900 T16 1989 Turbo problems

Where does the needle go on the boost valve? Into the red, or just yellow, or white? Is that down from normal?

Unless your turbo is making whiny, grindy noises, yes, it is unlikely to be the turbo itself but rather something telling the pressure to be reduced.

Yes, any number of things can open up the wastegate, making you lose top-end power. Easiest would be something physically rattling in the engine compartment, making the engine management (APC system) think you are having predetonation (ping) and backing off the boost. Do you have any rattles? How about air leaks? did it get worse all of the sudden, or gradually?

We'll get there, there's really not too much that can go wrong in that area, and most fixes are inexpensive.

Dave Hinz

Hi... What shows the turbo pressure needle, i.e what's the pressure in low/high revs (under load, say when going up the hill)?

Jindra

In boost the needle goes to the end of the yellow zone, not into the red.

No, it's not making any strange noises. What I noticed was that the engine is strugeling to deliver the power. Reving the engine is hard work, and the engine makes more (not strange) noise.

The strange thing is that I don't lose top-end power. It's just the power in the beginning. When I press the pedal down it takes some time (much longer than it used to) to give me pressure, although the turbo is spinning. On the gauge it's not building up pressure at that moment. Later on it's building up normal. So it's really the low-end power I'm missing.

I lost my power all of a sudden, not gradually. Strange thing is that it came back sometimes after I turned the TPS a little bit. But that lasted no longer than a week.

I hope this gives you a bit more information.

I hope we find the solution

Grtnx Felix

So you're getting only basic boost then, I think.

Good. So mechanically we're sound then, it's just an engine management problem.

That's puzzling.

What's a TPS in this context, please?

I wonder if your AMM's internal adjustable resister is the next thing to check. Do you have an ohmmeter? Anyone else want to jump in here, I'm not getting a good picture of it yet.

Dave

Hello,

This is what it always did. So there has nothing changed.

It feels like some valve/sensor is blocking the boost at low revs. It also feels like it accelerates with little, hardly noticable, hickups. Like if a regulator is gradually allowing more boost as the revs go up. Difficult to explain in a foreign language :-) (I'm Dutch) See below..

Throttle position sensor. The switch that tells how far the throttle valve is open.

What is the AMM ???? Air Mass Meter???? I have an ohmmeter. Tell me where and what to mesure please.

Grtnx Felix

That may also be a problem, but maybe not related.

No, your English is just fine, no problems there at all getting your point across. If you hadn't said something, I wouldn't have noticed.

Is that just a wide-open throttle switch, or what does the '89 have?

Right. This will give you extra fuel, and a few other things change, when the throttle is wide open. You should not have that switch activated except near and at wide-open.

Yes. There is an adjustment (potentiometer) behind the round brass plug (about 8mm in diameter). There are two pins on the connector which are across the bridge circuit in question, I don't recall which pins, I don't recall the resistance it should be, and I lent that particular manual out to someone who has chosen not to return it.

It's a long shot, but worth trying. By any chance, does it get better or worse in cold weather? The colder the weather, the more likely you are to run into this problem.

Dave Hinz

Felix, I have the manual ("Vraagbaak" :-) ) in Dutch. Can look up some things for you, or send some scanned pages. The AMM check is in that manual.

Where are you located? I am in Utrecht.

Richard.

Salutations:

Felix - this has nothing whatever to do with your problem - but could you tell me if there is any difference between your (Dutch) home electrical systems and mine (Canadian, North American)? Any chance this tuner might work in North America without a special 110v adapter?

Sorry to have intruded - never mind - the unit is appearently sold. Rats..

This car doesn't use a vacuum advance on the ignition does it? I've seen some problems similar to that from sticking advance mechanisms on other cars.

Hello,

OK, checked the AMM. Works like it should be.

I have bought the manual myself. Still can't find the cause of my problem:-(

I don't notice a big diference between warm or cold weather. What I think is that it must be the AIC valve or the wastegate.

Do you, or anybody else, know what influences both valves?? I mean who tells them to open or close? Maybe I can get a bit closer to solving my problem.

Grtnx Felix

Hello,

I just bought the Official Service Manual.

It's always better to have something in Dutch :-) Please mail me a scan of some test to do for my problem (AMM, AIC, Wastegate).

Thank you very much!!

Bedankt,

Felix