I'm working on a 1997 formula with a procharger. The car has a bad off idle stumble that actually shuts the car off at times. I check for codes with a diagnostic tool and I get no codes. I've checked fuel pressure during the stumble it's a rock steady 45psi. I checked the output voltages of the TPS and MAP sensors ok. There is a contant reading of -41deg from the coolant temp sensor when looking at the scanner data mode and it never seems to change whether I unplug it or even change the coolant sensor. It seems like the computer won't turn the service engine lite even if I unplug sensors . I also checked the MAF for leaking plumbing back to the charger and it barely runs when I unplug it. What are the symptoms of a bad crank sensor maybe or distributor? Any help would be greatly appreciated.

 

u would get codes for either CPS or bad opti......sometimes the opti wont throw a code for a long time b4 it finally gives way....

as for ur coolant temp ....i think u should start there...theres somthing about coolant snesors and stuff that keep ur car from starting or running bad....correct me here

check both sensors...there should be one that reads ur temp fro ur dash and another that runs to ur PCM(i could be wrong i might be but correct me if im wrong, been along day).


EDIT: u said car stumbles at idle...im a dumbasss first thing i shoulda said was IAC...idle air control....not sure if it will throw codes