A10ECGent

Ok I am a lot closer to getting this APV straightened out but I'm looking for more help.here are the vitals 94 Lumina APV 3.1 fresh overhaul 100 miles on it.This thing was running like the cam was a tooth out so I finally broke it back down to find that it was right on the money. (by the way it was not throwing any codes prior to this).I pulled a plug to do a compression check and found that my brand new delcos were blacker than coal and smelled like raw gas at arms length,so I put in a new set of plugs new o2 sensor test drive time again.While the engine was warming up it ran great as soon as it went into closed loop it became a dog again and backfired through the intake. checked the codes when I got back and had a 13(o2 sensor),and a 34(map sensor voltage low).Also the egr was stuck open halfway so i cleaned it and made sure it was sealing before this test drive.Now I am at a loss as to where to go next .Any idea's or thoughts are appreciated

nelsontj

Is this TBI? If so check the IAC. It will not through a code if bad. You can check the counts with a scan tool.

A10ECGent

Yes it is tbi but it has a new iac

nelsontj

Have you tried a new ignition module? If you have a bad one, they can act weird, good one day bad the next. It could also be the high tension coil. If the plugs were black and full of fuel, it sounds like it is not getting enough spark to burn everything. That would also explain why it runs good when cold and worse when it gets hot.