Finally! It all makes sense now!
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Problem Still Not Fixed!
Update on post #13. Problem STILL not fixed! ****!
This morning, same old thing with idle. Wouldn't idle when I first started it up. Unplugged est wire, idled great. I also began to diagnose a recent knocking sound at low rpms from the rear of the engine. The pass. side bolt that holds the flywheel to the torque converter has backed out, no cracks in flywheel.
Take a second to chew that over. (Jeopardy music plays)...
If you're like me, a light bulb should appear over your head. The knock sensor is close to the flywheel (somewhat). It's picking up the banging sound from the flywheel and retarding the timing! The sound is only noticeable while at low rpms, which is where the timing problem is.
This is still a theory I guess, haven't actually confirmed this being the case, but it sure does make sense to me. Thoughts?
This morning, same old thing with idle. Wouldn't idle when I first started it up. Unplugged est wire, idled great. I also began to diagnose a recent knocking sound at low rpms from the rear of the engine. The pass. side bolt that holds the flywheel to the torque converter has backed out, no cracks in flywheel.
Take a second to chew that over. (Jeopardy music plays)...
If you're like me, a light bulb should appear over your head. The knock sensor is close to the flywheel (somewhat). It's picking up the banging sound from the flywheel and retarding the timing! The sound is only noticeable while at low rpms, which is where the timing problem is.
This is still a theory I guess, haven't actually confirmed this being the case, but it sure does make sense to me. Thoughts?
Last edited by cwyates4; Jul 29, 2008 at 05:10 PM.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Yeah, he replaced the belt tensioner, set timing, adjusted my throttle cable to where I can get WOT, and fixed the valve covers.
I'll go get that $40 he ripped from me.
^ Sorry for the sarcasm. He's a personal friend, I'd never try to get money back from him. When I first got the car, the only problem it had was the IAC, the install of that was free. Injector install was $30. You see my point.
My theory makes sense or no? Now that I think of it, I seemed to have a slight knock start from down there about the same time the idle issue started. Seemed to get progressively worse over time, bolt backing out further...?
I'll go get that $40 he ripped from me.
^ Sorry for the sarcasm. He's a personal friend, I'd never try to get money back from him. When I first got the car, the only problem it had was the IAC, the install of that was free. Injector install was $30. You see my point.
My theory makes sense or no? Now that I think of it, I seemed to have a slight knock start from down there about the same time the idle issue started. Seemed to get progressively worse over time, bolt backing out further...?
Last edited by cwyates4; Jul 28, 2008 at 05:12 PM.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Loose bolt hasn't been fixed, should have clarified that. Its at the shop now, and I'll be out of town tomorrow-Friday, so I won't know for sure until the weekend, I feel good about it though.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Talked to the mechanic. He said he'll get the car on the lift tomorrow and get that bolt back in, if it isn't broke. It's real hard to tell from the position I was looking from. If the bolt being loose wasn't the problem, he's going to check the timing and see where its at, should be a 10 btdc though. We might try pulling it down and see what happens if things still aren't correct.
How sensative are knock sensors? Should it pick up the sound, even though its not overly loud? (if you get on the ground by the front tire, it sounds like an engine knock) Maybe my knock sensor is old and getting more sensative too? Its only a $30 part, might replace that at the same time.
How sensative are knock sensors? Should it pick up the sound, even though its not overly loud? (if you get on the ground by the front tire, it sounds like an engine knock) Maybe my knock sensor is old and getting more sensative too? Its only a $30 part, might replace that at the same time.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Talked to the mechanic. He said he'll get the car on the lift tomorrow and get that bolt back in, if it isn't broke. It's real hard to tell from the position I was looking from. If the bolt being loose wasn't the problem, he's going to check the timing and see where its at, should be a 10 btdc though. We might try pulling it down and see what happens if things still aren't correct.
How sensative are knock sensors? Should it pick up the sound, even though its not overly loud? (if you get on the ground by the front tire, it sounds like an engine knock) The noise that travels through the metal of the block has an better transmission medium versus air. The sensor very possibly could be hearing a very substantial noise. Maybe my knock sensor is old and getting more sensative too? Its only a $30 part, might replace that at the same time.
How sensative are knock sensors? Should it pick up the sound, even though its not overly loud? (if you get on the ground by the front tire, it sounds like an engine knock) The noise that travels through the metal of the block has an better transmission medium versus air. The sensor very possibly could be hearing a very substantial noise. Maybe my knock sensor is old and getting more sensative too? Its only a $30 part, might replace that at the same time.
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Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
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From: Jasper Texas
I've been fighting this problem for a while now, had a big thread on it a couple of weeks ago. Car is an '85, its in my profile. I find it easier to just disconnect the timing wire, but unplugging the esc module (which is brand new!) or the knock sensor should, in theory, have the same effect as unplugging the timing wire. If unplugging the esc with the timing wire plugged in does not correct the idle, than the problem lies somewhere after that circuit. Is that right? :o
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Is that right?
BTW, Gorden Killebrew recommended to me an upgrade from the OEM ESC module, details on my site.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Or, it could be overly advancing too. I've not got a solid answer on how a car runs with timing too retarded, and timing too advanced.
Mine won't idle when its cold with the wire plugged in, once I can get it to run, its still very rough, occasional pops out of the exhaust when decelerating. Bucking and hunting at lights, etc.
I thought those symptoms indicated too much advance, but the guy I took the car to yesterday says it sounds more like its retarding.
