Random stalling, got me stumped.
04-05-2016, 10:36 AM
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Random stalling, got me stumped.
hi everyone first time poster long time jeep fan. being as this is my first post, a brief intro. my name is Dan, and i like things with motors!
last year i purchased a 1990 xj 2.5 i4 2 door 5 speed that has been nothing but a nightmare. since purchasing, I've replaced the clutch (leaking internal slave), completely went through the front suspension (death wobble fixed), fixed rust and replaced some body panels (looks really clean for a 26 year old Wisconsin 4x4). I've owned this jeep for a whole year, and have only been able too log 900 miles on it because as my name suggests, it stays broke.
last winter it started to missfire randomly, and then it began too randomly just cut off. it would always restart immediately. sometimes before i could even turn the key it would pop start itself. it never showed any symptoms of "only when cold, or only when wet" some days it never missed a beat and wouldn't shut off.
to remedy the issue ive done the following;
replaced throttle position sensor and adjusted properly. this made it idle and modulate smoother.
checked ignition timing (don't remember what it was but it was in spec)
checked too see if I'm loosing spark and it appears too have spark even as the engine is dying. (its a pretty quick shut off, like its loosing ignition but the light continues too blink on all 4 wires)
cleaned every electrical connector i can find and also ran a temporary ground to the battery from the engine by the ground strap.
replaced o2 sensor (shotgunning...)
completely cleaned distributor cap and dried with heatgun
found i was loosing voltage thru the ignition switch too the ignition control module. replaced ignition switch.
verified im getting proper fuel pressure at tbi (installed fuel pressure gauge)
there are two relays, passenger side above front wheel, checked schematic and swapped relays with eachother. i believe they are fuel pump relay and "b+ latch relay" per the book
replaced spark plug wires and cleaned/gapped spark plugs.
checked iac operation
checked for, found and repaired a vacuum leak
cleaned / dried fuel injector insulator (rubber part)
removed, cleaned and checked egr valve
and I'm sure a few things I'm forgetting. what do i do next? anyone have any advice? my girlfriend is starting to think i don't know what I'm doing and I'm starting to side with her lol
last year i purchased a 1990 xj 2.5 i4 2 door 5 speed that has been nothing but a nightmare. since purchasing, I've replaced the clutch (leaking internal slave), completely went through the front suspension (death wobble fixed), fixed rust and replaced some body panels (looks really clean for a 26 year old Wisconsin 4x4). I've owned this jeep for a whole year, and have only been able too log 900 miles on it because as my name suggests, it stays broke.
last winter it started to missfire randomly, and then it began too randomly just cut off. it would always restart immediately. sometimes before i could even turn the key it would pop start itself. it never showed any symptoms of "only when cold, or only when wet" some days it never missed a beat and wouldn't shut off.
to remedy the issue ive done the following;
replaced throttle position sensor and adjusted properly. this made it idle and modulate smoother.
checked ignition timing (don't remember what it was but it was in spec)
checked too see if I'm loosing spark and it appears too have spark even as the engine is dying. (its a pretty quick shut off, like its loosing ignition but the light continues too blink on all 4 wires)
cleaned every electrical connector i can find and also ran a temporary ground to the battery from the engine by the ground strap.
replaced o2 sensor (shotgunning...)
completely cleaned distributor cap and dried with heatgun
found i was loosing voltage thru the ignition switch too the ignition control module. replaced ignition switch.
verified im getting proper fuel pressure at tbi (installed fuel pressure gauge)
there are two relays, passenger side above front wheel, checked schematic and swapped relays with eachother. i believe they are fuel pump relay and "b+ latch relay" per the book
replaced spark plug wires and cleaned/gapped spark plugs.
checked iac operation
checked for, found and repaired a vacuum leak
cleaned / dried fuel injector insulator (rubber part)
removed, cleaned and checked egr valve
and I'm sure a few things I'm forgetting. what do i do next? anyone have any advice? my girlfriend is starting to think i don't know what I'm doing and I'm starting to side with her lol
04-05-2016, 10:50 AM
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i should add the issue has only got worse, it will only run for about 10-15 seconds then just shut off. sometimes it missfires the entire time other times it runs smooth. last week i put about 60 miles on it in 1 day and had absolutely zero issues (i thought i fixed it but next day same junk)
04-05-2016, 11:45 AM
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Update, i just replaced the cap and rotor because, well, it was cheap.
Since the ignition switch replacement i verified in getting proper voltage to the ign control module.
How do i test the output labeled "tach" from the ig module? It goes too the diagnostic port. I'm beginning to think even though its getting spark, its just not at the right time. Can i test this with a multimeter somehow? Or do i have to install an actual tach? I verified timing before, but never actually as it shut off. It does continue too fire though, this I'm sure of.
Is there av way to test the flywheel pickup sensor, besides replacing it? I only have a digital meter not an analog.
I should note... I did do tests on the coolant temp sensor and it fluctuates smoothly like it should. But the numbers i was getting mean nothing because i don't know what it should be. Its not jumping all over the place, though.
Since the ignition switch replacement i verified in getting proper voltage to the ign control module.
