dtrombley

Hey guys, I'm new here but I'm trying to figure out whats going on with the gf's car. We haven't noticed any loss in performance, shaking, change in the sound of the engine, etc - but the check engine light has been on for a couple weeks now, so we stopped by autozone to get it scanned last night. (The one thing the gf did mention was a pretty significant drop in mpg - usually we get around 23ish and she said last time it was 19)

They scanned it, and screen that popped up on their POS said:

codes read:
ignition coil


Possible related error codes:
Misfire cylinder 1
Misfire cylinder 2
Misfire cylinder 3
Misfire cylinder 4
Misfire cylinder 5
Misfire cylinder 6
MAP sensor high circuit value
Random misfire


Which of course makes no sense, because a pcm would never tell you "ignition coil failed" or whatever. But the cashier gave us a print out, and on that print out it did say "Codes Read", and then the above codes. However, based on what I saw on their computer, I can't say I trust it. I'm probably going to get it scanned at advance or oreillys to double check and try and get an accurate reading. But I just wanted to see if anyone has run into anything similar on their TL. The thoughts I'm having based on these "codes" and how the cars behaving are:

1. It was just a fluke random misfire (kind of unlikely based off the drop in mpg)
2. The MAP sensor is going out and affecting all the cylinders
3. There IS a misfire on ONE cylinder, and based off of that autozone's pos recommended a coil, and then listed all codes that could relate to an ignition coil and something got lost in translation when printing out the report
4. It is in fact misfiring on all cylinders, but has no noticeable loss in the butt dyno, sounds like its running great, and has no noticeable or unusual vibrations



Something possibly related, possibly unrelated - a couple days ago (at least a couple weeks after the check engine light came on), i was doing 80 down the highway (in D5, not the shiftmatic), and all of a sudden the D5 light went out, I lost all engine power, and the vehicle started decelerating for about a second. Then everything started working again, engine had full power etc., and it hasn't happened since.


Some maintenance info: Spark plugs were done probably less than 10k - but probably about a year ago (we don't take her car a whole lot), just because of poor mpg and high mileage on the car -231000 currently, transmission was replaced with a reman unit around 210k miles I believe, we never go more than 3500 miles for an oil change and always use high mileage synthetic blend, and always use premium fuel.

justnspace

iTrader: (1)

there's a bad coil pack...
one bad coil pack will show multiple misfires...

find the bad coilpack by unplugging while the engine is on. if engine sound changes, move to the next coil until there is no engine sound change...that is the bad one

dtrombley

Interesting. Normally I would think you'd feel a loss in engine performance with a bad coil. Anyways, I'll try that over the weekend, thanks for the speedy reply!

justnspace

iTrader: (1)

technically, you did.

thoiboi

iuno, to me, that issue sounds like your battery cables are corroded and you had a sudden loss of power. Also when you have finicky battery or cables, it can cause all sort of odd systems including random codes to pop up. How old is the battery? Replace it if old and check the cables for corrosion at the terminal AND along the cable itself. Replace as necessary.

Roblee23

Yep! I remember when a coil went out for the first time, i was like wtf. I got it scanned and it showed multiple cylinder misfire, but after some testing, turned out to be one bad coil by using justn's method of testing.

dtrombley

By the way, do you guys have a recommended brand for coils? My plan is to use rockauto to save some coin

dtrombley

Good suggestion thoiboi. I'll check that as well, and I agree - I've never had a bad coil show that kind of symptom before and the battery sounds more likely (at least for that issue and the cars I'm used to)

justnspace

iTrader: (1)

in for results, then

dtrombley

Okay, when I unplug it, every coil presents a pretty obvious misfire. Battery cables look good and vacuum gauge reads a pretty constant 20 in hg (although it does sound like there is a vacuum leak). I tried the smoke test and using carb cleaner to find a leak, and I can't find anything,

Any suggestions? Should I try just unplugging the battery and resetting the computer and seeing if the light comes back on?

thoiboi

How is your EGR? and thorttle body.


What kind of spark plugs did you put in... I hope they were NGK Iridiums.

dtrombley

I couldn't have told you off the top of my head, but I know I did a good amount of research to get the right ones (I'd always heard acura were picky) and ngk iridiums definitely sound right. Throttle body was fine when looked it over when we did the plugs, not sure about the egr. Looked in good shape from the outside, but I know that doesn't mean shit. What should I be looking for with the egr?

thoiboi

carbon build up. lots of it.

01tl4tl

omg you cant see clogged egr passage and ports from outside, and the valve itself has little to do with the problem of carbon buildup-blockage

I see 2 hours of diy time in your near future
remove intake manifold from car, place on workbench and clean main egr passage with 3 cans carb cleaner and a wire coat hanger- no kidding see diy section
Clean each cylinders egr port same method

Good time to clean IACV on bottom of throttle body and clean inside throat of TB- Deep Creep or carb cleaner are fine

reset ECU by removing the CLOCK fuse on passenger end of dash for 1 minute- then reinsert
Its the secret backup power for the ecu and causes a full system clear- so it will relearn to run properly

dtrombley

well yea obviously I know you can't see inside the egr from the outside.. I just haven't gotten around to pulling it off yet. I'd like avoid pulling the intake manifold off if I can, but if it needs to be done it needs to be done. I guess I'll see what the passages look like when I pull of the egr.

So the IACV doesn't need the sensor safe cleaner? Interesting. And great tip for resetting the ECU, thanks for that!

TLer trash

The one thing I see most often that causes misfire codes you can't feel is tight exhaust valves. I'm guessing you've got more than 150,000 miles. If so, get the valves adjusted.

dtrombley

Been a while since I've been able to even think about having enough time for this car (too many other projects and trying to move), but what is the procedure for adjusting the exhaust valves? You wouldn't happen to have any specs either would you?

Kris9884

Your misfires are pretty much guaranteed a dirty EGR or a coil. Its SUPER easy to get to, just a few 10mm nuts to take off and a plate comes off the top of the intake manifold. You DO NOT have to remove the whole manifold. Use a wire brush and some brake clean and just get it all cleaned out. I bet that'll fix it. I replaced plugs and cleaned my EGR and the misfires haven't been back since.

dtrombley

Good to know, I was trying to figure out how to budget time to remove the while manifold and do gaskets etc. I'll still need a gasket for the egr though right?