lamar c

OK guys, after exetensive research on this topic and futile attempts to fix my car I am now forced to post a thread. So heres the situtation, I have had the multiple cylinder misfire codes being thrown and pooor performance out of my car for sometime. (Rough idle, only about 14 mpg and overall poor performance). From doing research and diagnostics I concluded that it was the cylinder misfire problem others are having that can be fixed by replacing one coil. Well after doing the coil swap method and not getting any results and a reoccuring CEL (after resetting and swapping coils) I ended up buying a multimeter to test the ohms on each coil to pinpoint the bad one(s).

After pinpointing two bad coils, I replaced these two but I am still having the misfire. When I tested the Ohms i figured out the bad ones were reading around .8 Ohms and the good ones were reading between 1.5 and 1.6 when replacing the 2 bad ones it actually boosted the ohm level of all the coils to around 1.8. ( Is this the proper ohm level for the coils?)So now that all of coils are reading the same levels I am assuming that they are all good, to my dismay this did not fix the problem.

After still getting misfire codes I proceeded to clean the EGR port and when I did I found out that the previous owner of this car already did so. I also seafoamed my engine (lots of carbon build up, did help but did not fix misfire or help misfire) and I replaced my spark plugs with NKG's.

When I replaced the spark plugs I did notice that in Cylinder #2 the old spark plug was over covered with more fuel compared to the others ( possibly fouling it out).

SO there you have it, all igntion coils are reading the same amount of ohms, EGR port is cleaned, engine has been seafoamed and spark plugs have been changed and I am STILL GETTING the P302 - P305 and one that says "multiple cylinder misfire" codes.

I saw that that the moderator fsttyms1 suggests replacing an 02 sensor. I plan on doing that tomorrow, but wich one do you suggest replacing? Tomorrow I plan on replacing the one before the catalytic converter. Is this the correct one to replace or do I need to replace both? If that doesn't fix it what next? ECU?

(I also plan on replacing my EGR valve in which I have already inspected the current and it looks as if it already has been replaced once)

Any suggestions or tips on this issue would be greatly appreciated

o yeah, fsttyms1 - if you could pm me with some help that would be awesome, thanks.

SatinSilverTypS

iTrader: (1)

don't be offended by my questions, i just need to be sure we have all the right info. do you know *for sure* which cylinders are misfiring? i see you said you changed out coi l#2, and P305 is for coil #5, but you didn't mention specifically that you changed that one too. do you know the numerical order? (it's easy to guess wrong if you don't actually know) what did the dealer tell you? or did autozone just give you the codes? i have a spare coil in my trunk so i will try to run out and measure that for you when i take my lunch break.

fsttyms1 knows what he's talking about, so if he suggests changing the O2 sensor i would go ahead and do it. you're only likely culprits aside from that are the plugs (which you changed), oil in the plug wells (which you would have seen when you changed all your plugs), the coil packs (which for now we will assume you fixed the right ones) and the ECU (which is possible but highly unlikely).

maybe someone else has an idea that i missed, but i would say that you should get detailed codes from the dealer first.

fsttyms1

Typically its the front O2 that ive seen cause it. BUT before you go any further buying stuff, try some more things. If you feel comfortable doing things, take the intake off and clean the EGR ports throughly. While its off, swap the fuel injectors from front to rear and see if the misfire follows (put a dab of vasaliene on the o rings and they will slip right into place) . If not Do a compression test to see if the ones affected are worse than the non. Also while the intake is off inspect the wiring to the coils as good as possible. The last thing would be to have the dealer test out a known good ecu to see if that solves the problem

turbobore

In my 2002 RL I have had a multi cylinder missfire for several weeks now. The shop had the car for several days and can't find the problem so I may have to take it to the dealer to see if they have encountered this before.

The following have been done. New plugs, EGR system cleaned, coil swap check, extensive computer diagnostics and diagnostics by the mechanics and they can't find the problem.

Has anyone else had this problem and if so what was the remedy. Please, no suggestions for basic diagnostics as the mechanics have tried all of those. I need a solution or fix from someone who has had this problem fixed.

01tl4tl

this is the TL section- please post your needs in the RL area for better help
But way to find a 3 year dead thread!!

if the techs cant figure it out it needs the dealer at this point
can be so many things that beyond the basic test its a guess

most TL-s with multi misfire has been one coil failed