Truck cuts off at high rpm

[Mdmax]

not stacked with anything

 

[DAVe3283]

What areas should I be looking at? Also I cant get the dashboard to work on the scan tool any trick to it?

I personally just use black box logging, so you can leave the laptop at home if you want.

I would record desired rail pressure, actual rail pressure, throttle position, engine rpm, vehicle speed, and injector pulse width.

 

[Mike_S]

when you log the truck, just select the pre loaded imperial pid selection file. this is generally enough info for basic diagnostics.

 

[Mdmax]

Recorded a couple sessions, Is there a way to post it up on here so you guys can look at it? Do I need a memory card to record with the black box?

 

[Mdmax]

bump someone help me before I set my truck on fire. the logs dont seem to mimic what im seeing on the tach. Cant really tell anything is happening.

 

[JoshH]

Recorded a couple sessions, Is there a way to post it up on here so you guys can look at it? Do I need a memory card to record with the black box?

You can put the logs in a zipped folder and attach it to a post.

 

[Mdmax]

Heres one hopefully it works. I really appreciate any help I can get. thanks

 

[JoshH]

Frame 122 shows a sharp drop in both MAF and boost pressure. Can you get another log that shows vane position?

 

[Mdmax]

Ok got 2 more logs with vane pos. and a few more pids that may help. I noticed on this one the difference in rail pressure was off almost 2k psi. Is that normal? Another thing right when it cuts off theres a big hiss and a huge plume of light gray smoke.

 

[disspose]

Anything else? Did you ever find the problem? I have a LB7 and it was jerking/cuting out at 2500-2800 in every gear.... I need help....!!

 

[LWATSON]

You getting any codes?

 

[disspose]

No Codes
Parts changed...
Fuel filters
Fuel pressure regulator
FICM
ECM
BCM
Crank and cam sensors.
Went to stock tuning- still does it

Use a scan tools snap on... watch while it does it and everything looks fine.

I am lost.

 

[LWATSON]

Dont go throwing money at this thing on account of what I say, but I helped diagnose a truck a while back, LB7, it was doing some crazy things. Limited to 2000 rpms, falling on its face and it was bone stock. It didnt set any codes which made it difficult. Ended up being the Cp3.

 

[GMC_2002_Dmax]

Unplug your insight and see if it goes away

 

[disspose]

We have unplugged the insight... Hence how would we plug a scan tool in??

Lwatson.... We are swapping out parts off a running lb7.. So I am not buying all of those.
ALso.... It holds rail pressure when turned up with a scan tool. Did that one you fixed hold it up to 23k?

 

[Mike_S]

At idle it holds rail pressure when commanded up, or it holds through the whole rpm range? I have a weak CP3 that will hold pressure at idle, but barely holds pressure at higher revs.

 

[LWATSON]

We have unplugged the insight... Hence how would we plug a scan tool in??

Lwatson.... We are swapping out parts off a running lb7.. So I am not buying all of those.
ALso.... It holds rail pressure when turned up with a scan tool. Did that one you fixed hold it up to 23k?

We did not check rail at idle but under throttle it would only hold about 14k.

 

[disspose]

It holds it when commanded by the scan tool and while driving.
Desired vs actual is basically the same.

 

[disspose]

Another guess we have is if one of the injectors ir grounding out or failing, it would take out three other ones as well on that string. But the weird part is that should set a code. No codes are ever given with any scan tool we use(insight or snap on) or even a dealers.

 

[disspose]

bump.....


Also.. where can I get a new engine wire harness??