I've been lurking here for a bit now and have solved many problems by searching, alas I now have one I can't figure out.

I recently bought a new to me 1998 Firebird Formula, 151k on the body and (as per the previous owner) 80k on the motor. It has the motor from an 01 WS6, it does have the correct heads and intake for an 01 LS1 so I believe this to be true. Since I bought the car I've been combating rough running, erratic idle, and bad MPG. So far I've cleaned the MAF, reconnected and cleaned the IAT, cleaned the IAC, replaced the O2's with Densos, and checked for vacuum leaks (the best I could without a smoke machine). Everything seemed to help to a degree but it's still not right.

The car is basically stock, it has long tube headers, air injection deleted, no EGR because of the 01 motor, cats deleted, 4.11 gears, and that's about it.

Now for the problems. As the stands now it idles between 900-1100 randomly, and will sometimes drop down to 500-600 for a second, usually when decellerating with the clutch pushed in. I have been averaging about 14 MPG with my very best tank (almost all highway) being 17. With the car idling it smells like it's running rich. There is no SES or any other lights on.

Tonight I decided to break out my scanner, AutoEnginuity, and see what if I could spot anything wrong. When I connected the scanner it recognized the car including the VIN, but when I attemped to do any bidirectional control I just got errors, and when I tried to view live data everything just showed "0". I'm at a loss because I've never seen this before, I know the port has power, and the scannner communicated at leasst to some degree because it knew what kind of vehicle it was, but I seem to have no communication with the PCM at all. Please help!

 

Did you previously use that scanner with a different car? Some of them will lock to a certain car's VIN and refuse to communicate with any other car unless you reset them or whatever the specific procedure is.

 

I've used it with tons of other cars, in fact I used on my buddies truck about 5 minutes before hooking it up to my car. I thought it might have been an issue like that at first too, i restarted the program disconnected everything, started it all back up, and had the exact same results. I'm 99% sure it's an issue with the car itself.

 

I figured I would post a few pictures of the car so people wouldn't just assume it was a 150k mile POS.

 

 

Nice. That's exactly my intended setup too lol.

As for the port, Tried it with both leaving it in accessory and starting it up I'm assuming?

 

I only tried with the car running as I wanted to make sure all the sensors were reading correctly.

 

Any other ideas?

 

Scanner mfgr have a tech desk?? If so, call them.
Get that scanner to work, or find someone w/ EFILIVE, download the tune, do a couple data logs, and post them up.
Otherwise, U R shooting in the dark....