Just getting ready to start tuning a LBZ and my customer is complaining on turbo hesitation when he goes to WOT. I'm assuming the variable vane turbo is most of this. Has anybody been able to adjust the vane position to get a better response? If so, how much adjusting did you do and where? I appreciate any and all feedback.
Thank You

I have a "Race" tune. It keeps my boost levels high so when i mash the throttle in my LBZ it doesnt need to build alot of boost.

Also if he complains about turbo lag off I line, I fixed that by building lots of boost at about 800rpm. When I mash the throttle I go from about 6psi to 25 psi in a split second.

Hope it helps some :)

If you've tried the normal boost tables and boost scaling table tricks you can then dive into vane tuning. You can make them slightly more aggressive in the area the truck is having difficulty but be careful. Too much can cause overboost and turbo bark.

Is the customer talking about times like going down the highway and hitting the throttle to pass and there is a hesitation before it goes?

Is the customer talking about times like going down the highway and hitting the throttle to pass and there is a hesitation before it goes?

Yes, during that time mainly. He is also looking for quicker spool up from a dead stop. Not wanting much for hp. I have a 45-50 hp tune in it now, I am just trying to get the hesitation from a stop AND during a pass down to minimal.
thanks

Unfortunatly this seems to be a problem in the LBZ, some of my programs have been better than others. I dont think its a turbo lag problem, since usually have 2-3psi already built when driving down the road. Generally as we all can tell, once you have enough impeller speed to build a little boost it dosnt take long to hit max boost.

Seems to be more like the computer is taking to much time to think between what you want and what it wants the engine and trans to do.

Someone else may know more but I think it is a defuel for a downshift.

:iamwithst

Seems to be more like the computer is taking to much time to think between what you want and what it wants the engine and trans to do.

Interesting thought, problem is, the CPU in these are pretty fast, there 'might' be some sort of dampening effect the ECM is trying to achieve.
The only way to tell would be to log the boost and vane positions to see what is going on and to see how close they are to what you are trying to achieve. Logging speeds on the LBZ are very fast (if you keep it at the magic 24 PID channel mark) so the logs would be very useful.

Cheers,
Ross

Interesting thought, problem is, the CPU in these are pretty fast, there 'might' be some sort of dampening effect the ECM is trying to achieve.
The only way to tell would be to log the boost and vane positions to see what is going on and to see how close they are to what you are trying to achieve. Logging speeds on the LBZ are very fast (if you keep it at the magic 24 PID channel mark) so the logs would be very useful.

Cheers,
Ross

Thanks Ross
I'll see if I can get some logs on this truck. I don't have access to it everyday, so maybe somebody here that drives a lbz, that is having these symptoms, could do some logging also. I'll email some as soon as I get access to the truck again.

When I take mine back out on the highway I will put the stock program back in and log it. Most of the time I run all back roads and dont have a problem.

I may be wrong but I believe this "hesitation" has been discussed before. Check the vane positions with the egr open and with the egr closed. Has anyone been able to "tune" the egr out on the LBZ yet? I know I was experiencing power fluctuations with McRat's freebie tune until I installed my blocker plate. I am not sure if we are able to "disable" the egr completely on the LBZ's yet. Just my $.02.

There was EGR discussion here - http://www.dieselplace.com/forum/showthread.php?t=147849

I think some of it might be the six speed tranny cause it takes longer to drop two gears. I put mine in the manual setting and downshift to 5 then get on it that way the motor revs up creating a little more boost and faster kickdown.

Logged this scenario and there is also a timing issue that comes into play here as well. If cruising at 65-70 and put foot into it the timing drops 4 to 6 degrees for almost 2 seconds.

Interesting!