalk or white-out. While turning the engine over, put your finger/thumb over #1 spark plug hole. As the mark on the balancer approaches the marks on the front cover, if you are coming up on #1 TDC, pressure in the cylinder will push on your finger. If there's no pressure, you're at #6 TDC and need to crank the engine over until you see the marks coming together and you get pressure. Set the mark on the balancer to the 0 mark on the front cover.
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#8
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,565
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#9
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
#12
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Joined: Jan 2012
Posts: 3,170
Likes: 311
From: Australia
Year: 1997 (RHD)
Model: Cherokee (XJ)
Engine: 4.0 ltr
The only straight thing on an XJ, is the name straight-6.
Your issue is likely related to many of the other (pretty straight) forward causes of 'missing' at idle.
For the longer starting: try the " poor man's prime" technique so see if that speeds up your starting time.
Your issue is likely related to many of the other (pretty straight) forward causes of 'missing' at idle.
For the longer starting: try the " poor man's prime" technique so see if that speeds up your starting time.
#13
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
"that's where it should be." OK then. I thought it should be just bit ahead, a tad past, or just leaving the #1 electrode. Yea, it will still run a tooth off. Idk, just a thought.
#14
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
The whole reason for this question was because when I did set it I left it a tad before hitting cylinder one. Maybe making it a tad retarded and causing a long start/choppy idle. Also I was told when you drop the rotor back in it shifts a little. So I left it ahead so when I dropped it down it would face cylinder one. I simply just wanna know if it would still run if it was off by even a little bit. I know how to set the timing, I understand where it should be pointing.
#15
Thread Starter
CF Veteran
Joined: Feb 2012
Posts: 2,652
Likes: 2
From: Kansas
Year: 1994
Model: Cherokee
Engine: 190-hp, 4.0-liter I-6
I've tried priming the pump, doesn't start any quicker. My pressure at the rail is 40.