VMP 2.5" pulley and 90mm idler installed on '08 GT500. Questions???

[venams03]

Well I was able to get my 2.5" VMP pulley and idler installed with the help of OMICRON from McHenry. Thanks for the help Paul!!

So results: Stock boost gauge went from max of 7 lbs boost to about 11 lbs. It runs fairly well but stumbles when first started and for about the first 5 minutes of driving. Is this normal? I was expecting to be in the 13-14 psi range with these mods?

*Offroad X and 3" SW exhaust (very open and loud!)
*JLT Carbon Fiber BIG AIR KIT (127mm)
*VMP 2.5" pulley and 90mm idler
*Lund tune on X-CAL3

 

[CodyK7]

Stock gauge? Did you just put the intake on?

 

[venams03]

Stock gauge? Did you just put the intake on?

Stock gauge. Intake and exhaust were existing mods and the LUND canned tune was supposed to account for both. PER Lund the tune was graphed for the the new intake and MAF and mentioned that when I added pulley no need for new tune since it was already adjusted and would account for the increased air in the existing tune.

 

[CodyK7]

Stock gauge. Intake and exhaust were existing mods and the LUND canned tune was supposed to account for both. PER Lund the tune was graphed for the the new intake and MAF and mentioned that when I added pulley no need for new tune since it was already adjusted and would account for the increased air in the existing tune.

Check to make sure the filter is as far down as possible. That seems odd about the tune though. Do you mean you are running the same tune as before the pulley?

 

[venams03]

Check to make sure the filter is as far down as possible. That seems odd about the tune though. Do you mean you are running the same tune as before the pulley?

Yes. Filter is on all the way. Lund gave me a new tune when I added the BIG AIR JLT intake (127mm) and specifically told me that I did not need a new tune when I added the new (smaller) pulley since the tune would already compensate for the increased air. Is something AMISS here? Sure would like to know as I wouldn't want to unnecessarily grenade my engine!

 

[CodyK7]

Yes. Filter is on all the way. Lund gave me a new tune when I added the BIG AIR JLT intake (127mm) and specifically told me that I did not need a new tune when I added the new (smaller) pulley since the tune would already compensate for the increased air. Is something AMISS here? Sure would like to know as I wouldn't want to unnecessarily grenade my engine!

I've never heard of someone going from a stock pulley to a 2.5 pulley without a revised tune. Just doesn't make sense. On another note make sure the filter is as far down on the tube is possible. It doesn't need to be pushed way up on the tube.

 

[venams03]

I know I questioned Lund but was repeatedly told the same thing. No need for a different tune after the smaller pulley because the MAF will already compensate for the increased air which is already in the tune.

I really can't move the filter any further down because it runs into the fender. I initially had problems with the filter popping off the tube because I didn't have the filter fitted all the way on which kind of fits into a notched groove. I don't understand how having the filter fully seated up into the tube would be a problem?

 

[CodyK7]

I know I questioned Lund but was repeatedly told the same thing. No need for a different tune after the smaller pulley because the MAF will already compensate for the increased air which is already in the tune.

I really can't move the filter any further down because it runs into the fender. I initially had problems with the filter popping off the tube because I didn't have the filter fitted all the way on which kind of fits into a notched groove. I don't understand how having the filter fully seated up into the tube would be a problem?

If you are in that groove you are good. On the other topic..... Paging Bj paging BJ

 

[fullboogie]

First of all, the stumbling problem when cold (and particularly at part throttle) is not that uncommon. There's a long thread on the "other" forum with lots of guys seeking an answer to the problem - nobody knows why it's happening. I have the same problem across several tunes. As far as no tune, there's no way that's right. Were you dealing with Jr. or Sr.?

 

[Shaker1]

FWIW: I've got a 2008 with the original JLT CF intake (110 I think). I did switch to a pulley tune when I added the VMP 2.59" pulley. I have run both an EVO tune and now a Lund tune. I live in Northern Illinois as well, and am currently running a Lund "emissions" tune, as I just had the car emissions tested. Car runs like stock, except for the extra HP! Has been fine on all tunes I have used. 11 PSI is about what my stock gauge reads.

On a side note, I am sort of curious how you guys pass emissions in states with OBD-II "readiness" testing while using off road exhaust?

 

[VNMOUS1]

O no

Well I was able to get my 2.5" VMP pulley and idler installed with the help of OMICRON from McHenry. Thanks for the help Paul!!

