A serious problem

[gbrtng]

Originally Posted by A26B

I'm a little confused with the "short runner intake." What exactly is that?

Your problem, being intermittent and worsening, sounds to me like an electrical issue. Loose connection, bad ground(s) or open/short in the harness. Part of it sound like it's restricted to closed loop except that once you reach 5000rpm it craps out again. If it were O2 sensors, you should have a code, same as with any other sensor.

I'm leaning towards a bent pin on the ignition module (easy to do) or bad ground(s). If you could data log, you might be able to chase it down.

If you have acess to another known good ECM, I would suggest trying that too.

I agree on the ECM - if it's flakey there's no telling what weirdness
can occur. You might not be able to log data either.

I fought with similar problems on my wife's L98 a few
years ago. That one would throw random SES codes which made
think it was a bad ground or related connector problems. Ran like
new with a good ECM.

Glenn
91-1341 and 91-9405

[tomtom72]

I bought a used snap-on MT-2500 scanner. I sometimes use it when I drive just to see what the ECM sees from the sensors. I know for sure that the guys that do "data logging" use software programs that let you hook up a laptop to the ALDL port and drive & record the data for play back later so you can study it. I'm not too swift on this 'puter stuff so all I know is there is a soft ware that you can buy, a cable to plug the laptop into the ALDL, and you can either use it on a dyno or you can do "street tunning" by logging the data(recording the data on the hard drive(?)) & look at it later.

Sorry that's all I know about this stuff.

A thought just hit me: If the scanner is plugged into the ALDL maybe it is just reading the data flow? Maybe if you use a "jumper" you are putting the ECM into test mode??? I know that I use my scanner to do the KOEO readings and I can start the car & watch as the data changes as the car goes from "open loop" to "closed loop". Stupid Q from me: you know that the ECM is good? If not sure I have a spare ECM with a 90 EPROM in it I could send to you to test if you think that would be of any use?


Tom