ken3983

Well. me and my brother took off the plenum to pull the fuel rail out to look for a leaking injector. We had the rail suspended and turned the key 2 times to make sure the the fuel pump filled the rail. Found no injector leaking or dripping whatsoever. We let it sit a few minutes to make sure and none leaked. We put it back together with sensor safe RTV to be safe. I reset the ECM and road tested the car after the ECM re-learned. My scanner still showed block learn at 100 and integrator at around 10 down to 85. Still showed running rich after I got back in the driveway. Unplugged the O2 sensor and the scanner showed 444-448 mvolts coming from the o2 sensor. I did'nt think I would get a reading at all being unplugged and I also thought the ECM would throw a code once it was unplugged. Still could be a bad ECM.

Ken

Maverick H1L

iTrader: (8)

The O2S only "ramps up" the voltage signal produced by the ECM, which, IIRC, is in the ballpark of 200 mV. I'd look for a short to power somewhere along the O2S wire. I'll have to get my FSM to make sure of this.

Maverick H1L

iTrader: (8)

My FSM says that the O2S circuit voltage should be below 350mV with the O2S disconnected and the O2S pigtail (from the harness, not the sensor) being jumped to ground. However, you would need some sort of scanner to check this reading, as this is checked through the ECM.

If this voltage is still high, then you will need a new ECM. If not, then you will need to look for other problems. These include a bad TPS, problem with the charcoal can not purging, fuel pressure too high, interference on the ignition module reference low circuit, or stuck EGR pintle.

Gumby

Its usually the cold start injector, can find post where folks ditched it.

Maverick H1L

iTrader: (8)

Anything newer than 1988 doesn't have the CSI... His is a 91.

ken3983

I'm leaning towards a new ECM. We had an Autoxray scanner hooked up and the car on ramps. The o2 sensor was disconnected as the car was running. The scanner showed 444-448 mvolts before and after the o2 sensor was grounded. I tried 2 or 3 differnt TPS' on it and IIRC, they all tested good anyways. Fuel pressure was around 44 while running and 46 psi while primed. I don't know about the purge canister. The scanner shows a duty cycle of 99.4% at times while driving, so it says its working. As for the egr, I have taken it apart and cleaned all the carbon off the pintles and inside where the pintles go. The egr gaskets seem to be ok as well. Not sure what to look for or how to check for ICM interference.

Ken

Maverick H1L

iTrader: (8)

Your fuel pressure is at the high end of the scale. FSM says that the ideal KOEO pressure is between 40.5 and 47 PSI. You need to make sure that the fuel pressure drops a minimum of 3 PSI with the engine running, and check the vacuum signal to the FPR if it doesn't before you look into a new FPR. Also check the closed throttle reading at the TPS (.55 VDC). But, yes, your system fits the description of having ECM problems.

As for EMI at the ignition module, check to make sure your plug wires are relatively undamaged and routed away from the module connectors, and the blower motor connections as well (high current creates a strong mag field around the wires).

:edit: You DID disconnect the O2S before you grounded the harness connector, right? Just checking.