How do i test the output labeled "tach" from the ig module? It goes too the diagnostic port. I'm beginning to think even though its getting spark, its just not at the right time. Can i test this with a multimeter somehow? Or do i have to install an actual tach? I verified timing before, but never actually as it shut off. It does continue too fire though, this I'm sure of.
Is there av way to test the flywheel pickup sensor, besides replacing it? I only have a digital meter not an analog.
I should note... I did do tests on the coolant temp sensor and it fluctuates smoothly like it should. But the numbers i was getting mean nothing because i don't know what it should be. Its not jumping all over the place, though.
04-05-2016, 02:20 PM
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Year: 1994
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You've done so much already I can only think of one thing to try.
Next time it's misfiring pull each plug wire one at a time then replace it. The one wire that doesn't make it worse is the cylinder to check first.
Next time it's misfiring pull each plug wire one at a time then replace it. The one wire that doesn't make it worse is the cylinder to check first.
04-05-2016, 06:05 PM
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Hi,
Good thought RIVER, I'll break out the fuse puller and give that a try and see what it reveals. Safety first! Always ground your forehead too lol (kidding don't do this)
I hunted around but i fear i lost my tachometer. Was going to hook it up and see what the ignition control module thinks is happening. Arrr.
Good thought RIVER, I'll break out the fuse puller and give that a try and see what it reveals. Safety first! Always ground your forehead too lol (kidding don't do this)
I hunted around but i fear i lost my tachometer. Was going to hook it up and see what the ignition control module thinks is happening. Arrr.
04-05-2016, 06:06 PM
#6
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When science fails... pray...
And... start "wiggling."
My oak-tree-mechanic advice is to put on a rubber Mechanix type glove. Then cover with a cotton glove. Start the Jeep in park. Open the hood. Start wiggling wires and connections till it stalls. Beware of moving parts and hot stuff.
Sometimes a wire will come loose from its clip or a wire will short. Just enough to cause issues while vibrating and bouncing down the road, but run fine while sitting. The one I couldn't track down, after doing pretty much everything you did was the thick black wiring harness across the firewall above the engine. The wires inside had worn thru their casing and we're touching. Only occasionally.
My other issue was the connection of a wire at the coil being corroded and loose. Wiggled it. It died. Fixed it. Fixed the Jeep.
Good luck. Try it. Cheap and nothing to lose.
And... start "wiggling."
My oak-tree-mechanic advice is to put on a rubber Mechanix type glove. Then cover with a cotton glove. Start the Jeep in park. Open the hood. Start wiggling wires and connections till it stalls. Beware of moving parts and hot stuff.
Sometimes a wire will come loose from its clip or a wire will short. Just enough to cause issues while vibrating and bouncing down the road, but run fine while sitting. The one I couldn't track down, after doing pretty much everything you did was the thick black wiring harness across the firewall above the engine. The wires inside had worn thru their casing and we're touching. Only occasionally.
My other issue was the connection of a wire at the coil being corroded and loose. Wiggled it. It died. Fixed it. Fixed the Jeep.
Good luck. Try it. Cheap and nothing to lose.
04-06-2016, 08:06 AM
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
When science fails... pray...
And... start "wiggling."
My oak-tree-mechanic advice is to put on a rubber Mechanix type glove. Then cover with a cotton glove. Start the Jeep in park. Open the hood. Start wiggling wires and connections till it stalls. Beware of moving parts and hot stuff.
Sometimes a wire will come loose from its clip or a wire will short. Just enough to cause issues while vibrating and bouncing down the road, but run fine while sitting. The one I couldn't track down, after doing pretty much everything you did was the thick black wiring harness across the firewall above the engine. The wires inside had worn thru their casing and we're touching. Only occasionally.
My other issue was the connection of a wire at the coil being corroded and loose. Wiggled it. It died. Fixed it. Fixed the Jeep.
Good luck. Try it. Cheap and nothing to lose.
And... start "wiggling."
My oak-tree-mechanic advice is to put on a rubber Mechanix type glove. Then cover with a cotton glove. Start the Jeep in park. Open the hood. Start wiggling wires and connections till it stalls. Beware of moving parts and hot stuff.
Sometimes a wire will come loose from its clip or a wire will short. Just enough to cause issues while vibrating and bouncing down the road, but run fine while sitting. The one I couldn't track down, after doing pretty much everything you did was the thick black wiring harness across the firewall above the engine. The wires inside had worn thru their casing and we're touching. Only occasionally.
My other issue was the connection of a wire at the coil being corroded and loose. Wiggled it. It died. Fixed it. Fixed the Jeep.
Good luck. Try it. Cheap and nothing to lose.
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04-06-2016, 03:39 PM
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Ive done a whole lot of wiggling! Think I'm Going to fire this bad boy up at night and see if i see anything short out. I'll pay extra attention to the wires you suggested. Ive done so much wrenching on it it's possible i nicked a wire myself.
