i was wanting to know what my problem was with my 94Z A4. you see it has a rough idle and when i get on it at about 3500 rpms it cuts off and throws a large puff of black smoke from the exhaust and it doesn't pull from then on i have to let off the throttle. i just changed the fuel pump, the opti and plugs and wires. the wires are good. would it be the fuel pressure regulator. i think it has the stock one still on there. i have a cat on there. my SES light is throwing these codes. DTC 29, DTC 32, DTC 44. i don't mind the light on but does this have to do with my problem? sometimes it will work fine without cutting out but most of the time it cuts off and throws smoke at 3500-4000 rpms. would this mean that i'm running lean or rich? need help ASAP.

 

DTC 29 = Secondary Air Injection (AIR) pump circuit

The fuse for the AIR pump is blown (or you've deleted the system incorrectly). Will not cause the problems you are having.

DTC 32 = Exhaust Gas Recirculation (EGR)

The PCM isn't seeing the required change in MAP when it opens/closes the EGR valve. Have you deleted the EGR? If not, a valve that is stuck open could be contributing to the problem.

DTC 44 = Bank 1 (left) Heated Oxygen Sensor (HO2S) Circuit (lean exhaust indicated)

A "false" lean will cause the engine to run excessively rich, and that means its going to pour black smoke out at WOT.

See some possible connections here?

How long have you been staring at the SES light, and not taking the time to look up the codes?

http://shbox.com/1/Dtcs.htm

 

the AIR pump fuse keeps blowing out but who cares. how would i check the EGR valve. the EGR valve is still on the car. i have a cat on there but would that make much of a difference because it's an OBD1. the light has been on for a long time. i can't remember how long. you see i went with one of my friends at a chevy house and he hooked up a fuel pressure gauge and it was down to about 25 psi at idle when he would rev the engine it would just stay there. it wouldn't climb. would the EGR valve have something to do with that?

 

Simple to fix on an OBD-I car (93-95). Unplug the harness connector from the AIR pump. THEN replace the fuse = no code/SES light

At idle, try forcing the EGR valve open, either manually, or by pulling a vacuum on the line that goes from the solenoid to the EGR valve. It should make the engine run bad enough to stall it. If it does, its probably working OK, but may still be stuck open slightly by carbon in the pintle. Remove the valve and clean the pintle, and the hole in the back of the manifold it sticks into.

Whether you have or don't have a cat has no affect on your engine, and will not set an SES light if its not there.

No. The EGR has nothing to do with fuel pressure. If you only have 25psi, you have a problem. That would explain the code for running lean. But that also wouldn't account for running rich and a black cloud of smoke.

Seems like you know you have problems with the fuel, you've been staring at the SES light for who knows how long... do you even care? Doesn't seem so.