Full throttle acceleration at 35-40 mph to WOT

[EssEss]

Hello all,

A while back I posted in http://forums.trailvoy.com/showthread.php?t=6826 my displeasure with WOT from a rolling 35 to 40 mph. To summarize: huge lag, lots of noise while engine spools up, flat, flat, did I mention flat, acceleration in some cases. NO BUENO! I have the Vector Tune. It has not improved and I am growing pretty tired of it. Unfortunately I do not have the capabilities to post video but I was wondering if anyone with the Vector Tune can duplicate a 35-40 mph hammer drop and post it so I can see the comparison. If what I am experiencing is normal, I have to think there would be louder grumblings because it is ridiculously annoying. I'm not necessarily saying it is tune related either, but I put my tune on at 500 miles exactly and NEVER went full throttle during that first 500 miles, so I have no basis for comparison.

Did I just get a crap-O ECM/TCM?:cry:

Maybe Chris can come to the rescue and send me a different module?

It would be great if I could get some feedback from the group and/or video would be greatly appreciated!

[Fishhunter911]

I can honestly say, I do that almost everyday while merging onto I-95 leaving work.. I dont have that problem. Anywhere in the MPH and RPM range when I floor it it goes!!!! I am thinking there is something amiss with your truck. I would take it in to get looked at.

[Sentinel]

I have the same issue. I have to say the transimission on the truck is rubbish. I can floor it and almost count to 2 before there is ANY acceleration. thats engineering for you.

I was hoping the Vector tune would fix it.

I find if you roll on the throttle it goes. But go WOT and you have to wait while the engine revs and you dont accelerate at all.

[Obsessed]

I have the same issue. I have to say the transimission on the truck is rubbish. I can floor it and almost count to 2 before there is ANY acceleration. thats engineering for you.

I was hoping the Vector tune would fix it.

I find if you roll on the throttle it goes. But go WOT and you have to wait while the engine revs and you dont accelerate at all.

When you floor it, I am sure the engine changes up the timing before it shifts, so this is the reason for the delay. I will be getting a tune this week and be back next week, so we will see.

WHen I had my Diablo installed, it ran pretty good. Pulled pretty nicely in almost any RPM range. Having the TCM tuned is going to make a much better difference I think.

Are your expectations of the vehicle too high, maybe? I know these are not the fastest vehicles out there, but high 13s or low 14s for an SUV is DAMN good.

Where are you from? What was the temp you tested it at? I gain almost .4 in the quarter and .2 0-60 if it's below 70 degrees.

[EssEss]

When you floor it, I am sure the engine changes up the timing before it shifts, so this is the reason for the delay. I will be getting a tune this week and be back next week, so we will see.

WHen I had my Diablo installed, it ran pretty good. Pulled pretty nicely in almost any RPM range. Having the TCM tuned is going to make a much better difference I think.

Are your expectations of the vehicle too high, maybe? I know these are not the fastest vehicles out there, but high 13s or low 14s for an SUV is DAMN good.

Where are you from? What was the temp you tested it at? I gain almost .4 in the quarter and .2 0-60 if it's below 70 degrees.

No our expectations are certainly not too high. Trust me, you would agree. I am to the point that I think my unit is defective. Sounds like Sentinel's unit was manufactured at 4 pm on a Friday and mine was at 4:30. I concur with Sentinel that you can indeed count two full seconds, it makes lane changes/overtakes embarrassing at times. I have an email out to Nelson Performance as they have had good success on GTO's. I think this is a great SUV, but I promise this level of performance is not tolerable.

[easyalexSS]

Sorry to hear about the slow response time on accel. I only have 800 miles on mine and it is stock as a clock and I don't have any problem like that. On many occasions I've accelerated into traffic from on ramps, push it to floor it just grabs another gear and hauls ass. No lag ,no stumble just goes.
You may have something not right, 'cause it oughta move out.
Good luck with that

[Hawaiian SS]

Sorry to hear about the slow response time on accel. I only have 800 miles on mine and it is stock as a clock and I don't have any problem like that. On many occasions I've accelerated into traffic from on ramps, push it to floor it just grabs another gear and hauls ass. No lag ,no stumble just goes.
You may have something not right, 'cause it oughta move out.
Good luck with that
I agree, 3300 miles on mine, stock, and no issues.

