RED SHARK 1990

Have you replaced this part already?Its sit by the trasmission tunnel just behind the MAF towards the back .

Mongo

I tried a cold start this morning. Idles very rough and surges between 800 and 500 RPM. After letting it run for about 5 minutes I shut it off and attempted to restart. Car started and ran horribly again. It almost seems like it's a temp II sensor. There is corrosion on the bottom of it (and it's new!)

Mongo

I took an ohm readout of the Temp II right now at the sensor itself rather than from the LH & EZK plugs.

My resistance was 0.850-0.854, putting me in the temp range between 104-140 degrees fahrenheit per the WSM.

I grounded to the water jacket for this reading. That mean the Temp II is functioning?

Bill51sdr

I would check your O2 snsor and connections as your problem seems to manifest as the system tries to go into closed loop. Did you even look at it after the last time this happened. You said your plugs were in bad shape, I can only imagine how the O2 sensor looks.

Mongo

Video Evidence:

This was done with a cold start. You can't really see the tach on the video but it's idling between 800 and 300 RPM.
After I did this video, there was a smell of gas for a good 10 feet away from the car.

O2 sensor still a possibility???

Bill51sdr

Yes, because it is likely you have fouled yet another set of plugs.

Mongo

@#@%%@#!$#^^#$!@@^%&#

stolarzj

With a multimeter, what is the voltage with the car running? Caught a quick glimpse of the gauge at the end. It sounds evil like the plate, I swear I can her voices coming out of the engine in the engine bay shots.

Mongo

The factory voltmeter shows 10. Is that a bad alternator? It has already been replaced though back in 2001. I did think about this a little more. A while back I had an ignition coil fail causing the engine to run on 4. If there was a lot of fuel dumped into the exhaust it could have damaged the O2 sensor back in June. If that's the case, I think I understand why it's running horrible now with a new LH. The LH is probably detecting the O2 sensor is 100% dead now.

Gonna be a while till I put some more money into this thing again. I disconnected the battery and threw the cover on it. Back into hibernation it goes...

ew928

+14.4

I was going to throw it out as a wildcard.
How's the alternator and associated ground straps. (battery box and engine bay)
Start the car. Turn on headlights (high beam) then kick in A/C. That's a good power drain. On my flakey alternator, that's how we figured out my alternator was going and why the car would stall at intersection. (Couldn't hold voltage when the cooling fans kicked in) Car would start but once I turned on high beam. Poof. Dead car.
From the first 15 seconds of the vid, the pod voltmeter never went above 12V.

Get one of those digital cigarette lighter voltmeter. It's not accurate but will give a rough idea of what voltages are running around the car.

stolarzj

Maybe somebody has an old used O2 sensor kicking around. I'd give you mine that has been sitting around on the floor for a while, but half the threads broke off when I removed it.

dprantl

If you think your problem is the O2 sensor, just disconnect it. The LH will go into open loop mode and set the correction factor to a mid-point. A stock car should run well with the O2 sensor disconnected.

Dan
'91 928GT S/C 475hp/460lb.ft

Cosmo Kramer

Unplug the O2 sensor and let it run on open loop, that should tell you if it is the sensor or not.

Opps I got Enzo'ed!

Bill51sdr

Good idea... once he changes the plugs again.

AO

You had the intake off (a long time ago). Check the grounds for the harness at the back of the intake. An intermittent ground back there can cause all kinds of running issues. As me how I know. Those two bolts that hold the harness to the block cast me a lot of money! Don't just check them, tighten them!