86 sluggish cold starts
Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
Just guessing now but....is anything in the distributor that if going bad would display these symptoms im having??
Ignition Coil?
(ICM) Ignition Control module?
From what i have read these 2 parts act up when hot??
Your thoughts would be appreciated
Ray
Ignition Coil?
(ICM) Ignition Control module?
From what i have read these 2 parts act up when hot??
Your thoughts would be appreciated
Ray
Intermediate
Joined: May 2012
Posts: 35
Likes: 1
hEY, i HAVE A 86 VETTE, iT STARTED COLD FOR 4 SECONDS & SHUT OFF, TOOK 20 CRANKS TO START THEN SPUTTER FOR A WHILE, THEN RUN. oNCE WARM IT RAN ALL DAY FINE, iT WAS THE COIL, i ALSO REPLACED THE IGNITION MODULE IN DISTRIBUTER, lET ME KNOW, MINE STARTS FINE NOW.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I think the ignition coil is pretty immune to heat. A friend of mine told me recently that he had a problem with his coil because the wires were not crimped correctly to the terminals. He soldered the connections and fixed the problem.
There is also a "pickup coil" under the distributor rotor. It picks up the magnetic pulses from the pole piece and turns them into electrical pulses. The pulses get amplified by the ICM. I have heard of the pickup coil falling apart. I guess that means that the plastic breaks. I think this is an old problem and the technology is better now so no longer a problem.
The ICM gets VERY hot. It needs to have heat conducting grease under it to help remove the heat. The grease fills in the air gaps, which are insulators for the heat. If the grease wasn't put under the ICM, I suppose it could cause a problem.
There is also a "pickup coil" under the distributor rotor. It picks up the magnetic pulses from the pole piece and turns them into electrical pulses. The pulses get amplified by the ICM. I have heard of the pickup coil falling apart. I guess that means that the plastic breaks. I think this is an old problem and the technology is better now so no longer a problem.
The ICM gets VERY hot. It needs to have heat conducting grease under it to help remove the heat. The grease fills in the air gaps, which are insulators for the heat. If the grease wasn't put under the ICM, I suppose it could cause a problem.
Team Owner
Joined: Aug 2006
Posts: 25,105
Likes: 3,156
C6 of Year Finalist (appearance mods) 2019
My 85 has the same symptoms as the OP. I am thinking it is either a vac leak down or the TB. I know the TB are prone to wear out. Anyone have these symptoms caused by a bad TB?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Usually if the throttle body shaft holes are worn the idle will wander around. Air gets sucked in where the throttle body is worn. Each time the throttle is closed the shaft lands in a slightly different position so the idle changes.
I have a vague recollection that there is a bushing kit that can be installed to fix this. I don't think it's something the average guy can do because it requires precision boring of the holes to get a press fit for the bushings.
I have a vague recollection that there is a bushing kit that can be installed to fix this. I don't think it's something the average guy can do because it requires precision boring of the holes to get a press fit for the bushings.
Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
I have a new ICM coming this week through EBay...will post results later.
gonna Vacuum test the EGR valve...could be sticking open a bit??
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I've been having some wandering idle problems lately myself for several weeks. It finally revealed itself when I was backing out of the garage yesterday and the brake pedal was hard as a rock. It was fine when I drove in the day before. The diaphragm in the brake booster ruptured. After I plugged the vacuum hose the idle smoothed right out.
I think the diaphragm had a small rip that allowed the vacuum to leak but it wasn't large enough to affect the braking. I'll take it apart when the new one arrives and see what happened. I replaced the diaphragm about 15 years ago. Back then there was a split about 4" long. That one failed while I was driving on the freeway.
You could disconnect the EGR tube from the intake manifold. When I did that I stuffed a wad of aluminum foil into the pipe. It blew right out as soon as I started the engine, so there is quite a bit a pressure there (at least when the engine first starts -- it might be a lot less at idle).
I think the diaphragm had a small rip that allowed the vacuum to leak but it wasn't large enough to affect the braking. I'll take it apart when the new one arrives and see what happened. I replaced the diaphragm about 15 years ago. Back then there was a split about 4" long. That one failed while I was driving on the freeway.
You could disconnect the EGR tube from the intake manifold. When I did that I stuffed a wad of aluminum foil into the pipe. It blew right out as soon as I started the engine, so there is quite a bit a pressure there (at least when the engine first starts -- it might be a lot less at idle).
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Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
You could disconnect the EGR tube from the intake manifold. When I did that I stuffed a wad of aluminum foil into the pipe. It blew right out as soon as I started the engine, so there is quite a bit a pressure there (at least when the engine first starts -- it might be a lot less at idle).
What would disconnecting the EGR tube from the manifold do or prove?
