855 Turbo won't run faster than 2500rpm! Topic is solved

badcadman · Post by **badcadman** » 28 Jan 2004, 11:55

Hey folks, my 850 is having some problems. This morning it was 3

ras32758 · Post by **ras32758** » 30 Jan 2004, 14:04

We had -9 degrees this am and the car (1994 turbo wagon) would move but only very slowly (auto trans had fluid) seemed to be starting in third, very low revs on engine regardless of pedal pressure. Eventually car would shift into second but not third.

Something simialr happened several years ago after being parked in winter at airport. We were able to drive slowly along until it warmed up. Then was fine.

badcadman · Post by **badcadman** » 03 Feb 2004, 11:45

My car was doing the same exact thing. It would move very very slowly for quite a while, then after about 15 minutes it would start acting nurmal. I double checked to make sure it wasn't in winter mode (starts out in second instead of first I think), and it wasn't.

My theory is that the trans is telling the engine computer that the trans fluid isn't up to temperature yet. This will not let the engine above x rpm, in this case 2000-2500. I don't know if my transmission fluid is petroleum based or synthetic. In the case that it is petroleum based, the viscosity of the fluid changes with temperature. A synthetic will be less likely to change, if at all. This will be my next step for both the engine and the trans.

steve '95 850 T5 · Post by **steve '95 850 T5** » 09 Mar 2004, 22:39

Had same problem - key thing is that it occurs only in very cold weather. Turned out that the intercooler was freezing. This restricts airflow to the engine as all air flow goes through intercooler after air filter and into intake manifold. So, if it is restricted then you can't get enough air through to the engine. This naturally limits rpm.

Key diagnostic is to have somebody get the car to as high rpm as it will go will you have the hood open and look at the air hoses going to intercooler (this is around radiator at front of engine) If restricted airflow is the problem, then the hose collapses. You can visually see that happening on that big hose going to intercooler.

The tricky part is why did the intercooler freeze? Well... that means you have a lot of moisture in the system. I had blocked crankcase ventilation system that caused oil and moisture to be introduced into the airflow stream.

Had to fix this problem in the end and since then fine. Runs better in all conditions now.

So, your problem is probably intercooler freezing. This can be something that will go away and is due to normal moisture in the system or could be due to like me something causing extra moisture in the system.

steve

badcadman wrote:My car was doing the same exact thing. It would move very very slowly for quite a while, then after about 15 minutes it would start acting nurmal. I double checked to make sure it wasn't in winter mode (starts out in second instead of first I think), and it wasn't.

My theory is that the trans is telling the engine computer that the trans fluid isn't up to temperature yet. This will not let the engine above x rpm, in this case 2000-2500. I don't know if my transmission fluid is petroleum based or synthetic. In the case that it is petroleum based, the viscosity of the fluid changes with temperature. A synthetic will be less likely to change, if at all. This will be my next step for both the engine and the trans.

badcadman · Post by **badcadman** » 10 Mar 2004, 06:16

steve-

Thanks for that bit of info. I never really though of the intercooler being the problem area. I'll check the PCV this week.