LS376/525 stops responding to ETC

[prsmsurf]

I hope someone can offer suggestions on my problems. The engine is a LS376/525 with the GM Performance Controller. Exhaust is 1 7/8? individual tube headers running to 4? collectors on side pipes. The 02 sensors are mounted on the inboard side of the collectors. The transmission is a Tremec TKO 600 manual. The MIL goes off while cranking but comes back on almost immediately after starting. At first everything seemed to function, although the scan indicated it was rich. After about ten minutes, and both times at a stop light, it would stumble and after that it would not respond to the ETC. I though with full length headers going out the side into 4? collectors I?d get a lean reading on the sensors and was surprised to see it rich. This is my first attempt with computers, and I?m lost. In fact right now I'm just hoping I attached the files.

Thanks,
Denny

[Earwax]

Any codes stored?

[prsmsurf]

Any codes stored?

Sorry for the delay, I couldn't get to it until today. This is what I copied to a text file:

0x7E8: P0102 - Mass or Volume Air Flow A Circuit Low (Pending, Current, Permanent)
0x7E8: P0606 - ECM / PCM Processor (Pending, Current, Permanent)
0x7E8: P0607 - Control Module Performance (Current)



Confirmed Emissions DTC's: 2 MIL is ON: True

Misfire Not Supported Catalyst Not Supported
Fuel System Not Supported Heated Catalyst Not Supported
Components Complete Evaporative System Not Supported
Secondary Air System Not Supported
A/C Refrigerant Not Supported
Oxygen Sensor Incomplete
Oxygen Sensor Heater Complete
EGR System Not Supported

It's been over 40 years so anything beyond a timing light, dwell meter, and scope is new to me.

[prsmsurf]

I don't know if I should have done it this way but I cleared codes with the engine running. Clearing caused the engine to die. When I restarted the only code that came back up was p0102. p0606 and p0607 have not appeared after starting and stopping engine three times.

[Earwax]

After a quick look,it appears that the MAF sensor in not reading.
The MAF reading on your log never changes?
I would check the MAF and PCM connectors for loose pins or wires.



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[MikeOD]

I don't know if I should have done it this way but I cleared codes with the engine running. Clearing caused the engine to die. When I restarted the only code that came back up was p0102. p0606 and p0607 have not appeared after starting and stopping engine three times.

When you cleared the codes the engine died because your MAF sensor is either not present or not working. When the P0102 code is present, the computer is running the engine without a MAF signal. When you clear the code, it immediately looks to the MAF signal, which shows no frequency, which means no airflow, so that in turn means it commands no fuel.

Do you have a MAF sensor installed? Can you check the wiring to it, and can you also check the flow direction? Most of the new MAF sensors have arrows on them indicating which way air flows. The arrows should point away from the filter and towards the throttle body.

[prsmsurf]

It was the ground terminal in the female MAF connector. Thanks for your help! If it wasn't for both of you pointing me toward the MAF sensor I'd probably still be trying to figure it out. The attachment is a scan after replacing the terminal.

Thanks again,

Denny

[Earwax]

Glad to help.
At least it was an easy fix.

[Howedeman]

PRSMSURF....Do you have the original tune that came in that controller or have you changed much in the above posted tune. I have the same crate motor but am using the E38 and looking for good compare info. Thanks.

[prsmsurf]

Sorry for the delay Howedeman, I've been away. The tune I posted is close to original. I think the only changes I made were for a 160 thermostat. I saved just about every read, just changing the date or time of day and the one posted is the earliest save. I'm still not happy with the way it's running. The headers are 1 7/8" individual tubes going into 4" collectors on the side, then into Hooker side pipes with straight through mufflers. The 02 sensors are mounted almost at the end of the collectors and with minimum back pressure I think I'm getting slight reversion on decel and at idle, so the sensors are probably reading lean even if it's not. The CHP is paying too much attention when I go by so I'll probably go with more muffler, increasing back pressure and I hope getting a more accurate reading.