So my buddy and I have been working on a Challenge Fiero. It has a built 3800SC motor in it and after a metric ton of time spent nailing down the wiring harness and putting a million little things in place it started and ran. But after a couple minutes it petered out and died. Tried to restart and got a pretty good backfire through the intake. Discovered a bad coil (one of three) and replaced that.
Started again and sounded great but again petered out and wouldn't restart. Now if we crank it we get wet plugs but it doesn't seem to even try to fire. New gas, new fuel filter, verified injectors are all working. I feel like it has to be a sensor causing our issue but which one?
Any words of wisdom about this setup? 1987 Fiero GT, 5 speed, Beretta brakes, 17" wheels.
Have you verified fuel pressure is correct?
In reply to vwcorvette (Forum Supporter) :
It's 40 psi (no leakdown). Internet seems to indicate 48-55 is ideal but it did run at 40.
What year 3800, and what is running it? A stock ECM?
You need a scan tool. Not a code reader, but something where you can read data.
Verify that the temperature sensors read appropriately. Verify RPM signal when cranking. If the plugs are wet then you probably are getting fuel, which means you should be getting spark because the computer gets its crank signal from the ignition module and the ignition module gives spark no matter what.
Obviously if you have no spark, but have an RPM signal, you have a bad ignition module, which is common when the coils failed, which was common when people let the plugs go a long time.
I have done a lot of mass airflow pigtails on all flavors of 3800 Series II. For whatever reason they get stressed and fail because the terminals are weak. Don't disconnect/reconnect them more than you absolutely have to (really this goes for any automotive connector) Also have done a lot of MAF sensors. Easy to test if you have a graphing scantool or preferably a scope - watch for the signal dropping out. Rapping the MAF with a screwdriver handle can make them drop out if they're bad.
Noddaz
PowerDork
11/23/22 11:13 a.m.
Nothing to add, just watching to learn something.
In reply to Pete. (l33t FS) :
Ignition module. Bingo.
She's running again, thank you good sir.
