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High Oil Pressure / Misfire


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I have a 2017 Sierra 5.3 doin the exact same thing maybe three times now. Soon after starting and driving maybe 100 or less feet the oil pressure spikes and the engine light flashes with the traction control light coming on. Dry pavement and under 40 km/h. 

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Petermackenzie: 

 

Curious: Start engine cold and let idle. Watch the Oil Pressure.

 

If same as mine, you should be able to hear the oil pump solenoid click, then the oil pressure will spike.

??

 

Also: Rough idle after spike

 

Just a long shot: Unrelated events for me: Have you changed thermostat and/or temp sensor recently?

Edited by Bentley
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  • 1 month later...

HawaiianRR: This has been a relatively complicated problem. Please read thread to see what I have done.

 

Presently, there is vacuum pressure problem on cylinder 8 and misfire, which is now spreading to 7 etc.

My guess is there is some kind of back pressure into the oil pump which is nullifying the pressure relief valve.

 

If I were crazy, I would bring it into GM and they would now replace lifters and rods, but then I would not know if the Cam is scored. So then replace the Cam, but then I don't know if the Cam bearings are shot (leaky). [I am guessing that the oil is leaking through the bearings causing the back pressure...]

 

Of course, after spending thousands, I still would not have addressed the heads and valves....

 

My solution: I have ordered an engine. So far I have been waiting about 2 months.

 

When the engine comes and is installed, I will immediately add a catch can and possibly nullify the AFM electronically.

 

CONCLUSION: I will never buy a truck newer than 2007 again. The fella replacing my engine said he has a lineup of GMs, Fords, and Dodges waiting for engines. The cause is all the emission control crap, direct injection etc. 

 

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3 minutes ago, Bentley said:

HawaiianRR: This has been a relatively complicated problem. Please read thread to see what I have done.

 

Presently, there is vacuum pressure problem on cylinder 8 and misfire, which is now spreading to 7 etc.

My guess is there is some kind of back pressure into the oil pump which is nullifying the pressure relief valve.

 

If I were crazy, I would bring it into GM and they would now replace lifters and rods, but then I would not know if the Cam is scored. So then replace the Cam, but then I don't know if the Cam bearings are shot (leaky). [I am guessing that the oil is leaking through the bearings causing the back pressure...]

 

Of course, after spending thousands, I still would not have addressed the heads and valves....

 

My solution: I have ordered an engine. So far I have been waiting about 2 months.

 

When the engine comes and is installed, I will immediately add a catch can and possibly nullify the AFM electronically.

 

CONCLUSION: I will never buy a truck newer than 2007 again. The fella replacing my engine said he has a lineup of GMs, Fords, and Dodges waiting for engines. The cause is all the emission control crap, direct injection etc. 

 

Should have ordered the L8T as a replacement engine. There's no AFM on it. 

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10 minutes ago, Bentley said:

HawaiianRR: This has been a relatively complicated problem. Please read thread to see what I have done.

 

Presently, there is vacuum pressure problem on cylinder 8 and misfire, which is now spreading to 7 etc.

My guess is there is some kind of back pressure into the oil pump which is nullifying the pressure relief valve.

 

If I were crazy, I would bring it into GM and they would now replace lifters and rods, but then I would not know if the Cam is scored. So then replace the Cam, but then I don't know if the Cam bearings are shot (leaky). [I am guessing that the oil is leaking through the bearings causing the back pressure...]

 

Of course, after spending thousands, I still would not have addressed the heads and valves....

 

My solution: I have ordered an engine. So far I have been waiting about 2 months.

 

When the engine comes and is installed, I will immediately add a catch can and possibly nullify the AFM electronically.

 

CONCLUSION: I will never buy a truck newer than 2007 again. The fella replacing my engine said he has a lineup of GMs, Fords, and Dodges waiting for engines. The cause is all the emission control crap, direct injection etc. 

 

Man o man, not looking good. I’m gonna take off the valve cover and see if I have a rocker/lifter issue. 
 

thanks for the reply!

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On 6/7/2024 at 5:57 PM, Bentley said:

HawaiianRR: What is the mileage on your truck?

 

230k lol

took off the valve cover saw the bent rod. Took out the bent rod looked in the hole with a scope and the lifter is collapsed and fell apart when I put a magnet to see if was busted. Yup, it’s toast 

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HawaiianRR: Ughh. Curious what your plan is.

 

I told my wife to post on fb that I keep forgetting to take the keys out of my truck. Perhaps someone will jump on the opportunity to drive the truck into the lake. (lol)

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17 minutes ago, Bentley said:

HawaiianRR: Ughh. Curious what your plan is.

 

I told my wife to post on fb that I keep forgetting to take the keys out of my truck. Perhaps someone will jump on the opportunity to drive the truck into the lake. (lol)

Lmao. That’s a good idea too!

my plan is to take the passenger side head off and pray that the cam lobe is fine. If so, I’ll change the lifters on that side with OEM afm stock ones to match driver side and get hp tuner and reprogram the ecu to delete the dod/afm

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2017 Yukon 5.3 

same issue here I’ve been chasing down the cold start misfire and or random cylinder misfire for a couple weeks. Noticed the spike in oil pressure this afternoon that matched perfectly as the TC and CEL came on flashing. And the misfire starts. This only happened when the engine is cold. I can shut it down clear CEL and start right back up and no misfire no CEL.

replaced 

injectors

plugs

wires

O2 bank 1 sensor 1&2( this is for the random air fuel bank 1 CEL)

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HawaiianRR: Ughh. Curious what your plan is.

 

I told my wife to post on fb that I keep forgetting to take the keys out of my truck. Perhaps someone will jump on the opportunity to drive the truck into the lake. (lol)

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16 hours ago, Bentley said:

HawaiianRR: Ughh. Curious what your plan is.

 

I told my wife to post on fb that I keep forgetting to take the keys out of my truck. Perhaps someone will jump on the opportunity to drive the truck into the lake. (lol)

Pulled the head off and took out the broken lifter. Camshaft lobe is not damaged. I plan to put 8 new gm lifters and guides. Replace the 1 bent pushrod. Change the filter in the VLOM because it’s easy on the top and can’t imagine that would hurt anything.  Button it back up with gm gaskets and get the HP tuner software to disable the DOD/AFM in the ecm. Then pray all holds up for some time 

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