1990AccordEX

2005 Coupe EX V6 6MT 42,000miles


I had two misfire episode during my short ownership of my accord.

During the first time it misfired at high rpm/ hard acceleration long enough to blink the MIL

Second time under same conditions but i felt it and got off the gas no MIL at all.

I have done a compression test on all 6 cylinders and all come back with 195 psi. Spark plugs are original and in good shape. I have had it on a scan tool at school and even at idle it would count small misfire in all cylinders. It does seem to have a rough idle all the time.
I dont know what to look at next. The car drives nice, smooth, and powerful despite the misfiring.

LPED

So this is intermittent when nailing it or misses ever time ?

here few things I would check if no codes are stored .
1) check all grounds to motor ,making sure proper voltage is getting to all ECU systems .
2)If V6 has EGR valve check that it is working ok and not gummed up with carbon
3)try some fuel injector cleaner and note if any improvement at all (if so "might" be something with injectors (bad gas etc)). also check for proper fuel pressure .
4) replace spark plugs even if they look ok visually .

How is oil consumption , does it use a lot of oil ?

1990AccordEX

So this is intermittent when nailing it or misses ever time ?

here few things I would check if no codes are stored .
1) check all grounds to motor ,making sure proper voltage is getting to all ECU systems .
2)If V6 has EGR valve check that it is working ok and not gummed up with carbon
3)try some fuel injector cleaner and note if any improvement at all (if so "might" be something with injectors (bad gas etc)). also check for proper fuel pressure .
4) replace spark plugs even if they look ok visually .

How is oil consumption , does it use a lot of oil ?

The problem is intermittent. In the past 1,500 miles since i changed the oil i havent lost any.

I have tried fuel injector cleaner, I haven't noticed anything differents yet. My gas mileage is anywhere between 24-28.

At idle and at operating temperature i'm getting 1.2 volts from the EGR. Is that within spec??

LPED

Ok, If its intermittent then i don't think its EGR . My comment on EGR is on some cars the valve and passage way can get blocked or block the valve from closing properly which can cause rough idle and higher misfire rate .

I don't know on EGR voltage valve (I don't have manual on your car handy) . I would still replace the plugs and see if it comes back .

There no codes stored ?
I would think if mil light came on you should get some codes stored .

Targa250R

I had a similar issue with a car in my shop last January, but it wasn't intermittent; the car was running poorly all the time. '03 Accord V6 with 47,000 miles, CEL showed random/multiple misfires in every cylinder. Compression and plugs were all good. We eventually traced the problem to faulty #3 and #4 fuel injectors.

J-series V6es can be very picky about fuel as well. Has this problem reoccurred recently in short succession, or has it been a long-term problem over multiple tanks of fuel? Do you normally fill up at the same station all the time?

90sedan

Yes. It should be between 1.1-1.25v at idle.

I've also seen a couple sets of faulty injectors on the v6's. If you have been using the same quality fuel, i would recommend swapping them out for a known good set.

1990AccordEX

I took it in to honda to have it looked over, and to have the 3rd gear done.

They found nothing wrong with it. they test everything and it come back fine.

I hope thats the end of it.

Thanks

onepoint6i

Have the valve lash adjusted, we get alot of misfire's because of it on V6 accords, odysseys and pilots..

1990AccordEX

That was the only thing the technician recommoned.

So im going to had it done.

LPED

This is from Honda doc on misfire , I can't post whole thing but some important "could be problems"
Yours being intermittent makes it a bit tougher to diagnose, especially with no codes .

""Misfire Detected in One Cylinder
The scan tool indicates Diagnostic Trouble Code (DTC) P0301: Cylinder 1 misfire detected.
The scan tool indicates Diagnostic Trouble Code (DTC) P0302: Cylinder 2 misfire detected.
The scan tool indicates Diagnostic Trouble Code (DTC) P0303: Cylinder 3 misfire detected.
The scan tool indicates Diagnostic Trouble Code (DTC) P0304: Cylinder 4 misfire detected.

Description
Misfire detection is accomplished by monitoring the crankshaft speed with the crankshaft position (CKP) sensor which is
attached to the crankshaft.
If misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTC
P0301, P0302, PO303 and/or P0304 will be stored. Then, after the misfire has ceased, the MIL will come on.
If misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTC
P0301, P0302, PO303 and/or P0304 will be stored.
NOTE: If some of the DTCs listed below are stored at the same time as a misfire DTC, troubleshoot those DTCs first, then
troubleshoot the misfire DTC.
P0106: MAP sensor
P0171, P0172: Fuel supply system
P0401, P1491, P1498: EGR system
P0441: EVAP incorrect purge flow"
P1359, P1361, P1362: TDC sensor
P1381, P1382: CYP sensor
*: Sedan KL (SE, LX without A6S)/Wagon

Possible Cause
Fuel injector clogging, fuel leakage, air leakage
Fuel injector circuit open or shorted
Injector resistor malfunction
Spark plug carbon deposits, fouling, malfunction
Ignition wires open, leaking
Distributor malfunction
Compression low
Valve clearance out of specification ""

onepoint6i

Yeah, especially on M/T V6 engines, they tend to get revved higher then auto's

99blackcivicSi

x100 there

i am doing at least 2 a week.

1990AccordEX

UPdate....


Finally got the valve adjusted and it idle smooth now. but it made the MIL blink like crazy. It made it blink 4 times in a 60 mile trip, By the third time it finally left me a store to read.

P0301
P0305

Misfire in cylinders 1 and 5

I can't find the TSB on MIL code store with the 301-305 code, something about the cranksensor and it Learn ability.

onepoint6i

yeah, go back to the dealer have them pull the code..theres a service bulletin (08-022)

they have to update the ecm with the HDS (honda scan tool)

1990AccordEX

Ok had the updates done and now no more MIL/misfire issue.. YEAH

Thanks for the help

onepoint6i

cool man, hope all goes well...

Rink

I just had a 2014 Honda Pilot declared a lemon by American Honda due to a misfire issue they couldn't resolve. I wonder if this is related? It was pretty bad and annoying to continuously take it in for service. They thought if they replaced the four rods that it would fix it - and it actually made it worse.

Here's to hoping that the vehicle replacement has zero issues!