Holy crap!
Thread Starter
Instructor
Joined: Jul 2011
Posts: 109
Likes: 0
Holy crap!
Last week my engine's idle (1985) was rising and falling in idle and the car would stall at stop signs. I was told it could be the MAF, Burn Off or even the ECM. I disconected the MAF and the problem remained so I ordered a used Burn Off and a new ECM.
The used Burn Off came today and I installed it. Reconnected the old ECm since the new one isn't here yet and I wanted to see if the Burn Off would fix it. Within seconds of starting, smke billowed out from both sides of the engine from the bottom. I have lots of oil in it.
Now I'm afraid to start it again. Any thought?
The used Burn Off came today and I installed it. Reconnected the old ECm since the new one isn't here yet and I wanted to see if the Burn Off would fix it. Within seconds of starting, smke billowed out from both sides of the engine from the bottom. I have lots of oil in it.
Now I'm afraid to start it again. Any thought?
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I can't think of anything that could have happened but I wasn't there. If there is something wrong internally then the damage is already done so starting it again won't change much.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Noise before smoke? Oil under car now? Any obvious damage? What does the dipstick look like?
Thread Starter
Instructor
Joined: Jul 2011
Posts: 109
Likes: 0
There is no oil under the car and I had just changed the oil so it still looks like new on the dipstick.
I can't see any obvious damage.
I'm wondering if I should wait for the new ECM or not. If I do and the engine blows, I'm out another $250.00 for the part. Is there ANY chance that it could have been from the used Burn out module I bought, because that's the only different part I put on. No, eh? Could a faulty ECM be sending the wrong message to somewhere?
Oh, not that I think it matters, but both the Burn Out and the ECM are not yet mounted back to where they belong and are just hanging now.
Thread Starter
Instructor
Joined: Jul 2011
Posts: 109
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Well, end of story for this thread, I suppose. I bit the bullet and went out and started it again, knowing that it might result in a blown engine. Nothing bad happened! No noise, no smoke, nothing!!!
But it still leaves me with the original problem. After running for about 5 minutes, the engine idle rises and falls to almost a stall. I've changed the plugs, burn off module, and raised the idle just a bit by bending the metal stopper that controld the idle linkage speed. It still rises and falls and stalls at stop signs. That leaves the MAF, which I am inclined to believe is not the problem.
I had installed a while back, a performance chip and took it off since I didn't notice any change. I've ordered a new ECM in the hopes that this might fix the problem and it should be here in a day or so. IF that doens't fix it, anyone have any other ideas? I appreciate everyone's suggestion and just want to get this thing on the road before the snow flies. Thanks
But it still leaves me with the original problem. After running for about 5 minutes, the engine idle rises and falls to almost a stall. I've changed the plugs, burn off module, and raised the idle just a bit by bending the metal stopper that controld the idle linkage speed. It still rises and falls and stalls at stop signs. That leaves the MAF, which I am inclined to believe is not the problem.
I had installed a while back, a performance chip and took it off since I didn't notice any change. I've ordered a new ECM in the hopes that this might fix the problem and it should be here in a day or so. IF that doens't fix it, anyone have any other ideas? I appreciate everyone's suggestion and just want to get this thing on the road before the snow flies. Thanks
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I'd hold off on the ecm for a while, I really don't think that is the problem. First of all, quit doing things like bending tabs on the throttle body. If you don't have the fsm to get the proper idle setting procedure LEAVE IT ALONE! You have already messed up the tps setting. This sounds more to me like a vacuum leak and that is what I would be looking for.
Racer
Joined: Apr 2008
Posts: 275
Likes: 0
From: BOHEMIA NY
Agree with above and check for vacuum leaks!
My 87 jst did this and i ended up finding out the plastic brake booster had a crack in it causeing a eng vacuum leak.I disconneced the hose goin to vacuum booster and plugged it and eng idle turned perfect!
New brake booster is on the way.
Check for vacuum leaks!
My 87 jst did this and i ended up finding out the plastic brake booster had a crack in it causeing a eng vacuum leak.I disconneced the hose goin to vacuum booster and plugged it and eng idle turned perfect!
New brake booster is on the way.
Check for vacuum leaks!
Instructor
Joined: Jun 2011
Posts: 182
Likes: 0
From: Bowling Green Ky
Last week my engine's idle (1985) was rising and falling in idle and the car would stall at stop signs. I was told it could be the MAF, Burn Off or even the ECM. I disconected the MAF and the problem remained so I ordered a used Burn Off and a new ECM.
