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2008 2.2LT Has Stange Problem

31K views 27 replies 8 participants last post by  dawkness 
#1 ·
Hello all. Hope you may offer some advice and help cure a problem my vehicle has developed. 2008 2.2 ltr LS. Was taking my son cross country, San Diego to Michigan. Half way through our trip the car developed what felt like a miss. After a few minutes I lost the accelerator. At this point I pulled over and let the car idel for a few minutes and the accelerator began to work once again. As we continued, the miss would come and go. At one point I thought the vehicle was going to stall so I shifted from 5th to 4th and punched the accelerator. Oddly enough the miss went away, but at the same time my tach fell to 0. Long story short, we took the car to the shop and was told the crank sensor was bad. Replace it and two weeks later the problem has returnred. Every time this miss occurs, the tach will fall off and engine runs fine. Problem will return once the engine is turned off and restarted. I am now receiving a code that states bad crank sensor. Any Ideas? Took the car back to the dealer but they could duplicate the problem.
 
#2 · (Edited)
Don't know why (yet) your "ECM" would give you a faulty crank position sensor, because what you are describing is a faulty cylinder #① ignition coil. Tach gets it's information from ignition coil one, if it fails you lose your tach, if you lose your tach you lose rpm information to "ECM" it then falls into limp mode or engine management mode if you prefer that term. The only thing that bugs me is why didn't you get a P0301 code.....and why a P038*
 
#4 ·
Yes, because it cools. They are all the same so just move two around and see if the symptoms change.
 
#5 ·
Good morning Taylord,

I see that you've visited the dealership and they were not able to duplicate the problem, and it looks like Coby7 is on the case as well. If you had wanted for me to follow up on your visit with the dealership, please let me know! I will provide you with my email address (as you're newer to the forum, I don't believe you can private message yet) and we'll go from there.

Sarah, GM Customer Service
 
#7 ·
Hi Taylord,
Thanks for the update! We hope you're on your way to finding the source of the misfire. Just checking - is your shop one of our dealerships? I want to make sure to be available to you if you should need any assistance.

Sarah, GM Customer Service
 
#8 · (Edited)
I doubt that even the first sensor was bad, they will probably find a chafed,burnt or frayed wire. DTCs are a guide to trouble shoot not an absolute.

DTC P0336
Circuit Description
The crankshaft position (CKP) sensor is a variable reluctance sensor. The CKP sensor indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC voltage output depends on the crankshaft position and the battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor connects to the powertrain control module (PCM) through the following circuits:

• The CKP sensor signal circuit

• The low reference circuit

If the PCM detects an excessive number of resyncs from the CKP sensor, DTC P0336 sets.

---------- Post added at 02:01 PM ---------- Previous post was at 02:00 PM ----------
So you can probably disregard this DTC
DTC P0507
Circuit Description
The throttle actuator control (TAC) motor is controlled by the powertrain control module (PCM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.
 
#9 ·
OK, just got off the phone with the local dealer, and the service department claims my problem is a binding throttle body. Repair for this is in excess of $650. Need some input here, as this is the third time to the dealers and it seems like every time I take this vehicle in the problem diagnosed keeps changing. Furthermore, the dealer now wants $100. just for tlooking at the car. As a note, this car is not under warranty. Is there a way to test the throttlr body myself, and does anyone have any other thoughts as to my problem given the codes listed. I know I have a small vacuum leak, but this problem occured after the fact and is something I can easily fix myself.
 
#10 ·
Buy a used TB for less than $100 and replace it yourself. It's only four bolts! If that even is the problem.
 
#12 ·
Take off your TB and make sure it's not all gunked up with carbon first.
 
#14 ·
If you can move the valve easily (not all the way open, do not put extra pressure to open it!!!) it's as good as new. There might be a problem with the electronics inside, but I would doubt that.
 
#16 ·
Perferably you should take the entire TB off the car to clean both sides of the valve. You can try moving it then.

It's litterally four bolts holding it onto the manifold.
 
#18 ·
Ok,got it back fro the dealers, same problem. Throttle body checks good, cleared the codes and took her for a run. Same issue. Runs fine for a while then bucks three or for times the tach falls to 0 then engine runs fine. So far I have checked all wires vacuum lines switched crank sensor, moved and checked coil packs, cleaned throttle body and changed plugs. I am at a loss. Still idles a bit high as well. Any other thoughts out there?
 
#19 ·
If you already paid to get it fixed and the issue wasn't resolved bring it back. Sarah here should help you with any dealer issues. You should not have to pay a second time for the same problem.
 
#21 ·
Did you ever isolate the problem? I have a 2008 that does exactly the same thing. The first time to the dealer they thought it was the Cam Position Sensor, changed it, and any time it was really hot it would do the same problem, shutter, loose power, loose the tach, then run fine. I was going to try the Crank Position Sensor myself, but found this thread.
 
#23 ·
Aircraft800,

If you would like for me to follow up on your visit with your dealership, please contact me either via private message on the forum or by the signature in my email (include your name and contact information, the last 8 of your VIN, a summary of the situation, and the name of your dealership).

Sarah, GM Customer Service
 
#24 ·
What is a crank relearn? Just changing the CPS requires some type of calibration, more than just setting the gap? Hmm.. I'm a DIY type, would sure like to fix it myself.

Thanks Sarah, I'll contact you if I have any dealer issues, they've been good to me, just couldn't shell out the price for some repairs that I know I can do in 1/2 the book time.
 
#26 ·
Thanks for all the great help!! It was the Crank Position Sensor, well sorta...

The wire harness to the sensor has three wires, the one in the center was broken off right at the plug. As I was researching that, I also noticed the Knock Sensor wire was holding on by one strand too. Then I noticed the harness that wraps around the front of the block adjacent to the cartridge oil filter was chafing into the block, burned half way threw the electric fan wires and melted another. I am very disappointed with the quality of the wire harness and it's poor routing. The wires are of low strand count, and with vibration and flexing are breaking. I'm sure this means huge electrical problems in the future.. It's a 2008 with 98K miles. I was hoping to drive another 100K before I ran into these type of problems.

I did change the Crank Position Sensor and the Cam Position Sensor as precautionary with OEM. I didn't do a crank relearn, seems to be running great and my fuel economy returned to normal.

Thanks again for all the help!!!!!
 
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