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Old 04-20-2015, 01:33 AM   #1
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Boost drops

I just a 2.4 upper Pulley on my 2013 GT500 with the same stock belt, and I did a dayno run the boost start ok and then drops 2-3 psi and the picks up again near the cutoff. What could this be ?
And also the throttle which is stock too when I floor it , it does not open immediately, it opens gradually is the what causing the boost drop or vise versa ?


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Old 04-20-2015, 01:41 AM   #2
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Sorry I may be misinterpreting but if you replace the pulley with a smaller one you probably need to get a new tensioner, you may have some slippage
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Old 04-20-2015, 08:34 AM   #3
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How are you reading the boost, the dash gauge or a separate boost gauge ?
( the dash gauge may no longer read accurately after the pulley swap )
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Old 04-20-2015, 09:47 PM   #4
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Both of these guys are dead on. If you went smaller, you should definitely consider what they've already said. One of the 2 is likely the problem.
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Old 04-21-2015, 03:57 PM   #5
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I did install an idler pulley too to pick up the slack. And yes I read the boost in separate gauge. Some people say it's the belt so i will replace that with a new one and others say it's the throttle body and I'm not sure what's right.


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Old 04-21-2015, 03:58 PM   #6
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Quote:
Originally Posted by maldalo View Post
I did install an idler pulley too to pick up the slack. And yes I read the boost in separate gauge. Some people say it's the belt so i will replace that with a new one and others say it's the throttle body and I'm not sure what's right.


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I would bet belt before throttle body.
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Old 04-21-2015, 04:01 PM   #7
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I went with JLT intake with the stock throttle body that could be a problem too ( bottle neck).
I'll replace the belt for now and do another run before I replace the throttle body.


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Old 04-21-2015, 04:03 PM   #8
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Quote:
Originally Posted by maldalo View Post
I went with JLT intake with the stock throttle body that could be a problem too ( bottle neck).
I'll replace the belt for now and do another run before I replace the throttle body.


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Might need a monoblade
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Old 04-21-2015, 11:17 PM   #9
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Try cleaning the mas, and tb.


Too much never enough.
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Old 04-21-2015, 11:21 PM   #10
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javascript: { var vid = document.getElementById('video_1691355915'); if (firstTime) {vid.load(); firstTime = false;} if (vid.paused) vid.play(); else vid.pause(); }
I'm regard to the monoblade

---------- Post added at 09:21 PM ---------- Previous post was at 09:21 PM ----------

Sorry,
http://www.americanmuscle.com/13-14-...00-build3.html
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Old 05-07-2015, 03:43 AM   #11
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I replaced the belt and the throttle body now I don't see drop in the boost, but the boost now is increase gradually even tho I floor the peddle. The boost is supposed to be steady all the way until cut off not exponential increase. What do you think guys ?
Should I install back my original pulley and swap the lower pulley 10%
Or heat is a factor here as they say?


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Old 05-10-2015, 08:35 AM   #12
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Heat soak should only be a factor after you have ran it hard for a little bit. I swear it still seems like there is slippage somewhere. Once my boost kicks in, I'm gone. Until I let off. I can basically control it with the amount of pedal.
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Old 05-10-2015, 01:23 PM   #13
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Could have slack in it still. Maybe take a picture for us
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Old 05-15-2015, 04:35 PM   #14
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You can see the boost in greenClick image for larger version

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Old 05-15-2015, 08:30 PM   #15
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What throttle body did you have on when you saw the drop in boost? When you installed the new one, did you tune the car?
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Old 05-17-2015, 12:01 AM   #16
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Ford racing TB 65mm and yes this is after tuning.
Now is it's 690 rwhp as I expected from the mods I installed but I still don't think that this the normal graph for the boost. Boost as far as I know should be steady horizontal line with no dips, even tho the rwhp matches what is expected from the package I installed .


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