Lly dsp5 tune hesitation/cut out from dead stop.

[vern650]

I recently got a trans safe dsp5 tune for my 05 lly from a reputable tuner and on positions 2-5 I get this horrible hesitation going from a dead stop straight to the accelerator pedal. It cuts out sort of like a bad accelerator pump on a carbureted vehicle. If you let the truck start rolling it does not do it when you hit the gas pedal, only from a dead stop. Also doesn’t do it when the engine is cold. Only when up to operating temp. Doesn’t do it on the stock tune or on position 1 of the dsp5 tune, only 2-5. I don’t want to name the tuner because I’m not intending this to be, nor do I want to turn it into a bashing post, but it is one of the few big name epa approved tuners and they have been very helpful in trying to figure this out. They’ve sent multiple tunes but so far nothing seems to fix it, I’m simply asking here for some ideas that maybe have been missed by either myself with the truck itself, or the tuner as I know there are a lot of knowledgeable guys here. Is it safe to assume if it was something with the truck itself I would have the issue all the time? Even on the stock tune? I appreciate any possible tips.

This should be a video demonstrating the hesitation. The first few hits are with foot on the brake. Then a few going from brake to gas, and the last two throttle hits are on pos 1 showing no hesitation.

Source: https://youtu.be/ZUXzxgMjlPk

 

[Ron Nielson]

It looks like the engine is responding but the transmission (maybe the torque converter) isn't turning the driveshaft, or the brake is still applied.

 

[vern650]

It looks like the engine is responding but the transmission (maybe the torque converter) isn't turning the driveshaft, or the brake is still applied.

The first few throttle blips in the video I kept my foot on the brake. If you listen carefully you can hear the cut out right when I blip the throttle pedal.

 

[2004LB7]

can you log it and see if it's actually cutting fuel? might help use determine where to look. I'm leaning towards a limiter or compensation table, or maybe even the defuel table. but I'd have to pull up a tune on my computer to look it over and see which one

 

[vern650]

can you log it and see if it's actually cutting fuel? might help use determine where to look. I'm leaning towards a limiter or compensation table, or maybe even the defuel table. but I'd have to pull up a tune on my computer to look it over and see which one

I’ve logged it and sent it to the tuner a couple times. He says he can see it in the logs, we just have to figure out what’s causing it. He’s sent me about 6 different tunes trying to figure it out so far but so far it hasn’t helped. I can feel differences in the tunes themselves so stuff is changing, but the hesitation remains. Says he’s put everything off idle on some of the later tunes back to stock, but still didn’t help. It’s always fine on position 1 but cuts out on pos. 2-5. One tune he recently sent he said was stock on all 5 positions, I’m guessing to test the switch or something, and it did not appear to cut out in any position but the next tune with added power it was back. I don’t know enough about this stuff to know what I’m looking at in the data logs or anything really about tuning so I’m just going off of what he’s telling me. So I can’t say what kind of stuff he’s already tried, but I’m sure he’s looked at all the simple or common stuff.

Is it possible to share logs on here? I’d have to do it when I got back to my laptop.

I do have soft codes that pop up for c0035 and c0055 for speed sensors as soon as you turn on the key, but he didn’t sound concerned about those. Speedo and everything functions like normal though and I would assume if those were causing an issue it would show in the stock tune as well.

 

[2004LB7]

put the logs in a zip file and upload them here

 

[vern650]

I’ll see if I can figure it out, I’m not much of a computer guy.

 

[vern650]

try this, this is from one of the most recent tunes. i have a couple more from some of the other tunes if this works and we need to look at more.

 

[2004LB7]

what I see in the log is driver demand engine torque and main injection quantity is lowered right as the throttle goes to 100%. if you look at an LLY tune in that same RPM range for the throttle base injection quantity there is a drop in that same area. same for the base torque map. I wonder if the increase in the main injection pulse for the other DSP tunes is exacerbating this drop if it wasn't adjusted for in the throttle base injection quantity and possibly even base torque.

I believe this drop in the tune was intended to reduce smoke off the line when one smashes the throttle from a stop. Tuner will need to play with this area to get it to respond better without smoking too much

 

[vern650]

Is this something obvious that an experienced tuner would see and understand? I don’t know what kind of stuff he’s tried, but he did say he’s put everything right off idle back to stock in some tunes and it still didn’t fix it.

