Normal performance problem

[Ayata]

Hi,
i really need help, no mechanics have the idea about the problem. if anybody can help i will be glad.

1997 850T5 2.0, all parts are original (except the turbo, it was repaired using s70 parts, the pressure is now 0,9-1 bar - and the oxygen sensor, it is the Bosch equivalent). My problem is under 2krpm the engine performance is too low and the turbo indicator is showing lower than half. But when i kick the pedal it gives more than a normal T5 (because of turbo pressure i guess).
We tried turbo pressure sensor and air flow sensor, but could not solve the problem. One year ago, with a different analysis kit, the result was "the engine was working with rich mix in the low rpm's" but it did not give reason for this. By the way, in low rpm's fuel consumption is very high. This is my 5th 850, so i can see the difference between them.

Help needed, pls.

Regards

[RickHaleParker]

Sounds like the turbo off the S70 is a High Pressure Turbo (HPT). The HPT does not spool up until about 3000 RPM but when it does, there is no mistaking it.

What S70 did you get the turbo off of? Year, engine and trim level. Check the identification numbers on the turbo also.

[abscate]

Salaam, Ayata

Check that you have the right Turbo as Rick notes - it does sound like the wrong one.

Also, you will not get boost by revving without load - boost is only turned on my BOTH throttle request and detected load.

[Ayata]

Thanks a lot,
But 850t5 uses hot also if i am not wrong, and s70 turbo is a very close one to 850t5 turbo.
anyway, is there a way to tune it for 850 without changing the turbo?

thanks in advance

regards

[RickHaleParker]

"1997 850T5 2.0"

They did not makes a '97 850 T5 with a 2.0L.
The '97 850 T5 where all 2.3L and there are three different turbo chargers for the '97 850 T5.

You need to figure out what you got first.

[erikv11]

OP is in Europe (oops ! edit: Turkey), where there was a 2.0 T5 for I think all years, 93-97. He probably has what he says he has.

Check exactly which turbo you have installed, it is on a plate on the housing. Just look at the plate on the turbo. If it is a 16t (S70, HPT), then it is just fine to swap it into your 850 (shipped with 15g, HPT) without any additional tuning, and the problem is not the turbo.

If the car is moronic 4.3 (check this, I don't know the 2.0 models ...) then it is pretty easy to tune your 97 ECU (or better, a replacement m4.4. ECU) for the 16t and white injectors that shipped on an S70 (http://m44.wikia.com/wiki/M44_Wiki), but it may not be worth it. The car will run just fine with a 16t in place of the 15g.

As for the problem described in the original post, has the front O2 sensor every been replaced (might even try just unplugging the O2 sensor, see if that changes it)? I would also consider the ECT sensor (check resistance values or swap in a known good one), and of course the fuel pressure regulator (is there fuel in the vacuum line? what is the pressure at the rail?).

[abscate]

I know 4.4 was smarter but moronic 4.3 is a little harsh.

[rspi]

It is hard to determine if you have a problem with the comments above. What does "below half" mean? What boost gauge are you trying to describe? Is it in the white area or black area if it's the stock gauge?

As mentioned above, the boost should not really "kick in" until the RPM's are high to protect the engine from damage.

Also, you should NOT swap a 4.4 ECU into a car with 4.3 as it may damage the AC system somehow.

[erikv11]

Robert you are correct that AC is important to think about, however just FYI there is no danger of AC damage in this case. The danger comes when running a 4.3 ECU in a 4.4 car, that will cook the compressor. But this swap is the other way around. If you run a 4.4 ECU in a 4.3 car the AC simply will not work unless the 4.4 ECU is also modified slightly after flashing. It won't be damaged, it just won't work. Or just drive the car without AC (not my preference, but one option). This information is included in the link I posted up above.

"1997 850T5 2.0"

They did not makes a '97 850 T5 with a 2.0L.
The '97 850 T5 where all 2.3L and there are three different turbo chargers for the '97 850 T5.

You need to figure out what you got first.

Oops I didn't even notice this additional mistake until now. Also OP, note that there is in fact only one turbocharger for the'97 850 T5. It is the 15g (TD04HL-15G).

[erikv11]

I know 4.4 was smarter but moronic 4.3 is a little harsh.

The spell-check is Freudian!