DIY - Testing and Cleaning the Idle Stabilization Valve (ISV)
04-26-2018, 12:28 AM
#16
Rennlist Member
You do not want to use brake cleaner, carb cleaner, xylene, tolulene (aka. carb cleaner), methanol, MEK, acetone (aka brake cleaner) on the ISV which is nothing more than an unsealed electric motor. Stick with rubbing alcohol and a q-tip or you will end up having to replace it.
04-26-2018, 12:39 AM
#17
Rennlist Member
I hope the OP still visits this thread as I would like to know what the response time is for the solenoids. More specifically if idle hunting is due to an underactive solenoid response?
Also, has anyone disassembled one of these? I'd like to picture how the solenoids are mechanically configured.
Also, has anyone disassembled one of these? I'd like to picture how the solenoids are mechanically configured.
05-23-2019, 01:17 AM
#18
Rennlist Member
Bumping a great thread!
I had an occasional CEL issue after my DE and AX events. Car runs strong during my runs, but when I am cooling down and then restart, the CEL would usually come on. I replaced the spark plug wires which helped with eliminating a CEL for 2 cylinders whenever I drove the car, but didn't eliminate the CEL completely. Talking with @p000830 he suggested I should clean the ISV. I did this past weekend and wow what an improvement. I thought my motor was running smooth but now it is running even smoother. Had to use an entire can of carb cleaner to remove the debris and had to even shake it while spraying it to loosen the valve so it can finally move freely like a rattle can of paint. I don't have an oscilloscope readily available so used a 12V battery to test the valve. Before it would sort of work, after the cleaning the valve would snap open and close easily with a 12V input. Did an italian test drive to shake out the car and so far so good!
I couldn't figure out what everyone was saying about rattling the ISV as mine was stuck and would take a few tries with the 12V battery to get the valve to actuate. This is what I assume a clean ISV should be...
I had an occasional CEL issue after my DE and AX events. Car runs strong during my runs, but when I am cooling down and then restart, the CEL would usually come on. I replaced the spark plug wires which helped with eliminating a CEL for 2 cylinders whenever I drove the car, but didn't eliminate the CEL completely. Talking with @p000830 he suggested I should clean the ISV. I did this past weekend and wow what an improvement. I thought my motor was running smooth but now it is running even smoother. Had to use an entire can of carb cleaner to remove the debris and had to even shake it while spraying it to loosen the valve so it can finally move freely like a rattle can of paint. I don't have an oscilloscope readily available so used a 12V battery to test the valve. Before it would sort of work, after the cleaning the valve would snap open and close easily with a 12V input. Did an italian test drive to shake out the car and so far so good!
I couldn't figure out what everyone was saying about rattling the ISV as mine was stuck and would take a few tries with the 12V battery to get the valve to actuate. This is what I assume a clean ISV should be...
01-31-2021, 01:00 PM
#20
Advanced
Great write-up! Very comprehensive and educational. Adding it to my 993 procedures folder, well done!
Shade Tree mechanic weekend man's valve testing, not perfect but seems Ok as part of the cleaning process:
Andy
Shade Tree mechanic weekend man's valve testing, not perfect but seems Ok as part of the cleaning process:
- Detach the valve from its hoses and electrical connection;
- Clean the electrical plug and socket with spray electronics cleaner, dare I say the CRC brand?
- Clean the valve internals with choke cleaner spray;
- Verify after cleaning that the valve seems to float between its open and closed position and when twisted in your hand it freely rocks like on a spring back and forth;
- Apply 12 volts+ to the common (middle pin) pin and negative to one of the other pins for a moment and verify that the internal valve snap to a fully closed or open position;
- Apply 12 volts+ for a moment to the common pin and negative to the other pin not used above and verify that the internal valve snap to the opposite position to the above;
- Reassemble the valve to its hoses;
- Plug the valves wiring harness plug back in making sure the sealing gasket inside the plug is in the correct position and the plug fully seats.
Andy
Today I also checked my ISV.
is it normal behavior when I connect 12V to the middle pin and GND to the other pin for open the valve it feels very stong with a nice loud "clock" sound.
But when I connect GND to the other pin for closing the valve it's more quiet and it feels not so strong.
regards
Peter
02-06-2021, 02:05 PM
#21
Three Wheelin'
For people who installed a light weight flywheel and have stalling issues...
There was a thread on this forum that showed how to adjust the idle with the ISV. I removed my ISV for cleaning and adjusting, There are three small screws with what might be epoxy sealing access to the screw head. I first marked the position of the round body where the screws are. Cleared the epoxy out and loosen the screws. I don't recall which direction to turn the body, but a little trial and error should get the proper, stall free setting.
Having the reference position mark will be a big help while adjusting.
Good Luck!
There was a thread on this forum that showed how to adjust the idle with the ISV. I removed my ISV for cleaning and adjusting, There are three small screws with what might be epoxy sealing access to the screw head. I first marked the position of the round body where the screws are. Cleared the epoxy out and loosen the screws. I don't recall which direction to turn the body, but a little trial and error should get the proper, stall free setting.
Having the reference position mark will be a big help while adjusting.
Good Luck!
06-24-2021, 03:32 AM
#22
Instructor
same here with ISV in engine & just ignition on (engine not running|). Is that normal ?