200 20V 3B 1.5 bar Question

Brett Dikeman brett at cloud9.net
Fri Aug 20 00:54:26 EDT 2004

At 10:26 PM -0400 8/19/04, SuffolkD at aol.com wrote:

>BPV & factory $$$ O2 sensor last Aug....old BPV removed still seals okay too.
>The engine in 4th from 2000RPM on up, pulls 1.5 bar tops.  Doing WOT test.

>I suspect surging because of the ISV (idle does "lope" from 400 to 1000 RPM)

O2 sensor disconnected, either heater or signal?  ISV failure is easy 
to check- use a 9V battery to apply voltage across the 
terminals(polarity is marked).  It should also hum/vibrate with the 
ignition on, and often if you turn off the engine with the hood up 
and listen carefully, you can catch the "cloink!" noise the ISV makes 
when it closes.  There's also the ECU output tests.

>Would WGFV limit boost too?

Yes, but if disconnected, or if the MFTS sensor is going flunky on 
you, dash will read 1.2-1.3 bar.

>Wastegate diaphram?

Check by applying vacuum to the (heh) test port on the wastegate ;-)

Some other things to check out- coolant sensor on the back of the 
head, and the charge air temp sensor.  Both are best checked from the 
ECU connector (gently, don't press the meter probes in!)  Actually, 
for the charge air temp sensor, it's pretty much the ONLY way to test 
it since it is soldered.  The coolant sensor is a royal pain to get 

With both sensors, if the ECU detects a problem(which it'll throw a 
code for) it will assume worst case scenario- virtually overheating 
or superhot charge air temps, which means rather moderate boost 
levels, but not complete limp-home mode.

Have you pressurized the entire intake system?

"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin

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