07 yukon XL denali dies at idle when hot after 15 min

[tony maccaronio]

I have found dozens upon dozens of these posts all over in every forum with no solution. I found the issue. After initially changing fuel pump in winter then reading a post about changing the fuse block then being told to change the ecm, I found another post that said to check wires by power steering pump which run thru the p/s hoses. Well they were ok, but in that harness is the cmp and cxp wiring. I pulled the entire harness apart and found about 3 inches from ckp-the problem. The 3 wires fused together and when hot they would destroy the signal to computer and injectors. Replace pigtail, individually tape the wires, change ckp while you are there and test-it will no longer stall when hot and not restart-GUARANTEEED. This is only for those of you with no codes and good fuel pressure when it stalls and won't restart

[tony maccaronio]

ckp pigtail is the issue!!!!!!!!!!!!!!! replace it. the wires fuse together.

[It's Tim]

49 minutes ago, tony maccaronio said:

ckp pigtail is the issue!!!!!!!!!!!!!!! replace it. the wires fuse together.

Most peeps on this site would rather just throw parts and money at it rather than actually performing any type of diagnostics.

[Black02Silverado]

Spark chasing is a master art all on it's own.  Hopefully the OP will see the post on the ckp.

[AEHEART]

Thanks Tony gonna look into this

[nick kraskoff]

On 2/24/2020 at 8:57 PM, Joeroket said:

I have an 07 yukon xl1500 denali that runs good until about 10 minutes or so of driving after it is warmed up. It runs as long as I keep the throttle cracked a little but at idle it will die and wont start for around 20 min. Has been to a local shop that was stumped and the dealer who said they couldnt reproduce it and told me my battery and negative cable was bad and that was probably causing the issue. The local shop did tell me that he watched all sensor voltages slightly increase for no apparent reason and that has him thinking its an electrical issue. The dealer told me they were seeing voltages randomly dip, thus their diagnosis that the neg cable and battery were the culprit

 

 

I have changed the fuel pump, crank sensor, the three cam position sensor components, throttle body, alt, battery (it was actually bad) connector for the crank and cam sensors, and both battery cables. I have also cleaned the ground points and connectors for the both battery cables. When testing the grounds I have never seen more than .1 ohms from any point to any other point. The positive side shows full continuity from the starter post to the fuse block.

 

When it warms to running temp it runs rough. Tonight it died so I waited it out and started it up after about 20 minutes. While it was in the driveway I popped the hood and grabbed my meter, it was running pretty rough, to verify voltages and ground. Everything seemed fine but I noticed that after the hood was open for about 5 minutes it started idling better. I shut the hood and gradually the idle started to get rough so I opened the hood again and the idling smoothed out. Closed it once again and the roughness returns. It certainly seems like a heat issue in the engine bay. Also I have never been able to reproduce the dying issue in my driveway no matter what I do. It only does it when on the road.

 

The only thing I can think of now is that the harness has an issue somewhere and something is increasing in resistance under the high temps of a closed hood.

 

Any ideas?

I had same problems, replaced tcm cps vvt acuater transmission control module fuel pump same problems still so I bought a tuner and turned up idle and wow no more stalling 

[nick kraskoff]

On 2/24/2020 at 8:57 PM, Joeroket said:

I have an 07 yukon xl1500 denali that runs good until about 10 minutes or so of driving after it is warmed up. It runs as long as I keep the throttle cracked a little but at idle it will die and wont start for around 20 min. Has been to a local shop that was stumped and the dealer who said they couldnt reproduce it and told me my battery and negative cable was bad and that was probably causing the issue. The local shop did tell me that he watched all sensor voltages slightly increase for no apparent reason and that has him thinking its an electrical issue. The dealer told me they were seeing voltages randomly dip, thus their diagnosis that the neg cable and battery were the culprit

 

 

I have changed the fuel pump, crank sensor, the three cam position sensor components, throttle body, alt, battery (it was actually bad) connector for the crank and cam sensors, and both battery cables. I have also cleaned the ground points and connectors for the both battery cables. When testing the grounds I have never seen more than .1 ohms from any point to any other point. The positive side shows full continuity from the starter post to the fuse block.

 

When it warms to running temp it runs rough. Tonight it died so I waited it out and started it up after about 20 minutes. While it was in the driveway I popped the hood and grabbed my meter, it was running pretty rough, to verify voltages and ground. Everything seemed fine but I noticed that after the hood was open for about 5 minutes it started idling better. I shut the hood and gradually the idle started to get rough so I opened the hood again and the idling smoothed out. Closed it once again and the roughness returns. It certainly seems like a heat issue in the engine bay. Also I have never been able to reproduce the dying issue in my driveway no matter what I do. It only does it when on the road.

 

The only thing I can think of now is that the harness has an issue somewhere and something is increasing in resistance under the high temps of a closed hood.

 

Any ideas?

 

[swathdiver]

2 hours ago, nick kraskoff said:

I had same problems, replaced tcm cps vvt acuater transmission control module fuel pump same problems still so I bought a tuner and turned up idle and wow no more stalling 

Did you take the throttle body off the intake and clean both sides of it?  

[Gabeuse]

Did you solved your problem Joroket?