I did the coil swap and CEL came back the next day....same exact 3 codes...300, 301, and 302. So that rules out the coils right? Or maybe not? And the plugs are tight - ruled out.

Next up compression test tomorrow. Please let it check out good.

 

Do a plug swap ( or new plugs).Next an injector swap.Wish you good luck and hope it's not a valve issue,wasn't for me.

 

Compression test results:

Cyl. 1 - 195
Cyl. 2 - 210
Cyl. 3 - 210
Cyl. 4 - 245

Not exactly the results I was hoping to see. Seems too big a difference between 1 and 4, I'm going to re-do the test again tomorrow to verify.

So am I right thinking if I still have these numbers the next step is check valve adjustment and have a look at the retainers and after that a another compression test and if still bad a leakdown test?

Or should not worry too much about these #'s and go forward with the injector swap?

 

Didn't get time to re-do the compression test but I did swap spark plugs while I had them out. They were all burning good...all light brown and gaps were within spec.....swapped #2 with 3 and # 1 with 4. I also cleaned my CAI filter for good measure.

So now I'm going to drive it again until the CEL comes back and re-check codes to see if they moved with the spark plugs. Then if they didn't move I re-do the compression check again to verfiy the #'s I got the 1st time and go from there. Can anybody say for sure if it's a bad plug, coil, or injector and you swap those items the codes WILL move with the problem? Again the 302 shows everytime so far and the 301 and 300 have also come up but not everytime.

I'm still inclined to keep going down the check list and checking things before I have to take it somewhere for the valves. I know the compression #'s aren't what they should be but are they bad enough to cause misfires? Would the valves needing adjustment possibly cause these kind of numbers? Any thought's

After seeing the compression numbers I got I'm a bit worried about even driving it...as in can it suddenly implode or something? It runs perfect except for maybe a little rough idle and even that may be my imagination. No weird noise or smoke and uses absolutely no oil. If it were not for the CEL I wouldn't even know anything is wrong. I definately do want to pull off the valve cover and inspect the top side and do a valve adjustment.

 

4 trips of 35-40 miles each with cool down period in between each and a couple short trips and no return of dreaded CEL light yet.

The amazing thing is how good it's running now.....idle is perfect and low rpm throttle response is much better. Purrs like a kitten. Go figure... the air filter was dirty. I just cleaned it cause I was already working on my car...not thinking at all that it might be the fix.

Do you think.....that possibly all along the root cause of the CEL was the air filter?

I guess you could argue it was bad gas and the Lucas finally doing it's job since it was towards the end of the second tank with Lucas mixed in the gas that it started running better. My vote goes with the air filter.

 

Could have been a combination of things but your air filter would have to be pretty bad to cause misfire codes.I had the same issue as you and my air filter was clean and relatively new.My vote goes to bad gas and you just had to run the tank out.I know since I started using the Lucas snake oil my car has never idled so smooth.Glad you resolved it and there were no major problems.

 

I think archtop is right...a combination of both. I know for sure I'll be cleaning my air filter more often and I'll keep using the Lucas. And I'm still going to adjust the valves. Just hope that light stays away.

Edit 8/13: So far so good. However not ready to call it fixed just yet. Time will tell..

Edit 8/19: CEL came back. Same codes 301, 302 and 300... I reset those and the next day got a 302 only. This weekend I intend to swap injectors... valve adjustment comes next when I can get to it. The cars runs fine when warm but with the a/c on the idle will drop really low and almost stall when coming to a stop also if you rev in nuetral and let come back to idle with the a/c on it will drop to really low idle and then recover to normal. Seems better running but something is definately still wrong.

 

Did another compression check, this time with a good warm engine:
#1 - 200
#2 - 215
#3 - 215
#4 - 245

So that pretty much verifies my first test and to me these numbers don't look all that good....but yet to me at the same time not conclusive. Any opinions?

The problems I have with these compression numbers being the cause of my misfire codes:

1. I always get # 2 cyl misfire code and sometimes cyl. # 1 misfire code but never have had a code on cyl's 3 or 4 ......... so why am I not getting a code on #3 when it has the same compression results the same as #2?
2. And why do I get cyl #1 codes only some of the time when it's the worst cyl?

I guess I need to check valve adjustment and re-test.

 

Misfiring came back recently. I noticed the bottom of the coil packs look burnt. They have a brown tint to them where they meet the spark plugs and I've already tried changing the plugs once.. Is this common, or could I have bad coil packs?

I'm going to try to borrow a buddy's coil packs as well, just thought I'd ask in case anyone thought this might lead to believe the coil packs need to be replaced.

Thanks.

 

So now it's not idleing rough with the a/c on like it has been....I didn't do anything...seems to have corrected itself. So now I'm wondering if the CEL light will stay away since that rough idle with the a/c on was when it all started.

Although I'd like to know what is definitely causing this CEL this actually makes me feel a bit better about the whole thing....a bent valve would not fix itself...so this development seems to rule that out. We'll see.