I have a 1995 firebird with the 3.4 and obd1.5, I have no way of pulling codes but Im having an issue at idle. Ive replaced cam/map/iac/o2 sensors, as well as icm, coils, wires, and plugs, and fuel filter. At idle I have to keep one foot on the brake and my other foot on the gas to keep it from dying at a light, and sometimes it even dies while making a turn. While its sitting in park, it has a moderate shake and after about a minute or so it will struggle to stay alive (rpms going up and down) and eventually dies. If it dies going down the road I can kick it in neutral, start it, throw it in drive and continue on. But Ive ran out of ideas of what could be causing it. All my vacuums are good, I can hear the fuel pump pumping, and I just recently replaced all of my coils, and tested to make sure they weren’t faulty. It also smells to me like its burning rich, I could be wrong though. Any help would be greatly appreciated.
k.michaelknight
95’ firebird 3.4 random stalling issue
To clarify a misconception.... Your vehicle is not "OBD-1.5". It is simply an OBD-1 PCM with a 16-pin OBD-2 style data link connector (DLC). A true OBD-1.5 PCM is a hybrid that can produce both OBD-1 (DTC xx) and OBD-2 (Pxxx) codes. Your PCM can only produce OBD-1 diagnostic codes.
The PCM can be scanned with an OBD-1 code scanner. In order to connect a typical 12-pin OBD-1 scan connector to a 16-pin DLC you need either 1) a 12-pin to 16-pin convertor plug, or 2) jumper wires as show below (yes that indicates it's for the LT1, but pinout is similar on the 3.4L V6):
Alternatively you can also use a combination OBD-1/OBD-2 scanner.
It appears GM planned to use their "OBD-1.5" system (this is a GM term, not a published standard) on the 1995 F-bodies, installed the 16-pin connector, but didn't follow through with modifying the PCM. For example, the LT1 V8 model has the similar 16-pin connector with OBD-1 PCM, and GM did convert the 1995 Corvette LT1 PCM to OBD-1.5, But they didn't do it on the 1995 F-Body.
The PCM can be scanned with an OBD-1 code scanner. In order to connect a typical 12-pin OBD-1 scan connector to a 16-pin DLC you need either 1) a 12-pin to 16-pin convertor plug, or 2) jumper wires as show below (yes that indicates it's for the LT1, but pinout is similar on the 3.4L V6):
Alternatively you can also use a combination OBD-1/OBD-2 scanner.
It appears GM planned to use their "OBD-1.5" system (this is a GM term, not a published standard) on the 1995 F-bodies, installed the 16-pin connector, but didn't follow through with modifying the PCM. For example, the LT1 V8 model has the similar 16-pin connector with OBD-1 PCM, and GM did convert the 1995 Corvette LT1 PCM to OBD-1.5, But they didn't do it on the 1995 F-Body.
There are several of us trying to help you. But at least two of us need more info in order to help you. If your problem is still not resolved, you need to respond. I can see that you have signed into the site since the last post above.
My suggestion was is a long shot but, this sounds very similar to what I went through, even replaced about all the same parts, and a few more like injectors.. I got a code reader, could not pull a code. Finally got to the point it would start and run a few minutes then die. I called a friend over, told him ses light would come and go but can't get pull off a code. Here is the embarrassing part, funny now, he instantly figures out, reason I couldn't get my code reader to work was because the fuse was blown. Replaced fuse. Code revealed mass air flow - so I unplugged it and the car fired right up. Really hope you're lucky and this is all it is.
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