So results: Stock boost gauge went from max of 7 lbs boost to about 11 lbs. It runs fairly well but stumbles when first started and for about the first 5 minutes of driving. Is this normal? I was expecting to be in the 13-14 psi range with these mods?

*Offroad X and 3" SW exhaust (very open and loud!)
*JLT Carbon Fiber BIG AIR KIT (127mm)
*VMP 2.5" pulley and 90mm idler
*Lund tune on X-CAL3

Call Lund and tell them about the cold start issue.

The boost thing has to do with the change in mass air transfer function. Not abnormal. And you are putting out 12-13 psi at sea level. You are at 750 fr msl. No biggie.

The pulleys make no difference in the calibration. The cal compensates. His does, ours does. Back in the day it was different.

It has nothing to do with the filter placement in this case.

You're fine but if the cold start characteristics bug you, call them.
Jon, JR or Ken can all assist the same.

Bj

 

[fullboogie]

BJ - has Justin figured out the cold part throttle stumble/hesitation between 1,800 and 2,500? Lots of guys are experiencing this, and it really puts a damper on driving the car. I'd love to get a revision that fixes this issue.

 

[VNMOUS1]

send me your latest datalog and full car config with serial and I'll get with him. Thanks.

bj

 

[Justin@VMP]

Yes. Filter is on all the way. Lund gave me a new tune when I added the BIG AIR JLT intake (127mm) and specifically told me that I did not need a new tune when I added the new (smaller) pulley since the tune would already compensate for the increased air. Is something AMISS here? Sure would like to know as I wouldn't want to unnecessarily grenade my engine!

I've never heard of someone going from a stock pulley to a 2.5 pulley without a revised tune. Just doesn't make sense. On another note make sure the filter is as far down on the tube is possible. It doesn't need to be pushed way up on the tube.

Depending on how your cal is set up, it can be done. There are positives and negatives for various directions, but generally, on a stock car ford does not tune for different boost levels caused by different elevations or a clean vs dirty air filter, so calibrations are already set up for this, and aftermarket calibrations build on this greatly.

The pic basically sums it up in the most basic sense, there is more, especially on returnless fuel cars and the 11 up DBW, but this is where it starts.

 

[Justin@VMP]

BJ - has Justin figured out the cold part throttle stumble/hesitation between 1,800 and 2,500? Lots of guys are experiencing this, and it really puts a damper on driving the car. I'd love to get a revision that fixes this issue.

There are many reasons for this, depending on year and level of modifications.

The most basic issue, especially on a cold start, is the maf transfer function being off a little. When you make your MAF housing bigger, as basically every aftermarket part does, you increase the variability at low airlfows and the sensitivity to MAF reading changes from outside forces like filter placement, how close a heat shield or hood is, etc.

Other things, like too much EGR, which the factory loves to do to hit MPG and emissions targets, is another culprit of "trailer hitching" or surging.

Hit us up with your info and we can look at your specific situation.

 

[fullboogie]

Thank you, Justin. I'll get a cold datalog over to you with my info, along with the date of the last tune you sent me.

 

[venams03]

I contacted Lund and although I explained that I installed the larger 90mm idler along with the 2.5" upper he thinks I'm getting belt slip which is why the OEM gauge is reading only about 10.5 psi.

Can anyone else with similar mods chime in Please? Is anyone getting readings like me or is your boost up near 13-14 like VMP says it should be? I'm at a loss where to go right now and I really don't want to spend the time/driving/money to get a dyno tune just to find out what's happening

 

[venams03]

I contacted Lund and although I explained that I installed the larger 90mm idler along with the 2.5" upper he thinks I'm getting belt slip which is why the OEM gauge is reading only about 10.5 psi.

Can anyone else with similar mods chime in Please? Is anyone getting readings like me or is your boost up near 13-14 like VMP says it should be? I'm at a loss where to go right now and I really don't want to spend the time/driving/money to get a dyno tune just to find out what's happening

Anyone?

 

[Shaker1]

So, 13-14 PSI is normal if the gauge is reading correctly? Even with a 3" catless exhaust?
I though 11-12 PSI was expected, but apparently not.

Admittedly, I am not usually looking at the gauge when I am pushing it hard.

 

[Taxan]

Anyone?

I have the VMP 2.5" pulley and a steeda CAI and a VMP tune, and i´m getting the same PSI reading as you at sea level . But i am using the stock exhaust...