VAM Problem?

btw this is my first post, and I have to say I love the site, this is also my first TC


ok This is with my 88 turbo coupe.

Ok heres the situation, I get in the car and start it, go to take of and in every gear, while its cold, the motor Violently Sputters/cuts out all thought the Rpms.

So... I let the car warm up to op. temp.

But While its sitting in the drive way idleing it will be fine for a few mins, then Start Surging badly, like almost die, then Idles up to normal, and runs fine, but the car has to warm up atleast 10-20 mins for it to run normal.

Lights dim and brighten alot, like after the car is warm the headlights are dim, but once I take off and get the rpms up they brighten back up.

also Car seems faster at 3/4 Throttle then at full throttle (16-17# boost) if that makes sense.


I was told that its most likly the VAM that I need to remove the plastic cover and adjust the voltage, But I need to know what the voltage should be.

any help is appreacited.


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Hello and welcome.

Can't say for sure at this point but it's more likely that the problem is not the VAM than it is the VAM. For some general background on engine running problems, see this post and look through the links, especially those related to "running the codes" because that is the first thing you should do.
http://natomessageboard.com/cgi-bin/ulti...0;t=000004


Also note the tuneup parts that work and don't work. These cars are real picky about plug wires and somewhat piky about plugs. Chances are this is not your problem, but it is always good to make sure the tuneup is fresh when doing engine diagnosis.

Also see the very last link in that post about "idle problems only when cold" There are a couple possible culprits there. My money would be on the ECT or the TFI. Since an ECT can be partially bad and not set a code, it can be tough to diagnose. It is the sensor in between the 2 center fuel injectors on the lower intake. I will send some info on further testing it.

Pull the codes and let us know what you get in each step. The engine needs to be warm.

Lights dim and brighten alot, like after the car is warm the headlights are dim, but once I take off and get the rpms up they brighten back up.

I'd guess you need to get your alternator output checked. Many parts stores will do it if you carry it in. Cleaning all the connection and major grounds would be a good idea, Here is a list of 87-88 grounds:
http://www.turbotbird.com/FAQpage/FAQpag...0Locations

also Car seems faster at 3/4 Throttle then at full throttle (16-17# boost) if that makes sense.

My personal theory: The computer is known to richen the mixture alot at WOT for engine safety. At 3/4 throttle it isn't so rich so it makes more power. Every turbo Ford I have owned did this to one degree or another.

I agree with Pete, you problem is likely not the VAM. Also, unless you know exactly what you are doing, and have a WBO2 as a tuning aid, do NOT mess with the spring in the VAM.

Originally posted by OneShot:
But While its sitting in the drive way idleing it will be fine for a few mins, then Start Surging badly, like almost die, then Idles up to normal, and runs fine, but the car has to warm up atleast 10-20 mins for it to run normal.

See this link for adjusting the idle, this little article was the key for me in fixing a wandering/surging idle that I chased off and on for 15 years. Now it idles at 900 rpm +- 50 practically all the time. Every once in a while it'll blurp.

http://www.turbotbird.com/techinfo/Idle-...e2005.html