86 vette starting problems...
Thread Starter
Heel & Toe
Joined: Apr 2010
Posts: 20
Likes: 0
86 vette starting problems...
hey guys hopefully yall can help me. i have a 86 vette L98 acourse. i started noticing it getting harder and harder to start and now what it does is get in it when its cold and starts up fine then automaticlly goes dead refire it and it starts up instantly then goes dead and it does that untill the engine gets up to 130 to 140 engine degrees and it will sit there and run on its own fine. but when it is still cold you have to keep on taping the gas to keep it running, you cant hold the gas or it goes dead. and this is every time i go to move it and i dont drive it very much but i want to get it fix please help.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Could be the cold injector not working, also idle rpm too low, leaky injectors. Measure the fuel pressure and see how long it holds up with the ign off. It should hold for a long time. Rapid drop in pressure can be due to leaky injectors.
Team Owner
Joined: Sep 2003
Posts: 20,172
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Thread Starter
Heel & Toe
Joined: Apr 2010
Posts: 20
Likes: 0
now what do you mean by the cold injector? and i have checked the pressure and it holds about ten mins before its back to zero. i have replaced the fuel pump the filter cleaned the trottle body. i had mested with the trottle body sensor and now i have it idled up to high so i know its not the low idle. and the reason why i dont drive it much is because of this because it littery takes me 20 to 30 mins to get it to run. I would if i could get this fixed but everyone i have talked to has no clue on my year, ( i work at a gm dealer).
Race Director
Joined: Jan 2006
Posts: 10,039
Likes: 0
From: CA
now what do you mean by the cold injector? and i have checked the pressure and it holds about ten mins before its back to zero. i have replaced the fuel pump the filter cleaned the trottle body. i had mested with the trottle body sensor and now i have it idled up to high so i know its not the low idle. and the reason why i dont drive it much is because of this because it littery takes me 20 to 30 mins to get it to run. I would if i could get this fixed but everyone i have talked to has no clue on my year, ( i work at a gm dealer).
Don't know what you are calling throttle body sensor. There is a TPS sensor and an AIC valve.Could very well be the AIC valve.If you work at a GM dealership check with the shop mgr.They may have an old manual laying around and dusty.Your going to need one anyway if you plan on keeping this car for any time.You can't just keep throwing parts at it. You need to go by the book. Good luck to you.
Team Owner
Joined: Sep 2003
Posts: 20,172
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Base line. You need to get back to baseline.
Reset the idle air controller. IAC
Confirm the TPS voltage.
Adjust the idle set screw to factory settings.
Fuel filter, air filter, all that good stuff (replace as necessary)
Pull the ninth injector, Clean and check operation
Reset the idle air controller. IAC
Confirm the TPS voltage.
Adjust the idle set screw to factory settings.
Fuel filter, air filter, all that good stuff (replace as necessary)
Pull the ninth injector, Clean and check operation
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
I dont believe the cold start injector would cause this problem.I unplugged mine on my former 86 and it just took a little bit longer to start,but once it started,it ran fine.
You can unplug yours and see if theres any difference.
Also,it sounds like you may have a problem with the egr valve system.
Unplug the egr and put a rubber vacuum cap on it and see if the problem goes away on start up.
An egr stuck will cause it to be hard to stay running until it gets warmer.
On a tpi its hard to see if the egr plate is stuck because of the tpi runners in the way.
You may want to have someone with a scanner look at the computer when the car is running to see what the sensors are doing.
Also,the CTS could be bad...just take some checking and investigating to see whats up.
You can unplug yours and see if theres any difference.
Also,it sounds like you may have a problem with the egr valve system.
Unplug the egr and put a rubber vacuum cap on it and see if the problem goes away on start up.
An egr stuck will cause it to be hard to stay running until it gets warmer.
On a tpi its hard to see if the egr plate is stuck because of the tpi runners in the way.
You may want to have someone with a scanner look at the computer when the car is running to see what the sensors are doing.
Also,the CTS could be bad...just take some checking and investigating to see whats up.
Team Owner
Joined: Jan 2003
Posts: 20,293
Likes: 240
From: Summerland B.C. Canada
Test the idle air control valve http://members.shaw.ca/agent86/IAC%20Diagnosis.pdf
Also, there is a specific method of setting the minimum idle and then re-setting the throttle position sensor idle voltage. If you mess with the minimum idle screw, you mess up the TPS idle voltage.
Read this
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Also, there is a specific method of setting the minimum idle and then re-setting the throttle position sensor idle voltage. If you mess with the minimum idle screw, you mess up the TPS idle voltage.
Read this
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
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