Hello, I'm a new user but a regular visitor to this forum. I've been having problems with my 1987 Pontiac Fiero with the 2.5L Iron Duke and I'm hoping I'll get some help with my issues because I'm about to give up.
These are the main problems: -On a Cold start the engine will start at 2000rpm (or 1500) and either search for idle between 1000rpm and 2000rpm. (This doesn't always happen, sometimes it will start at 1500rpm, and be very smooth... until it tries to lower the rpm under 1000 then it sounds like it's going to stall and the ECM catches it in time and brings it back slightly above 1000rpm and then after a while the cycle repeats)
-When Cold and driving, it hesitates on acceleration, if trying to push the gas more it will stall or suddenly surge up and accelerate (more often than not the former). (This is also intermittent, sometimes it drives perfectly fine while cold, can even punch the throttle from a stop and it'll go no problem)
-When Warming up the engine and driving, the engine will make a loud bang and the rpm will drop a lot before picking up again, obviously with a immediate reduction in road speed, if traveling at low speed it may even stall the engine. (Very rare has only happened a couple of times, still thought I should mention it though)
-When Warm, driving at low speed, stopping smoothly, stopping harshly, the car will be at around or slightly under 1000rpm and will just... stall. Not fun if you have cars behind you... (This one is regular, almost every trip will have this happen at least once)
That's it for the problems, minus other little things here and there. Now is the list of things for the engine that have been changed -Fuel Pump -Fuel Filter -Vacuum lines (minus PCV and brake booster but both were found to be good) -Spark Plugs and Wires -Crankshaft Position Sensor -Battery and Air filter (usual maintenance) -Fuel Pump relay
I think that's all, this has already gotten long enough, but I've also checked a bunch of things, obv feel free to inquire or ask any questions. Thank you all for your time.
Hello, I'm a new user but a regular visitor to this forum. I've been having problems with my 1987 Pontiac Fiero with the 2.5L Iron Duke and I'm hoping I'll get some help with my issues because I'm about to give up.
These are the main problems: -On a Cold start the engine will start at 2000rpm (or 1500) and either search for idle between 1000rpm and 2000rpm. (This doesn't always happen, sometimes it will start at 1500rpm, and be very smooth... until it tries to lower the rpm under 1000 then it sounds like it's going to stall and the ECM catches it in time and brings it back slightly above 1000rpm and then after a while the cycle repeats)
-When Cold and driving, it hesitates on acceleration, if trying to push the gas more it will stall or suddenly surge up and accelerate (more often than not the former). (This is also intermittent, sometimes it drives perfectly fine while cold, can even punch the throttle from a stop and it'll go no problem)
-When Warming up the engine and driving, the engine will make a loud bang and the rpm will drop a lot before picking up again, obviously with a immediate reduction in road speed, if traveling at low speed it may even stall the engine. (Very rare has only happened a couple of times, still thought I should mention it though)
-When Warm, driving at low speed, stopping smoothly, stopping harshly, the car will be at around or slightly under 1000rpm and will just... stall. Not fun if you have cars behind you... (This one is regular, almost every trip will have this happen at least once)
That's it for the problems, minus other little things here and there. Now is the list of things for the engine that have been changed -Fuel Pump -Fuel Filter -Vacuum lines (minus PCV and brake booster but both were found to be good) -Spark Plugs and Wires -Crankshaft Position Sensor -Battery and Air filter (usual maintenance) -Fuel Pump relay
I think that's all, this has already gotten long enough, but I've also checked a bunch of things, obv feel free to inquire or ask any questions. Thank you all for your time.
sounds like its randomly lean. try the regulator yet or checking fuel pressure? also any codes?
sounds like its randomly lean. try the regulator yet or checking fuel pressure? also any codes?
The regulator isn't leaking, for the fuel pressure I haven't checked since the fuel pump was changed and it was within the right range of PSI. I'll check fuel pressure again, but I don't have the adapter so I'll have to ask a friend.
Any EGR leakage will play havoc with idle especially cold idle; confirm that your EGR is really closing.
Check/Clean the Idle Air Control (IAC) passage
Also, the MAT sensor should be checked too
I thought it was EGR as well, but it was tested blocked off and sealed and with installed and tested to be working so I don't think it could be that.
The IAC passage was cleaned, however I didn't check the IAC itself because it seemed to be reacting correctly when reading the "counts" through the OBD1 port.
The MAT and CTS is for sure good, did the old school Ohm test as well as read the ECM through the OBD1 port, it all checks out.
