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Okay guys, i have a problem here with my 3.1. It started to "jerking" when the engine was cold, idle was okay, hold it without problems but i heard somethings not right, when i hold my hand to the exhaust i feel how the engine runs little rough. When the engine was warmed up it was just fine, no problems at all. After 2-3 days it got worse it and it was jerking in gear when the engine was warm too. Sounded pretty much like "little" missfires when accelerating.. it also was some lazy to rev up the engine. It went so bad that i didnt even drove the car for some days and i orderd a set of ignition coils. It was pretty loud under load (exhaust popping) and was really lazy in every rpms. After that i put in new ignition coils and i got better. Ignition plugs and wires are installed about 3000km ago.
As i said its better now but somethimes it still runs not that good and has little of missfires and dont want to be rev up that nice, just feels lazy and i can hear it poping from the exhaust when going truh the gears. That was 2 days ago, yesterday it ran like there was no problem at all... then today drove for some minutes and it again did it from when i started the engine....
Kinda weird cause i have that problem one day and the other day it runs fine...

My first guess was a igntion problems, thats why i changed out the ignition coils... they were 20 years old. But know i think it could be a injector problem too. What do you guys think?
It also dont want to give me any trouble codes and i am not that good on tuner pro to read wheres the problem exactly.

Check your fuel rail pressure. Might not be getting enough fuel to the injectors. Might not be a coil problem at all, but I would start there.

Well i pulled the plugs on the front to see if theres anything wrong on the plugs and will pull them on the rear tomorrow. How do you guys check which injectors is bad?
I hope i can see tomorrow when i pull the last 3 plugs on which cylinder the problems is since its running on 5 cylinders alot...

i had 2 bad injectors in my 3.1 made it run a little crappy, i also had to replace the crank sensor at one point and o2 sensor runs like new again.

check fuel pressure to start, then get a ohm meter and test the injectors, should be around 12-13 ohms if they are 10 or under or 15 and above i would change them, you will probably only find 1 or 2 that might be bad if your lucky.

check vacuum lines too.

I wonder if its a bad connection at the ECM that is pretty common on the older cars, little bit of moisture and the plugs get corroded pretty quick.

Ok thanks guys. i fixed the problem. One i have learned... never trust plugs and wires, even if they are "new". I pulled the ignition plug on cylinder#1 and it was shot pretty bad... The plugs have under 5000km on it. The rest was okay, i put 3 used bosch plugs in... I dont remember what brand these plugs were but i think the old bosch's are better, lol.
It runs very nice now, i think the ignition coils were worth it too.