Hey everyone, I need some help here.
Working on a 99 SL1 automatic.
Car is normal in netual and park, but in reverse or drive car misfires and idle is rough and the gas smells very rich. Also shifts hard while driving.
Just replaced:
throttle position sensor, MAP, idle control valve, O2 sensor, tempature sensor, ignion coil packs, spark plugs ( yes the NGK (7755) BKR4ESA-1) and wires, PCV. Also cleaned egr, throttle body, and sea foamed the engine. All of the above got rid of the codes, so the only code I'm getting now is "misfire".
car has bad days and good days so I want to rule out fuel filter and CAT since those parts should ethier be working or not - no inbetween, right?
Im stumped.
thanks in advance!

 

What codes were there that disappeared?
how did the car run with all of said codes?

How many of those parts did you seemingly throw at the car at once?

From where did you source the parts?

Have you done a compression test?
Which misfire code? Cylinder specific 030X? Or random misfire 0300. Makes a huge difference.

Thanks

 

Thanks for your reply.
I got the car running for now (fingers cross) but in case this is helpful to someone else:
I think I had several failures at one, maybe bad luck or maybe they caused each other.
The car is a family members and they didn't describe the symptoms very well. From what I think happend was about 1 or 2 months ago a misfire was happening and I unknownly put iridium plugs in. Car was fine for a few weeks then ran horrible: rpm was serging and it wouldn't accelerate, drive under 40mpg, etc. At this point it only had a egr and stall code...It had no misfire code. I pulled the map sensor off and set it aside and there was no map code ethier for some reason. So I changed the TP sensor (and a bunch of other sensors) and it stopped serging and seemed fine for a day, then it was stalling and misfiring in D and R again, It finally had a misfire code p0300. I pulled 2 wires at once, saw that they both were not contributing, noted both was to the same coil pack so I replaced the pack. The car was fine for 3 days....then it wasn't, another misfire code p0300. It was back to low rpm in drive and reverse, but it idled fine in P and N. I replaced the ICM last weekend and car has been fine since (actually runs better than ever with all that new stuff I did).
But it might be to early to tell since something else fails every other week 😅 lol.