Hi All,
Tried doing a search on the title of this post but came up with nothing. I have a 1987 GMC Jimmy S15 2.8L running rich (black deposit on rear bumper). It is a manual and a 4x4. I have replaced the following... EGR valve, plus solenoid... MAP sensor, IAC, TPS, O2 sensor, catalytic converter, muffler, all vacuum lines except those going down to the transmission area. Plugs, cap, rotor, wires, Ignition module on firewall and the one in the distributor. I still get a EGR code when I get go on the highway or even in town from time to time. Code clears as soon as it is shut off, but then comes on later when going down the highway. Also will randomly die when letting off the gas, but will start right back up. Really frustrated, can anyone help?
thanks in advance,
Bob

 

Leaky fuel injectors?

When I had a '92 W-code, the injector spider started leaking and caused my O2 sensor to trigger a code and so I replaced it hoping it was a bad sensor. Instead, it was working correctly and was indicating over-rich mixture due to fuel being dumped directly into the intake ports.