L5P Stutter

[DuramaxRamRod]

Having a new issue with my truck since I swapped back from a S464 to a S472. Around 1/3 throttle the truck will start stumbling/stalling most notably in 4th gear. Once the issue started I changed fuel filters and filled the tank up to rule those out. I've logged a little bit so far with HPtuners, rail actual vs desired looks good, but it does log some cylinder misfires. I saw 7/8 misfire which makes me think injector harnesses but looking over more of the log data I see the TCC Slip going up to 40 rpm and as a low as -40 rpm at times. Will the TCC slip cause the truck to defuel?

It seems more unlikely that 7/8 injector plugs just went bad but I was babying the truck more with the S464 as I never had the tuned changed. Which then leads me to a convertor issue which is a Goerend R.

 

[2004LB7]

Injection pigtails connectors are a known issue with the L5P. Somewhat similar to the LLY issue.

And too much slip in either the TCC or any clutch will cause the ECM to pull back power.

 

[Chevy1925]

Unfortunately, the L5 P injector connectors will just randomly go bad. What happens is the internal connector starts to arc within itself to the point where it loses connection all together. If you pull the connector off and you see a bunch of brown material all inside of the plug, that’s a great indication of it doing that and the connector no longer having a good connection.

We use the fish tuning connectors as he changes the ends to a better connector so they don’t do that anymore. We’ve done a lot of 17 to 19 trucks with those connectors and yet to have any come back

 

[DuramaxRamRod]

I suspect the connectors just seems odd to me that they're all going at once. Or maybe with a few intermittently bad others started to fail. I'll have to take a closer look at them tomorrow.

I was more worried about the TCC slip after I got a chance to look at the logs.

 

[Chevy1925]

I’d bet it’s been doing it longer than you thought. If they killed a lot of the codes that catch them failing, you wouldn’t know till they are real bad.

Yes, the ecm will yank power back with tcc slip being too high. I’d have to dig around on operation theory to see how much it would need to see to pull power out though

 

[JoshH]

Can you post a log? The biggest issue I've seen on trucks like yours with issues you are describing is MAF sensor signal drop out.

 

[DuramaxRamRod]

Heres one of them

Edit: cant attach an HPL file not supported

 

[DuramaxRamRod]

Definitely have some arcing in the at least the two I checked.

 

[2004LB7]

Heres one of them

Edit: cant attach an HPL file not supported

Non supported files can be put in a zip, then uploaded here. Alternatively you can change the extension to .txt or something else supported and just mention what it needs to be changed back to in order to use the file

 

[DuramaxRamRod]

Non supported files can be put in a zip, then uploaded here. Alternatively you can change the extension to .txt or something else supported and just mention what it needs to be changed back to in order to use the file

Thanks for that tip

 

[DuramaxRamRod]

To update I de-pinned all the injector connectors and cleaned them as well as crimped down on the pins where they slide over the injector pin. Truck seems smoother but could be a placebo and the issue still persists.

When I unplug the MAF the truck will no longer stumble like it does with it plugged in.

Can you post a log? The biggest issue I've seen on trucks like yours with issues you are describing is MAF sensor signal drop out.

Have you found bad MAF sensors or another issue with them?

 

[JoshH]

I've seen bad MAF sensors cause a stutter under load several times. I've also seen some bad rail pressure sensors cause some problems as well, but they usually throw the truck in limp mode when they screw up and often throw codes if someone hasn't turned them off with tuning. MAF sensors don't usually throw codes when they act up, but you can see it in the log.

I just looked at your log. It is 100% a MAF sensor problem. Could possibly be a bad connector, but more often than not, it's a bad sensor. Get a genuine GM sensor, and your problem should go away.

 

[DuramaxRamRod]

I've seen bad MAF sensors cause a stutter under load several times. I've also seen some bad rail pressure sensors cause some problems as well, but they usually throw the truck in limp mode when they screw up and often throw codes if someone hasn't turned them off with tuning. MAF sensors don't usually throw codes when they act up, but you can see it in the log.

I just looked at your log. It is 100% a MAF sensor problem. Could possibly be a bad connector, but more often than not, it's a bad sensor. Get a genuine GM sensor, and your problem should go away.

Thanks I just ordered one.

 

[DuramaxRamRod]

Got the new MAF in and it fixed the issue