 

[Chevy1925]

Is this something obvious that an experienced tuner would see and understand?

yes he should if he knows what hes doing.

 

[vern650]

With the reputation he has I would assume he’d see it then.

 

[Chevy1925]

With the reputation he has I would assume he’d see it then.

it might be something else but its definitley tune related because the stock tune runs perfect. this is where being a remote tuner can bite you. now its a matter of trying different things to see if you get a change.

 

[vern650]

Yeah, that’s pretty much where we’re at. He’s been good about sending me tunes to try he just hasn’t nailed it down yet. We have a few local diesel shops but I’m pretty sure they just get tunes from an outside source as well, and they all seem to be more Cummins oriented but do work on all brands. I borrowed an off the shelf PPE tuner from a buddy just to test and it was fine as well, so I would agree it must be the tunes. Hopefully he can figure it out, truck runs great other than this little hiccup.

 

[Dozerboy]

If it works on the stock tunes not a lot of changes in the can be made in the DSP's that it should be that difficult to find. If it is just the tune issue. I think you really need to find somewhere that can look at the truck in person. You might reach out to the tuner and see if there's any shops he works with that would help troubleshoot it.

 

[Chevy1925]

Yeah, that’s pretty much where we’re at. He’s been good about sending me tunes to try he just hasn’t nailed it down yet. We have a few local diesel shops but I’m pretty sure they just get tunes from an outside source as well, and they all seem to be more Cummins oriented but do work on all brands. I borrowed an off the shelf PPE tuner from a buddy just to test and it was fine as well, so I would agree it must be the tunes. Hopefully he can figure it out, truck runs great other than this little hiccup.

ask the tuner if he is using the biggest tune as the base tune or the stock tune as the base tune (this is not the same as tune 1 or tune 5). if he is using the stock tune as the base, have him switch it all around so the base tune is the biggest.

he might be trying to use the stock as the base tune and then upping power from there. problem is, you dont get all the tables needed for upping power for each dsp tune. The DSP tables will reference back and use tables from the base tune as it does not need every single table. if you swap it around, you kill off any issues of not having enough tables because you made the biggest tune and eliminated the limiters or issues BUT you can still easily pull power back and make a stock like tune for the smallest tune.

easy way to go about this is have him send a single tune of the biggest tune and worklog from there. if the issue goes away, he now has a good base tune to start making your DSP from. Just dont go hammering down all over the place, strictly use this for diagnosis.

 

[vern650]

Thanks for the ideas, I will see if I can find anything else out

 

[Bdsankey]

Are all of your tunes rumble idle or is tune 1 a hiss/factory type idle?

 

[vern650]

Are all of your tunes rumble idle or is tune 1 a hiss/factory type idle?

Tune 1 did seem to have more hiss than the rest at first, but through the course of trying to figure this out the idle on the others has changed to have more hiss like tune 1.

 

[vern650]

ask the tuner if he is using the biggest tune as the base tune or the stock tune as the base tune (this is not the same as tune 1 or tune 5). if he is using the stock tune as the base, have him switch it all around so the base tune is the biggest.

he might be trying to use the stock as the base tune and then upping power from there. problem is, you dont get all the tables needed for upping power for each dsp tune. The DSP tables will reference back and use tables from the base tune as it does not need every single table. if you swap it around, you kill off any issues of not having enough tables because you made the biggest tune and eliminated the limiters or issues BUT you can still easily pull power back and make a stock like tune for the smallest tune.

easy way to go about this is have him send a single tune of the biggest tune and worklog from there. if the issue goes away, he now has a good base tune to start making your DSP from. Just dont go hammering down all over the place, strictly use this for diagnosis.

I emailed him your suggestion and this was his reply:

“They are correct... but the issue its having (Which I haven't seen before and no reply from EFI on it yet) is that its FORCING itself into the maps in the selections 2-5... Even though they are matched to stock - its not listening as its forcing itself into a mode we DO NOT WANT... nothing harmful - just annoying. The DSP folders only have pilot injection C and D... That is what is causing it as I could see it in the datalogs, but unfortunately it doesn't allow us to even copy the tables (Tried it) from the other maps into it.

I was hoping maybe efi could find me a way to shut that function off.. but doesnt look to be.

I can make 5 single tunes if you want? This one kinda has us stuck.”

I’ll probably just go for the 5 individual tunes for now and see if that fixes it and maybe efi will get back to him with a solution.