Neighbor has a 99 Accord V6 coupe. Check engine light is on and the codes are:

- P0108 MAP Sensor
- P0122 TPS Sensor
- P0301 #1
- P0302 #2
- P0304 #4
- P0305 #5
- P0306 #6
- P1399

What confuses me is how come every cylinder except #3 is throwing a miss fire?

Also, what would trigger the MAP and TPS sensors to throw a check engine light?

 

i think your next step is to clear all the codes and see which ones come back...and go from there

 

Hi,
Mine is 00 V6 Coupe and I have seen the same problem three or four times in the past. I don't think I have seen P0108 or P0122. Last time I got to see (and FEEL) that problem was yesterday. The car has 271000 kms and I am the original owner.
The interesting thing is that this happens when the car has warmed up (never when cold) has been turned off for something like 10 or 15 minutes with the ambient temperature around +12 degrees Celsius and then restarted. Things get back to normal after it warms up again - with the exception of the set trouble codes. And yes, the P0303 is never there.
There is a service bulletin for something similar but it mentions that a freeze frame would indicate the engine was above 4000 RPM. I am reasonably sure the engine was not at 4000 RPM when it was misfiring in my case. Spark plugs are fine too, just drove 80 kilometers (50 miles) without any problems...

 

I have a 99 accord coupe 3.0 v6, and mine popped up with alot of codes like the map sensor and one of the misfirings (can't remember which one now) and also egr flow insufficient. after replacing my egr, map sensor, and my temp sensor all codes went away for a day, then the egr is reading again, so i replaced the egr again, and now its reading again. my accord is still doing this stalling thing sometimes as well.

 

Hello,
I now have put an additional 500kms on my V6 Honda and there is no hint of that problem. I should mention that I really go out of the way to fix anything that is wrong on this car - had to re-solder the odometer and the headlamp control unit this year. Anything that goes wrong gets ma attention... fast.
c.w.boi
I have heard that the EGR port needs some serious cleaning when replacing EGR, so... Did you clean the EGR port?
From what I understand the EGR valve has a vacuum connection which is controlled by an electric valve, so if the valve is stuck in the open position there will be some misfiring problems , but not with EGR flow insufficient. I wonder how the computer knows that the EGR flow is insufficient...

 

I cleaned out the EGR Chamber before replacing the egr the second time. I guess i could try it again. I was told i should use a oem egr valve instead of the one i got. any more help would greatly help. my accord is high mileage...285,000 miles.

 

Hello,
Well, I just had that misfiring problem again. On Saturday the ambient temperature was just right for this, and after about 25 minutes in the parking lot, when I got back the car would be misfiring. No codes triggered. This time I decided to just let the damn thing cool down a bit more, came back 30 minutes later and... the problem was not there. I really need to get one of those ODB2 things that can show sensor readings.

c.w.boi - I took my EGR valve off this weekend, just to have a look. During the last Emissions test I noticed some NOx particles which I have not seen before. There is an interesting document about the EGR problem:
http://www.tegger.com/hondafaq/tsb/accord/A99-085.pdf
Take a good look. Honda had a warranty extension! I remember I had this problem after six years of driving - at about 135000 km (~83k miles). London Honda fixed this at no charge. I am now at 273000km so it is probably time for another go at this. You might have to take the intake manifold off, just like that service bulletin describes.
Let me know how it goes.

 

So the 98-02 3.0 vtec engine has a tech bulletin regarding the intake manifold port clogging due to the port being slightly too small. It caused multiple missfires and egr malfunction. The Dealer would drill out the manifold port to a specific size then thoroughly clean, manifold, throttle, replace the egr valve. Once back together the fuel system would be cleaned. I clean my 3.0 about every 50k miles. I bought my 01 new. The coil packs and valve clearance will absolutely cause a p1399 to set. Fuel injectors are hardly ever an issue on these 3.0's at least in my area. Fuel choice and the state you live in has direct effect on these engines long term. (Different state regulations on fuel additives). If the valves are within specification and the spark plugs have been replaced and P1399 returns the next thing that needs your attention will be the ignition coils. Start with basics and specific manufacturer recommendations before throwing in the towel. Now if the engine is driven with p1399 (especially if DTC flashes) then there's a chance of burning up your exhaust valves. Usually takes a lot to do this but absolutely can happen. With proper maintenance these 3.0's can easily reach a million miles. I've seen it time and time again. However I've also seen them blow with less than 50k specifically due to abuse and ignoring warnings.