-40C loss of boost

FCPEURO · Post by **FCPEURO** » 11 Dec 2009, 06:55

It is probably just warm enough for the heated air coming from the turbo to keep the water (moister) from freezing. Once it gets down to -40C, the cold air coming through the intercooler is probably so cold that the hot air coming from the turbo cools to much to unfreeze the ice in the intercooler.

You could also be getting some icing in the throttle body.

monty · Post by **monty** » 11 Dec 2009, 09:45

I'm having the same problem with my '00 XC70. I've found that shutting the car off for several minutes clears the no boost problem, not enough time to thaw a frozen IC though. It will throw a P0237 and occasionally a P1237 code. It did this last winter, but without the codes.
Last spring I installed a boost gauge and noticed on launch the pressure would jump to 12lbs. briefly then drop to 3 lbs. instantly. Upon restart it would do the same thing, but I didn't pursue it because my sons are the only ones that drive the car. Less power=good thing!
The power loss this winter is more severe though, affecting driveability on the hwy. After reading other posts it seems the MAP sensor may be the culprit, but I'm not 100% convinced.
Any thoughts?

Post by **jblackburn** » 11 Dec 2009, 10:20

12 pounds is a LOT of boost for that turbo! 3-4 is normal for the LPT engine. I'm wondering if your ECU is over-correcting for the high boost (I'm thinking maybe a stuck wastegate actuator that isn't closing all the way) and then automatically cutting way back on the throttle.

The MAP sensor does absolutely nothing as far as I can tell and is a useless piece of extra expensive junk. I have a turbo model, and live in the mountains ~3000 ft. Mine kept throwing codes for it being bad, and wondering what it did, I totally unplugged the thing. No difference in power. I cleaned the connector and put it back on, and haven't had a problem since.

The MAF also shouldn't be limiting boost, but it is possible. You could try cleaning it with some MAF cleaner spray and see if it helps at all.

I agree with what FCP says about the intercooler in the really cold weather. I don't guess you can start troubleshooting until it gets really cold and starts happening again!

monty · Post by **monty** » 11 Dec 2009, 11:50

Could it be the TCV? Would it be at fault, allowing the boost pressure to rise that high before bringing it under control? With the present cold temps (-30C) it throws it into a no-boost, low power mode.

FCPEURO · Post by **FCPEURO** » 11 Dec 2009, 14:44

Also, have you considered a frozen wastegate function of some sort?

I know that truck drivers in weather that cold leave their diesel trucks running 24 hours a day. I'd imagine your oil that high in the system simply is not getting up to temperature, as well.

Post by **IVIUSTANG** » 12 Dec 2009, 21:52

It was minus 37C today and my car sat outside for 7 hours facing the wind. It started pretty good, but it sure felt like a brick. The boost loss must have been a fluke as it is working 100% now. I can really feel the transmission and brake fluids being really stiff though, does dot 5.1 and synthetic transmission fluid help with this? I already run 5w30 synthetic oil which I strongly credit with unassisted cold weather starting. I normally park in an unheated garage which helps ALOT, but was in the countryside today... -37C makes things so stiff!

- Jesse

Post by **IVIUSTANG** » 17 Dec 2009, 07:37

I had access to a nice heated shop all night so I let my car sit then took off the intercooler hose. I got maybe a 1/4 cup of water out; is this enough to cause a minor restriction(full throttle boost went from 3 inches of vacuum to about 2 PSI on a different drive)? BTW, is "intercooler" one word or two? My spell check hates most technical words for some reason.

- Jesse

Post by **jblackburn** » 17 Dec 2009, 08:08

I'd think that would be enough to restrict it somewhat. How often do you let your car get all the way up to normal operating temperature up there? It probably just needs a good long drive every now and then.

Post by **IVIUSTANG** » 17 Dec 2009, 08:14

All city driving, and I let it idle a bit to warm up before I drive when it is cold. Max 15 minutes from city end to end with clear traffic. I took it for a highway run for a good 90 km the other day, but that is not normal. The water also seemed to have a little bit of a brownish hue to it that wasn't quite mixed in with the water perfectly, maybe rust? Although it did seem a little hydrophobic and oily. As usual I checked my fluids and not a drop missing from anywhere.

- Jesse

FCPEURO · Post by **FCPEURO** » 17 Dec 2009, 12:04

A faulty TCV would definitely cause and boost issue like you are describing. The cold weather could be causing it to stick and it takes a second for the ECU to get the TCV to resonate.

You could try cleaning out the PCV or get a better once then the factory unit, but in -30 to -40 degree weather, I don't even know if that will help.

-40C loss of boost

Re: -40C loss of boost