This morning my wife called me saying when she was driving up the hill the truck started to shake. Short story we swapped cars and I attempted to reproduce the issue. It started to shake even trying to accelerate harder on flat road plus couple of times on my way to work it just did it for couple of seconds while coasting. It seems to do it every time I try to accelerate harder then just slight acceleration. The first time I tried accelerating perhaps the hardest my service light started to blink but as soon as I let go it stopped (I do have an engine light on for months for a sensor so not sure if new code was generated as of right now, will scan when I get home tonight). I did replace spark plugs about 1-2 months ago and couple of the selenoids were covered in white acid looking stuff (like battery gets dirty) which I cleaned off. Perhaps they are going bad? Any ideas would be appreciated before I start calling mechanics. The light does not blink when it starts shaking on any other occasion. The vibration is almost like when you go off the road and those holes that are meant to keep you awake start shaking your car just without the noise and a lesser intensity. I also installed a new K&N filter within the last month but I don't think that's it?
At one point I accelerated up hill and it started to shake, when the car down shifted it stopped shaking.
When I scanned for codes after replacing plugs they were P0128, P0128P and P0068. The last code has been on for a few months, maybe over a year.

 

P0068 is telling you to clean your MAF sensor. Buy some MAF cleaner and do it. If cleaning it doesn't work, then it may be bad. It is also telling you you have a possible intake leak downstream from the MAF. Check the intake manifold bolts, they are known to get loose on the I5 H3s and look at the PCV hose to the the back of the valve cover under the intake, those crack. Last, your MAP sensor may be bad. The sensors are super easy to replace and fairly cheap.

P0128 is telling you your engine is running to cool = bad T stat. Cheap and easy to replace.

Rough running engine is a symptom. You are probably getting some chitty MPG to boot.

The CEL is on because the PCM cannot correlate the input between the sensors to control fuel and spark properly.

 

When I replaced the spark plugs I cleaned the MAF sensor and the throttle body, maybe I messed something up or the sensor is bad? When I was at the dealer for an oil change last time they read P0106 code but I am not seeing that now. I read somewhere if you are getting both P0068 and P0106 its a bad MAF sensor possibly?

Any links on how to replace MAP? I think I looked it up once a while back and didn't seem to be easy but I also didn't find any good instructions.


Edit. Found another site with some pics on the MAP replacement, I don think this is what I originally looked up for a code I has as that part was under the car, this does seem very easy right on the top.

 

It is likely one of, or a combination of, 3 things:
1) dirty or bad MAF;
2) intake leak downstream from the MAF, or even at the MAF for that matter; and/or,
3) bad MAP.

Yes the MAP is right on top of the intake manifold at the back, pinch and plug.

See this thread for more: https://www.hummerforums.com/forum/h...ocation-34054/

 

Thanks Doc, but I scanned again just now and getting different codes. Still getting the P0128, but now also P0030, P0135 and P0304. the first two maybe related to the same oxygen sensor located close to the MAF ? I am not sure which is the 4th cylinder though to investigate, is it 4th one counting from inside the vehicle, or 4th counting from standing in front of the car? Couple of the selenoids looked pretty bad when I was replacing the spark plugs so I feel maybe one of them has gone bad?

am I looking at the right sensor for the two codes ? ACDelco 213-3207 GM Original Equipment Heated Oxygen Sensor?
Can it be that my exhaust is leaking and its not really a bad sensor?

 

When I said selenoids I meant the ignition coil. so confused sometimes.

 

When you cleaned the MAF sensor, did you use MAF cleaner or something else?
If you used MAF cleaner did you just spray it and let it air dry (the proper way) or did you touch the MAF sensor face at all? (if you did the MAF may be damaged).

 

Those codes are for bank 1 sensor 1, check the wiring to make sure nothing is chafed or rubbed through. po304 is going to be a misfire code - most likely a coil. Swap coils with another cylinder and see if the code moves to that cylinder

Brand:ACDelco
Manufacturer's Part Number:12592592
Part Type:Oxygen Sensors
Summit Racing Part Number:ADO-213-3207

 

Yes I cleaned it properly as I have done one time in the past also, but as I mentioned there is no code for the MAF sensor anymore. It is possible the code was there before I cleaned it and just has not cleared when I read it again after cleaning..... I could have sworn I cleared the codes at that time but maybe I just don't remember.
thanks jbwk for the part number, I Was thinking that but wasn't sure. Any ides which cylinder is number 4? not sure at which end to start counting but I think its the 2nd cylinder from me when standing in front of the car.

 

How many miles on the motor? A plugged cat will give the same symptoms.