A friend's '93 Trans Am will idle very rough at about 400 rpm's when cold, and the exhaust smells very rich. It is fine once it is warmed up. ? Midas told her it was her fuel pressure regulator, which I argued with them about, and sure enough she still has the problem after they replaced it. Now they say she has to replace both coolant sensors, her water pump, and the optispark.

Any ideas as to what would make it do this when cold, but fixes itself once warmed up? It is dumping way too much fuel during idle. As far as I know, nothing except the plugs and wires have ever been changed on the vehicle. It has 105,000 or so miles on it. The fairly new plugs are very fouled now that it is running so rich when you start it.

 

eh.. mine does the same thing. 93's don't have a MAF so i think they kinda have trouble with that. I was thinking o2 sensor? but eh whatever.

 

Check for leaking fuel injectors! I just had that problem on my 93 and failed smog becuase she was too rich.

BTW a local midas wanted to change my waterpump when the were going to fix the injector, said it was in the way. I was like . The bad injector was on the #5 cyclender (3 back drivers side) the wp is nowhere near there! And they wanted ~$900. Needless to say I left got the injector from a chevy dealer and put it in that night. only cost $120 and took 1.5 hours. Midas said 9 hours. Be carefull with them.

EDIT: they were also after the opti, which has no problems.

 

If you had a leaking injector you'd probably have a bit more of a problem. You'd probably have a fire.

 

Mine was leaking for a little while. When I say leaking, I mean the valve inside would not close all the way, causeing fuel to be shot into the exhaust, not leaking as in leaking outside onto the engine. Hope that clears that up.