Random1

Any help/insights are appreciated, the engine runs great except at idle or below about 3k with no load. Under acceleration the engine runs great including VTEC. My theory is that it may be a single failure common to all cylinders since they all started misfiring at the same time? This is a bit long, but I wanted to provide enough information.

I have read many threads on rough idle and misfires and have tried some of the recommended solutions. I have also used the shop manual and followed some of the trouble shooting paths for the codes indicated below, but there are limitations because the manual assumes a code on one cylinder not four. So, swapping around an ignition coil, spark plug, or fuel injector won

Slows2k

A cylinder leakdown test will tell you if the valves are not sealing.

Random1

Thanks for the pointer.

Should a leak down test should be done with the engine warm like when doing a compression test?

I plan to use a pressure regulator set to 100 psi and the hose from my compression tester to perform this test. What is an acceptable result for this engine? I'll also listen for air sounds at the intake and exhaust.

This is my first time doing one of these.

I'll post the results.

Partshelper

I had three coils go bad at one time, got new ones and it fixed the problem

Slows2k

The engine needs to be at operating temp for a leakdown test, just like a compression test.

yogi

[QUOTE=Random1,May 19 2005, 09:00 PM] Compression test (variation across all cylinders 161

Utah S2K

Random1

That sounds unusual. Were your symptoms the same as mine? I think there is a way to test them in the shop manual, I'll check it out.

Thanks

Random1

The spec is 135-228 psi with a max variation between cylinders of 28 psi. So, my numbers (161-171) certainly meet spec and are 30-40% along the allowable range. I don't know if this appropriate for milage of 48k miles? I don't run the car too hard during the week while commuting, but I do autocross at least twice per month.

I will go ahead and do the leak down test regardless just to be complete. This should happen tomorrow some time.

Thanks

yogi

So it's certainly within spec (on the low end), hopefully the leakdown test will reveal something.