Idle problem-SOLVED
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Idle problem-SOLVED
Still bad when cold! Have an idea-post #8!
Got the car back from the mechanic today. Cranked it up, ran beautifully. Held a nice steady 800 rpm idle at every light I came up to, averaged 18.5 mpg over the recent sub 16 mpg. When I got it, it wasn't completely cold, so I won't know 100% until the morning, but...it feels great now, really smooth ride. I'll update again tomorrow after running it completely cooled down.
What was the problem? As many suggested, it was the timing. "WAY advanced" were the words of my mechanic. He pulled it down to 6 degrees initially, but said it like 10 better, so thats were it sits now.
I never thought the timing could have been so off, nobody has touched the distributor since I puchased the car. Guess I was wrong!
Thanks for all the help guys! "I told you so's" are welcome. :o
Got the car back from the mechanic today. Cranked it up, ran beautifully. Held a nice steady 800 rpm idle at every light I came up to, averaged 18.5 mpg over the recent sub 16 mpg. When I got it, it wasn't completely cold, so I won't know 100% until the morning, but...it feels great now, really smooth ride. I'll update again tomorrow after running it completely cooled down.
What was the problem? As many suggested, it was the timing. "WAY advanced" were the words of my mechanic. He pulled it down to 6 degrees initially, but said it like 10 better, so thats were it sits now.
I never thought the timing could have been so off, nobody has touched the distributor since I puchased the car. Guess I was wrong!
Thanks for all the help guys! "I told you so's" are welcome. :o
Last edited by cwyates4; Jul 28, 2008 at 01:02 PM.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Oh, heres the link to the problem I was having:
http://forums.corvetteforum.com/show....php?t=2076515
http://forums.corvetteforum.com/show....php?t=2076515
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
Way advanced?
So I guess when you plugged in the esc, it was advancing it out of 'operable range'? I thought the esc retarded timing (which would have NOT put it in 'inoperable range, but into BETTER operable range)
I smell
So I guess when you plugged in the esc, it was advancing it out of 'operable range'? I thought the esc retarded timing (which would have NOT put it in 'inoperable range, but into BETTER operable range)
I smell
Last edited by schrade; Jul 27, 2008 at 03:33 AM.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
The est wire allows the computer to control timing. If the chip is burned for advance, thats what it will do, unless it picks up a knock, then it will retard it.
Unplugging the esc did nothing for me, it was the timing wire that was making the difference.
This morning, the car cranked and died twice. On the third try, I gave it a little foot on startup and it fired right up and ran beautifully. I did the base idle adjustment, we'll see how that goes tomorrow. I had gotten a code 33, so I think it was off.
Maybe I still have a small vac. leak somewhere (bet its the rear intake!) or some sensor is whacky when cold. I'm trying to get the diacom hardware for my laptop from a fellow member, maybe that will lead me somewhere.
Either way, its definitely running alot smoother, no popping out of the exhaust, stumbling at lights, etc.
Unplugging the esc did nothing for me, it was the timing wire that was making the difference.
This morning, the car cranked and died twice. On the third try, I gave it a little foot on startup and it fired right up and ran beautifully. I did the base idle adjustment, we'll see how that goes tomorrow. I had gotten a code 33, so I think it was off.
Maybe I still have a small vac. leak somewhere (bet its the rear intake!) or some sensor is whacky when cold. I'm trying to get the diacom hardware for my laptop from a fellow member, maybe that will lead me somewhere.
Either way, its definitely running alot smoother, no popping out of the exhaust, stumbling at lights, etc.
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
With factory settings, initial advance is 6 degrees. The ECM controlled total idle spark advance should be about 20 degrees.
The ecm is advancing the spark at idle by about 14 degrees when the EST is connected to arrive at the 20 degree total
If you had too much initial advance, the additional 14 degrees that the ecm provides would likely put you beyond optimal advance which is consistent with your mechanic's findings.
By running the 10 degrees initial that you have now, your idle advance will now be closer to 24 degrees total.
Your car may respond well to the additional advance over factory settings.
The ecm is advancing the spark at idle by about 14 degrees when the EST is connected to arrive at the 20 degree total
If you had too much initial advance, the additional 14 degrees that the ecm provides would likely put you beyond optimal advance which is consistent with your mechanic's findings.
By running the 10 degrees initial that you have now, your idle advance will now be closer to 24 degrees total.
Your car may respond well to the additional advance over factory settings.
Drifting
Joined: Feb 2006
Posts: 1,423
Likes: 96
From: Magnolia Tx
Mine('86L) is nearly stock and it is really cold natured. It always starts
very easily, it just wants to warm up a bit or it will pop and buck.
It sounds like you about have it ironed out. benny
very easily, it just wants to warm up a bit or it will pop and buck.
It sounds like you about have it ironed out. benny
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Started it up cold this morning, painfully bad idle. Didn't want to run by itself at all. All I was trying to do was get the car up on the ramps, died 5 times. 
I've checked everywhere possible for vac. leaks except:
A. rear of intake manifold
and
B. Brake booster
^This one has me thinking. If I cap off the line to the booster and it runs good, there's the problem right? Or, I guess it could be something after the brake system. Looks like alot of lines go from it to the area by the driver's side headlight. In that area, that stuff is a mess on my car. Cut lines all over the place. I traced every line though and can't find a line with vacuum coming to it. I hosed that area down with carb cleaner too with no result.
I've checked everywhere possible for vac. leaks except:
A. rear of intake manifold
and
B. Brake booster
^This one has me thinking. If I cap off the line to the booster and it runs good, there's the problem right? Or, I guess it could be something after the brake system. Looks like alot of lines go from it to the area by the driver's side headlight. In that area, that stuff is a mess on my car. Cut lines all over the place. I traced every line though and can't find a line with vacuum coming to it. I hosed that area down with carb cleaner too with no result.
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