2008 Tahoe P0300, Rough Idle After Work

[davidkramer]

Hey ya'll I had my oil pump, pickup tube, lifters and all gaskets replaced on my 2008 Tahoe 4WD with 120k miles on it. About 5min after driving it, I had a service traction control/stabilitrak light and P0300 light come on with a rough idle. Looking at my computer, it is saying Cylinder 1 and 7 are misfiring (7 worse then 1). We then replaced the plugs, wires and ignition coils and still the same exact codes and symptoms. The fuel injectors are all coming back as OK on our scan computer as well.
Anyone have any additional ideas? We drove it the other day and when it warms up/highway speeds, the light goes off but immediately comes back on when you are sitting at a light.

 

[Dustin Jackson]

@davidkramer Did you have a lifter failure or why did you do all that work?

 

[davidkramer]

@davidkramer Did you have a lifter failure or why did you do all that work?

Yes. I had lifter noise for the past 6 months getting worse and I had low oil pressure that rose after driving, indicating the o-ring failure. Instead of just replacing the failed lifter and o-ring, I had my friend do the oil pump, all lifters, head gaskets, plugs, coils and wires while he was there.
We troubleshooted a bit more: Cylinder 1 is misfiring a little and Cylinder 7 is misfiring a lot. When you rev it, the misfire goes away. We swapped cylinder 1 and 7 plugs, wires and injectors with others and it was still misfiring, so that isn't the problem. He put in some seafoam and Lucas oil stabalizer to see if it will help if one of the new lifters was sticking, but it didn't do anything. We still have the code. He is going to take apart that head next Friday as he said it is pointing to a bad new lifter.

 

[strutaeng]

You didn't remove or inspect the camshaft? What if one of lobes for the intake or exhaust is wiped out? I'm just asking. Did any of lifter wheels have any damage?

 

[Dustin Jackson]

@davidkramer I would inspect the cam too

 

[bfishing]

Hey ya'll I had my oil pump, pickup tube, lifters and all gaskets replaced on my 2008 Tahoe 4WD with 120k miles on it. About 5min after driving it, I had a service traction control/stabilitrak light and P0300 light come on with a rough idle. Looking at my computer, it is saying Cylinder 1 and 7 are misfiring (7 worse then 1). We then replaced the plugs, wires and ignition coils and still the same exact codes and symptoms. The fuel injectors are all coming back as OK on our scan computer as well.
Anyone have any additional ideas? We drove it the other day and when it warms up/highway speeds, the light goes off but immediately comes back on when you are sitting at a light.

Hi! I have just helped a friend clear stabilitrak and violently shaking engine by removing and cleaning the throttle body also changed the throttle body sensor which may not have been needed but he's running smooth once again, check that if you haven't done so as yet!
PS I also found a broken wire on the sensor connector

 

[davidkramer]

You didn't remove or inspect the camshaft? What if one of lobes for the intake or exhaust is wiped out? I'm just asking. Did any of lifter wheels have any damage?

My friend did the work. I asked him and he said "the camshaft looked fine and none of the push rods were bent". I will ask him about the lifter wheels in the AM.

 

[davidkramer]

Hi! I have just helped a friend clear stabilitrak and violently shaking engine by removing and cleaning the throttle body also changed the throttle body sensor which may not have been needed but he's running smooth once again, check that if you haven't done so as yet!
PS I also found a broken wire on the sensor connector

Thank you. Did it have any specific codes on it that you remember? I will do this in the AM

 

[bfishing]

Thank you. Did it have any specific codes on it that you remember? I will do this in the AM

I didn't log the code, I remember the problem did state throttle sensor was a problem with stability also an issue, I forgot to mention I also went under driver side an cleaned the ground wire connected to frame underneath, once I repaired the broken wire from sensor the motor shook, so then I proceeded to clean throttle body, both problems cleared away...

 

[j91z28d1]

wait.. did you replace the afm lifters with non afm lifters? or new afm and if afm what brand?

