Please Need help fast!!! Motor shakes and low vac.
I never heard of map breaking down before... i have checked the mapes on the pfc and there is nothing unusual there. No CEL or any codes stored.
It would be great if there was a "Blown engine" light
It would be great if there was a "Blown engine" light
well as far map breaking down is that most map sensor work like a potensiometer such as a tps and maybe at idle it has a bad spot so it's telling the computer that it's under some load and the ecu then just give it more gas than what the motor really needs. if you have access to a graphic scopemeter, check the signal wire and and it should be at certain spec at idle and changes smoothly as you rev it up or with koeo, using a vacc pump apply 15'' hg what is the map reading and bleed it off wacth the scope line it should be progressive and smooth not having glicthes... but be sure to have the specs first. "most automobile work between 0 to 5 volts for map sensor" or if you a friend with a good running fd that has a similar sensor swap it to just rule it out.
i think if you had a blown engine, you would have low power through out the power band not just at idle... another thing if your car still have its emission device ,the egr, it could be stuck open just enouh to cause a low idle... but if it's been removed disregard this suggestion.
Joined: Aug 2002
Posts: 4,152
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From: Pittsburg, KS.
I have the same problem too. After a 4th gear pull up to 7000rpm the car idle like crap. I'm going try the compression test tomorrow. Damn I only put 700 miles on a rebuilt w/ the RA seals.
I had a very similar problem last week after racing my car, when I got back to the pits the car had a really bad idle problem, lot's of backfiring and the engine was really hard to start but the engine still boosted to 13 psi and the car had the same power as before at the higher rpm's. The problem, in my case, was a poor electrical connection at the ECU - specifically the cable that controls the Idle Speed Control (ISC) valve. I have a PFC. I fixed the end connector on the ISC cable at the ECU and the problem is gone. Car idles fine, no more backfiring.
I hope you problem is as simple as mine. Good Luck.
I hope you problem is as simple as mine. Good Luck.
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