waxen Posted July 21, 2010 Share Posted July 21, 2010 Well it's been a long time since I've been playing with my Megasquirt setup. I have had the Bosch idle valve disconnected because I cannot get it to work properly, so after a few months or so of fiddling and resorting to Niges original settings I tried today to get it working on warmup............Success well for a short time, it all went pear shaped after I tried to adjust the air bleed screw on the valve to trim the idle down about 50 or so RPM. As the screw was adjusted the idle jumped up to 13-14 hundred RPM, the same result I had been getting all along. So... what I think I have discovered is that the valve is unable or not strong enough to stay closed against the engines vacuum demand. A few things that might be at play here, i suspect are: Faulty valve? A need to readjust the throttle body or something screwy going on at the electronics end. I have tried various pulse widths with the valve in my hand and watched the idle dc gauge in Megatune and it has remained stable. Does anyone have any ideas or similar experiences? Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted July 21, 2010 Share Posted July 21, 2010 I have only quickly read your post so excuse if I am wroing BUT Common fault is the way people adjust things with the PWM in place, it sorts of fights you steps to set up REMOVE PWM and block off both pipes with lump of solid rod etc then when engine is WARM set the tickover via plemum adjuster / cable etc till OK THEN put PWM in, and set the settings into the ECU, this then will ADD air on cold start ups over and over what has been set without it, and also if set right maintain tickover etc when warm Just disconnecting the PWM doesn't work as its "Powered" Closed HTH Nige Quote Link to comment Share on other sites More sharing options...
Paul_VR6 Posted July 22, 2010 Share Posted July 22, 2010 Agreed. Totally off it passes about as much air as it does 35% duty. 20% duty is fully closed on the 2 wire valves we have in the US. Quote Link to comment Share on other sites More sharing options...
waxen Posted July 23, 2010 Author Share Posted July 23, 2010 The adjustment line of thought makes sense now that I think about it......It does seem that the valve is not capable of withstanding the full vacuum signal, it is after all there as an air adder to increase the idle not decrease it...........'tis clearer now after discussion:rolleyes: Thanks Quote Link to comment Share on other sites More sharing options...
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