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1990 VW FOX IDLE FI...
 
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1990 VW FOX IDLE FIASCO ~ CIS-E Fuel Injection

  

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Dear Mr. Kilmer, Trust all is well.
Most recently the Fox started surging at idle especially it seems after I drove it any distance. When I stopped to park it it would surge.
A possibility was the Idle Boost Valve/solenoid part# 026906283C. I have not been able to test it. I did mess very gently with the idle mixture using a 3mm long t-handle hex wrench. But was told to use/build a DPR test harness (which I don't have) so I can read the current that the ECU is sending to the DPR - at idle/operating temp it should fluctuate between 4 and 16 milliamps. I installed a new BOSCH CTS which helped considerably. Now, when the car is first started (cold) it doesn't idle normally for lets say 30 seconds and giving it a little gas seems to help it stabilize. Once that stage is over it will start and idle smoothly and what I would consider normal the rest of the day until it sets lets say overnight. I could live with this, but its not the way these cars idle and I've had 3 of them in the last two decades. Might changing the oil have any bearing in this? 
So, I would very much appreciate any suggestions or ideas about how to get the FOX totally healthy again. 
Thank You! Keep up the great work...
kind regards, Raphael
{black}:wink:


3 Answers
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Man that thing is older to hell but I can tell you from my experience of old foxes the fuel distributors generally need to be rebuilt with new seals and rings and then reset


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Topic starter

Thank You Scotty!

How much more do you know about the CIS injection system? The Fuel distributor was recently replaced so I don't believe that is the issue.

Idle boost valve/solenoid kicks in when the rpms fall below 750. The Bentley Manual is the *bible* for VW's and if have one on hand checking that briefly might help refresh your memory. Just a thought.
My recent test findings is that it will start and idle without the Idle boost valve/solenoid connected and powered. It tends to run a little bit rough when it's first started unless I give it some gas just above roughly where the idle would be set. Within 30 seconds it will smooth out and idle, but the idle is a little low and there is *NO surging *(a good thing). It should start and idle with the Idle boost valve/solenoid connected and powered.
I plan to replace the plugs, distributor cap, rotor and change the oil as well as the fuel filter. Would fresh oil and this basic tune-up help this situation do you know?

Hope this has done some good and will help someone else out there.

Any other suggestions appreciated!

 

Kind regards,
Raphael
{black}:wink:


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Topic starter

Hi Scotty!

Whats the good word?

 

Thank You!

Best, Raphael {black}:idontknow:  


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