boost level not returning after shift...
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11 Second Truck Club
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From: Dallas, Georgia
boost level not returning after shift... boost usually climbs to 10+ #'s...drops to 5-6 #'s @ 1-2 shift...then climbs back to 10+ #'s...(TB converter)
last night:
boost climbs to 10+ #'s...
1-2 shift...drops to 5-6 #'s...
boost then only climbs back to around 8 #'s...
changes from last tuning session:
smaller tires...30" street tires to 26" MTDR...have always run these though...when tuned last w/ street tires, tune was changed to shift by rpm instead of mph...which should have eliminated the need to change tune to run the smaller tires, correct?
93 octane to 110...if too much octane, it could decrease power but not boost level, correct?
changed tires back to 30" street tires...filled up w/ 93 on the way home...SAME TUNE...stopped...went WOT...boost climbed to 10+...1-2 shift dropped boost to 5-6...then it climbed right back up to 10+ before letting out...
last night:
boost climbs to 10+ #'s...
1-2 shift...drops to 5-6 #'s...
boost then only climbs back to around 8 #'s...
changes from last tuning session:
smaller tires...30" street tires to 26" MTDR...have always run these though...when tuned last w/ street tires, tune was changed to shift by rpm instead of mph...which should have eliminated the need to change tune to run the smaller tires, correct?
93 octane to 110...if too much octane, it could decrease power but not boost level, correct?
changed tires back to 30" street tires...filled up w/ 93 on the way home...SAME TUNE...stopped...went WOT...boost climbed to 10+...1-2 shift dropped boost to 5-6...then it climbed right back up to 10+ before letting out...
Last edited by Superado; Jul 21, 2007 at 10:37 PM.
Launching!
Joined: Mar 2007
Posts: 227
Likes: 29
From: DC Metro area
I dont own a Procharged car, but I do own a Roots-blown car (1998 GTP)...
I've only seen the boost drop on my car while WOT 2 times. Once when the bypass valve control solenoid went bad, and the other when the blower belt unexpectedly began to shread. I put a belt on it the week before (cheap Autozone crap) and it began to fail in the middle of a street "encounter".
Imma take a guess and say belt-slip, maybe? Thats where I would start. Since I dont have a lot of experience with centrifugals, I might be way off the mark.
I've only seen the boost drop on my car while WOT 2 times. Once when the bypass valve control solenoid went bad, and the other when the blower belt unexpectedly began to shread. I put a belt on it the week before (cheap Autozone crap) and it began to fail in the middle of a street "encounter".
Imma take a guess and say belt-slip, maybe? Thats where I would start. Since I dont have a lot of experience with centrifugals, I might be way off the mark.
Thread Starter
11 Second Truck Club
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From: Dallas, Georgia
I understand your answer based on your experiences, but it doesn't do it with the taller tires and 93 octane...or hasn't I should say...before AND after doing it at the track on 26" tires(which I've ran several times w/o issues...including my best ET) and 110 octane...
Launching!
Joined: Mar 2007
Posts: 227
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From: DC Metro area
Originally Posted by Superado
I understand your answer based on your experiences, but it doesn't do it with the taller tires and 93 octane...or hasn't I should say...before AND after doing it at the track on 26" tires(which I've ran several times w/o issues...including my best ET) and 110 octane...
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From: boostville
First off, how are you measuring boost? is it thru a MAP sensor or by the old eye ball method?
Second, have you ever done a boost leak test? If not that would be the first place you should check.
Tire size & octain rating have zero effect on changing the amount of boost you are making so I don't think they are factors. With a SC, your boost is fixed so you should always be making Xpsi @ XXXXRPM. the exception to this rule would be if you have a boost leak.
I've never experienced belt slip first hand but I would *guess* that if your belt is slipping, in 1st gear it would be the most obvious because the engine is spinning the fastest.
Second, have you ever done a boost leak test? If not that would be the first place you should check.
Tire size & octain rating have zero effect on changing the amount of boost you are making so I don't think they are factors. With a SC, your boost is fixed so you should always be making Xpsi @ XXXXRPM. the exception to this rule would be if you have a boost leak.
I've never experienced belt slip first hand but I would *guess* that if your belt is slipping, in 1st gear it would be the most obvious because the engine is spinning the fastest.
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I would have to say due to the smaller tire it is not having time to build up the boost because it go's thru the gear so quick. My supercharged camaro I had did the same thing.That would be my guess? 
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