FI (AFM related) problem

[jmead]

OK, I posted before about a problem I was having. Sometimes car would backfire off idle during acceleration. Would run ok after that, maybe a little lacking in power, but driveable. Got a suggestion about a bad AFM. Got a new (used) one....same thing. Another...same thing.

 

I took it off the road to fix the leaky gas tank. Fixed the tank, but now the car won't start. I can crank and crank, sometimes it will start for a second, run real rough and then quit, most of the time it doesn't even get that far.

 

But I tried something out of desperation. With the AFM connected to the ECU, but not to the intake...same thing....but when I disconnected the AFM all together (both from the intake and the computer), it started and ran! Now, I didn't run it very long (no filter), and I didn't try to drive it, but at least it started.

 

Now, what does this mean? Bad wiring? Something with the ECU? Did FI this old even have a "limp mode"?

 

So...any suggestions? I love this car, but I can't figure it out...I really cant stand to have it just sit in the garage.

 

Thanks for any input

[Guest zpeedracer25]

I'd say you either have a bad AFM, or an air leak after the AFM causing a lot of unmetered air to enter the engine bypassing the AFM. I've run into both bad AFMs and air leaks on my Zs causing this same problem. I've also ran into a bad ground wire on the AFM causing this too.