smokey

I'm sorting out my new track car for the season opener (destroyed the last one at Mosport) and I have a problem: it will not boost above 1.2 bar until the engine is warmed up. After I've driven it for a while, I get full boost. The car is a totally stock 1989 951 (E Class PCA race car). When I test for the blink code with no boost, I get no signal. Anyone run into this? I haven't done any diagnostics except trying to get the blink code, but I thought someone might have run into this. My guess is the temp sensor, since the car is also hard to start - takes a lot of cranking. Maybe it's running too lean when it's cold, setting off the limp-home mode. But in that case, I believe I should get a blink code message. Thoughts?

Luis de Prat

Here's my guess from what I've read:

You have a leak in one of the vacuum hoses. As the car warms up, the hoses expand and close the leak. When the car is cold, the leak reappears.

You need to find the leak when the car is cold. End of problem.

hosrom_951

You should NEVER use boost UNTILL the engine get's warm, even then the oil pressure should be in the 2.0-3.0bar (depends what you get once warmed up).

You are seriously looking into destroying the turbocharger, as well as shortening the life of the motor.

Porsche-O-Phile

What he said. The oil needs to circulate and warm up some first. Ideally you should never go for boost until the oil has "thinned" although admittedly with some multi-viscosity oils (like Mobil-1 15w-50, I'm currently running this), this can take quite a while. You would be able to detect this by a decrease in the indicated idle oil pressure (warmed-up oil is less viscous and will create less pressure at the sensor head). If you don't want to wait this long (can be over a half hour) then at least wait until you've gotten the coolant warmed up; maybe wait five minutes past when the coolant temp. gets to the first line or something. I typically will not engage boost until at least 10-15 minutes into my drive, which is not ideal, but it's a heck of a lot better than doing it cold.

smokey

Good points. Thanks. I should know better. I never try it without five minutes of warm up. I'll check for a vacuum leak. I don't understand why I don't get a blink code, however.

hosrom_951

5 mins is not enough, even whith temperatures reaching 140F in summer, it took 10 mins for the car to get warm (coolant) and another 5mins or so for the oil to reach proper temp/pressure.

Jaak Lepson

Smoky ... I would look for an exhaust leak.

superloaf

Isn't there a built-in protection where the computer will not allow full boost until the engine has warmed slightly? I used to notice this in my car when just driving off on a "cold" LA morning (45-50 degrees or so). The car had NO power even while consciously trying to avoid boost and I would hear a whooshing sound as if the wastegate was wide open. I just assumed this was the case in order to protect the engine when cold. I'm surprised none of the cold weather folk responded to this, though. Unless I'm completely wrong but I know what I experienced and the car has never had any boost/turbo/engine problems.

turbinek

The best way to kill a 951: full throttle when oil temp is low! (even if everything else is o.k.)
Since I installed a oil temp gauge I know that it may take from 20 - 60 Minutes until 80 deg Celcius are reached depending from outside temp/condition - in winter time you may be lucky to keep temp around 50!
Every oil needs temp 70-80 to work - so be lucky your car allows boost when warmed up I would like to have that too. But one more thing - by the time the watertemp is allrigth - the oiltemp may be still far far far far away from that!
kind regards Frank