Re: TQC boost problem?

[Robert Myers <rmyers@wvit.wvnet.edu>]

George,

Do you have an address or phone number for Hitachi?  That might be a good
starting point.

While typing this note I did a Webcrawler search for Hitachi and got 500+
hits.  I betcha if youd spend a while at it, you'd be able to get a contact
form that source.

At 11:55 PM 3/30/96 GMT, you wrote:
>At 09:18 30/03/96 -0700, Dave Lawson wrote:
>>
>>George,
>>
>>>My theory is the brain thinks I'm overboosting and is retarding the timing.
>>>How can there be overboost even when the engine is not running????
>>>Any help appreciated.
>>
>>On this euro 85, I am assuming that the ECU has a boost pressure
>>display signal comming from it. Could be wrong. Or does the dash
>>display still have its own pressure gauge, just digital in this instance?
>>
>>I would start by looking through the check valves in the vacum line
>>system going to the ECU. Not sure of a failure mode of these, but
>>maybe it has trapped boost pressure in the line feeding the ECU
>>pressure sensor. After this I would test the pressure sensor, pull the
>>hose from it, and see if it reads 0 bar, then maybe attach a piece of vac
>>line on it and slightly blow on it to see if the display changes. If it
>>doesn't read 0 or change with different pressures, something is wrong
>>with the ECU and/or pressure sensor.
>>
>>Good luck and report back the findings.
>> -
>>Dave Lawson  dlawson@ball.com  
>>
>>
>>
>
>Dave,
>As you correctly said, the boost gauge on the dash takes it's signal from
>the ECU. I tried your suggestions re trapped boost but having removed the
>hose from the pressure sensor the gauge still reads overboost i.e last three
>segments of display light up. One thing I did try was to plug the hose and
>start the motor.
>Result....no difference: still reads overboost and still running VERY lumpy.
>Next step was surgery. I opened the brain and disconnected the three pin
>connector from the pressure sensor, started the motor and HEY PRESTO now got
>a smooth idle and seems to rev normally! Reconnect sensor...back to old
problem.
>It appears as though the sensor has failed in the overboost position.
>Out with multi-meter. No continuity between centre pin and either left or
>right pin while applying pressure OR vacuum to sensor. Continuity between
>left and right pin while applying both pressure and vacuum. I don't know
>what reading I should be getting but I would have thought the resistance
>would vary.
>I've been told the sensor cannot be bought....you must buy the complete brain?
>Starting to panick at this stage...I believe brains are REAL expensive!
>I drove the car gently this afternoon with the sensor disconnected but its
>not performing very well probably as the brain connot now vary the timing
>depending on pressure or vacuum. However at least it is running and useable.
>The sensor is marked   HITACHI PS2-02 Pressure sensor. The brain is MAC-01
>Where to from here????????
>
>George.
>
>
>

___
	Bob 
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