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Q&A regarding engines, turbos, and intercoolers and power upgrades
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power drops off after about 4500 rpm

Sat Feb 27, 2016 2:33 am

Just bought this car, it is a 91 all trac with 91000 miles. I replaced the timing belt, water pump, plugs, fuel and air filters, changed all fluids. I rigged up a cheaper boost gauge and disabled the vsv it was boosting to about 6-7psi I installed a manual boost controller and now I'm running about 12-13psi. The car runs really smooth and has the low end power but when it hits around 4500-5000 rpm's the power drops off pretty bad. The boost pressure isn't spiking or anything so I'm pretty sure it's not hitting the fuel cut. So the question is am I losing fuel pressure or could it be something with air flow? When does the intake runner thing kick in?
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Re: power drops off after about 4500 rpm

Sat Feb 27, 2016 3:47 am

It opens at that rpm.

Re: power drops off after about 4500 rpm

Sat Feb 27, 2016 3:56 am

Yeah I just found that, I guess I'll check that out tomorrow at my shop..

Re: power drops off after about 4500 rpm

Mon Feb 29, 2016 12:42 am

Find anything else at your shop?

Re: power drops off after about 4500 rpm

Mon Feb 29, 2016 2:02 am

Not yet, the whole system is tucked back under the intake. I didn't have a chance to put the car on a lift. I had some other work to do. Then I have to figure out test it. I'm pretty sure it's the problem though.
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