just wondering if a 1.7 decel valve will work with a 2.0 motor?

sure as its the same part

they have differnent part numbers though....

The part number wasn't too important to me... I was more careful about where to install it....



It didn't take me long to decide......






And here's a photo to help illustrate where it goes.......












Sorry... Couldn't resist. If you actually want that part in your system, I respect that.

sure.....I was doing some research and found an old posting about how it is nothing more than an emissions part and that you could just plug the hoses that go to it...

I guess it will go in the trash can.....

thanks......

Depends on what you're after.... There is value in keeping your system stock.

I was happy to eliminate and clean up that part of my system... But my car will never be anything near a concourse or even basic stock system.

Do what's right for you.

how does it run with it off and is there anything i have to do if i romove it?

Paul Anders has been doing some research on them. Basiclly, it let in air at a overrun condition so the fuel mix isn't too rich. For example, you exit on to a freeway offramp decelerating from 70 mph to 30 mph in 5th gear. The throttle is closed but the rpms are still high. The FI is still dumping gas into the cylinders so its pretty rich unless the decel valve opens to let in bypass air so lean out the mix.

Keep your decel valve running and lower Greenhouse Gasses!

I know the common wisdom is that the decel valve is only an emissions device, but it also may serve to increase the life of the very, very expensive manifold pressure sensor.

The decel valve (when adjusted and connected correctly) limits the intake manifold vacuum to no more than 19 inHg (based on data I took on an decel valve that Geoff sent me that had not been tweeked from the factory setting). Under high rpm overrun conditions (e.g. closed throttle at near redline conditions), the intake manifold vacuum may exceed 25 inHg without a limiter in place. This high vacuum causes the aneroid cells in the MPS to become maximally compressed. This additional compression adds to the normal metal fatigue the cells experience and may lead to early failure.

That's the theory - in practice, I haven't seen any MPS's so far that have failed aneroid cells. The guys at Bret Intruments, who do MPS rebuilds, tell me that they see them all the time, so there may be some truth to the theory.

Oh, one more comment - if you do decide to get rid of your decel valve, don't just throw it away, it's a discontinued part and there won't be any more of them made. Sell it on ebay, even the most crusty part will net you $10 at a minimum, and probably more. Somebody out there probably wants it!

I think the inner stop keeps the diaphram from compressing the cells too much but the high vacuum could wear out the cells. I have yet to see bad ones.....

I have been researching the copper used in the diaphrams. Why does everyone think they are copper/berylium? They look like just 36 gauge hardened copper sheet. I remember when RustyWa tested the OEM one thats what it was.

I have also been taking apart a few that are handmade brass diaphrams. pretty crude.

thanks for you information guys.....

Geoff,

A few months back, we had a vendor come in to my work, to show off a new XRF analyzer they were trying to get us to buy. I don't remember the source this analyzer was using, but it was better (and fresher) than what we had. It also had better software.

Anyways, I grabbed that piece of the diaphram you sent me and brought it with me to see if I could stump the machine. This machine still couldn't find the beryllium (just the nature of the beast) but it could find the compositions of all the other elements. Taking all that info it "deduced" that the material was BeCu. I think it was grade 172 if memory serves.

ok, I know of a source for that! I'll see if they will send me a sample.

wankers.....

The full-load diaphragm stop plate prevents high vacuum from stressing the diaphragm, but the aneroid cells react to whatever vacuum level is applied to the port. The overstress problem for the full-load diaphragm is positive pressure, which can occur if you spin the car with the clutch engaged and the throttle plate closed - which I know Geoff knows.....

yep, blew out a MPS that way AXing. Didn't get the clutch in on a major 360 spin.