Jake.Z

I bought a 96 firebird.. found out it had a spun rod. Rebuilt it.. 3 months later.. still tweaking it. Replacing things as i go. Ive been under my car 20+ times on a lift and there are no connections disconnected.. my cigarette lighter works.. my fuses are all fine.. my speedo reads 22mph roughly when im on the hwy doing 70. My tripometer runs 3 times slow as well as the speedo..i will make a 55 mile trip and my tripometer says 17.9 miles.. but the odometer works fine.. and rpm and gas guage etc. I get no communication to my pcm as well.. ive used obd1 and obd2 scanners.. snap on and crappy autozone/oreilys ones just for ***** and giggles. my engine light is on because of my right upstream o2 sensor.. i know this because i plugged the o2 sensor in.. its brand new.. and engine light stayed off permanently.. but it ran awful awful.. stalled.. misfired.. it went haywire. So i unplugged the o2 sensor and it runs fine.. i get about 23 mpg on hwy with a cam and DR's with a 6 speed..

My mods are msd opti and slp fan switch that has to do with electrical.. the rest is motor mods. If anybody can help me out, id appreciate it.

Bigtoyz

iTrader: (2)

For the scanners to you have a module that go betweent the computer and the OBD connector. For my autotap there is a serial connetor to the computer and one to the module and a serial out then goes to the OBD2 connector. For the 96-97 OBD2 I like autotap and its pretty reasonable priced. Comes with cables, module, and software which is upgradable through the website.

Since it is running pretty good I would rule out the pcm, tuning part anyways. That is odd that you replace with new O2 and it dont run right.

96capricemgr

iTrader: (1)

Look at the pcm and see what the PN is.
94-95 16188051
96 16214399
97 16242921

The speedo issues suggest it is not the original pcm to the car.
Many OBD1 scanners don't like the 94-5 LT1 pcm and to me it seems likely what you have is an untuned or improperly tuned OBD1 swapped car.

Jake.Z

Well it was dyno tuned and tuned from pcmforless. I have both receipts. Both because of adding new mods

96capricemgr

iTrader: (1)

and they can handle any of those pcms.
If it was dyno tuned by them and now the speedo is WAY WAY off that could suggest the dyno tuned pcm was removed.

Jake.Z

Talk about gettin sold a lemon.. where can i find the PN number? Inside of the pcm? It has a warranty void sticker..

Jake.Z

I cannot see anything on the back of the pcm. Its all faded. I looked at the receiptd from the previous owner and the dyno tune used an obd1 computer.. hoping thats the same computer. I also bought another speedo cluster with low low miles but still doesnt read right.