[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

5KTQ Turbo boost question?

I recently purchased a 87 5KTQ (137K mi) and was wondering if the
turbo is peforming correctly. I want to get all engine functions
working because I am thinking about dong a chip mod!!!!! 
Here are my observations, if anyone can give me info I would
appreciate it. Car is in stock condition (turbo, wastegate, ECU

1) Is the boost gage accurate? With the ignition switch on and the
motor not running it reads .8 bar. I figure it should read .832 at
his altitude (Denver - 5000ft) so this seems correct.

2) From 35 mph in 3rd gear if I floor it the boost comes up to .9 bar
fairly quickly then at 3000-3500 rpm it gradually increases to 1.0
bar. If I continue it will creep up to 1.1-1.2 bar above 4000rpm.
With a shift to 4th gear (still floored) the boost stays at .9-1.0
until about 4000 rpm where it increases to 1.1 bar on up to 5000 rpm.

3) I have rarely seen over 1.1 bar although during a long uphill 4th
gear climb I did see 1.3 bar once. Isn't the stock wastegate supposed
to be 1.3 bar?  How fast is the boost supposed to come up to 1.3?

4) Can the wastegate spring weaken over time causing it to dump boost
too early?  I was told this could happen and a new spring from Audi
Only with increased boost was $50. Has anyone heard of increasing
boost with a spring only (realizing that the fuel cutoff will still
happen at 1.5??? bar).