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View Full Version : Turbo II - how do I tell if it is working ?


G6 GSD
14th April 2003, 08:21 PM
I bought a 1989 Turbo II convertible last summer. It had a reconditioned engine fitted by Rotechniks 9,000 miles prior. I've since done 5,000 trouble free miles. On driving, it is very smooth and gives no reason to believe there is anything wrong. 0-60 time is close to the book number of 6.5 secs.
However, there are a few things that make me wonder if the turbo is doing what it should :
1) The booster guage will sometimes not read at all, sometimes show a reading starting from 1,000rpm proportional to the amount of throttle but only going half way up the dial, occasionally show boost with very little throttle going up to three quarters full reading. I assumed this was just a faulty dial.
2) There is no noise of a turbo cutting in.
3) The power has a very smooth delivery with no sudden surge at a given number of revs.
4) The power appears to fall off at high revs.

Fuel consumption is about 20mpg, and there is are no blasts of smoke.

As you may be able to tell, my mechanical knowledge is not the best, so a low-tech explanation of what may be happening would be appreciated.

Thanks,

Glenn Butcher
14th April 2003, 08:48 PM
Hi Gary,

Best thing to do would be to get an aftermarket boost guage, plumb it into the system (even temporarily) and check to see it is boosting ok.

Your local garage should even be able to do this (there is a tap-in/out point on the top of the inlet manifold) specifically designed for this type of trouble shooting.

Not sure why you can't hear the turbo - but if you do the above, you will know for sure if it is boosting correctly.

View page: F2-41 of this document (LARGE FILE):
http://www.iluvmyrx7.com/2ndgen/manuals/89-92%20Manual/04b_fuel_and_emission_control_systems_turbo.pdf

j9fd3s
8th May 2003, 04:59 PM
easiest to hardest
4) the power will drop off at high rpms, its a small turbo
3) the boost also will come on smoothly
2) it should sound a little like a jet, the actual turbo whine is quiet in these, when they are stock

1) the boost guage should always function. they use a boost pressure sensor to get a boost reading which is shared between the guage and the ecu (bascially), the ecu needs to see the boost pressure in order to retard the timing under boost, that is kind of important

mike