LLY: breaking up at 4k

jdlover1

jdlover1

437 Cubic Inches
Oct 4, 2006
538
0
16
chapanoke,nc
i dont think i data logged that. I'm wondering if it is the injectors return to much or maybe valves are starting to float since i usually run at 4500rpms.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
jdlover1 said:
i dont think i data logged that. I'm wondering if it is the injectors return to much or maybe valves are starting to float since i usually run at 4500rpms.
Click to expand...

thats not valve float. Thats a sharp "hard" defuel. Its an electronics/control problem, Ill put money on it. Something wrong with the FICM, or the ECM is losing timing/CKP reference intermittently.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
Heres what a loose CKP sensor sounds like. A loose reluctor wheel would sound very similar.

http://www.youtube.com/watch?v=0Pb1dVzO4hc

pull the CKP sensor from the front cover and see if you can wiggle the reluctor wheel with a screwdriver.

If the ECM is losing CKP ref intermittently, you will NOT see anything abnormal with a scan tool, because the Class 2 databus on the LB7/LLY simply doesnt refresh fast enough to see the CKP signal dropping out/picking back up again.
 
Stingpuller

Stingpuller

The Pusher Man
Jan 11, 2007
2,019
35
48
57
central Ohio
Miss

I have the same problem! Mines about 4400 but acts the same. That's the problem I have been fighting all summer! It run fine at first but now it misfires around 4400. It makes it hard when you leave the line at 3900. I have already been into the crank and reluctor but still have the problem. I have had mine on a scope but didn't see anything.
 
jdlover1

jdlover1

437 Cubic Inches
Oct 4, 2006
538
0
16
chapanoke,nc
I've been having this problem since may. First it was a fuel line fitting leaking, then i forgot to plug in maf sensor, then fuel pressure was dropping come to find out cp3 in valley was on the outs. Seem like everytime i fix one problem another one would show up but the truck still acting the same like in the video.
 
D

Dan@PPE

Diesel Enthusiast
Aug 8, 2006
2,570
0
36
So Cal.
Stingpuller said:
I have the same problem! Mines about 4400 but acts the same. That's the problem I have been fighting all summer! It run fine at first but now it misfires around 4400. It makes it hard when you leave the line at 3900. I have already been into the crank and reluctor but still have the problem. I have had mine on a scope but didn't see anything.
Click to expand...

What year engine? how much peak pulse in your tune?
 
McRat

McRat

Diesel Hotrodder
Aug 2, 2006
11,249
26
38
64
Norco CA
www.mcratracing.com
You cannot have injector overlap. This occurs with a single pulse (no pilot) at about 3000 microsec at 4000 rpm. You'd have to do the math.

You need to shorten the duration. I've got datalogs up to 5200 rpm out of a Dmax.

At PPE, I dyno'd the GT42 mag and it made 798rwhp at 4800 rpm. Dan was there. Stock injectors.
 
D

Dan@PPE

Diesel Enthusiast
Aug 8, 2006
2,570
0
36
So Cal.
McRat said:
You cannot have injector overlap. This occurs with a single pulse (no pilot) at about 3000 microsec at 4000 rpm. You'd have to do the math.
You need to shorten the duration. I've got datalogs up to 5200 rpm out of a Dmax.

At PPE, I dyno'd the GT42 mag and it made 798rwhp at 4800 rpm. Dan was there. Stock injectors.
Click to expand...

:thumb:
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
its not injector overlap. It keeps coughing and missing even when the RPM's drop back down low.

I still say its caused by the ECM somehow losing CKP ref.
 
Stingpuller

Stingpuller

The Pusher Man
Jan 11, 2007
2,019
35
48
57
central Ohio
tune

I run 100 over injectors with a 1800 pulse. That's it! In the white truck I run 2900 with the same setup. It run well over 5000 also. When I ran my 8.10 pass it was with a 1800 pulse tune and 35* timing at 3900rpm and up. Mine had a bad miss witch was the sensor but it's fixed. The tach would jump around and the shifter would go off so I knew it was rpm/signal related and that is fine now. I still have the high speed miss and if I turn it up any it just gets worse.
 
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