Got a CEL about a couple months ago. First time I blamed it on a loose dipstick. CEL went away for about a month and then came back. Pulled the codes this time - misfire cyls 1, 3, 4.

Ran some injector cleaner and swapped #2 & #3 injectors. CEL stayed away again for a couple more weeks, then came back with same codes.

Car seems to run fine - I have never observed any obvious misfiring.

Did compression check:
~250 psi in cyl 1, 2, & 4.
195 psi in #3. (then 250 psi with wet check - after pouring in a couple teaspoons of oil)

Did valve adjustment for good measure - exact same compression numbers after.

So - 195 psi is within spec itself but the max cylinder to cylinder variation is way out of spec (50+ vs max=28). My understanding is that all this points to the piston ring or cylinder wall, and may only be fixed by rebuilding the engine? Any other possibilities I might be missing? Why would I be getting codes for 1, 3, & 4 if only #3 is off?

How bad is this? Should I stop driving the car completely? Or if I will be needing a rebuild anyway should I just keep going for now? Will I damage anything that isn't already damaged?

 

if u aint burning any oil, then i wouldnt worry about it yet.

 

You can try a can of Restore (not a cure but, a band ad) It comes in a silver and black can. The stuff works It should bring your numbers a little closer in line with each other.
Good luck

 

If you are rebuilding soon this stuff will hold you over but i wouldnt recommend on a regular basis

 

For the misfire codes...the fix for most folks is a new set of injectors.

On the compression...as others have said don't worry until you are ready to rebuild.

Might try some Seafoam through the intake on the off chance that it is just a sticky ring rather than a cracked one.

 

[QUOTE=S2KPUDDYDAD,May 30 2007, 05:22 AM] You can try a can of Restore (not a cure but, a band ad)

 

i might be in the minority but when i see misfire and low compression i think head damage. The AP1 S2k head has lots and lots of problems... mine was rebuilt around 30K, never over rev'd, always taken care of....

 

Still not clear what the consequences of this are?

Again, the cyl 3 is within spec itself, its just the max variation that is out of spec. Subjectively the engine seems to be running fine. Not much oil burn. No audible misfiring.

I agree symptoms may be pointing to head damage (BTW in this case AP2). Perhaps pretty minor though?

Still confused about whether this is a problem that needs to be addressed immediately? Or if it makes sense to just carry on for now (maybe try the seafoam) and plan for a rebuild if/when the problem gets noticeably worse?

Will continuing to run this way for now make the eventual rebuild more difficult/expensive? Will it break anything else on the car?

 

The problem isnt your #'s its that you have one cylinder that is 55 out. That is a 20% difference. This could be causing unforeseen problems as that one cylinder will be running much different than the other 3. Odd that you dont get the misfire for cylinder 2 though. Would seem to me that as far as your codes go you should get misfires for 1, 2, and 4 are you sure it isnt the #2 cylinder that is bad?

 

Cylinders are numbered front to back, right? If so the misfire codes I was getting don't make sense to me either...

BTW - I don't even have a CEL at the moment - went away after the valve adjust.