Extreme throttle response (Over adjusted wastegate?)

Dave K · Post by **Dave K** » 30 Mar 2012, 15:05

Picked up a 1995 T5 that has very very aggressive throttle response coupled with lots of turbo waist gate noise. I have had many 850s (one with an adjusted waist gate) but this one is WAY WAY faster then the others. 1/4 throttle pedal will rocket you to 70 mph. If you floor it on the freeway the boost gauge pegs and the it starts poping and backfiring. I assume someone shortened the waist gate 2 to 4 turns.

I think I am going to start by adjusting the waist gate rod out 2 turns. I know it is dangerous to your motor to over shorten it to much but is it also dangerous to make it to long? The car is going to be driven by my 18 year old son so I would like to detune it as much as possible. Would it be safe to go a few turns longer than stock? I dont have a vacuum gauge to make the adjustment properly

Thanks for any help

Post by **Matty Moo** » 30 Mar 2012, 15:08

That's not good.

I had the same thing happen when I forgot to hook the vac line back up to the wastegate, and another time when the vac line fell off at the nipple at the bottom of the turbo.

Check your lines, then check the wastegate.

Dave K · Post by **Dave K** » 30 Mar 2012, 15:27

As soon as it cools I will pull the heat shield and see if anything is wrong. Would having a turbo line disconnected throw a code?

Thanks

Dave

Post by **jblackburn** » 30 Mar 2012, 15:29

I agree - vacuum lines are probably broken or something. The line to the turbo broke on mine and there was a definite increase in power, but it couldn't have been good for the engine.

And don't turn it out too much. I left the nut loose on mine after "adjusting" it, and the power didn't pick up til around 4000 RPM with your foot on the floor. It made merging into traffic downright dangerous.

Usually the turbo control vacuum lines do not throw a code like other broken ones will do.

Dave K · Post by **Dave K** » 02 Apr 2012, 19:18

Yup two broken vacuum lines. All fixed now.

It is a lot smoother but the car still accelerates like a rocket. A buddy of mine rod in and he said it pulls considerably harder then his 850R. I think I am going to have a Volvo mechanic take a look at it and see if he knows why it is so fast.

Thanks for the tip on the vacuum lines.

Post by **jblackburn** » 02 Apr 2012, 19:21

Yank the negative battery cable, tap the brakes, and reconnect it to erase the computer.

It will then re-learn how to boost properly.

Dave K · Post by **Dave K** » 03 Apr 2012, 21:12

Found one more broken vacuum line to the turbo (the only one that we had not already changed)

Car drives great now and very smooth.

Thanks for all the help

Dave

dadd24boys · Post by **dadd24boys** » 17 Sep 2012, 22:15

Dave,

Where were the bad vacuum lines?

I just bought a 94 850 turbo sedan.
It needed a few things, primarily from sitting for a while.

But also, similar to yours. It pulls really hard at only 1/4 pedal and will jump up to higher speeds very quickly.
I have replaced some of the vac lines already. one at bottom of turbo housing that comes up to air filter box, another from air fllter box down to a vac diaphragm at turbo, one that goes to intake hose just at air filter box and one that goes from intake manifold at left side at top(between runners) to vac tree at other end of intake manifold.

I am getting an occasional 172 code (running rich).

I am having trouble with ABS and TRACS lights coming on occasionally and the REC and A/C lights blink sometimes.
I am getting a code 141 from the ABS diags. Possible switch in the brake pedal.