Thanks guys, won't be able to work on it until this weekend. I'll install a tach, double check my computer ground, figure out a way to tap the injector to view what's happening with the grounding circuit thru the cpu, and get my jiggle on again lol
Thanks guys, won't be able to work on it until this weekend. I'll install a tach, double check my computer ground, figure out a way to tap the injector to view what's happening with the grounding circuit thru the cpu, and get my jiggle on again lol
05-03-2016, 09:38 AM
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update,
jeep is still broken.
injector is shutting off. its for sure a fuel issue.
how can i test to see if the injector is bad or its just not getting ground? its definitely always getting power. verified. sometimes i can actually hear the injector firing... click click click click then nothing and it stalls.
the injector is over 100$ rather not just shotgun one in there. anyone got any ideas how too test furthrr?
I've ran new ground wires to the ground cluster by the oil dipstick an jiggled every wire imaginable. I've also unplugged inspected and replugged the computer connections
jeep is still broken.
injector is shutting off. its for sure a fuel issue.
how can i test to see if the injector is bad or its just not getting ground? its definitely always getting power. verified. sometimes i can actually hear the injector firing... click click click click then nothing and it stalls.
the injector is over 100$ rather not just shotgun one in there. anyone got any ideas how too test furthrr?
I've ran new ground wires to the ground cluster by the oil dipstick an jiggled every wire imaginable. I've also unplugged inspected and replugged the computer connections
05-03-2016, 09:41 AM
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I'm leaning toward roasted computer, due too it was getting crap vdc from my ignition switch but really would like ideas how too test further. I'm at a loss. my meter isnt quick enough too see the ground the computer supplies.
05-03-2016, 03:42 PM
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Is the misfire constant on the same cylinder (meaning it is not "random" and occurring on multiple cylinders)?
Since its definitely fuel related, you could try just switching injectors around to see if the issue follows the "bad" fuel injector.
If it does not than it could be wiring, it could be PCM related (though the PCM is pretty hearty and I have yet to see on fail personally). You can check the wiring with a "noid" light that you can rent at the auto-parts store to see if the injector is getting a proper signal to fire.
When you switch the ignition to "run", the injectors get constant power. The pcm sends a ground pulse to the injectors to cycle them, so you should have 12V constant at the plug which *should* tell you if the wiring is good or bad.
Since its definitely fuel related, you could try just switching injectors around to see if the issue follows the "bad" fuel injector.
If it does not than it could be wiring, it could be PCM related (though the PCM is pretty hearty and I have yet to see on fail personally). You can check the wiring with a "noid" light that you can rent at the auto-parts store to see if the injector is getting a proper signal to fire.
When you switch the ignition to "run", the injectors get constant power. The pcm sends a ground pulse to the injectors to cycle them, so you should have 12V constant at the plug which *should* tell you if the wiring is good or bad.
06-05-2016, 03:43 PM
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Is the misfire constant on the same cylinder (meaning it is not "random" and occurring on multiple cylinders)?
Since its definitely fuel related, you could try just switching injectors around to see if the issue follows the "bad" fuel injector.
If it does not than it could be wiring, it could be PCM related (though the PCM is pretty hearty and I have yet to see on fail personally). You can check the wiring with a "noid" light that you can rent at the auto-parts store to see if the injector is getting a proper signal to fire.
When you switch the ignition to "run", the injectors get constant power. The pcm sends a ground pulse to the injectors to cycle them, so you should have 12V constant at the plug which *should* tell you if the wiring is good or bad.
Since its definitely fuel related, you could try just switching injectors around to see if the issue follows the "bad" fuel injector.
If it does not than it could be wiring, it could be PCM related (though the PCM is pretty hearty and I have yet to see on fail personally). You can check the wiring with a "noid" light that you can rent at the auto-parts store to see if the injector is getting a proper signal to fire.
When you switch the ignition to "run", the injectors get constant power. The pcm sends a ground pulse to the injectors to cycle them, so you should have 12V constant at the plug which *should* tell you if the wiring is good or bad.
the missfire is not, as far as i can tell, even spark related whatsoever. I'm getting solid spark thru all wires, replaced the plugs... i didn't do a compression test, but it wouldn't ever run right if it was a bad ring or something mechanical. it runs FANTASTIC when it wants too.
ide like too add, i was NOT getting 12vdc until i replaced ignition switch. i don't have the schematic handy, but i was also losing vdc at the ignition module. now i seem to be getting very solid voltage, but I'm questioning the computer because of varying voltage it was getting. finding a replacement locally seems terribly difficult
i bought a new fuel injector just now. getting it tomorrow I'll install it Wednesday. i can hear it loudly click sometimes and it seems abnormally loud at times. so loud i can actually hear it shut off...
I'm so frustrated. If this doesn't fix it im hitting it with a sledgehammer and calling the scrap guy.
Last edited by staybroke; 06-05-2016 at 03:55 PM.
06-05-2016, 04:07 PM
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My standard answer... when all else fails, wiggle wires... harnesses, connections. After every scientific way of checking, put on some mechanix or leather gloves, start it up, and grab harnesses and shake em. The wires inside of the protector across my firewall wore through. I replaced EVERYTHING at much cost. Then had someone crank it while I wiggled and it started up. Get it started, and wiggle. Cheap and won't hurt. Watch the hot and moving parts of course. Good luck.