The used Burn Off came today and I installed it. Reconnected the old ECm since the new one isn't here yet and I wanted to see if the Burn Off would fix it. Within seconds of starting, smke billowed out from both sides of the engine from the bottom. I have lots of oil in it.
Now I'm afraid to start it again. Any thought?
The used Burn Off came today and I installed it. Reconnected the old ECm since the new one isn't here yet and I wanted to see if the Burn Off would fix it. Within seconds of starting, smke billowed out from both sides of the engine from the bottom. I have lots of oil in it.
Now I'm afraid to start it again. Any thought?
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Pro
Joined: Mar 2000
Posts: 658
Likes: 7
From: Perth Amboy New Jersey
I just thought of something that happened to me a few years ago. My idle was up and down, no one at the shop could figure it out until the throttle body was removed to loan to a friend to see what a 58mm would on his 406 instead of 52mm. When it was laid down on the bench, one of throttle blade was cracked, just a tap and it fell apart. Did not cause any smoking. If you can borrow another throttle body, try it.
Pro
Joined: Mar 2000
Posts: 658
Likes: 7
From: Perth Amboy New Jersey
I just thought of something that happened to me a few years ago. My idle was up and down, no one at the shop could figure it out until the throttle body was removed to loan to a friend to see what a 58mm would on his 406 instead of 52mm. When it was laid down on the bench, one of throttle blade was cracked, just a tap and it fell apart. Did not cause any smoking. If you can borrow another throttle body, try it.
Thread Starter
Instructor
Joined: Jul 2011
Posts: 109
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Great pictures. I'll pull it off in the morning and have a look. As for the idle air control valve from a later post, my idle isn't really rough, it is more flowing with a rise and fall and rise again. I appreciate the idea though. This is getting expensive replacing every possible part, but if the throttle body isn't it I suppose the air idle control is the next cheapest thing. BTW: I did find a vacuum leak, but it was to the cruise control and didn't help when repaired. Maybe I'll have cruise now. Who knows. Thanks
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
How did you check for vacuum leaks? Did you just eyeball the hoses? You also have to look at the end of the hose where it is connected such as the one between the runners on the drivers side, the ones at the throttle body, the connection at the brake booster, how tight the pcv valve is in it's grommet, etc. etc. Just checking the integrity of the hose is only half the job. You need to do a lot more searching & checking unless you enjoy throwing money at it in hopes of fixing the problem. I've got an '85 too and I argued until I was blue in the face that I had no vacuum leaks, I was wrong.
Burning Brakes
Joined: Dec 2008
Posts: 1,021
Likes: 7
From: Morgan Hill and Marina California
I had the variable idle problem (no stalling though) on my '87. It turned
out to be a broken vacuum hose at the left front. (I'd had to take it
to a test-only California smog station. He caught it, said "I'm not allowed to fix it,
but here's a pair of cutters, cut the end off straight and reinstall it."
He's got my business forever. And he's now a Gold Shield station, which
means he can do test-only AND fix stuff.)
Over on the Pathfinder board at nicoclub.com, there's a fellow who seems
really knowledgeable who suggested blowing a little propane (unlit torch)
into the air intake. If the engine revs up, you got a vacuum leak (it's
running lean, and the propane richens it up a bit so it runs a bit better
(faster).
Chuck
out to be a broken vacuum hose at the left front. (I'd had to take it
to a test-only California smog station. He caught it, said "I'm not allowed to fix it,
but here's a pair of cutters, cut the end off straight and reinstall it."
He's got my business forever. And he's now a Gold Shield station, which
means he can do test-only AND fix stuff.)
Over on the Pathfinder board at nicoclub.com, there's a fellow who seems
really knowledgeable who suggested blowing a little propane (unlit torch)
into the air intake. If the engine revs up, you got a vacuum leak (it's
running lean, and the propane richens it up a bit so it runs a bit better
(faster).
Chuck
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
A no cost possible fix is to remove the IAC and clean it. You'd be surprised how dirty they get. If the IAC is sticking, the ECM will try to compensate and cause the idle to fluctuate.
Definitely look at every hose to make sure they are connected and not cracked.
Replacing parts because they might be the cause is a very expensive way to troubleshoot. Your money would be better invested in a shop manual and scanner.
Definitely look at every hose to make sure they are connected and not cracked.
Replacing parts because they might be the cause is a very expensive way to troubleshoot. Your money would be better invested in a shop manual and scanner.
