LBZ: What makes our trucks have rail bounce?

DetailsUnlimited

DetailsUnlimited

Active member
Oct 26, 2009
1,264
0
36
Benton, Ar
Had an issue with two stuck needles in injectors #6#8. Fixed the problem. And the tunes I ran in my truck before will bounce at WOT now. Had a soft code P0103 that is in the truck now reading high MAF. What sensors would effect rail bounce besides PPE box and regulators? Both pumps are stock LBZ.
 
cstephens93

cstephens93

New member
Oct 13, 2014
677
0
0
31
Tallahassee, FL
I have had this code about 4 times pop up after hard WOT runs on my max effort tune from Idaho Rob

After trying to diagnose it many times (its hard without Rob personally there) he was thinking it was due to my engine being under load and somehow "pulling" on the harness and causing a short of some sort giving the code
 
DetailsUnlimited

DetailsUnlimited

Active member
Oct 26, 2009
1,264
0
36
Benton, Ar
That's a possibility on the harness getting pulled. 2000rpms and at 70 mph is where you can really feel it (truck jerk)in the truck also. One set of dsp5 tunes it tune 2. And another set of dsp5 tunes on tune 4. But all at wot.
 
cstephens93

cstephens93

New member
Oct 13, 2014
677
0
0
31
Tallahassee, FL
Yeah same here, all at WOT.

One of my cousins used to have that issue as well...one of his motor mounts was broken and the engine itself was lifting up and tugging the harness
 
mike diesel

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
We had to kill my limp mode to keep the p0103 from shutting my truck down. As long as I didn't hit 80 psi boost, it wouldn't throw it. But on my big tune at 105mph everytime after the hard launch it would shut me down. Regardless of what we did tuning wise, finally just shut limp mode off. Not exactly what we wanted to do, but it was all we could do. Tried 5 or 6 tune revisions as well. My motor doesn't move more than a hair either.
 
cstephens93

cstephens93

New member
Oct 13, 2014
677
0
0
31
Tallahassee, FL
mike diesel said:
We had to kill my limp mode to keep the p0103 from shutting my truck down. As long as I didn't hit 80 psi boost, it wouldn't throw it. But on my big tune at 105mph everytime after the hard launch it would shut me down. Regardless of what we did tuning wise, finally just shut limp mode off. Not exactly what we wanted to do, but it was all we could do. Tried 5 or 6 tune revisions as well. My motor doesn't move more than a hair either.
Click to expand...

Thats weird.

I didnt know the code would actually trigger limp mode
 
DetailsUnlimited

DetailsUnlimited

Active member
Oct 26, 2009
1,264
0
36
Benton, Ar
The P0103 did not set a red code (performance) in EFI. It was blue. But not sure if it was effecting anything tho. I'll switch the MAF out with my van and go from there.

Any other suggestions to the big rail bounce? Your experiences with this? Why after changing injectors this would happen or just a fluke and it's something else.

When I get back home today I'll be checking voltage on sensors and so on.
 
JD Dave

JD Dave

In way over my head
May 19, 2008
2,388
0
0
Caledon, Ontario
I had terrible rail bounce in my truck and you could see it in the smoke. The log looked like just a constant up and down line, not straight at all. I was told it was my pumps, regulators or something else on the truck not the tune. I swapped everything and it still did the same thing. Different tuners tried to fix it and Mark did fix it.
 
DetailsUnlimited

DetailsUnlimited

Active member
Oct 26, 2009
1,264
0
36
Benton, Ar
Mark fixed the Normal driving erratic rail. He said it was the ECM not playing nice. The update fixed that problem then raced Saturday and it was crazy at WOT. I was out of state and couldn't afford to brake something with the family with me. I've blown a motor out of state before and it's no fun not having a trailer!

Remember the first tune mark wrote worked great with just minimal rail bounce. And ever since the two bad injectors were replaced now it's got worse. I don't want to have tuning cover something up that's a hard part issue. Or am I going about this wrong?
 
zf>allison

zf>allison

you never had your car.
Apr 30, 2013
3,394
0
36
elsberry mo
Are you guys talking just duel fuelers trucks? Or crazy hp? I had a bad mounts and with the stick on a 3k and 4k dump my engine was torqing so bad my front drive shaft knuckle wore into my rear engine plate and I never had any sort of code.
 
JD Dave

JD Dave

In way over my head
May 19, 2008
2,388
0
0
Caledon, Ontario
This was only at fuel wot I had rail bounce and I was around 1000 hp then. This was on an LMM. I think they were more of a problem then LbZ.
 
You must log in or register to reply here.
Top Bottom