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Discussion Starter · #1 · (Edited)
first time here and first time having a problem with diagnosing this problem (misfire diag)

For reference to everyone with what they are helping/working with...

I am an ASE cert tech that works mostly on Subaru's and Hyundai's profesionally and turbo dodges as a hobby.

I have an OBD2 scanner.

I have no experience with late model Honda's/acura's other then racing against them on the street.... :)

Car has 87 octane with cheveron gas (I have NEVER gotten a bad tank with them and I run 18 lbs of boost on my Turbo Dodge) but this could be the first. :(

alternator is putting out 49 amps. A little low (for a Suby) but shouldn't be too low to run the ignition system.

Thanks in advance.

I have a misfire on all 6 cyl but 3,5,6 on start up imediatly and the rest set a code after a short drive. Test drives like a dog and idles just as bad.

Alternator seems ok but is steadily dropping in voltage with all acceries on. (about .4v's every min) I watched it get down to 12.7v.

I know that with a direct coil ignition, low operating voltage will cause a weak spark but on start up there is the full 14.3+ and the misfire is very present. I have searched and found info (here) that there is a carbon build up possibility (solution was... it went away) bad spark plugs, (just replaced with factory denso's) and a reset of the ECM by pulling the fuse ( I haven't done that yet, I have just cleared with scanner.

Any thing from dealership experience of diag or self diag? I have monitor data (trim %, o2 readings, etc) if that helps any of the pro's out there.

Thanks in advance.

Steven
San Diego
 

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Not sure if i can help, but i work at a honda dealership and we use something called an HDS (honda diagnostic system) which has an ob2 scanner and a whole bunch of other cool functions. Using the HDS i can look up the trouble codes and are able to look at what load the engine was under when these codes were set in the ecm, this is called freeze data which tells you things such as what rpms you were at, speed, if the engine was cold or warmed up, throttle, alot of other things these are just the major ones. It would make things easier if you had this. But if you give me some trouble codes i can look them up for you and give you some possibilities that could be wrong with the car.
 

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have you

- checked the actual wires for impedance to GND and possible shorts?
- tried replacing the actual ignition coils?
- checked the injectors for proper operation? (could be clogged or have an abnormal spray pattern)
- done a compression check on the misfiring cylinders? (just throwing this out, you never know)

carbon build up? naaaah


99-00 Maximas are known for having misfire codes and the culprit is ignition coils done gone bad. Replaced one myself, and due to a lot of long trips that I do, I keep 2 spare in my car along with tools and my OBD-II scanner just in case one decides to crap out in the middle of nowhere.
 

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BTW, post some pics of your turbo GLH. An Omni right? "Goes Like Hell" Those things are badass. :D
 

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For example the other day i got a brand new a 06 accord v6 in the shop for missfires on cylinder 5 took the engine cover off and the ignition wire wasnt plugged in all the way and would come loose at times! Could be something as simple as that it really depends.
 

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Might have to check the Electronic Load Detector(ELD). I know that the Element, Accord, Civic all had problems with them. The only way Iknow of checking it is with the HDS. I will try to check on it tomorrow at work.
I would not reset the ECU if it will not idle ok. If you reset the ECU you have to let it run for 10-15 min for it to idle learn.
 

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oSCaR
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n00b question... what kinda damage, if any... could a misfire cause?

:hide2:
 

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7thgen said:
Might have to check the Electronic Load Detector(ELD). I know that the Element, Accord, Civic all had problems with them. The only way Iknow of checking it is with the HDS. I will try to check on it tomorrow at work.
I would not reset the ECU if it will not idle ok. If you reset the ECU you have to let it run for 10-15 min for it to idle learn.
If that is the case, wouldn't he have seen the P1297 or P1298 code for a faulty ELD?

SteVTEC said:
- tried replacing the actual ignition coils?
I don't think all 6 coils can just suddenly go bad like that :p . It has to be something else that is affecting the timing of the engine.
 

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v6_ccord_2k5 said:
n00b question... what kinda damage, if any... could a misfire cause?

:hide2:
It really depends on the nature of the misfire. It can screw up emissions which is why the CEL comes on. A mild misifire is usually just an irregularity in the firing (dirty or worn plug, clogged injector, etc) which is picked up on crank acceleration rates and irregularities in that. If you completely drop a cylinder like when the coil went out in my Maxima you're dumping raw fuel into the cats and can nuke the cat. You're also not doing the engine any favors since a V6 running in V5 mode doesn't fire evenly, but engines are designed with enough strength to be able to handle misfire conditions like that. I only had to limp my car a few miles home to fix it though. You definitely would not want to be running at full throttle and high revs with a misfire just to err on the side of caution though.
 

