I did some work today but haven't figured out the exact problem as to why my car lost power and stumbles under load and at idle. I disconected my MSD and went back to straight HEI, no change. I did more observation on my FP, looks good. I checked my timing, looks good. I looked for vacuum leaks/breaks/line damage, looks good. I swapped PROMs, carriers, no change.

I then scanned my car while it was happening, checking TPS voltage, speed, RPM, and MAF rate among all the other variable like EGR cycling, temp, O2, voltage, BLMs, knock, spark, etc. I then noticed that my MAF rate is significantly down. At 4800~5000 RPM at WOT (TPS@ > 4.6v) I usually have 230~235 gps (grams per second). But now I am only showing around 142 gps. A significant difference indeed.

One of my initial beliefs was that my CAT is broken up inside and blocking my exhaust because I first noticed the problem after I nailed my undercarriage on a speed bump. I wonder if the blockage in my exhaust would hinder my intake airflow that much or if my MAF sensor is just bad?

Another thing I examined that seemed odd is that my exhaust comming out of my tailpipe is freaking hot as hell. I mean if I left my hand there I would burn myself. I don't seem to recall exhaust being that hot before. I believe that if my CAT was blocked my exhaust temp would rise.

Before I take a metal rod to my CAT tell me what y'all think.

 

I have an extra MAF sensor if you want to try that.

Dont ruin your new cat, we have your old one here you can replace it with.

 

well I wouldn't trash a CAT that didn't deserve. it without checking first. I unbolted the rear flangeand ground down the spot weld at the Y and remove the CAT. The CAT looked fine. Could see right throught the polarized biscuits no problem. It's not the CAT. The CAT doesn't have a scratch on it. It looks like my X-member has taken a few scrapes though.

By flogging it I can get the problem to surface and perhaps permanently fail, instead of intermittently. It even has a hard time idling when its doing it thing. I still want to check the MAF reference voltage, 5v I believe. I had a similar problem when my TPS was dying but wasn't dead. But the scans of that look good.

Right now my car won't idle but maybe the gremlin will leave by tomorrow morning. Right now I'm thinking MAF or ECM.

 

Did you try running it without the MAF? If that is the problem it should run with it disconnected.

 

I ran it without the MAF and it was similar. My MAF was giving the ECM data but not accurate data. Like it was saying 145 gps at WOT at 5000 RPM and 3 gps at 1000 RPM. The MAF is bad. I tried anothe MAF sensor and all was good. Instead of spending money on another MAF sensor I'll upgrade to speed density.