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boost problems


90moddedtgp

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I have a 90 tgp with some mods. The problem i am running into. Is I can only push 14 lbs of boost and then i get fuel cut. is there any thing that i could do to bypass the boost sensor. I have looked into new computers but that is way to expensive for right now. I would apperciate any input thank you

mike

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Are you going off the stock TGP boost gauge, or do you have an aftermarket installed? If you're talking about the stock one on your gauge cluster, they're anything but accurated, so don't take the figures it shows you too seriously. The stock chip only boosts to 7.5 psi, or so, with fuel cut-off around 9. A Jeff M chip bumps it up to 11 psi I think it is, but you still get cut-off at around 13, I believe. The 2 bar MAP sensor is only capable of 14.7 psi, anyways. Anything beyond that, and you're going to need to move up to a 3 bar. Plus, running anything above that 14.7 psi mark is pretty risky for the 3.1.

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Defeating fuel cut was discussed here a bit.

http://www.w-body.com/forum/viewtopic.php?t=34234

 

 

Make sure to take note of this statement though. "Keep in mind that if you defeat the fuel cut you are defeating your motor protection. " :wink:

 

 

BTW, you should mention that you're running a GT28RS and other modifications before someone tells you that the stock turbo is no good for that much boost.... :mrgreen:

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Yes i have the jeff m chip in there. also i do have an aftermarket boost gauge in there. i am not to worried about blowing the motor. i have rebuilt the motor to handel it nothing left sotck internally. also as he stated i have a gt28rs. aftermarket x-over pipe, msd ignition. the motor should be capable of holding more than 14 lbs of boost.

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Yes i have the jeff m chip in there. also i do have an aftermarket boost gauge in there. i am not to worried about blowing the motor. i have rebuilt the motor to handel it nothing left sotck internally. also as he stated i have a gt28rs. aftermarket x-over pipe, msd ignition. the motor should be capable of holding more than 14 lbs of boost.

 

Not if you detonate from more boost than pump gas will handle!! It's the gas that limits things like this when you keep cranking the boost, no matter how good the turbo, its still more air/pressure in the cylinders than pump gas octane can handle, UNLESS you dropped your compression ratio???? Maybe the turbo can push it, and maybe you can handle more boost than the stock turbo, but just know there are limits and they can hurt the wallet 8)

 

Jeff M

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Was hurrying to watch a movie with the family, forgot to mention :oops: , need more fuel for more mass air from a turbo upgrade that is going to run some higher boost. And with your list of solid upgrades, did not see larger injectors in there, so just some caution :) , be safe 8) , and kick some butt :twisted:

 

Jeff M

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I do have bigger injectors, also a rrfpr, and a higher flow fuel pump. sorry i did not mention all of that i am out of town and i had been drinking. i apperciate all of the help but what i am wondering. is can i get a chip to eliminate fuel cut. is there any one who burns them or what do i need to do. thanks for all the help!

mike

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Sounds very good, thanks for the update on the rest of your goods :cheers: Yea a chip can be made with the boost fuel cut out, only other things I would caution next is that even though the chip will run the engine past 15 psi, is at 16psi to whatever you hit beyond that, the chip will still be using those last fueling and timing values at 15 psi, its last known reference. 3 bar conversion can be a very large task, the tuner guys I know went through a lot of work to do it and their chip (Syclone/Typhoon) is quite a bit less complex to work in then the TGP. They also had a great deal of work trying to get the resolution of the same amount of chip tables entries to work with the larger range of a 3 bar map sensor. A conversion to MAF is another thought, plenty of MAF upgrades and interpreters and tuners for it, just some thoughts to toss around.

 

Jeff M

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  • 2 weeks later...

Jeff M. thanks for all of the help. I am also wondering if you know how much $$ it would cost for the chip. because we have put msd on the car so we can adjust the timing. thanks for all of your help

mike

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Programmable aftermarket EMS *Tech II/III* would be another route to take. If its a go fast only car the "niceness" factors of a GM programmed chip aren't really needed, and running a 3-bar MAP sensor won't be a painful task either.....and not nearly as difficult to figure out how to use, not that a GM one isn't.

 

*flame suit on against GM tuning nazis* :P no no j/k :lol: Just throwing out another suggestion to consider if its a "race" car

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It is not really a race car so to speak. but it is also not an every day driver. I have had the car for almost 6 years and we have only put about 7000 miles on it.

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I use an adjustable zener on my turbo dodges. Even though TDs are very different the adjustable zener (aka MAP clamp) works very well because it allows you to max out the range of the computers abilty to control the fuel and timing. On my Lancer, I found that overboost occured at 4.20v MAP output voltage. I set the MAP clamp to limit voltage at 4.15 and overboost was gone. I use higher flowing injectors and an adjustable fuel pressure regulator to supplement the fuel beyond 14.7 psi. I've been running 20 psi boost this way for about 10 months now. For you modded TGP guys that can't get a 3-bar setup, this may be worth looking into and is very cheap. A wideband meter would be a very good idea since you are eliminating the overboost protection.

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