JasonF

In anticipation of installing a lwf/RS clutch kit, a Steve Weiner chip, top end rebuild, M030 suspension, etc...I decided to give my ISV a thorough flushing with some carb cleaner.

Getting the ISV out wasn't too difficult, but I did have to use a 7mm nut driver to loosen the rear clamp screw since I couln't get enough leverage using a screwdriver. I used a 7mm socket to tighten the rear clamp when reinstalling the ISV.

As you can see from the pics, the valves were absolutely gummed up with crud and I used about 2/3 of a can of carb cleaner to flush everything out, using paper towels and q-tips along the way. I was satisfied that everything was clean when the fluid that came out was clear and the valve moved freely.

A test drive confirmed that the idle was much smoother and the car drove like some cobwebs had been cleaned out. It's such an easy diy everyone should do it periodically.

CarmG993

Nice ! Big difference.
Who is going to be doing the work on your car?
I am in North Jersey.

allill

I don't see a difference. LOL!

Man, that's a lot of carbon!!!

Mark Harris

Its great when that little gate breaks free again and it goes clink, clank when you rotate it with your wrist.

Here's mine from a couple months ago.....

Steve Weiner-Rennsport Systems

I like to do that at each oil change while the oil is draining,...

Terry Adams

What I don't understand is that the ISV is on the intake side, ie pre combustion, so where is all the carbon build up coming from?

As a comparison, here is an intake valve before the 120K rebuild. Bottle of Techron through the last tank before every oil change, and Chevron gas only. Would the Techron/Chevron gas do the same for the ISV?

tony soprano

Wow. I'd be interested to see what the back of that intake valve looks like but that port looks remarkably clean.

Terry Adams

tony soprano

Thanks for the pics Terry. Although that new pic shows the valve face. I was curious what the back of the intake valve looked like. The link below has a side-by-side comparison of two intake valves run on different grades of fuel - cheap vs. tier 1. After seeing your intake ports, if I wasn't a Techron believer before, I sure am now.

http://www.aa1car.com/library/dirty_intake_valves.jpg

Stealth 993

I just did it to the 95 yesterday, same thing, lots of crap in there. I also removed the intake boot & looked at the throttle body, noting there, it was clean.

Terry Adams

tony s, I did not take a pic, but it did look somewhere between the face and the port. Much closer to the port.

Which is why I still have the question, where is all the carbon coming from in an ISV?

Stealth 993

My thought is it's a low pressure area, & stuff gets stuck up there, then bakes in. kind of like the rear end always having much more dirt on it them any other place on the car.

JasonAndreas

The oil tank vents (red arrows below) directly in front of the throttle-body and into the ISV. The image below is from a 964 but the setup is materially the same on the 993.

Terry Adams

Thanks. Now I get it.

993MAN

OK, that looks impressive, but, what is an ISV and where is it?
Mine might need cleaning too.