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oSCaR
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hmmm... considering my car is still running, I think I'm ok... I hope. All 3-5 times it happened when the car was semi-warm... in all cases it happened while at WOT, and it seemed to come from the V2 CAI but maybe that was because the engine stopped sucking in air, I dont know what the heck... :crossingfingers:
 

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DO NOT reset the ECM. If you reset the ECM you have to go through idle learn(let car run through two fan cycles) and a Crank Position Sensor learn procedure. One possibility is that the crank position sensor got out of sync and began to cause a two cylinder missfire. The problem will progress as the ECM attempts to resolve the missfire. There was a service bulliten that indicates that if you have 2 or more cylinder misfire the ECM may need a program update. This needs to be done at a dealership on the HDS. How long has the mis been going on? If it has been for awhile some of the misfires could be due to fouled plugs. Check the plugs. Just some suggestions. Kind of hard without being in front of the car. Good luck.

As for the ELD they do not always show a code when bad. Some have to be confirmed with the HDS by checking the alternator output under load.
 

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Discussion Starter · #12 ·
Andrew said:
Not sure if i can help, but i work at a honda dealership and we use something called an HDS (honda diagnostic system) which has an ob2 scanner and a whole bunch of other cool functions. Using the HDS i can look up the trouble codes and are able to look at what load the engine was under when these codes were set in the ecm, this is called freeze data which tells you things such as what rpms you were at, speed, if the engine was cold or warmed up, throttle, alot of other things these are just the major ones. It would make things easier if you had this. But if you give me some trouble codes i can look them up for you and give you some possibilities that could be wrong with the car.
If you have a TSB on random misfires then that would be perfect. That's what the codes are
p0300 random misfire
p0301 misfire #1
p0302 #2
p0303 etc......
p0304
p0305
p0306

Freeze frame is irrelevent (in this case) because it "fails" all the time so re-creating the DTC happens instantly. The only weird thing is right from the start the short term fuel trim on B1 is -50% which is normal if the ECM sees a misfire. It richens up the fuel and then cuts it all back. BUT then it levels out to what is should be.

Sorry for the delay in reply. My HDS only works on Hyundai's. My OBD2 is for all makes but no bells and whistles.

Steven
San Diego
86 GLH
 

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Discussion Starter · #13 ·
SteVTEC said:
have you

checked the actual wires for impedance to GND and possible shorts?
Not yet. It doesn't seem likely that all 6 grounds would go (Probably only 2 but you see why I haven't done it yet)
SteVTEC said:
tried replacing the actual ignition coils?
That would be pretty pricy. they arc a good inch and a half to the plug when I tested them though. It could be 1 or two that are pissing off the other 4/5? maybe.
SteVTEC said:
checked the injectors for proper operation? (could be clogged or have an abnormal spray pattern)
I didn't want to pull the injectors just yet. It seems along the lines of low probability because it misfires on all 6.
SteVTEC said:
done a compression check on the misfiring cylinders? (just throwing this out, you never know)
Exactly, I haven't but my friend took the car to another shop and they said #6 had a dead hole. Sounds like crap (i'm going to do the compression check tomorrow). 1 dead hole would NOT cause 6 misfires. But then again, maybe it would, it just doesn't make sence either way.

carbon build up? naaaah


SteVTEC said:
99-00 Maximas are known for having misfire codes and the culprit is ignition coils done gone bad. Replaced one myself, and due to a lot of long trips that I do, I keep 2 spare in my car along with tools and my OBD-II scanner just in case one decides to crap out in the middle of nowhere.
Me too, but my culprit is usualy a hall effect sensor. :)

Thanks for you help. I have limited access to the internet so sorry for the slow reply.

Steven
San Diego
86 GLH
 

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Discussion Starter · #14 ·
Turbo GLH said:
Not yet. It doesn't seem likely that all 6 grounds would go (Probably only 2 but you see why I haven't done it yet)

That would be pretty pricy. they arc a good inch and a half to the plug when I tested them though. It could be 1 or two that are pissing off the other 4/5? maybe.

I didn't want to pull the injectors just yet. It seems along the lines of low probability because it misfires on all 6.

Exactly, I haven't but my friend took the car to another shop and they said #6 had a dead hole. Sounds like crap (i'm going to do the compression check tomorrow). 1 dead hole would NOT cause 6 misfires. But then again, maybe it would, it just doesn't make sence either way.

carbon build up? naaaah




Me too, but my culprit is usualy a hall effect sensor. :)

Thanks for you help. I have limited access to the internet so sorry for the slow reply.

Steven
San Diego
86 GLH

I'm an idiot.
Compresion on #6
10psi

GRRRRRRRRRRRRRRRRRRR

I thought these motors never did that?

Any way. Thanks for the help everyone. Sorry for the anti climactic ending

Steven
San Diego
86 GLH
 

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Discussion Starter · #16 ·
Plumaccordcoupe said:
How did that happen? Bent valves? Blown piston rings?
Won't know until the dealer opens it up. I would do it but why when it's under warrenty. I could check with a leak down test but, again... warrenty.

I'll update with the diag when it gets back to me.

Thanks
Steven R.
 

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00 maxima misfire?!?!

I just recently chnged my sparkplugs at 30k miles. Now the check engine light comes on and blinks continuously and there is great loss of power. the plugs are all correcly in and they are the right plugs...please help??????
 
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