Hi,

Having only recently bought an 850, I'm new to the forum, so first of all, Hello!!!

I've bought a '95 850 T5 with manual transmission. I didn't notice on the test drive, but during driving since, the car seems to surge at constant, light accelerator pedal openings (with perhaps a 2sec frequency - accelerates, decelerates, accelerates, decelerates etc). This can be either accelerating or at constant speed. There's no problem at full throttle, where it pulls very smoothly.

Has anyone else experienced this problem? I wondered if it was the throttle position sensor, which has gone a bit wrong (as I'm imagining there's a full throttle switch hence why no problem at full throttle), but I'm not sure what it would be affecting or what the ECU is then controlling to cause the power surge.

Any ideas?

Thanks in advance,

Yours, surging along,

Simon

 

Check for vaccum leaks and try cleaning the throttle body.

 

Many thanks - I will try this and see if it works.

How many vacuum hoses are there? I'm assuming one to the wastegate actuator, one to the brake booster, one to the fuel pressure regulator?

Any more?

Cheers,

Simon

 

If you have a T5R, there is not a vaccuum to the waste gate, it is electronically controlled. But on the under side of your hood is a vacuum diagram. Most likely it is the hose that goes from just infront of the turbo intake to the left side of the intake. The vacuum runs under the intake, if you look at the engine from the fron of the car. The hose will start on the left side of the intake, if you look between the intake and the power steering resevior you should see it. It ends at the back right side of the engine, follow the air coming from the air filter, just before the turbo, you will see a 'T' with a 7/32" hose and a 1/2" hose(not sure of exact sizes), the smaller hose is the one you are looking for. This hose is probably cracked or broken on one side.

 

Look good some car have a elbow on the side of the intake behind the power steering pump.

 

Thanks again guys, I just need to find some time at home now to have a look!

Simon

 

I seem to have an opposite problem, I get surging at full throttle, the RPM's don't bounce, but a slight surge is there, plus I don't seem to have the power like at half throttle...vaccum lines?

 

Possible has the throttle body been cleaned lately?

 

No, I suppose I should start there. Plus I guess a good tune up wouldn't hurt. Do you know what the dealer all does on a 110,000 service, if anything? I don't want to mess with stuff they should have done.

 

The 110,000 service is pretty much just an oil change

 

those sons a bitches, well I know what the rest of this weekend entails. Thanks for the info tech.

 

What did they say they did?

 

Nothing really, I asked them to give it a decent once over because I had just bought it. They didn't say anything, but I never really felt they really looked at all the stuff. They didn't really have much information for me and I just went with the flow. My fault for not being nosy about it. Maybe everything is fine though. Plus I know it wasn't cheap. Oh well.