tentonhammer 10 Posted October 15, 2012 (edited) Correcting some idle issues at the moment on my C (idle hunting) and want to eliminate fitted ISV. A few questions: To test ISV I presume I can jump from the 12V to the 2 pin terminals mounted on the ISV? Can someone confirm correct operating functionality for ISV i.e should it buzz or make a sound during use? What are correct meter readings during use etc. When ISV is removed the internal flap is stuck shut - Is this normal? If yes I presume it opens under load? I have noticed that the internal flap inside the ISV doesn't quite close fully leaving a small 2mm gap between the flap and internal gap wall (pic below is identical to mine) - I would have thought the flap would need to close right across the gap for it to function normally? This would explain why when I pinch the small vac pipe shut reducing the amount of air flowing into the ISV (flap side) I can attain perfect idle. Please confirm. [ATTACH=CONFIG]69889[/ATTACH] Also, If anyone has any spare ISV's for a 9A (must be in good working order) that you don't mind letting go of just in case mine is in fact faulty, could you let me know? Cheers, C 1992 16V 2.0 (9A) Edited October 15, 2012 by tentonhammer Quote Share this post Link to post Share on other sites
pbradley98 0 Posted October 15, 2012 Very interested in this as am working through the same issue on my VR6 - on initial playing it seems to idle better when the electrical connection is disconnected from the ISV with the idle revs increasing to around 750 - 800 rpm from 600- 650 when the ISV is connected. Guessing that the valve may close completely when energised, so when disconnected it's in the position shown in the photo and hence idle speed increases slightly? Quote Share this post Link to post Share on other sites
davidwort 0 Posted October 15, 2012 All you can really test is that the solenoid actually activates, i.e. the valve opens with 12v supplied, this won't tell you if it's operating completely correctly (duty cycle I think it's called), as the amount/duration of air bleed is controlled by the ECU. The easiest way is to swap to a car that you know idles correctly, otherwise you need to know the correct duty cycle and have the kit to test this off the car. In my experience the valves stick a little when worn so you'll either get revs hanging too high or dropping too low and hunting, sometimes this can be eased a little by cleaning and lubricating but once the solenoid is out of tolerance they'll never respond correctly. Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted October 21, 2012 All sorted. 2 x Faults found. Valve door on ISV unit not opening correctly, in fact barely at all (clicks but only opens partially). Replacement ISV unit fitted (pinched off an audi) I can confirm that the valve door opens fully under load when attached to 12 Volts, thanks David. I must also assume that the 2mm gap between door and valve opening is normal as the replacement ISV unit fitted had this gap as well and the car is running smoother than ever. 12 Volts not reaching ISV unit. Break in ISV wiring. A simple re-solder and tidy up sorted this ;) After a quick adjustment of the idle screw (located top of throttle body) the car now idles perfectly at 900-1000 RPM. Thanks for your help guys, Ten Ton Quote Share this post Link to post Share on other sites
sexybourbon 0 Posted October 21, 2012 Should it idle that high ? Mine sits a 5-600 rpm when on tick over i thought that was standard idle I had my isv off yesterday after following the annoying off throttle jerk thread and my isv also had the same two mm gap away from not being fully shut Quote Share this post Link to post Share on other sites
davidwort 0 Posted October 21, 2012 no, 850 minimum, varies slightly from 1.8 to 2L systems but shouldn't be as low as 600 on either car Quote Share this post Link to post Share on other sites
sexybourbon 0 Posted October 21, 2012 Just realised this is for the four pots will it be the same on a vr aswell Quote Share this post Link to post Share on other sites
aide 0 Posted October 21, 2012 Nope, vrs have greater rotating mass so can idle lower, saves fuel too :) Quote Share this post Link to post Share on other sites
pbradley98 0 Posted November 1, 2012 All sorted. 2 x Faults found. Valve door on ISV unit not opening correctly, in fact barely at all (clicks but only opens partially). Replacement ISV unit fitted (pinched off an audi) I can confirm that the valve door opens fully under load when attached to 12 Volts, thanks David. I must also assume that the 2mm gap between door and valve opening is normal as the replacement ISV unit fitted had this gap as well and the car is running smoother than ever. 12 Volts not reaching ISV unit. Break in ISV wiring. A simple re-solder and tidy up sorted this ;) After a quick adjustment of the idle screw (located top of throttle body) the car now idles perfectly at 900-1000 RPM. Thanks for your help guys, Ten Ton Have you got a part number for the ISV off the Audi / what audi was it off? Don't really fancy the £250 for a new one from VW....... Thanks Phil Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted November 1, 2012 (edited) Have you got a part number for the ISV off the Audi / what audi was it off? Don't really fancy the £250 for a new one from VW....... Thanks Phil It was a standard BOSCH ISV unit pinched off an audi (they share the same ISV). Part Number: 034133455B Edited November 1, 2012 by tentonhammer Quote Share this post Link to post Share on other sites
