Tom Jr

I've had the rough idle / misfire on all cylinders issue for a little while now, so I've been reading up on it. I started a new thread so as not to hijack someone elses, not to mention the problems are not always alike.

Background:
The car is a 2002 with about 45000 miles. I bought it used on 2004 with 4000 miles on it. The only 'mods' I have are a replacement K&N air filter and a T1R dual sparrow exhaust (with cat, no test pipe). My driving habits are generally benign, with the occasional spirited acceleration. No racing, no tracking.

The symptoms:
This started with the standard studder at the stoplight issue. This has existed since I bought the car in 2004. Last November (11/2006) I performed a valve adjustment and replaced the plugs (OEM NGK's) while I was in there. The old plugs were a bit white, indicating a lean condition, but otherwise looked pretty healthy. I replaced them anyway.

Over the winter and into this spring, the idle got steadily rougher, and I eventually started getting a CEL with a few misfires. This grew, over a month or so, to misfires on all 4 cylinders. The car generally seems to run well, but there is clearly a problem.

What I've done, so far:

Checked air filter - it's clean.

Checked plugs - they look like the old ones did, with white-ish tips. No oil on the tips, but some near the washer. There were trace amounts of oil in the plug tubes, but only at the bottom. I posted about it and Billman thought it might be bad plug seals. The plug tubes seem to be clean though, apart from the very bottom, so there seems to be no evidence that oil is getting past the seals and running down the tubes.

Compression Test - I performed the test as shown in this thread. The numbers were 226,224,224,225, so things look good there. I assume, from these results, that I shouldn't have oil in the combustion chambers. Correct me, here, if I"m wrong.

MAP Whack - I tried this, per the instructions in the FAQ. I also sprayed the contacts with electrical contact cleaner.

New MAP sensor - I replaced the sensor with a new one (with the zip tie). I sprayed the terminals with electrical contact cleaner again.

Misfire troubleshooting Tree - From the shop manual, I performed all steps that didn't have to do with swapping things, since the codes were for all 4 cylinders. I also skipped the ECU checks, since I don't have one to swap. I checked the coil pack connectors for voltage and continuity, and I checked the injector connectors for voltage and continuity. The injectors showed 13.5 ohms, where spec is supposed to be 10-13 ohms. This might be my meter being out of cal.

Inspected injectors - The injectors had quite a bit of gunk (dirt and oil or fuel?) on the ends, though not on the tips, very similar to what Random1 found in this thread, on page 2. I cleaned them with engine cleaner and put them back in. The idle seems a bit better, but not really good. It might be a placebo effect.

What now?:
At this point, per all the reading I've done here, it seems like new injectors might be needed, but I really don't want to treat injectors as a maintenance item. Any suggests people might have would be appreciated.

I'll keep this thread current until the problem is solved, for the benefit of future searches. It'll be yet another data point in people's quest for answers.

CKit

Did similar decision "tree" complete with replace MAP.

Professional 3-step fuel injector cleaner solved the problem completely for 17k miles. Now returning a little, seeing if the over-the-counter stuff will be fine for mild symptoms.

JimmyB

It maybe as simple as cleaning out the throttle body. Before I replaced mine cleaned it out and the car idled much better. Hey it is worth a try and it can't hurt. Good luck.

negcamber

Had the same symptoms...replacing the injectors did the trick.

There is a long thread about the misfire codes and various solutions...just about always solved by new injectors (not used or just cleaned...that just delays replacing the injectors)

Eluded

who knows, i thought mine was the injectors but the head was ruined You have good compression so your ok.

Honda_mann

coils? timing? did u check those things?

Tom Jr

Thanks for the suggestions so far. I'll do these this weekend:

Clean out throttle body
Timing check
Coil check

How, exactly, does one check the coils? I wasn't able to find anything in the shop manual. Perhaps I'm just not looking in the right place. I have an electronics background, so I'll be able to do whatever it takes, but I can't find a procedure.

EDIT: I just looked at the shop manual regarding timing. It seems I need to set an HDS tester in "SCS" mode. I don't have a tester at this time. Is there any other way to do it? Otherwise, can anyone recommend a good tester? I've read about scantool.net. Any opinions?

Thanks again

Honda_mann

unplug them one by one and if the and misfire doesnt change when say you pull cyl 3 you have isolated the cyl. is that clear? there should be markings on the timing chain cover/crank pulley, & cam gears. if im correct?

MikeyCB

I'm getting a strange rough idle as well now, without CEL. My exhaust makes a little pop sound every 3 or 4 seconds now, and the car gives a slight vibration.

From time to time I put my foot on the gas to go a little quick and it bogs for a second. That's not common though or easy to replicate.

stphotographer

I had the same symptoms last week, it was due to a bad spark plug. You mentioned that you inspected them, Try replacing all of them with new ones instead.