When cold, if I unplug the wire, everything is fine. That, to me, seems to rule out a vacuum leak, fuel problems, internal problems, or any other sensors besides the ones in the esc circuit.
Did something stupid yesterday! Took it to the mechanic because I couldn't reach the loose flywheel bolt, the starter was in the way.
I could have just cranked it real quick and got it to stop somewhere else, instead of driving 8 miles to the shop.
Mine won't idle when its cold with the wire plugged in, once I can get it to run, its still very rough, occasional pops out of the exhaust when decelerating. Bucking and hunting at lights, etc.
I thought those symptoms indicated too much advance, but the guy I took the car to yesterday says it sounds more like its retarding.
When cold, if I unplug the wire, everything is fine. That, to me, seems to rule out a vacuum leak, fuel problems, internal problems, or any other sensors besides the ones in the esc circuit.
Did something stupid yesterday! Took it to the mechanic because I couldn't reach the loose flywheel bolt, the starter was in the way.
I could have just cranked it real quick and got it to stop somewhere else, instead of driving 8 miles to the shop.
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
That updated ESC module makes a difference. I followed 65Z01's advice for my '85. Also, since you have an '85, you should be able to drive the car with the knock sensor unplugged, your ECM isn't smart enough to monitor the sensor directly. I used that process to identify some problems I had a while back, and was able to fix them. I believe it works on '84's too, because CFI-EFI runs with his knock sensor permanently disconnected. Anyway, just my experience, take that for what its worth.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
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From: Jasper Texas
Well, just got back from the mechanics. My tahoe's brakes are growling, so its new pad time.
He had the vette on when I got there. Flywheel bolt is back in. Lowered the car and cranked it, didn't die, but it wasn't completly cold (coolant was 130). Was a little rough, not bad though. Turned the car off and unplugged the est, ran much better.
Looks like that wasn't the issue. He said it sounds like a rocker is out of adjustment, and I'm having him put new valve covers on, so he's going to check that out. He said if no one has adjusted the valves for a couple of years, its probably that time, the solid roller cam will cause them to get out of adjustment.
So, he's got it and he's keeping it. He wants to check vacuum, check timing, check the rockers, etc. Fine with me.
As far as I concerned, he can keep it as long as he wants, I'm fed up with it.
He had the vette on when I got there. Flywheel bolt is back in. Lowered the car and cranked it, didn't die, but it wasn't completly cold (coolant was 130). Was a little rough, not bad though. Turned the car off and unplugged the est, ran much better.
Looks like that wasn't the issue. He said it sounds like a rocker is out of adjustment, and I'm having him put new valve covers on, so he's going to check that out. He said if no one has adjusted the valves for a couple of years, its probably that time, the solid roller cam will cause them to get out of adjustment.
So, he's got it and he's keeping it. He wants to check vacuum, check timing, check the rockers, etc. Fine with me.
As far as I concerned, he can keep it as long as he wants, I'm fed up with it.
Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
Bring it home, and do a static timing.
That's all you need to do right now. It's time to poop or get off the pot. Passin' gas just stinks stuff up, and makes ONE PERSON feel good, and that sound like what's gettin' done elsewhere.
That's all you need to do right now. It's time to poop or get off the pot. Passin' gas just stinks stuff up, and makes ONE PERSON feel good, and that sound like what's gettin' done elsewhere.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
NO joke. I live in the middle of nowhere. My towns population is 8000, no town for 60 miles in any direction is bigger than 3K. Nobody around here knows anything about efi setups.
The guy that has it now though has always done all the work on the suburban, tahoe, and van (obd 1). He always got them right and never has thrown parts at something, so I'm going to let him keep it while I'm out of town the rest of the week.
If it still ain't right then, I'll bring it home and work on it while I part out my trans am. If I can't get it right in a few weeks, it might just find its way on a thread titled "parting out highly modded 85."
I do have the diacom setup coming in the mail for the laptop, maybe that would show me something.
The guy that has it now though has always done all the work on the suburban, tahoe, and van (obd 1). He always got them right and never has thrown parts at something, so I'm going to let him keep it while I'm out of town the rest of the week.
If it still ain't right then, I'll bring it home and work on it while I part out my trans am. If I can't get it right in a few weeks, it might just find its way on a thread titled "parting out highly modded 85."
I do have the diacom setup coming in the mail for the laptop, maybe that would show me something.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Well, got the tahoe back from the shop, now I can stop!
We talked again about the issue. He told me he moved it earlier and it was cool (maybe not fully cooled off) and it seemed much better than before he tightened the flywheel bolt. He said it still has some roughness, and is improved with the wire disconnected, but it never tried to die on him.
I brought him some new valve covers and gaskets, while he does those, he's going to check out the rockers and make sure they are all within spec.
Who knows, maybe he'll figure it out. I really want to get my laptop hooked up to it and see what all the sensors are doing, especially the knock sensor. Will have to wait till the weekend to see!
We talked again about the issue. He told me he moved it earlier and it was cool (maybe not fully cooled off) and it seemed much better than before he tightened the flywheel bolt. He said it still has some roughness, and is improved with the wire disconnected, but it never tried to die on him.
I brought him some new valve covers and gaskets, while he does those, he's going to check out the rockers and make sure they are all within spec.
Who knows, maybe he'll figure it out. I really want to get my laptop hooked up to it and see what all the sensors are doing, especially the knock sensor. Will have to wait till the weekend to see!
