Hello! Recently my moms 86 Fiero was acting up, First the car would hesitate and stall upon idle when first turned on. Then the starter went so we had it replaced and the problems went away. Then we replaced the distributor, still no dice. The car would also stall when idling at a red light or coming to a stop. We replaced almost every sensor in the car and even the ECM and the PROM and CALPAK. We also put a Super-coil on to replace the old one. Now the car with the old throttle positing sensor will idle down and then stall. Once the car warms up apparently it can idle no problem. When the new TPS the car idles high and low but does not stall. The Idle adjustment screw has not been touched and the cap is still in place from GM.
On these cars you jumper the A & B terminals of the diagnostic port (in the center arm rest, take off the plastic piece that covers the lighter socket), then turn the key to on. The service engine light will flash in a sort of Morse code. If it flashes three times, then five, that would be a code 35, which IIRC is failure to set idle. This can be due to a bad or stuck idle air control, but often it's just a vacuum leak. Unfortunately the Fiero has many possible vacuum leaks. It could take quite a while just to describe all the possibilities. Anyway, can you check for codes? Welcome to the forum!
Recently my Neighbor and I checked for vacuum leaks and actually found none. The car gives code 15 (Coolant Sensor (high voltage)) but that sensor has been replaced.
Pull the electrical connector to the transmission and see if that makes a difference. If the TCC is locking up the engine will stall but only if its in drive. Its really time to scan the ECM to see what that indicates. Buy or borrow a good scan tool that covers 80's GM cars.
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We replaced the Coolant Temp Sensor. Once replaced the car was still giving that code. The Car has new ECM and PROM/CALPAK because we would get complete power lose while driving. I do plan on getting a scan tool. What would be a good on? I don't want to get a non reliable one.
If you've still got the code 15 then you need to check the connector itself and the circuit back to the ECM. Time to get the old multi meter out I think.
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The Fiero Store is having a sale tomorrow, Wednesday, December 9, 2015. They have a scan tool and software, although I haven't used any of these things. Look under tools.
The paperclip just runs through the stored codes from the ECM. The scan tool is used while the car is running to look at everything to see if I can spot and issue a.k.a fuel trim, etc.
[This message has been edited by DawknessTheDuck (edited 12-09-2015).]
