I have a 2009 Accord V6 that's been experiencing a strange engine issue that the dealer hasn't been able to diagnose.

The dealer hasn't been able to diagnose this issue because it's intermittent and is never there when I take it to the dealer.

The problem starts with a blinking "check engine" light. The engine runs very roughly at idle and the whole car shakes. At highway speeds, the roughness goes away and everything seems normal until I try to accelerate. As soon as the tach hits exactly 4000 RPM, it's like the engine hits a brick wall and the car won't accelerate at all. It's very similar to hitting the rev limiter, but that's up at 6750 RPM, not 4000.

Shutting the engine off and restarting it will often clear this problem. Sometimes this doesn't work, but as fate would have it, it's always gone before I can get the car to the dealer.

This issue happens about once a month, then goes away for another month before coming back. When it happens, it's very annoying and dangerous due to the lack of acceleration.

Anyone have this issue and/or know what causes it and how to fix it? The dealer claims to have never heard of this issue and says they can't do anything about it unless I bring the car in when it's happening.

 

My first question would be what are the codes...blinking CEL while driving is not a good thing. Usually means there is an issue sever enough to cause damage to other comp or systems....the ECU/PCM will store codes, so if there are no stored codes after the blinking CEL....my 3rd gens (86-89) store codes.

Next time it happens, stop by a store that will read the codes for free, get them-then take it to the dealer and when they say nothing is wrong...ask again.

 

It is best to check for stored trouble codes first. However, your problem sounds like this Honda TSB A10-033, which is to update the ECM/PCM software and replace any fouled spark plugs. Copy and paste link with quotation marks (" ") to view.

"http://mordor.rutgers.edu/accord/tsb/A10-033.PDF"

 

Interesting. I brought the car in for some unrelated servicing about six months ago and they noted on the service record that they had replaced the spark plug in cylinder #3 because it was fouled and also updated the ECM/PCM software.

If this is the cause of the current problem, I wonder why it's recurring again so soon if the software fix was supposed to address this issue?

What's really curious is why the problem will go away for several weeks and then come back again. I'd think that if a spark plug gets fouled, it would stay fouled until replaced.

 

Pull the spark plugs and see if they are fouled again. If there is a trouble code, that may help narrow down the problem. There are other Honda TSBs related to other codes.

Although there can be a few other reasons for a blinking check engine light, it is usually related to misfires.

 

You might find this thread interesting where people had the recurring problem even after the spark plug change and software update and it still came back. The dealer may be pulling your leg when they say they never heard of this issue.

"http://www.hondaclub.com/forum/accord/6707-2008-accord-engine-misfire.html"

 

If you pull the spark plug and it seems okay, it could also be a faulty ignition coil. Your car has individual ignition coils for each spark plug. If it is a misfire and you get the trouble code for a specific cylinder, you can try swapping the ignition coil from another cylinder to the misfiring cylinder to see if the misfire code changes to the other cylinder.

 

After manifesting itself for four or five days, the problem has gone away. No more blinking "check engine" light and no more rough idle or acceleration issues.

I have a hard time believing this is related to a fouled spark plug or bad ignition coil. If either of these was the cause, then why would the symptoms suddenly go away?

Of course, the problem went away before I could get the car to the dealer...