I'm new to this forum, not a DIY guy, and I know this issue has been raised umpteen times here, so I hope you don't hold this post against me. I read a number of responses to other posts on the check engine light issue and think I know what's going on, but I'm hoping folks here can help narrow down the problem.

The check engine light issue for me started last fall about 2 months after I got the big 105K mile service. The light started flashing when the car was idling, but then went off. No problems again until January of this year when the light came on solid. Dealership cleared the codes and said there was no problem. Engine light came on two weeks later while I was idling at a stop light. Dealership indicated I had a misfire code on cylinder 3, which they fixed. Check engine came back on about 5 hours after I picked it up while I was idling in my driveway. The dealer wanted to charge me $2K to send the engine to a machine shop. I said no way and got a second opinion. The second mechanic indicated I had a coil pack issue, which he fixed. The engine light came on again at idle about a week later. I took it back, he cleared the codes and found nothing wrong. Then I drove the car for about a month with no problems. The check engine light came back on. Took it back to the mechanic and he indicated that I had misfire codes on all of the cylinders. He did a fuel line flush and cleared the codes. The check engine light came back on before I could leave his shop. He cleared the codes again and I picked the car up yesterday morning. Drove it with no problems yesterday. This morning while I'm idling at a traffic light, the check engine light starts flashing and comes on solid. Took it back to the mechanic. He found misfire codes on four cylinders but insisted there was no major problem. Codes cleared and I have the car back.

Some important notes:

1. I always use 93 octane.
2. The compression check always comes back fine.
3. I have not experienced a loss of power, even with the check engine light on. Car always seems to run fine.
3. There have been a couple of instances where the car seemed to struggle to turn over on start up, as if it didn't have enough fuel or something.
4. If I keep my foot slightly on the gas pedal at idle, that seems to prevent the check engine light from come on.
5. The car is a 6-speed manual with almost 126K miles, (mostly highway)

Sorry for the glut of info. Hoping I can get some answers here.

 

1. Are you the original owner?
2. Are you certain the engine has never been over revved?
3. Were the valves adjusted during the 105K service?

 

I'm not the original owner (one previous owner - bought the car at CarMax with 30K miles on it) and I have no reason to believe the engine has ever been over revved. Not sure if the valves were adjusted at the 105K service but I can find out.

 

Can you post a complete numerical list of all the codes thrown? Also, the next time you get a MIL, take the car to any auto parts store (not your mechanic) and have them read ALL of the codes. (This is a free service).

The reason I asked about a previous owner and over rev was this thread:

https://acurazine.com/forums/3g-tl-problems-fixes-114/intermittent-p0300-related-codes-815212/

Read it, especially the last post.

The reason I asked about the valve job is because they have to remove the intake manifold for that. This could result in a vacuum leak due to a bad gasket, improperly installed or torqued ITM, or vacuum hose left off. Also, there are about 6 or 7 sensors that have to be disconnected and failure to reconnect one or more of these sensors could be the cause, especially the IAT or MAP sensors.

Who did the 105K service? If they did a valve adjustment, I'd go back to them and make sure they hooked up all the sensors/vacuum lines and used new ITM gaskets.

 

Yeah, I saw that post and it scared the crap out of me because that was the recommendation of the dealer after they couldn't figure out what was going on. I'm not prepared to spend that kind of money to get the car fixed. The dealer did the 105K service, so I'll see if they can check it over to make sure things are OK.

I noticed in some of your previous responses to this problem that you recommended getting the ECM flashed. Is that something you'd recommend in this case?

 

I'll get the codes read the next time the light comes on (which, based on the rate it has occurred in the last couple of months, should be any day now... )

 

Getting ECM reflashed can't hurt and I believe the '05 has a TSB for a reflash. It's always best to have the latest firmware. However, I doubt that it will fix your issue.

I'm suspicious of how this didn't happen until after the 105K service.

Yeah, like I said, don't go to the dealer. Use an auto parts store so you know you're getting the full picture.

In the meantime, try to find out if they did a valve adjustment. If so, then we can discuss checking the various sensors/vacuum lines for proper connection

 

Yep, but it didn't happen right away. Started happening about two months after the service.


OK. Thanks!

 

so when did the car overheat?
sounds like a clear case of blown headgasket. dont think a burnt valve might be at fault,since there was no indicatoin of heavy smoke

 

Where did he say that?

 

Oh, sorry. Missed that time lag. Could still have a bad sensor. Could be a fuel pressure issue, but I kind of doubt it since it seems to run OK under high RPMS.

Usually a MAP sensor will throw a code, but not necessarily so for the IAT.

Need to have the codes and we can go from there. Also, do you have a print out of everything that each mechanic did to the car?

 

Never overheated and no loss of coolant. My mechanic says it's most definitely NOT a blown head gasket.

 

I have all of the service records from the beginning of the year that I can scan in if that will help.

 

Call the dealer, or check your paperwork, and see if they adjusted your valves. If they put any of them even a bit too tight, then you can get misfires every now and then... especially when it gets cool/cold.

You can really damage a car if the valves are not adjusted right.

