Since getting an oil change, our '08 Accord 4 cylinder has not been running right. Symptoms are it sometimes stalls right after starting. Once running seems to run fine, but if you rev it up to 4800 RPM or higher, it stumbles as if a fuel limiter or something is kicking in (or a misfire?). On occasion, it will stumble under lighter loads than that high of RPM too, but I have not been able to replicate the stumble in my driveway below that RPM.

Normally I would start by looking for an ignition system problem, except it seems odd the problem is intermittent. Anyone else experience this, or have an idea?

 

Is the motor still cold when you do this? This is a high RPM protection feature of the ECU, to not allow the motor to rev into VTEC range until the motor is fully warmed up.

 

Ok, that could be what I am experiencing there. Thats not going to solve the stalling issue, but should help simplify my diagnosis efforts.

 

A bit more...

The car seems to idle fine on its own. In gear, under acceleration, it sounds labored and the engine feels rough compared to normal. The car still accelerates ok, maybe not as well as normal however.

 

Did you check the oil level?

 

Sounds ALOT like a misfire.

 

Oil level is ok.

This is what I was thinking. It just is not being obvious enough to pinpoint it.

Did a little more driving. It has some pickup, but seems a little down on power. Engine sounds like it is lugging a little when accelerating, sounds fine when rev'd without load (neutral).

At a stop, it will stumble, occasionally stalling, when the AC compressor cycles off. My guess here is that when the computer takes away some fuel at idle to compensate for losing the load of the AC compressor, with the engine not running optimally, it takes away too much causing the stumble and occasional stall.

Unfortunately, no check engine light yet. No noticeable arcing in the dark from coil packs.

My guess is that this is in the ignition system. I am just not sure how to find it.

 

You won't necessarily get a check engine code if you have a misfire, especially if it's a multiple cylinder misfire and it's intermittent. Has the car gotten exposed to water recently? Since you have coil on plug, maybe what you could do is first number the coils like you had them then swap the coils around with each other and see if it gives a check engine code. What could possibly happen is that since the misfire detection mechanism isn't that sophisticated, if you have one or two intermittent misfires, it may think it's regular engine noise and not detect it.

Just try Swapping the coils and or the spark plugs around as it might cause the misfire to happen sequentially or non sequentially, making detection possible. If you get a check engine code after moving the coils around, then you know you're onto something.


Check your spark plugs and maybe post pictures of them as well. Best to remove spark plugs when they're cold and don't torque very tight at all as it's an aluminum head. 13ft-lbs is likely the rating.


How many miles does the car have?

 

Be sure to use anti-sieze when re-installing because of this.

 

Light anti-seize. Don't be one of those people who adds too much and makes things worse.

 

when did you fill up with gas last? make sure to check all the basics before diving into deep diagnostics cause you can waste a lot of time doing that. bad gas can cause a lot of problems and can definitely cause the ones you're describing.

 

I haven't seen the need to use antisieze and unless there are people online saying that a particular vehicle has such and such problem, use this to correct it, I assume it doesn't need it. Ford F150s with the 3 valve engines from 2004+ had an issue with the sparkplugs getting stuck in the head and having to be removed prematurely so they don't break off and you have to remove the head.

 

Just thought I would drop in with an update.

Figured out the problem, and it was none of the above. In doing some checks of simple things, I found that the cover for the airfilter had been improperly installed. Both of the rear tongues were not in the hold-down slots, so it was allowing air in past the filter. Must have been messing up engine vacumn, or the MAF.

Either way, securing it properly cured my high load miss!

Oil Change place must have taken it apart when my wife took it in last week, and failed to put it back together right!

Thanks all for the troubleshooting advice!

 

Says right in the service manual for my 2003 Accord, to use anti-sieze. And yes, not a lot, but a steel plug going in an aluminum head is trouble waiting to happen if you don't.

Glad to hear the fix was something simple.

 

I lol at the thought that it was such a simple problem. Still seems odd that a loose air filter box would cause this issue.

So why do spark plugs not come with antiseize on them but o2 sensors do?

 

No idea.

2003-2006 Honda Accord Service Manual V6 Suppliment page 4-23, step 4 of spark Plug Inspection states:

Apply a small amount of anti-seize compound to the plug threads, and screw the plugs into the cylinder head, finger-tight. Then torque them to 18 N-m (1.8 kgf-m, 13 lbf-ft).

I guess that's up to you at this point. I'll continue to put anti-seize on steel plugs going into my aluminum head.