Waterboy.

Hello, This is my second porsche but first turbo. I bought the car in AZ and drove it to Salt Lake with no probles. Ran like a bat out of hell. When I got here, a day or two later, it seemed the the turbo was a little louder and not as powerful. Kind of sputtery. Any help would be most useful. The bar goes to one and then just smoothly continues as the car accelerates. No puch like it had, however not total turbo loss. Thanks!

Perry 951

Does your boost gauge read any higher than 1? It should be just shy of 2.

Check all hoses from the turbo to intercooler, and intercooler to intake. Some may have popped off.

jakell

check your blow off valve, BOV, and the vacuum line that runs to the valve. If the valve is blown it will make the car sputtery under boost and sometimes sound pretty strange when you let off the gas under boost, like a gobbling turkey.

Do a search on BOV to find the test procedure for the valve. It is very simple to test.

good luck

Waterboy.

My boost gauge goes up to two, but it just doesn't pull real hard. I also noticed when I let off the gas, the exhaust burps/gurggles a little, quietly. The turbo is a little louder, not much though. It sounds like when you whistle, but insteat of blowing out, you suck in. Weird explanation, but that's what it sounds like. Any clues????

Waterboy.

If my coolant is running normal, will my turbo water pump be ok also. I guess what i mean is, does my coolant gauge also tell me my turbo waterpump temp as well? thanks

DangerIsland

SLC is over 4000' above sea level. Any chance you're just noticing the elevation difference?

Waterboy.

Maybe, I think it feels like something else though...

proboner

elevation makes a huge difference, when i drive to utah/colorado my car is SIGNIFICANTLY slower.

Redshift

Check your spark plugs to see if you're running too rich. Back in the days when most cars were carbureted, you would tune the carb for high elevation use. Perhaps there is a similar way to fine tune the fuel in our cars. (of course, it would be perilous to drive this car back to lower elevations)

A lot of newer turbocharged cars use a MAP based air meter that can sense changes in elevation. The antiquated 'barn door' air meter in our 951's are incapable of doing this.

Konstantin

the 951 has an elevation valve

Konstantin

Waterboy.

What is an elevation valve? How do I adjust it and what does it change? Will it cripple me if I bring the car back down to sea level? Thanks.

kevin Dubois

hehe my friend and i had that same problem a year or so ago. we moved to dillon, CO (elevation 10,000 or so ft.) we drove his mazda 323 straight there from michigan not a single problem. when we got there the car would no longer start. the only way to start it was to floor the pedal a crank it, or to unplug an injector then start it. WAY to much fuel and not enough air was the problem. had to replace the oxygen sensor to make it work a little better, but there was still a consistant problem.

once we left the mountains the car started no problem.

jchaley

944 turbos have altitude compensation built in to the DME/KLR as it uses a internal MAP sensor, No adjustment required. There is a 20% loss of power in Denver at 5000+ ft unless you turn up the boost to compensate.

john

Danno

The built-in altitude compensation on the 951 is just an on/off switch that reduces fuel by 6.3% at 3000ft. There is no continous and gradual fuel-adjustment based upon exact altitutde. This -6.3% is actually a mismatch because that amount of fuel-reduction is appropriate to 1700ft.

In either case, you'll still be too rich at 4000ft which needs to have 13.6% fuel removed.

I suspect that you've got a wastegate issue. The stock wastegate can't even keep up with the stock turbo and leaks exhaust at high-RPMs. In the case of the K27, you'll have even more exhaust which will push open the wastegate more and earlier. You're still seeing 1-bar of boost because of the higher flow-rates of the K27, but it's being over-spun in order to generate enough RPM to compensate for the leaking wastegate.

Try shimming your wastegate and dialing back the boost-controller to give you the same 1-bar of boost as before. You'll find that boost will come on quicker and the car in general will feel faster and more reponsive.

I recommend that anyone you upgrade the turbo, it's a prerequisite that injectors and wastegate should be upgraded at the same time.