When your mechanic said that it was definitely not a head gasket, did he do a leak down compression test on your cylinders? A compression check could tell you if the valves are not adjusted accurately.

 

Can't remember if a leak down compression test was done or not. I'll need to check the service record. Anyway, the light came on again this morning while I was idling at a car wash (natch). Took it to AutoZone and the following codes came up:

P0303 - cylinder 3 misfire
P0304 - cylinder 4 misfire
P0306 - cylinder 6 misfire
P0300 - random multiple cylinder misfire

Engine light is out now. Car seems to run fine. Even had it indling at one point for about 10 minutes with no issues.

Thoughts?

 

Need to know if they did a valve adjustment....

 

Looking at the invoice from the 105K service (done last July at 110K miles). Here's what was done:

New oil filter
New drain washer
Six new spark plugs (SKJ20DR-M11)
New timing belt
New tensioner
New water pump
New compressor belt

No mention of a valve adjustment. I went to the dealer for the first time about the engine light in December 2010.

Helpful?

 

More info:

P0300 code detected by dealer 12/16/10 - reset and test driven by dealer with no problem

P0303 code detected by dealer on 1/28/11 - -injector replaced by dealer on cylinder 3 on 1/28/11. Engine light came on again about 5 hours after I picked it up

Coil pack replaced by indie mechanic on cylinder 3 on 2/4/11. Engine light came on a week later. Codes cleared. No problem until about three weeks ago.

BG fuel induction service by indie mechanic on 4/19/11

 

They used Denso instead of NKG for plugs. Shouldn't be the issue, but NKG seems to be the preferred plug.

You might pull #4 and #6 plugs just to take a look.

 

OK, thanks!

 

Here's a summary of the SM troubleshooting procedure for random misfires:

1. Fuel quality?
2. Plugs.
3. Fuel Pressure
High-replace regulator
Low- check pump, fuel feed pipe, filter. If they're OK, replace regulator
4. Check connections at coils, injectors, and ecm

I left out replacing the injectors and coils since you've already done that.

 

Awesome. Thanks! It's been more than a week now since the engine light last came on. I've bookmarked this in case it comes on again.

 

 

I'm also having similar issues with my 06 MT. Will improper fuel pressure not throw a code of its own?

At 96552 miles I got a code for misfire cylinder 6, so I replaced all my spark plugs with NGK IZFR6K11 plugs. That did not fix anything.

Now I'm just over 100k miles, and I just read 12 codes off the car (misfire in cylinder 6,3,random,1,4,5,2,6,1,2,4,random).

The check engine light would go on and off and blink sometimes. I haven't experienced any drivability issues, and I don't want to throw money at it, so that's why I haven't taken it in yet. Plus, initially, it was just cylinder 6, so I was planning to switch the coils around to see if the misfire would move to a different cylinder.

High RPM power is just fine and idling is usually ok. When I first start it in the morning, it sounds kinda funny, like it's stumbling (just during the cranking), but the idle RPM seems ok (it doesn't rev up or do anything that unusual). Warm starts are fine. MPG hasn't changed.

Last dealer service was back at 76k miles for the power steering hose recall. I've been changing the oil myself, and I take it to Firestone for tire stuff.

I'm getting ready to take it in for a new TB and related items (water pump, valve adjustment, tensioner, belts, TB adjuster, idler pulley, thermostat, side engine mount maybe?). I don't want them to tell me I need 6 new coils and then all kinds of other stuff that won't fix the problem, if I even have one.

Any idea what to do next? Thanks in advance.

 

I just noticed this thread. I wonder if this could be the problem.

https://acurazine.com/forums/showthr...6#post12960316

Also, a correction to my earlier post. It does idle a little funny. Sounds like a "muscle car," i.e. not smooth.

 

Ok, here's the plan. Let me know what you think.

I'm gonna take it to Firestone for a compression test. Most likely, it will indicate problems.

They can then take the heads off and send them to a machine shop.

http://terrysmachineshop.com/

Firestone quoted me $900 for labor plus the "time it takes to switch stuff over."

I called the machine shop and they said it would cost $650-700 to work on the heads.

How does this idea sound? Much better than the $4200 that the dealer quoted me. Another Acura dealer quoted me $1700 just to take the heads off and put them back on.

I know for sure I overreved accidentally, so would it be better to just skip any other diagnostic procedures? If I get a valve adjustment now and it doesn't fix the problem, I'm out $300-400. I guess the flip-side is that if the valves are fine, then I'm out $1000.

The machine shop also quoted me $80 per head for a valve adjustment.

Is there anything else I could have the machine shop do to the heads that could improve performance and not negatively impact fuel economy?

What to do?

 

get a leak down and compression test.
then decide from there.
650-700 is not bad for some head work

 

Thanks. Will those tests be able to differentiate between bent valves and the need for a valve adjustment?

And I'm wondering why replacing a few valves would cost $700. Does it require special skills/tools?

Is it possible to have slightly stronger springs installed so that the chances of this happening are reduced?

I wonder if I should have them replace all the springs since they're in there already...

