Long Start. 85 Vette
Thread Starter
Intermediate
Joined: Apr 2013
Posts: 40
Likes: 0
From: Culver City CA
Long Start. 85 Vette
Hello all,
I am new to the corvette scene. I just bought my 85 vette Auto trans about a week ago. my question
when cold it takes a bit of effort for the car to start. it turns over fine and it does start after a number of turn over "cycles". any ideas what could be the cause of this?
also the idle at times at be rough more so in heated traffic.. any help would be greatly appreciated
thanks
I am new to the corvette scene. I just bought my 85 vette Auto trans about a week ago. my question
when cold it takes a bit of effort for the car to start. it turns over fine and it does start after a number of turn over "cycles". any ideas what could be the cause of this?
also the idle at times at be rough more so in heated traffic.. any help would be greatly appreciated
thanks
Instructor
Joined: Jan 2008
Posts: 217
Likes: 0
From: Coopersville MI
The rough idel could be a number of things. I'd start with checking/setting the timing (8-10* base advance), check Idle Air valve, adjust as set as necessary, and check and set the throttle position sensor.
I run premium in my 85 and run 14* advanced timing, some my say this is to high, but I dont ever notice any knocking or poor performance even on hot race days. You could run mid-grade and be fine with 8* advanced timing. Out 85's have forged flat top pistons and a large combustion chamber that give a 'low' 9.0:1 compression.
I run premium in my 85 and run 14* advanced timing, some my say this is to high, but I dont ever notice any knocking or poor performance even on hot race days. You could run mid-grade and be fine with 8* advanced timing. Out 85's have forged flat top pistons and a large combustion chamber that give a 'low' 9.0:1 compression.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
First, line up a fuel pressure gauge from someone line Autozone and take the pressure. There is a Schrader valve on the fuel rail on the passenger's side. It looks like a tire valve with a steel cap on it. Unscrew the cap and hook up the gauge. Turn the key tot he ON position, do not start the car. Watch the gauge. It should pump up to about 36-39 pounds and hold that pressure level. If the pressure drops fast there are other issues which would contribute to your hard start.
Under the throttle body is a passage way that the Idle Adjustment Control (or some words like that IAC) screws into from the passenger's side. This passage way will often choke up with carbon build up. It is also possible that your IAC itself is giving up. This little valve controls the air into the throttle body at idle. You have to remove the TB to get to this.
PM sent to you.
Under the throttle body is a passage way that the Idle Adjustment Control (or some words like that IAC) screws into from the passenger's side. This passage way will often choke up with carbon build up. It is also possible that your IAC itself is giving up. This little valve controls the air into the throttle body at idle. You have to remove the TB to get to this.
PM sent to you.
Burning Brakes
Joined: Aug 2011
Posts: 878
Likes: 2
Hello all,
I am new to the corvette scene. I just bought my 85 vette Auto trans about a week ago. my question
when cold it takes a bit of effort for the car to start. it turns over fine and it does start after a number of turn over "cycles". any ideas what could be the cause of this?
also the idle at times at be rough more so in heated traffic.. any help would be greatly appreciated
thanks
I am new to the corvette scene. I just bought my 85 vette Auto trans about a week ago. my question
when cold it takes a bit of effort for the car to start. it turns over fine and it does start after a number of turn over "cycles". any ideas what could be the cause of this?
also the idle at times at be rough more so in heated traffic.. any help would be greatly appreciated
thanks
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Might be a problem with the cold start injector and/or thermo switch.
The thermo switch is mounted on the front of the intake manifold under the throttle body. It has a connector on it that looks like an injector connector. The cold start injector is mounted in the center of the intake manifold between the runners on the driver's side. It has a small piece of tubing that connects to the rear of the driver's side fuel rail.
The thermo switch is mounted on the front of the intake manifold under the throttle body. It has a connector on it that looks like an injector connector. The cold start injector is mounted in the center of the intake manifold between the runners on the driver's side. It has a small piece of tubing that connects to the rear of the driver's side fuel rail.
