Dies at a Stop Light
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Dies at a Stop Light
My '92, 351W/E4OD, will sometimes die when I'm at a stop light. It usually idles very smoothly but the engine will occasionally miss, at idle & while driving. I recently had to change out the intake manifold (did something stupid to the thermostat housing bolts). This idle problem started after that change. The fuel pump & filter are new so I'm thinking something in the EGR/TPS/IAC neighborhood. Any bright ideas? I didn't replace the EGR gasket during reassembly. Would that be enough to cause the miss? Also, the truck started that BS where it would idle rough on cold mornings after the manifold change too.
Thanks in advance.
Thanks in advance.
Last edited by 92EBnTX; Nov 16, 2004 at 01:06 PM. Reason: left out information
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Cut, pinched, broken plug wire? Maybe chaffed and will only occasionly arc. Maybe one of the wires not seated on the plug or the cap and will occasionaly arc internally. Id just think that kind of a miss would be more pronounced under a load than at idle.
You could also have a vaccum leak somewhere. The iac would compensate closed in an attempt to controll the idle but the end result would be a rather rough idle if the leak wasnt large enough to make the idle scream.
Um, any possible way when the intake manifold was off the egr got wired into the wrong vaccum circuit? For example the solenoid bypassed and straight vaccum to the egr valve. That would make the egr open at high idle vaccum and cause a pretty nasty vaccum leak which would result in a rough idle/miss symptom. Only problem with that theory is that it would pretty much have that leak at idle at all times and i wouldnt think you would ever see it run smooth.
Some thoughts anyway, sorry i couldnt help out more.
You could also have a vaccum leak somewhere. The iac would compensate closed in an attempt to controll the idle but the end result would be a rather rough idle if the leak wasnt large enough to make the idle scream.
Um, any possible way when the intake manifold was off the egr got wired into the wrong vaccum circuit? For example the solenoid bypassed and straight vaccum to the egr valve. That would make the egr open at high idle vaccum and cause a pretty nasty vaccum leak which would result in a rough idle/miss symptom. Only problem with that theory is that it would pretty much have that leak at idle at all times and i wouldnt think you would ever see it run smooth.
Some thoughts anyway, sorry i couldnt help out more.
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Thanks for the input. I labeled everything during disassembly so that everything got put back together correctly. The problem is intermittent, the worst kind of problem. I haven't had the codes pulled so that would probably be a good place to start. I suspect the EGR because I was rather careless in handling it. By reassembly time, I was more than frustrated with the whole ordeal. I'll try cleaning teh EGR valve and replacing the gasket I left out. That may help.
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From: Fort Worth
Does it go away when ever you step on the gas but come back as soon as you let off? And is just completely random about when and for how long it lasts? If so its the same thing thats happening to my Truck, its a '93 with a 351/E4OD. It started after I had the engine rebuilt and I still havent found the reason why and of course, it never does it when I take it to the shop. What I do is just keep the accelerator pushed in enough to keep it at at least 1000 rpms and end up driving with 2 feet till it goes away on its own, which it seems to do after about 10-15 minutes(Ya, I know, not real smart, but I have to get to school and to work somehow). Its also not doing it nearly as often now as it used to so thats good. Sorry I can't help you with your truck, but if you figure it out, I'd love to know what you did.
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--92, i must have missed that part. The egr gasket is not there? Definitly start there. With no gasket you would most definitly have a vaccum leak between the manifold and egr valve. That would indeed cause your rough idle.
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FBB--- the idle is generally smooth. It just dies at a stop light when I have my foot on the brake. It never dies in PARK. It does miss in PARK and while driving though. There's no discernable pattern to the miss (like having a dead cylinder).
Joboo--- I hear what sounds like an exhaust leak on the EGR side of the motor so the missing gasket may be the problem. I'll keep y'all posted.
Thanks again for the input.
Joboo--- I hear what sounds like an exhaust leak on the EGR side of the motor so the missing gasket may be the problem. I'll keep y'all posted.
Thanks again for the input.
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From: Gateway to the West
Pull the computer codes, if any. This will at least give you something to start with. Any condition that is enough of a problem to kill the engine will trigger a code in the computer. This will also avoid endless wild goose chases searching for the root of the problem.
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I replaced the EGR gasket today. We'll see if that helps. I may end up replacing the ECT sensor too. That may be the cause of the rough idle on cold mornings. I'll keep y'all posted.
PS... went to the Zone today to get my codes pulled and no one seemed to know what I was talking about. I'll have to try another place.
PS... went to the Zone today to get my codes pulled and no one seemed to know what I was talking about. I'll have to try another place.
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It hasn't died at a stop light since I replaced the EGR gasket. That's not to say that it won't though. It also doesn't seem to have that intermittent lope like it had before. I'll just keep an eye on it for now. The IAC is on the list of projects though. Thanks for everyone's help.
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OK... after an exhaustive search, I cannot find a simple set of instructions for cleaning the IAC. Can anyone help me out here? I have the TB cleaner, I just need some help with the instructions. Thanks.
Lead Driver
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From: Wheatland, Mo
Remove the 4 bolts holding on the plastic intake cover. It has the engine size imprinted on it....Locate the IAC on the top back of the intake manifold. 2 bolts hold it on...3 or 4 wire harness - unplug. I used brake cleaner....spayed out the inside till all the black crap drained out. Then blew dry with a can of air. Air hose would work faster. Re-install, plug in harness....start truck and see if it helps.
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From: Marshall, TX
if i ever get my 86/89 302 running, these all sound like things I need to know about. Whats the IAC? and next, theres a missing piece between the two ends of my EGR pipe. the pipe coming off the valve goes under the intake, then theres a 1" gap, then the pipe that goes into the motor. will this create a problem? is there a way to clean the EGR or do I need to actually replace it? thanks guys.