[PEDRO]

i had the same prob when stock and with vector...the rpm goes up in a hurry but the truck dont move...but now it just pulls at any time:)

[Blue Beast]

I can honestly say, I do that almost everyday while merging onto I-95 leaving work.. I dont have that problem. Anywhere in the MPH and RPM range when I floor it it goes!!!! I am thinking there is something amiss with your truck. I would take it in to get looked at.

Never miss an opportunity to merge, that's what I always say. Fish, are we all going to get together soon or is everyone too busy/lazy?

[TuneTimePerformance]

Are you referring to a flat spot at the bottom of second ? where it will miss the 1st gear drop ? There is a lot to that situation to consider . Temp,Heat soak,Fuel ? I'm sure Chris will help you out or explain to you why . As far a Nelson we [ Westers,Vector,ADM] have a lot of R&D on him and many trucks with our tune's . You can try but I feel you will lose some hp&tq compared to us .

[Sentinel]

Hmm maybe ill have the dealer check it out.

[ylab]

I remember seeing quite a few SS owners complaining about the 1-2 and 2-1 shift problem when they first started shipping. I also recall early Vector tune adopters saying that the tune removed that delay or stumble when stomping on the pedal, unless of course Stabilitrac happens to kick in and nerf the motor. (Wasn't there also a PCM update by GM that was supposed to fix the 1-2 / 2-1 shift issue?......I would expect that Vector & Wester's both incorporated the fix into their tunes, since they usually take the latest GM code and modify it).

The thought arises that you might want to try turning off Stabilitrac and then try to duplicate the problem......if it goes away, you know its big brother causing the problem.

[EssEss]

i had the same prob when stock and with vector...the rpm goes up in a hurry but the truck dont move...but now it just pulls at any time:)

Pedro, are you running the ADM tune now? and not noticing the problem anymore?

I wonder if I can petition Chris to send me a new ECM/TCM? :undecided Please!?

Ylab, it seems like I have duplicated even with Stabilitrak completely off (hold for 5 seconds off) but I will re-try today. I am sooooo tired of screwing with this, I don't even drive it. My Silverado SS isn't as fast and is tuned with only a handheld, it doesn't do this though.

[B 4 U]

My TBSS has the Vector Tune, from 30-40 to WOT, it puts you back in your seat immediately at the downshift. The wife's is stock, her's has the split second were the mgt software thinks, then it downshifts and goes like hell. My truck has 7300 miles and the wife's has 5300 miles.

Sounds like there is something faulty causing the "2 second" pause. I feel bad for the trucks and owners with that problem.

[PEDRO]

yeah ADM now and the problem is gone:)

[azachata]

I never noticed it....Hmmm...something to try out after work :devil:

[azachata]

Damnit the smilie didnt work :(

[Blades]

Yeah... This is a problem. I will try to post a couple 'videos' of the scanner readouts as far as RPM, Speed, and timing advance goes.. during the downshift/upshift you can see a dip in timing. The problem is that the computer will downshift into second right around 34mph. I bumped my WOT 2-1 shift up to 35.. big deal.. still the same.. The CAI definately increased the power down in that RPM range but still, its the weakest point.. At 32mph, the trans will downshift from 3-2 at 62% TPS.. If you are going on a flat road and lay into it at say.. 33mph.. it will downshift into 2nd quick and the 'window' for the 1st gear downshift will be far past.

Perhaps I should raise up the 3-2 part throttle shifts a little bit and adjust the other stuff accordingly. Yeah, I think I'll give it a shot.

[ScarabEpic22]

EssEss, how long ago did you get your tune? Maybe it was before GM introduced the patch and so therefore Vector could not have implemented it. I bet if you talk to Chris directly and explain the issue he will have some ideas or be able to ship you a new set of cores.

[EssEss]

EssEss, how long ago did you get your tune? Maybe it was before GM introduced the patch and so therefore Vector could not have implemented it. I bet if you talk to Chris directly and explain the issue he will have some ideas or be able to ship you a new set of cores.

