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Re: Low boost problems -- at wits end -- HELP!
You said you shorted the connector pins on the WOT switch. Did you test
the WOT switch itself?
'98 Passat 1.8t
Gisli Ottarsson wrote:
> I recently purchased an '87 5KTQ with 180k miles on clock. Condition
> is much better than milage suggests.
> When purchased, the car had a punctured Michelin-man hose between the
> intercooler and intake manifold. After replacing this part, the car
> suffers from low boost, which maxes out at 1.1 bar according to
> in-dash pressure gauge.
> In troubleshooting this problem I have relied on Scott Mockry's
> excellent Troubleshooting Tips <http://www.sjmautotechnik.com>
> Is this guy *king* or what?!
> A list of my experiments follows in the hope that it will benefit
> someone and that someone might spot a hole in my reasoning.
> 1) ECU fault codes:
> Test drove vehicle for > 15 minutes. Wide Open Throttle in
> third gear. Performed ECU fault code dump. Only 4444 was
> blinked. Ergo: No faults were stored.
> 2) Does Waste Gate work?
> a) Applied 20 in Hg vacuum to Waste Gate. Waste Gate held the
> pressure. Ergo: Diaphragm does not leak.
> b) Quickly removed vacuum. Heard an audible "CLUNK". Ergo: Waste
> Gate is not stuck open.
> 3) Does Waste Gate Solenoid work?
> Connected vacuum gauge to the hose that connects WGS to WG.
> Unplugged Throttle Switch Connector and shorted two lower
> connector pins. Observed large swings on vacuum gauge.
> Ergo: ECU is speaking to WGS.
> 4) Multi-function temp sensor defective?
> a) Based on experiment 3) I conclude that pin 2 is not sending false
> ground to ECU.
> b) Coolant temperature gauge holds steady at midspan. Over-heat
> warning symbol is ordinarily off but proved itself to be working
> during a near overheat incident. Ergo: All seems well.
> Are there other tests available for Multi-function temp sensor?
> 5) Does Air Temp Sensor work?
> a) Disconnected ECU and measured resistance across sensor. I
> measured 500+ ohms at ca. 77 degrees Fahrenheit. Ergo: Sensor is
> good (?)
> b) Reconnected ECO and measured again. Resistance had dropped to
> 420 ohms. Ergo: Sensor has a good connection to ECU.
> 6) Vacuum/Boost leak in hoses?
> Connected vacuum pump to two rubber hoses at rear of intake
> manifold distribution pipe. Both hoses held 20 in Hg vacuum.
> Vacuum in one hose caused pressure gauge to read 0.2 bar.
> Ergo: No leak here.
> 7) Problem in Turbo or plumbing?
> I removed turbo cold side intake and turbo exhaust hoses. Hoses
> were solid and had no internal obstructions. No play was
> noticable in turbo rotors on the axis. A significant improvement
> in performance was observed when Michelin-man hose was replaced
> and boost comes up quicky. Ergo: All is well?
> I would really appreciate any feedback. What did I miss? Where did
> I over-interpret? What next?
> Thanks in advance and thank you very much Scott Mockry!
> Gisli Ottarsson, PhD
> Mechanical Dynamics Inc. firstname.lastname@example.org
> 2301 Commonwealth Blvd. Tel: 1-734-913-2550
> Ann Arbor, Michigan 48105 Fax: 1-734-994-6418