I'm looking for some opinions on troubleshooting a couple problems I've had. I have an '05 5AT with 52k miles.

My problems started out with with a shudder/vibration coming from the engine bay when I had the A/C on, car in drive or reverse, and at idle (ie. foot on the brake stopped). After reading through many posts I pinpointed bad motor mounts. After reving the engine in drive with the brake on I (thought I) saw about an inch or two of play...thought that might be 'excessive.' So I changed the front and side motor mounts thinking those are the most common failures. The shudder at idle did not go away. So I bought and installed a brand new rear motor mount and inspected all vac lines. Still no dice...the shudder didn't go away.

A day after installing the rear mount I went to start my car and noticed it was very rough. I proceeded to drive 4 miles on a highway home...on the way the check engine light came on and continued blinking. I put it in the garage and later that night went to O'Reillys and pulled the code with an Autoxray. The code was P0302 'cylinder #2 misfire.' After searchin on AZ I found it could be a multitude of potential causes including: spark plug/wire, coil pack, O2 sensor, ecm, etc. I drove home all while the car running very rough..misfiring no doubt...once home I switched the coil pack from cylinder #2 to cylinder #1. Car started up and ran normally with no misfiring.

So here I am a couple days later and the code hasn't come back. Unfortutely my shudder at idle is still there...it actually happens when the car is in neutral now. I'm thinking it may be a bad coil pack that is causing the rough idle...or possibly an O2 sensor? I haven't had any other codes come before or after this.

Does anybody have any opinions on whether this could be an electrical problem? Have I missed any troubleshooting? I hate to go buy a new coil pack just to see if that is the problem as I've already done that with 3 motor mounts. Sorry for the novel...just want to be thorough.

 

Make sure all your wirings is solid. I'm guessing it might have vibrated loose or something. Not really sure at this point. I would doublecheck the plugs just in case. Not hard to do anyway. Make sure all the contacts are good and clean. Sometimes corrosion gets to it and so the contacts fail.

 

Plugs, coil packs, wiring, in that order. Can be an ECU but not likely.

Pull the plug on cylinder 2 and see what you've got. You will either pull the plug on the coilpack while taking it apart and find that it's loose or has water in it. You will pull the coil off and find that it has oil in the hole from a bad valvecover gasket or that the coil is broken on the inside. If you get the plug out you can read it and see what that cylinder is doing or if the electrode is broken off.

If the plug is super clean like brand new you may have a blown headgasket.

If it's black you have a bad injector (not likely or it would have 02 codes as well) or it's burning oil on that cylinder.

If you can find no problems do a compression check while you have the plug out.

You can always have a bad fuel injector that's not firing.

Do you have a miss when the engine is under load or only when it's at idle?

Generally ignition problems show up more when hot and when under load.

Compression issues usually show up at idle and appear to go away once you put a load on the engine and raise the rpms up.

 

I missed the part about switching coil packs.

Most likely you have a weak/bad coil. On it's original cylinder it caused the plug to foul over time and eventually you had a dead miss. Switching the good with the bad allowed the fouled plug to fire and the good plug to "sort of" fire with random misfires.

 

Thanks for the replies!

IHC, I pulled the #2 plug and compared it to #4 and they look the same...neither look very fouled. Only camera I have is on my phone and its not good quality. Here's a link.



http://picasaweb.google.com/lh/photo...eat=directlink

The plug on the left is a 'good' plug and the plug on the right is from cylinder #2.

Do you think these possible dead misses from the bad coil may be the cause of the shudder at idle? I think the next logical step is to order a good coil pack and move it around until I see a change/improvement. Would you agree?

The car seems to run fine above idle and I only see the shudder at idle (mostly when in drive or reverse). Do you think it is worth getting a compression kit and testing the #2 cylinder to make sure the compression is good?

 

Those look perfect from what I can see. The gap looks really small on the one on the right but it may just be the picture quality.

At this point I would lean toward the coils.

I would do what you suggested, move the coil to another cylinder and see what happens. Obviously if the miss follows it to the new cylinder problem solved. If it stays on the same cylinder, move the plug to another one.

Just be quick because any sort of miss is hard on the catalytic convertors.

 

whats the porcelin part of the plug look like? Make sure theres no black lines on it. Black spots you can wip off with your finger are ok but iif you cant you have an arching plug or cracked plug

 

Porcelin section of the plugs looked fine...no major black spots or damage from arching

 

UPDATE: I just got a new coil pack and switched it with the old coil packs looking for improvement after each switch. The third coil I replaced seemed to fix the problem. I have been driving it for a day and the shudder at idle is gone. I am still a bit apprehensive to say it's totally fixed...but so far so good. I will give an update in a couple days after I'm sure...

 

Did the shudder disappear completely? I'm getting the same vibrations but I feel like it could be my steering pump...is that even possible?

I have the car in neutral and rev it real quick, as the revs slowly come down i feel a shudder around 1.5-2K rpms??

Any help would be appreciated!

 

Car is completely normal after coil replacement.

Why do you think it has something to do with the power steering pump? Does it only shudder when you turn the wheel? Please give a complete description of the issue...when it shows up, in gear or neutral, forward or reverse, A/C on or off, car stationary or moving, shudder only when rpms are decreasing, etc. Answers to these questions will help diagnose.

 

I've done a little dielectric grease on the plugs into the coil packs on a Ford before to help with smoothness. Of course it was after a tune up so that may be the only reason I noticed an improvement. Did you buy the coil pack online from Acura?

 

OEM coilpack from one of Azine vendors (acura dealers). It's actually a shared part number with accord V6.