Technical adjusting back to standard boost

[smiftersmifter]

I've recently got myself an uno turbo, the engine sounds alrite but it just seems to be running a little rough [it's been stood a while]. I haven't drove the car much as it's been stripped to have sills/arches/rear panel sorted. But i have noticed the standard boost gauge isn't working, i've read somewhere that people unplug it when they turn the boost up, is this true and is it simple enough to put the boost back or atleast see what it's running at.

Cheers Andy.

 

[smiftersmifter]

btt

 

[thepottleflump]

Trying to find out how the boost guage is plumbed in myself, I read somewhere the pipework runs from the AFM through the bulkhead. I can see a pipe running from what looks like the ECU but was hoping for confirmation.

 

[Louie Bee]

On the MK1 it depends on weather you have the digital or analogue gauges. The digital is apparently fed from the ECU by wire. Just reconnect the dangling wire and jobs a good en.

The analogue MK1 and the MK2 are mechanical. Unblock the pipe and connect back up and should work again

Best of luck.

 

[smiftersmifter]

mines the latter, thanks for the info

 

[alexGS]

To get back on topic...

Look for any bleed valves/taps that may have been added to the small rubber pipe that goes to the large capsule on the turbocharger. If you find anything that seems to interfere with the pipe, bypass/remove it or replace the affected pipe. Assuming there has been no other tampering (bending/removal of the wastegate actuator rod) your boost should now be back to standard, since the wastegate actuator will now open the wastegate at the intended pressure of 0.6bar. (Bleed valves work by reducing the pressure that reaches the actuator, so it will only open with the pressure being higher than the 0.6bar design limit).

Also reconnect the max. boost pressure switch on the end of the plenum chamber (car's left side) - the wires will hopefully be dangling nearby.

Since the engine's running a bit rough, it's also a good time to check all the pipework for splits/leaks, listening for whistles etc. while driving.

I found that the standard recirculating dump valve OFTEN springs a leak when it gets old, and this affects both the boost pressure reached AND the idling... check by sucking on it's vacuum pipe (after cleaning throughly...) should be no air passing through.

Try to adjust the idle speed using the setting screw and the throttle stop, e.g. by undoing the locknut and screwing the large screw all the way in, idle speed should get down to 700-ish with the throttle stop barely cracking the throttle open. If you can't get it this low, it suggests you have an air leak somewhere else. Note that correct idle speed is more like 850-900RPM, I'm only suggesting this 700RPM-setting as a test for other air leaks which will increase the idle speed to 1000RPM or more, and make the idling unstable.

Check the spark plugs (quoted replacement interval is just 7500km!)

-Alex