H3 '06 3.5L 84K Serious engine shuttering, bogging and p0301 misfire

Really need some sage advise/guidance on this particular issue....


Stats: 2006 H3 3.5L 84K miles
(girl friends) just bought 3+ weeks ago


We were on our way home and the truck started to loose power. It began to buck and stutter.
The CEL/MIL fired randomly and then went fully lit.

Coasting the truck it would be solid lit and then pulse when accelerating. There is seriously a bad shuttering and at 1/4 to 1/2 throttle it will drop to barely idle and come close to die'n....




We brought it home parked it in the driveway and ran diagnostics on it...(P0301 misfire cyc#1)
Note: She got gas last night on way home from work
Checked Oil (full and clean)
Checked Trans fluid (cleaned and topped off with Dexron VI)
Checked Antifreeze (cleaned and midway up overflow)




Took the air intake system off and the MAF, resonator assembly. (The TB,TBS, MAF and intake tubes were cleaned)


Disconected the Battery and removed 1st spark pack thru 5th...(Kept em in order they were taken out)
Removed the 1st spark plug and verified the spark plug had/has been firing (by color/look)
Went to Autozone and purchased all new spark plugs and a new COP for spark plug #1.
Replaced all sparks and COP #1
Recleaned MAF and installed all components as normal.
Reconnected battery.


Started engine and still surging, bucking and pulsating with reduced power. Engine is misfiring P0301.


Took MAF plug apart (i.e. weatherPac disassem.) cleaned with MAF spray and rebuilt.


Reconnected battery.


Started engine and still surging, bucking and pulsating with reduced power. Engine is misfiring P0301.


Truck ran fine all day till this issue began...


I'm wondering what would be the next logical step to take?


Chris:whaa:

Is the VIN (vehicle ID number) less than 287591? I ask since early model 06 H3s had a problem with the cylinder head, but usually that happened in the first 30K miles, but not always, and usually (again not always) posted a random misfire code of P0300.

Doubt if it is gas since it appears cylinder 1 is the only one to be affected. Normally bad gas would give a 300 code or all codes 301-305.

It appears you are not afraid to get into it and do some work. Not sure why the throttle body cleaning and MAF with the 301 code...but that's another story.

Ok I re-read your message and the plugs have been changed and probably no rust in cyl 1 or you would have noticed it.

I would move coil from 1 to around cyl 3 and see if the code jumps from 301 to 303.

If it is not electrical, it could be a bad injector on cyl 1. You could try the Techron additive that does work if it is a bad injector. You could move the injectors around.

Hate to say it, if all else fails the next would be a compression and air leak down test to see if the cyl head has failed.

Are there any other codes with the 301?

Thank 4 responding....
Yes the coil pack on one has been replaced.
Spark plugs 41-103.
Maf, Tb, intake all clnd a week + ago.
Im leaning toward fuel injector.
Chris
wondering could it be cam,crank sensor?

If it was a cam or crank sensor then you should also have one of cam/crank correlation codes (0016 or 17), or 0340/0341, 0365/0366 or 0335/0356 , etc.
Sometimes the computer will fail to pick up these codes, but usually, the computer does a great job.

If it is not an injector, then I would go for a compression test/air leakdown test. But first I would try some techron if possible to see if that helps. (That is if you can run a full tank of fuel through the engine. If the idle is too bad, you might want to schedule a trip to a good mechanic.)

The major shuttering, stumbling and general crap running with serious misfire was tentatively smoothed to a stumble from time to time.


After much of Friday and part of Sat. was able to get my GF's '06 3.5l 84K engine to smooth out and run correctly. Thank GOD! Alas short lived. The newest symptoms seem to be a blip, stumble in the engine that happens when at idle. It is random and very short lived. It is usually a milli second blip and the engine never comes close to dying or loosing rpm's.


Things that have already been done:
Checked Oil (full and clean)
Checked Trans fluid (cleaned and topped off with Dexron VI)
Checked Antifreeze (cleaned and midway up overflow)
Took the air intake system off and the MAF, resonator assembly. (The TB,TBS, MAF and intake tubes were cleaned and then re-cleaned)


Disconnected the Battery and removed 1st spark pack thru 5th...(Randomized them)
Removed the 1st spark plug and verified the spark plug had/has been firing (by color/look)
Went to Autozone and purchased all new spark plugs and a new coil for spark plug #1.
Replaced all sparks and COP #1 .....ACDel 41-103....Wells COP
The oem that I removed were ACDel ...also but different #.
Re-cleaned MAF and installed all components as normal.
Took MAF plug apart (i.e. weatherPac disassem.) cleaned with MAF spray and rebuilt.
Techron 2- bottles added today 12-10-12..
Reconnected battery.
Where is a good place to look next for the sudden blip in the idle?


She is now talking about taking it in at $125 per hour just to resolve this small issue. Ugh!


Chris

Also sprayed silicone in each boot when re installing COP 1-5.
Chris

I think it is time to follow F5's suggestion for a compression test