I've seen threads where guys put new Amazon/ebay(China) afm lifters and they fail from the first start having to do it all again. the only acceptable brands are oem gm, not bought from Amazon. either dealer, gm parts direct or rock auto seem to be the only trusted source these days. or millings, the company that makes the oil pumps.


before you pull the head, pull the valve cover and see if a rocker on 1 and 7 is loose meaning the lifter is stuck down.

good luck..

 

[davidkramer]

wait.. did you replace the afm lifters with non afm lifters? or new afm and if afm what brand?

I've seen threads where guys put new Amazon/ebay(China) afm lifters and they fail from the first start having to do it all again. the only acceptable brands are oem gm, not bought from Amazon. either dealer, gm parts direct or rock auto seem to be the only trusted source these days. or millings, the company that makes the oil pumps.


before you pull the head, pull the valve cover and see if a rocker on 1 and 7 is loose meaning the lifter is stuck down.

good luck..

Thank you. He purchased the lifters for both sides from RockAuto, I don't remember the brand but I believe Millings because that's what the oil pump is. He is going to take the valve cover off on Friday and check for the rocker arms and take the head apart again if that seems fine. I have the car sitting but was weird is that the misfire code almost goes away when the car is warmed up or if you are doing freeway driving. When it is cold or in stop and go traffic, it comes on quickly.

 

[bigboy215]

Hey can anybody answer this question for me I want to know if a 2014 stand with angle sensor will fit a 2009 Tahoe Chevrolet says the steering wheel angle sensor is discontinent so I want to know if the 2014 to fit on a 2009 if anybody here ever had this problem with the attraction stabilizer light coming on

 

[bigboy215]

Hi! I have just helped a friend clear stabilitrak and violently shaking engine by removing and cleaning the throttle body also changed the throttle body sensor which may not have been needed but he's running smooth once again, check that if you haven't done so as yet!
PS I also found a broken wire on the sensor connector

2008 Tahoe with traction stabilizer light on and I changed the steering wheel angle sensor and I still have the lights on and I already checked the wheel speed sensors I don't know what to do next

 

[j91z28d1]

2008 Tahoe with traction stabilizer light on and I changed the steering wheel angle sensor and I still have the lights on and I already checked the wheel speed sensors I don't know what to do next

best to start another thread.

I have no idea about steering wheel sensors on these trucks

 

[j91z28d1]

Thank you. He purchased the lifters for both sides from RockAuto, I don't remember the brand but I believe Millings because that's what the oil pump is. He is going to take the valve cover off on Friday and check for the rocker arms and take the head apart again if that seems fine. I have the car sitting but was weird is that the misfire code almost goes away when the car is warmed up or if you are doing freeway driving. When it is cold or in stop and go traffic, it comes on quickly.

pulling the valve cover should show pretty quickly if the new lifters are stuck.

just remember you can't use non AFM lifters on a afm cam. I don't know if that's what he did, but it's been tried before and it seems to lead to a miss. you have to use a afm delete kit that comes with cam, lifters and new pushrods I believe and then have it turned off in the tune as well if you want to delete afm. it all kinda snowballs at that point.

 

[bigboy215]

Hi! I have just helped a friend clear stabilitrak and violently shaking engine by removing and cleaning the throttle body also changed the throttle body sensor which may not have been needed but he's running smooth once again, check that if you haven't done so as yet!
PS I also found a broken wire on the sensor connector

2008 Taho ltz and I just changed the steering wheel column because my traction is stabilizer light was coming on and the angle sensor was bad and now I'm having a cold reading c0455 and co242 can anybody out here tell me what these codes mean

 

[davidkramer]

UPDATE:
Friend pulled the head off and replaced the all the lifters on the driver side, replaced the head and valve gasket, with the same brand. Tahoe runs great now with no hesitation, no misfire and full computer diagnostic is perfect.
He sent the lifters (Meling) and head gasket (FelPro) back to RockAuto. Defective lifters was the final verdict.
Push rods, rocker arms still looked great.