Hello,
I am new to this forum and am seeking some advice from you guys in hopes that someone here has come across this same issue as mine.

A little back ground. I just bought this 05 TL 6spd/nav 72k miles and during the test drive it ran fine. The next day the check engine light came on and sometimes even blinks. The codes that have come up are P0300, P0301, P0303,P0305, sometime in the past it was P0306 also..

I bought a new battery and installed it that had more cold cranking amps than the acura battery that was in it just for the hell of it.

Next I bought and installed new NGK iridium spark plugs, 6 new coil packs and did a compression test while the plugs were out. All were B/W 5-10 psi of each other in the 200+psi range iirc with the old battery cranking it over.
I reset the codes with my scanner and it ran well....
.....the next day it feels like a dead skip/miss at idle and sure enough the light comes back on and the same codes are there once again. I put it in 3rd gear and held it to the floor for at least 3 minutes on the interstate and the codes(after reset) didnt come back for the rest of the 1 hr trip ("now thinking" fuel injector related)

Next I bought 6 Acura/Honda injectors and the 2 intake gaskets and replaced them.
test run... no codes runs well.........
the next day on the ride home from work.... you guessed it rough idle and the same codes re-appear.

I can only think maybe this same issue has to have come up before with these cars. Does anyone know what is going on here or has anyone seen this issue before?
Any insight would be greatly appreciated!
Robby

 

edit:

The only detail I forgot to mention was before I replaced all 6 fuel injectors I ran 2 cans of sea foam and about 5oz of marvel mystery oil in 1 tank of gas and ran the entire tank out with no improvement-> thats when i bought new injectors from Acura.

Robby

 

So no one has any ideas or comments?

 

check your fuel pressure. It may be a failing pump.

 

P0300 is a general misfire code. P030x is a cylinder specific misfire code. A flashing MIL indicates that misfires are happening at a rate sufficient to damage the catalytic converters.

In the service manual, the trouble shooting for these codes is extensive (5 or 6 pages). You've already replaced most of the items: spark plugs, coils, injectors.

It looks like the misfires are predominantly on the rear side of the engine (cylinders 1,3,5).

If it was a fuel pressure issue, I'd think it would affect all cylinders.

At this point I think I'd look at either the upstream rear A/F (O2) sensor and/or ensuring the ECU is reflashed to the latest firmware, but I'd lean more toward getting the ECU reflashed.

You said you put it in 3rd gear and held the peddle to the floor for 3 minutes? So you drove it at redline for 3 miinutes? What was the purpose of doing this?

There was a rash of MILs from the early models (04-05) that came about under heavy acceleration into VTEC that was solved with an ECU reflash. This may be your problem....

 

Thanks for the reply(s)
(from what i have read)I was thinking the firewall side numbered from passenger side to driver side was numbered 123 then 456 on the bumper side.
I went to the Acura dealer here Locally And the service manager nor the
Tech I spoke to didn't give me any feeling that they knew their stuff. I don't want to pay someone to "learn" on my car at my expense. I told them basically what I have put on here and with this info and "assuming" they had the car at the time of it misfiring, what approach would they take to find out "why" it was skipping? I never got a straight answer. To me every tech that knows his crap has an idea of approach he would take to try to identify a problem or rule out other potential possible causes. I didn't get a that comfortable feeling of confidence in their ability to fix my car so I will keep looking for possible fixes and/or try to eliminate it myself or until I find a competent technician at a dealer or shop I will be searching here and the Internet for possible causes I guess

 

Edit:
I don't think it's a "pump" issue do to the motor performs very well under heavy WOT runs and doesn't surge or throw and "too lean" codes.
The reason I ran it WOT in third for an extended time was because the
Car started to really puss me off and I was curious if doing that would make it run better..... And after doing that and clearing the codes it ran ok for a while. The issue isn't definately repeatable in my opinion, it just does it on mostly warm re-starts sometimes almost like something is heat soaking maybe?
I like the idea of the re flashing of the ECM's tune but if it was for the VTEC part only I don't think it's my issue. It actually runs very well above 3500-plus rpms all the way to the rev limiter at 7100-7200 where it stayed for a while on that one run. The most noticeable "skip" is only under VERY light acceleration and mostly at idle you can hear and feel the dead miss. Then once you hear/feel it just after starting the motor soon after then code gets set some time after. Crazy thing is I can turn off the key and with key on/engine off and clear the codes after a run the codes don't come back. This happened yesterday. I cleared them and all day today no codes.

