I have a problem that really bothers me, I have had it since I bought the car but didnt notised it before yesterday when the new exhaust went on.

When your driving on for example first gear at 1500 rpm and lift your foot of the throttle the car missfires, It sounds like one rotor is missing, it only happens when you lift your foot of the throttle, and does so sometimes even over 2000 rpm.

And, the car also missfires at idle, not the whole time but gives some "boof" and "poff" once i a while.

The boost is normal, and the car goes very well, except when you lift of the throttle. I always use 98 Okt fuel.

My speculations are the spark plugs, does that give these failures?

Thanks for your time.

 

By the way, I got a autometer A/F meter installed and it shows nothing at idle, jumping around when driving and goes 2 leds from top when pushing the car.

 

Can be the spark plugs. If it's questionable the just change them, can't hurt. You may be running slightly rich. Have you removed the air pump and are you using a stock ECU or aftermarket?

 

The only mods is the catback exhaust, rest is oem.

the A/F meter is of scale om the lean side when problems is coming, so it shouldnt be running rich.

probobly good idea to chance the plugs as you say.

 

All RX's I've seen do this "boof" or "pof" every so often at idle, so I think you're ok there. As far as the misfire, I'm not sure, my car backfires a little when I take my foot off the gas after giving some throttle.

 

It's generally normal to backfire but it will get worse with age of the catalytic convertor and if the air pump system is not working well. The engine has a system to help reduce this consisting of a Dashpot which dampens the release of the throttle so the air isn't sudenly shut off, near throttle control and the ISC solinoid which is at the back of the intake manifold near the firewall. Ther is a proceedure for checking all this in the manual F-133 to 134.

 

I have been driving the car a couple of miles today and the missfires really disturbes me, when I drive at 1500-2500 and get of throttle it really sounds like one rotor missfires, and the motor slow the car down much more.

my boost is also to low at high rpm. only 6-7 psi.