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P0171 was the cause of death! Blown engine =/

4u33er

Well-Known Member
Messages
136
Location
NYC
Well after a year of ownership the motor blew cylinder #5. The piston, connecting rod and near by parts blew into pieces including a crack in the block. Thank god for the extended warranty!!!!

I've had the P0171 code that I've been trying to clear for about 2 weeks and finally the motor blew on the highway. Luckily no one was injured and was safely towed back to the shop.

I've been running an aftermarket air filter with stock airbox and resonator and the only other power mod was a flowmaster muffler in place of the oem muffler.

I got the PCMtuneforless done about 2 months ago and had the CASE CEL which was finally cleared.

After the CASE relearn I replaced my spark plugs (@ 75K miles) and serpintine belt along with the tensioner pulleys and the truck ran great, finally could REALLy feel the difference from the tune. It ran good for a week and all of a sudden I started getting a missfire (still no P0171 yet).

Fuel injector #5 was completely clogged (no idea how, it was not spraying at all!) so got that replaced. Now after another week or so the P0171 came on and found out that my intake manifold had a crack! It was causing a whistling noise at idle.

The previous owner/dealer who did the head gasket replacement under warranty must of damaged it during reinstall. So thinking thats what was causing the P0171 I got that replaced as well!

I have a scangauge and the car ran fine with this code present. I was able to clear the code and even pass NY-State inspection. But the code would kept coming back after 20~30 miles.

Went online and tried the suggested methods for P0171 which was a MAF cleaning spray along with Chevron fuel injector cleaner. That worked actually, the code went away by itself BUT it came back on after 50 miles or so and it kept coming on and off!

Thinking my MAF was just maybe busted, I got that replaced and it actually made it worse (it was OEM MAF from GM). The P0171 would now come on within miles of clearing it with my scangauge. Even clearing it with a tech II scanner would just make it pop up right on.

I gave up, was planing on trading it in soon anyways and just kept clearing it. Then BOOM! the motor went out.....

Luckily my warranty covers this and is getting a rebuilt complete motor/head put on.

Just wanted to share my story, P0171 was no joke! But still not sure what caused the P0171.....
 

4u33er

Well-Known Member
Messages
136
Location
NYC
I actually did thinking the misfire was due to the head gasket but compression was fine.
 

4u33er

Well-Known Member
Messages
136
Location
NYC
Well I dont think the PCM tune directly caused the lean code. PCM tune only caused the CASE CEL which was expected. After relearning CASE the P0171 popped up about a week or so.
 

Xlr8n

Well-Known Member
Messages
140
Location
Midwest
Well I dont think the PCM tune directly caused the lean code. PCM tune only caused the CASE CEL which was expected. After relearning CASE the P0171 popped up about a week or so.

Obviously something had to cause a lean condition that lead to a blown motor. A recent re-mapping of the air fuel mixtures could be one possible cause if something was programmed in error. Seeing you are running out of other leads, I just thought I'd throw it out there.

Before you run the re-mapped PCM on a brand new engine, it might be worth sending back in for verification of the proper tune. Or maybe not...
 

4u33er

Well-Known Member
Messages
136
Location
NYC
hmmm thats true! I guess after the motor swap and same PCM and the CEL still comes up then PCMtune could be blame...
 

Reloader

Well-Known Member
Messages
413
Location
Montana a free state
I have seen a weak fuel pump be the cause of a p0171 lean code on GMs with V8 engines. And we all know how common fuel pump failures can be on GMs. If it tests on the low end of its operating range it may not be producing enough volume to supply the fuel needs of the engine. This could be an intermittant problem and may also be responsible for poor starting. You might have them check the pressure after they get the replacement engine installed and running.
 

4u33er

Well-Known Member
Messages
136
Location
NYC
Fuel pump was replaced by the dealer when I first purchased the vehicle. It had failed once already.
 
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