Need help from guys using VMP GT500 TB

[Soap]

I noticed in my datalogs that my "Load" is not pegged at 2 and my "Throttle Position Absolute" is not pegged at 950 so it got me wondering if my TB blade is fully opening. I checked it out last night and found that with the gas pedal fully depressed the blade is only open about 80%. I never had this issue with my old Accufab on my ported Eaton. I also noticed the cam on the VMP TB is way different than my old Accufab. The Accufab cam was very linear (nice smooth arc) whereas the VMP is sort of exponential......it has a small curve then basically a straight line.

Anyway, has anyone had to do any adjusting to get their VMP TB to fully open? If so what did you do? I would like to add that I already have the carpet trimmed under the gas pedal, so that is not an issue.

Here is the blade with the gas pedal to the floor...

Here is with the blade fully opened...

Here is the TB cam...

--Joe

 

[whitedevil95]

Great Question! When I installed my throttle body I had my dad check this for me. When i first put the pedal to the floor he said it didnt open all the way. So I did it a few more times and then he said it was opening all the way. I might have to check this later today when I get home. Ill report back.

 

[beastmar]

I know with my Dragon TB, I cut the throttle cable and weld the end piece back on. My throttle cable was too long causing the throttle body not to open all the way

 

[whitedevil95]

Here's what I got. Sorry it was kind of a bitch with the high boost on. Top is closed bottom is pedal to the floor. Was hard for my wife to get a lower angle at it. Looks like mine is opening all the way...

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[WHITESTRIPES]

Does your gas pedal have some slop in it? I know I read a while back that people used a spacer in between the pedal and cable, essentially shortening the cable and allowing the throttle blade to fully open.

 

[Soap]

Here is my datalog from the track. I am only fully WOT at the very top end of the track (plateau on the right of the graph). When I launch I am at 70% throttle, then the blade even springs back closed just a bit

I modified the cable last night to account for the slack. I never even thought to do this as I never had the issue with my Eaton/Accufab combo. Oh well, I hope this solves the problem.

--Joe

 

[whitedevil95]

Here is my datalog from the track. I am only fully WOT at the very top end of the track (plateau on the right of the graph). When I launch I am at 70% throttle, then the blade even springs back closed just a bit

View attachment 1440856

I modified the cable last night to account for the slack. I never even thought to do this as I never had the issue with my Eaton/Accufab combo. Oh well, I hope this solves the problem.

--Joe

What exactly did you do to pick up the slack?

 

[Soap]

What exactly did you do to pick up the slack?

I made a small spacer/bushing to lift up the pedal. I had about 3/4" of slack in the throttle cable. I put it between the gas pedal and the end of the throttle cable. Thanks goes to SVT_Troy for the idea.

--Joe

 

[SVT_Troy]

Good to see you got it worked out Joe.

There’s been plenty before me to thank for this small but highly effective mod. Come down south and you’ll get to enjoy the cobra apt more!


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[Bdubbs]

Very interesting thread. This had me nervous about mine. I checked my logs and my load pegs at 2.00, and my TP maxes at 951.

I wonder why some people are having issues. Is it the cable itself causing the problem?

 

[Soap]

I wonder why some people are having issues. Is it the cable itself causing the problem?

I think the issue is that the location of the throttle body and cam is different from OEM which causes slack in the cable. I did not have any issues with my Eaton setup using the unmodified throttle cable. The location of the TVS setup created about 3/4" of slack in my cable which prevented the blade from opening up all the way. Luckily it was an easy fix.

--Joe

 

[Bdubbs]

I think the issue is that the location of the throttle body and cam is different from OEM which causes slack in the cable. I did not have any issues with my Eaton setup using the unmodified throttle cable. The location of the TVS setup created about 3/4" of slack in my cable which prevented the blade from opening up all the way. Luckily it was an easy fix.

--Joe

I see. But why isn't it consistent then? I would think a lot more people would be running into this problem.

 

[Soap]

I see. But why isn't it consistent then? I would think a lot more people would be running into this problem.

Not sure. Inconsistencies with the length of the OEM throttle cable?

Same reason why some people need a firewall adjuster to lift the clutch pedal and some people don't.

--Joe

 

[Bdubbs]

Not sure. Inconsistencies with the length of the OEM throttle cable?

Same reason why some people need a firewall adjuster to lift the clutch pedal and some people don't.

--Joe

Do you have any pictures? I may do it as a precautionary measure.

 

[01yellercobra]

Very interesting thread. This had me nervous about mine. I checked my logs and my load pegs at 2.00, and my TP maxes at 951.

I wonder why some people are having issues. Is it the cable itself causing the problem?

Those are pretty normal. Placement of the cable bracket also affects the slack in the cable. So aftermarket blower+aftermarket plenum+aftermarket throttle body..... I think you get the idea. I've done the gas pedal mod on a couple cars. I've used zip ties as well as fuel hose with hose clamps. Cheap and easy. And you can adjust the height for comfort as well as making heel-toeing a little easier.

As for load, the tune can affect that as well. Depending on how everything is scaled.

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[Bdubbs]

Those are pretty normal. Placement of the cable bracket also affects the slack in the cable. So aftermarket blower+aftermarket plenum+aftermarket throttle body..... I think you get the idea. I've done the gas pedal mod on a couple cars. I've used zip ties as well as fuel hose with hose clamps. Cheap and easy. And you can adjust the height for comfort as well as making heel-toeing a little easier.

As for load, the tune can affect that as well. Depending on how everything is scaled.

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Good info. I think mine's good, but I'll have the wife put the pedal to the floor so I can check the tb. Just seems like there is some slack. So just take cable off pedal and add some fuel hose in between as a spacer?

 

[SVT_Troy]

Good info. I think mine's good, but I'll have the wife put the pedal to the floor so I can check the tb. Just seems like there is some slack. So just take cable off pedal and add some fuel hose in between as a spacer?

You use a hard spacer not flexible fuel hose. Message me your number and I’ll text you the same pics I sent Joe.


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[Soap]

Agree with Troy. Since the spacer can be crushed between the end of the throttle cable and the gas pedal you do not want the material to be rubber, use plastic or phenolic. Here is a quick 2nd gear WOT pull from the other night, compared to the previous datalog I posted the result is quite obvious.

--Joe

 

[01yellercobra]

Good info. I think mine's good, but I'll have the wife put the pedal to the floor so I can check the tb. Just seems like there is some slack. So just take cable off pedal and add some fuel hose in between as a spacer?

I didn't even take the cable off. I split the hose then wrapped the hose clamp around it.

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[Comp04svt]

Originally had an LFP throttle body on mine. When I swapped to the GT500 setup I had the same issue. All I did was "adjust"/"bend" the cable bracket some and that took care of it for me. Also took care of the little bit of slack my cable had as well.