If i suspect that my valve is staying slightly open during cold starts would i not have to "on car" test it with vacuum somehow. Cant even get a square little mirror in place to see if the diaphragm moves...too tight in there
Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Geez.... This is a TEST. You don't leave it like that permanently. You just want to find out if it makes a DIFFERENCE with it disconnected. Whether it makes a difference or not will TELL you something.
Racer
Joined: Feb 2011
Posts: 467
Likes: 0
From: Vacaville Ca
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I have an idea: don't hijack somebody else's thread. It confuses everybody when the answers to your question are mixed in with the answers to the original poster's thread.
Start your own thread. Thanks.
Start your own thread. Thanks.
Racer
Joined: Feb 2011
Posts: 467
Likes: 0
From: Vacaville Ca
really wasnt trying to hijack anything. but my apoligies if i stepped on your toes!
8th Gear
Joined: Jun 2012
Posts: 8
Likes: 0
From: Jena
Last weekend i had time to try different thinks to solve my sluggish cold start problem. My focus was the cold start valve.
So first i disconnect the csv and try to start the engine, the problem was exact the same.
After that i checked the cold start switch with a volt- and ohmmeter.
I had 40 Ohm and both cables had electricity (csv - connector).
-> it seems the switch is ok
Next step was to remove the csv from the intake, only a small gap, to check for injected fuel. And there was no fuel while cranking!!
So i changed the memcal in the ecm from 1988 to 1989, and after that the engine starts fine.
I know you have tryed a 1989 memcal, but maybe you can check the csv in this way?
Now i have to find the vakuum leaks...
Best Regards,
Frank
So first i disconnect the csv and try to start the engine, the problem was exact the same.
After that i checked the cold start switch with a volt- and ohmmeter.
I had 40 Ohm and both cables had electricity (csv - connector).
-> it seems the switch is ok
Next step was to remove the csv from the intake, only a small gap, to check for injected fuel. And there was no fuel while cranking!!
So i changed the memcal in the ecm from 1988 to 1989, and after that the engine starts fine.
I know you have tryed a 1989 memcal, but maybe you can check the csv in this way?
Now i have to find the vakuum leaks...
Best Regards,
Frank
Racer
Joined: Feb 2011
Posts: 467
Likes: 0
From: Vacaville Ca
Last weekend i had time to try different thinks to solve my sluggish cold start problem. My focus was the cold start valve.
So first i disconnect the csv and try to start the engine, the problem was exact the same.
After that i checked the cold start switch with a volt- and ohmmeter.
I had 40 Ohm and both cables had electricity (csv - connector).
-> it seems the switch is ok
Next step was to remove the csv from the intake, only a small gap, to check for injected fuel. And there was no fuel while cranking!!
So i changed the memcal in the ecm from 1988 to 1989, and after that the engine starts fine.
I know you have tryed a 1989 memcal, but maybe you can check the csv in this way?
Now i have to find the vakuum leaks...
Best Regards,
Frank
So first i disconnect the csv and try to start the engine, the problem was exact the same.
After that i checked the cold start switch with a volt- and ohmmeter.
I had 40 Ohm and both cables had electricity (csv - connector).
-> it seems the switch is ok
Next step was to remove the csv from the intake, only a small gap, to check for injected fuel. And there was no fuel while cranking!!
So i changed the memcal in the ecm from 1988 to 1989, and after that the engine starts fine.
I know you have tryed a 1989 memcal, but maybe you can check the csv in this way?
Now i have to find the vakuum leaks...
Best Regards,
Frank
Becareful some FORUM **** might get his panites in a twist if you ask questions regarding your car on a thread you didnt start. See above.
Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
Your comments about the "forum ****" are not warranted or welcomed...keep your shat to yourself.
Cliff Harris is another member who has offered his help and knowledge over and over again on this thread and this forum. His comments are very much welcomed...in this case c5autoxracer...yours are not
Racer
Joined: Feb 2011
Posts: 467
Likes: 0
From: Vacaville Ca
thefbi has been contributing to this thread from the beginning if you care to read back and confirm...his issues were identical to mine and his thoughts and suggestions are more than welcome.
Your comments about the "forum ****" are not warranted or welcomed...keep your shat to yourself.
Cliff Harris is another member who has offered his help and knowledge over and over again on this thread and this forum. His comments are very much welcomed...in this case c5autoxracer...yours are not
Your comments about the "forum ****" are not warranted or welcomed...keep your shat to yourself.
Cliff Harris is another member who has offered his help and knowledge over and over again on this thread and this forum. His comments are very much welcomed...in this case c5autoxracer...yours are not
Thread Starter
Pro
Joined: Aug 2010
Posts: 617
Likes: 17
From: Hamilton Ontario
Installed a new ICM yesterday...this morning the car did not crank as long before starting...could be that the motor was still warm...been close to 100 degrees here the past few days...hot at night too.
Once it fired rather quickly...the engine idle sputtered still until warmed up 2 mins
Im gonna try new wires..that's about the only thing left from my tune up that is not new... acdelco's on order now.