[urq] 20VT poor running issues

[Steve Eiche]

Mike,
On 3Bs, there are a few things to check.  First, always check for codes.  The blink codes are OK, but connecting a diagnostic tool will give you more detail, as well as measuring block 000 data.  Next, check the intake to bypass valve hose.  It will likely need to be replaced, as the routing of it takes it right over the hot exhaust manifold.  The PCV hose from the side of the block to the valve on the back of the engine tends to disintegrate, as well as the one from the valve to the metal pipe that goes to the MAF to turbo boot.  I would suggest doing a pressure test of the system from the MAF boot.  A 2.5" PVC pipe cap with an air fitting works well.  Pressurize the system to 10-15PSI max.  Leak prone areas are the O-ring between the IC and crossover pipe, "Michelin Man" hose and anything in the PCV system.  I would also recommend replacing the bypass valve and WGFV if they are original.  The bypass valves I consider a maintenance item, and WGFVs don't last long, resulting in inconsistent boost.  The O2 sensor is another maintenance item, and could be an issue in your case.  Cleaning the ISV would be a good idea.  Check the plugs.  They should be Bosch F5PORs.  I haven't had luck with anything else on those cars.

It seems that the above items all need to be replaced around 100k miles, and once done should go another 60k or so.  

Steve

Mike wrote:

Recently purchased a 91 200TQ (110K miles) and plan transplanting the
motor 
to the Ur or my Vanagon...   Before that happens I'd like to begin
sorting it 
out a bit.   It runs just OK, it surges on acceleration sometimes, acts
like no 
boost others and always has a lumpy idle.   Also, it seems to run better
when 
it hasn't quite warmed up.   Any suggestions?

Mike Bond

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