http://www.mediafire.com/?y10tzx3txpn

Take a look at this idle log. The car stays in closed loop, and the o2's appear dead, but there is NO fuel correction going on with the PCM. What going on here?

Thanks Jason

 

Something happened at record 251 and it kicked back to open loop. The run time in the upper left box reset to 4 seconds, and the log time in the lower right jumped from 83 sec to 134-seconds in one frame. It stays that way to record 299 and then the "closed loop" flag sets again.

At no time does the "BLM enabled" flag go to "1", so that explains why the BLM's are not changing. I'd say that there is a data error on the "closed loop" flag, and that the system did not run for the 206-seconds required by the timer before it can switch from open loop to closed loop.

Do you still have the AIR pump hooked up? That would explain the right O2 bottomed out at "4", and the left O2 also on the low side, although fluctuating slightly.

Odd.... I have never seen that problem with any of the maybe 300 data logs I've looked at for people. Has it ever happened before, or since?

 

No air pump, no egr. The knock is from roller rockers without the LT4 KM I guessing. I just noticed something else funky look at the parts of the log where I give the car some throttle, it shows the MPH rising. The car is sitting in park!!! I'm lost on this one, any have an idea where to start? BTW this is on a new less then 2 week old 383 I built for a friend. It ran great, he took it on a road trip and everything was great going there (almost 24mpg!). On the way back it was raining and everytime he hit a puddle the car would stall. Also he he blew a header gasket and drove 200+ miles on it with 3 missing bolts that would be on the bank with the o2 stuck at 4. Changed the opti, plugs and coil since then, also has a new fuel pump. Car runs like a snail right now in gear, rev's fine in park though.

 

Swap the O2 sensors left to right, and see if the "4" follows the sensor. Is it possible the water has got into the wiring/extensions, and shorted the signal wire to ground?

 

The 4 will follow the sensor. Actually if I unplug the sensor and plug it back in the o2 will read 486 or so then once I start it, it will slowly sink back down to 4 as the car is running.

 

What happens when the data log reaches 206 seconds? Do the LT's start to change?

Have you considered replacing the sensor?

 

Ok I put a new o2 sensor in the bank that was at '4'. Again it will read 4xx then gradually drop to 4 again once the car is running. I didnt mess with the other side. I let the car run for awhile, more then 206 seconds. Neither the LT or ST counts change at all. Where else should I start looking?!?

 

Just swapped PCM's nothing changed!

 

Update! Found that the car is only running on 4 cylinders. Injectors 2,3,5,8 are getting no signal to fire from the PCM. Now where to go?

 

Did you check the fuses ? Each bank of injectors have their own fuse.

-- Lee

 

The injectors are not wired to the power supply in "banks". One fuse supplies 1/4/6/7, the other supplies 2/3/5/8

You should have had trouble codes for 4 injectors not firing. You should have been able to notice it wasn't running "quite right".

 

Since it isnt my car I didnt have a bunch of time behind the wheel. It feel like a turtle when I drove it. I checked the fuse and it was fine at first, I noticed the wiring harness had been very close to the header so I pulled to free to inspect. Some of the wires had been burned, but still had the insulation on them. I zip tied the harness out of the way and followed the +12 to the injectors back to the fuse box. At this point I rechecked the fuse and it was blown, so I replaced it and bingo +12 to the other injectors. Amazing enuff the 383 would idle and drive well, just down alot of power. I searched the harness for any breaks/knicks in the wiring but found nothing. IDK but things are back to normal now. The PCM never threw a code and that log was with the car running on just the 4 cylinders. Thanks for the help!