kkim

Dave,

FWIW, when the ISV valve is clean, the vane inside should be so sensitive to movement that when you jiggle the valve the vane inside should jiggle inside too, like it's spring loaded. (which it is) If yours wasn't that easy to make the vane move inside, you might want to try cleaning it again.

993Dave

Kelly: that's exactly the way it worked after I cleaned it. I didn't take particular notice of how it worked before I started cleaning, but it couldn't have been moving very freely because its freedom of movement afterwards was surprising to me. That's a good little maintenance DIY.

kkim

Dave... cool.

Did you notice any type of change in your car's drivability, before and after?

993Dave

Kelly: I'm pretty sure the idle is less lumpy that it had been. I don't know if the ISV is supposed to have an effect in any other rev range, but the car seemed to be running particularly smoothly last night (on the way to and from a really fun karting track, BTW). Thanks for the idea about the paint thinner, too. It worked really easily and well.

soltino

Where's that Kart track at, Dave?


tino

hn

I cleaned mine hopefully to improve the engagement point and it did. Thanks for the suggestion. I can go up my steep driveway much easier now without having to rev the engine too high.

993Dave

Out in Riverside. It's a great facility (the Red Bull Driver Search uses it), and karting, even in 13-hp jobs, is a blast. I linked to their website in my post above.

bmxracer4

Thanks everyone for the DIY! My idle came up to 800+ and the valve moved freely after the clean using WD40 to lube. I moved the clamps to an easier position and used Pedro Ice wax for the hoses and they slide in and out like a champ. The ISV had never been cleaned (28K on a 97' 993) and you were right about smoother shifting.... Peace

the_buch

Thanks to the nudge from this thread, I got around to this diy today ... started with Simple Green, then went on to the paint thinner and finished with a very small amount of WD-40 on the vane ... overall it was notable just how much carbon was caked in there :-)

For the resinstall, I found that rotating the ISV inside it's rubber bracket so that the far flange was raised and then rotating it down into the hose at the back worked well for this most difficult part of the whole procedure (along with some silicon lube).

This is worth the effort.

idle rpms up from (roughly) 750 to 780 with a very noticeable improvement in smooth feel at idle (formerly I would have described it as 'coarse' at idle)

just do it ....

Caveman

Thanks for following up on my query. Guess I'll add this one to my ever lengthening list!

Cheers,

David

Toga

An easy DIY for a great result isn't it!

dhicks

I am glad my thread stimulated a few others to try this simple DIY. It seems like everybody has noticed a rise in revs and a more stability at idle. Some others have even noted a smoothness further up in the rev band when changing gear...not sure I felt this but just felt the car was smoother at idle and take off....all in all it was an easy DIY with a very positive outcome. If you are looking to do your first DIY this is an easy one to get you started and with a very satisfying conclusion.

Alon

Is it safe to say that a failed ISV is something that is obvious? I assume that stalling would be a clear sign but if the ISV was cleaned out and the idle revs didn't change with no stalling issues, what could that mean?

morologous

I too have had a lumpy and fluctuating idle. I performed the DIY on Robin's site and the idle has become noticably smoother and rock-steady. It it still a bit low under some circumstances, but the overall experience has been positive.

Further, I concur with the previous posters that the hose clamps are assembled in a truly confounding configuration.

Lastly, the amount of gunk in the chamber is astounding. Q-Tips are definitely the best way to really get in there and clean everything up.