 

I brain farted. You're right, the firewall side is 123.

firewall
123
456
radiator

The reason the dealer is so iffy on this is that the troubleshooting procedure is very extensive.

I still think it may be as simple as reflashing the ECU.

 

I went to the dealer today again, they said they would reflash the ECM and diagnose my problem for $99 I guess we will see what comes of it
I will post the results then. Thanks for the replies
Robby

 

Well evidently my compression check didn't show up the issue.... The person who had the car at one point in time missed a shift or downshifted while trying to upshift and the valves hit the pistons slightly. The only way to determine this was by monitoring the map sensor voltage at idle and mine was not within spec. The other way was by doing a leakdown test. Surprisingly the compression test showed similar psi bw all cylinders.
I need to pull the heads and send them off to a machine shop.

 

I'm not sure how MAP sensor voltage can prove this. How do they know it's not just a bad MAP sensor or a bad connection? Did they actually do a leak down test in addition to checking the MAP sensor voltage?

 

The only way "to me" that the voltage reading would be out of spec and prove this is if I if the reading (voltage output wise) was accurate and the output from the map sensor read the same as a new sensors readings. I know it's a 5 volt reference style sensor, but I think he said mine showed 1v out at idle.
They didn't do a leak down test, so I borrowed a snap-on leakdown tester from a friend. I could possibly understand if the intake valves were bent slightly and it was pressurizing the intake on the compression stroke of each cylinder..... But all he did was check the output voltage with a scanner and it showed up out is spec on the map sensor at idle.
My thoughts are that this skipping only seems to happen when the
Motor has been hot for a WHILE and never cold. A mechanical issue would seem to me it would be there all the time Reguardless of temp and heat soak.
I will post up results of the leakdown test before I pull the heads.
Robby

 

Who is telling you this? Is it the dealer? If so, they don't have a clue what they're talking about. There is no reference voltage for the MAP sensor while at idle (at least it's not in the service manual). I think he's just pulling that out of his a$$.

The high/low voltage checks for the MAP sensor are done with the engine off and ignition switch to "ON". Again, this guy doesn't have a clue.

And what is he claiming a low voltage means? Over pressure in the manifold?

Did you get the reflash done?

Did you do the idle learn procedure after reconnecting the new battery? If the dealer reflashed the ECM, they should have done this as well.

 

Well unfortunately the dealer tech was correct. I had 12 bent exhaust valves but still had compression but the leak down test showed 80% leakage on the first cylinder i checked so I decided to tear the engine down......
I found evidence of where the exhaust valves smacked the pistons and made indents on them.
I pulled the heads and sent them to a machine shop......
that was an expensive joke!!!!!
I inspected them and had 4 valves leaking when i squirted a little paint thinner in the bowl area.
got the heads back and adjusted the valves and re-assembled the motor with new head bolts,gaskets, timing belt, tensioner, water pump,etc etc etc and NOW...this thing runs AMAZING!!! no codes, cant even tell it is idling, pulls hard all the way to the revv limiter.
so the cause was the previous owner(the one who sold it to me) mis shifted from 3 to 2nd(or similar situation) and mechanically over revved the motor and walla! 12 belt valves.....
BTW!!! be careful who drives your car.... if they down shift instead of up shifting..... be ready to drop some $$$$ on a new motor or rebuild yours.
Robby

 

Damn good job man, I know most people/mechanics would just say the engine is junk. Bravo for fixing it.

 

Thanks man. It took me a while doing it in the evenings after work but it finally paid off. I'm very happy with it now and hope it will live another 70k or more without me screwing with it any more. I just took a 4 hour road trip and ran the heck out of it on the way back, ran beautiful thankfully!
Now when I hear anyone say their TL is running rough at idle..... I just cringe

 

My TL idles rough.

Gets better after warming up. No codes.

Hope it is something else...