Today morning I've gone with the FD for a ride. No problem. Everything perfect, like always... I've done about 10 miles in the road, no cars at all, going at about 40-60 miles per hour. Then I have arrived at a point where the road was full of cars. Well man, no problem, just stop&go time... Then the problem has come.
At some point my car has started to backfire a lot, even at idle and going at 10 miles per hour maximum, in the lower rpm range. It was hard to drive. The rpm was going up and down, up and down. My air/fuel meter (not wideband) was also always in the "very rich" zone, but always moving. My car was full-warmed and I had never seen that at idle, only in a cold start... One importante thing is that the problem has dissapeared as soon as I've gone full throttle The cars have gone away and as soon as I have began to ride faster there have been no more strange things...
Then I've arribed at place and have stopped turning off the car. After some hours I've started the car again and I've made the same itinerary back home without any problem... Well, but I must think that the problem will come back again, sure...

Do you know where to begin in order to solve this damned problem?? Tomorrow I'm making a route with some Porsches

 

One more thing! The rpm at idle were very high, about 1400-1500 rpm... and vacuum gauge was also a little crazy, going up and down

 

I have been experiencing the same problems for months. I also have a lot of bucking issues as well.

 

check your map sensor. It may have come off.

 

Newbie reply: where's is the map sensor located??

 

Its on the firewall called BOOST SENSOR (it has a vacuum line attached to it running to the UIM). However, I don't think that's your problem since it "magically" fixed itself.

 

Ok, I will check it soon. I've also searched in other "backfiring issue" threads and I've read about resetting the ECU. Should I try this also??

 

well what are your mos on your FD?

 

Pettit Racing unlimited ECU, HKs downpipe, Bonez hi-flow cat, Greddy ti catback, Apexi power intake, HKS ssqv BOV, Koyo racing radiator, Greddy profec B (at 10 psi waiting for IC), etc

 

Map sensor checked. Everything at place... Any idea??

 

Possibly a vacuum leak? What is your vacuum at idle?

Jason

 

I get 20 at 1000 rpm