 

Engine light came back on this weekend while idling, throwing multiple misfire codes. Took it to a Honda/Acura specialist this morning. Diagnosis: The tiniest of cracks on the spark plug for cylinder 5. So tiny I could barely see it. Mechanic said it either cracked on installation (it was one of the replacement plugs I got at the 105K service) or it was cracked when it came from the manufacturer. I've basically been running on 5 cylinders since November. Anyway, plug was replaced and car runs fine (for now). $60 repair.

 

very doubtful that will fix it. but for your sake i hope it does. i cant imagine having a major headache like the one you seem to be fighting

 

I have the same symptoms as the original message in this post. At idle, the car would misfire badly and there was a shake to the engine.

I took the car in for a valve adjustment and that seemed to have corrected the misfiring issue for not even a day. The check engine light came back on and I have yet to pull the codes (happened today), but I am assuming it is the same issue, even though the car runs a lot better.

I am currently having the place put together a quote for going in and replacing valves within the car... I am uncertain if anyone knows how much this should cost and if this is the best course of action.

Thanks in advance.

 

So far so good, although the engine light did flash momentarily last night for about 10 seconds while the car was idling. It went away when I tapped the accelerator. Time will tell...

 

The quote I got from the dealer was $1800 just to remove the engine from the car and ship it to a machine shop.

 

Yea, grand total would be $3,078.58 for worst case scenario. This price would come down if not all valves were bad etc. They said that this would solve the problem with the misfiring. Does this seem reasonable?

FYI, included is the machine shop charging $1,400 for all cylinder heads.

 

I don't know if it's reasonable. I'll leave that for other more knowledgable members of the forum. All I know is that I'm not prepared to pay that kind of money for my car. That's way too much to spend on an '05/'06 TL with over 100K miles IMO.

 

I purchased my 04 TL 6MT with 66.500 miles. I now have just over 96.000 miles. Engine has ran great since purchase, did the normal cold engine start up procedure for emissions and no other problems. I have not mis-shifted the car, etc.

1 week ago or so, I noticed for first time the engine would crank over 2-3 more times before firing. Nonetheless, always firing. Just a few days ago, first time I ever seen CEL turn on. It was a permanent code, would not turn off when engine turned off (did this couple times). Using my mechanic friend's expensive Snap-on scanner, I pulled codes P0300 and P0301 thru P0306 (random misfire and all cylinders misfiring). Car ran fine with CEL and scanner did not detect another misfire on any cylinders while idling for 30 min+ while I was diagnosing, researching.

The scanner provided some tips, read them all. It noted several techs in field that observed several higher mileage TL's with tight exhaust valve lash that through same codes. They noticed MAP sensor voltage on good idling engine was 0.9 - 1.0 volts. Mine was 0.78-0.8 volts at idle. Scanner would not clear codes, had to pull the negative cable. It has been 4 days and no codes since.

Given my vehicle history, I have maintained all my Hondas myself meticulously, I am thinking I could benefit from a valve lash adjustment at 96K+ miles. This would be the first for this car in my possession (since 66.500 miles).

BTW, I drive about 85% HWY, 15% CITY and this car has given me 29-30 MPG consistently depending on how I drive. With more than 90% HWY driving, I can get up to 34 MPG.

I will update when I do valve lash adjustment and my results. Also, I will update if I receive any codes afterwards.

I'm wondering for those that know their vehicle history and maintain their engines, perhaps we are lucky and just need exhaust valve lash adjustments? I'm still learning this engine (first Honda V6, first OBDII vehicle and first DBW). I know Honda OBDI and prior very well, maintained and repaired several of them.

 

FYI...EGR valve is also under suspicion.

 

It seems most in this thread have a rough idle issue. Mine does not (except when cold engine start, going through emissions procedure = normal).

However, I have notice for first time in past week more cranking required before engine fires. A couple days after this issue started is when I got my first and only CEL/MIL. These were the codes P0300 and P0301-0306, misfires.

I am starting to think that perhaps I have a fuel pressure regulator leak, indicated in one of the TSBs. My longer cranking systems are much like what an engine does after replacing a fuel filter, takes a bit for fuel pressure to develop and then fires.

Tight exhaust valve lash is still suspect. However, I do not think I have bent valves or EGR problems. I received information from a member with TL EGR problems and my symptoms do not match his, he had very rough idle problems with other codes thrown.

So I'll perform valve lash and timing belt job when I reach around 100K miles, see what results are. If issue still exists, will look into fuel pressure regulator leak, replacing O-rings. EGR would be final suspect part, if it goes there.

 

It's been about 2 weeks since I had the first CEL codes indicating misfire on all cylinders and P0300 random misfire. These codes have not come back yet.

On some starts, engine seems to crank over a little more before firing. Other than that, engine runs fine and gas mileage has not changed (same as before, typical for 6MT).

Vehicle has over almost 98K miles now. If no codes, I plan at 100K miles to do valve lash adjustment, EGR valve & passage cleaning and new spark plugs. Later at 105K miles I'll do the timing belt package and accessory drive belt.

 

Do a valve adjustment. I went too long without doing one and I burnt out the valves in cylinders 2/5 and needed my heads redone, for a total of $3,700.