I like this idea a lot... I got my TB and my tune back in late February. I have not been able to keep up with the forum for quite a while due to work demands, so in that time that I was out of the loop I am gathering that there was a software patch that I may have missed out on? I was kind of hoping I might get comment from Chris. :D

Blades, I appreciate the info, but I am pretty much a tool when it comes to this stuff. Can you elaborate a little more? How are you able to make ongoing modifications?:confused:

[SSkeetobite]

Post Vector tune: I noticed in the 35 to 40 mph hammer drop, it seems to go all the way down to 1st gear, wind out (seems to take a while... like a fraction of a second, but noticable) and hit second very hard. Wheels chirp going into second and it pulls like crazy. Almost aggrevated an old rodeo injury, but it's cool.

[DrkPhx]

Almost positively a tuning issue. The TC is not releasing (unlocking) and the trans is not kicking down to the next gear. It sounds like the WOT Throttle kickdown and TCC release tables are not adjusted correctly. Usually they are the culprit when you encounter a complete flat spot like that. Will it kickdown at part throttle (i.e. 1/2 or 3/4)?

[mick]

So, what was the final verdict? I had this trouble only once when some fool tried to hit me and I kicked it wide open and got very little response.
If I "roll into it" it pulls much better but I've only had the one incident and I have no tune, it's all stock.
I'm not really looking to make the performnce that much better but I was a bit disappointed that day.
Mick

[Silver06SS]

Are you referring to a flat spot at the bottom of second ? where it will miss the 1st gear drop ? There is a lot to that situation to consider . Temp,Heat soak,Fuel ? I'm sure Chris will help you out or explain to you why . As far a Nelson we [ Westers,Vector,ADM] have a lot of R&D on him and many trucks with our tune's . You can try but I feel you will lose some hp&tq compared to us .

I agree with this...there is a certain speed where if you floor it, it won't downshift because of the shift speed programming. A few more mph before you floor it, and it will. I've seen this before and after a tune....unless the tune adjusts upshift/downshift shift speeds.

[Vector MS]

To take advantage of the higher shift points and rev limiter we do increase the MPH for the 3-1 downshift.
It is only increased a few MPH, but it may make the lag feeling feel a little worse.
When you are going about 38 MPH steady state the vehicle is in third or forth gear and the converter is locked. When you put the pedal to the floor what happens is this (in order)

The converter unlocks
The transmission is comanded to go to first gear
The engine goes from approx 1600 RPM to 5600 RPM

I believe the hesitation is caused by all three of these things happening. The fact that we let this happen at a higher MPH may make it feel worse because the engine has to spin up to a higher RPM.

Kirk

[PEDRO]

KIRK i think thats what happened when i had ur tune and they may be the case here Thanks for your answer:)

[Sentinel]

Ah interesting. That is a long and slow process :mad: . Keep in mind this is why given a choice I buy manual cars lol.

To take advantage of the higher shift points and rev limiter we do increase the MPH for the 3-1 downshift.
It is only increased a few MPH, but it may make the lag feeling feel a little worse.
When you are going about 38 MPH steady state the vehicle is in third or forth gear and the converter is locked. When you put the pedal to the floor what happens is this (in order)

The converter unlocks
The transmission is comanded to go to first gear
The engine goes from approx 1600 RPM to 5600 RPM

I believe the hesitation is caused by all three of these things happening. The fact that we let this happen at a higher MPH may make it feel worse because the engine has to spin up to a higher RPM.

Kirk

[DrkPhx]

To take advantage of the higher shift points and rev limiter we do increase the MPH for the 3-1 downshift.
It is only increased a few MPH, but it may make the lag feeling feel a little worse.
When you are going about 38 MPH steady state the vehicle is in third or forth gear and the converter is locked. When you put the pedal to the floor what happens is this (in order)

The converter unlocks
The transmission is comanded to go to first gear
The engine goes from approx 1600 RPM to 5600 RPM

I believe the hesitation is caused by all three of these things happening. The fact that we let this happen at a higher MPH may make it feel worse because the engine has to spin up to a higher RPM.

Kirk

If anything I would lower the 3>1 shift point a couple mph or leave it stock.