Engine Stalls

[rkailher]

I have an MK11, with a 302 that has the following upgrades. GT40 manifold, SVO aluminum heads, 20lb injectors, 60MM throttle body, small cam, bigger fuel pump and few other minor changes that I can't remember. I am using a stock computer. The car seems to run OK while driving but when coming to stops the idle jumps up and down and the car wants to stall. Feels like it is over loading with fuel. any suggestions on what I can do?

[DaleG]

When upgrading, a lot of things can happen; EECIV gets confused, or just plain doesn't care that you fiddled with stuff and pretends all is normal. Here are some explanations on what may be going on. Oops, files too large; PM your e-mail address and I'll send them to you. Describes what happens when you upgrade TB, injectors, MAF, etc., and how to fix.

[Avalanche325]

Probably as DaleG said, you have gone out of the range of what the computer can handle. The other, based on idle hunting, would be a vacuum leak. (un-metered air)

[CraigS]

Also the idle air control valve may be old and sticking. It's essentially a solenoid moving a valve, when the valve is dirty/sticky, the solenoid pushes-no movement, pushes harder-no movement, then finally pushes hard enough to get it moving, but now it moves too far. And now it needs to move it back some. So it is constantly behind on giving the needed movement, but it gets closer each cycle, until it settles down.

[AnthonyS]

You haven't come close to the max of what the stock computer can handle. How the ECU is dealing with the 24# injectors should be known whether its a "calibrated" maf sensor or via a tune.

Do you have EGR?

The two things that will cause the symptoms you are describing are usually: 1) A bad or gummed up IAC valve. 2) Bad, loose or failed TPS. Those are the most likely culprits. I recommend pulling the codes from the ECU though as that can tell you a lot.