Blackfc3srx7

iTrader: (1)

I am trying to figure out if I am missing a check valve on the thermal wax vaccum line to the uim or what. I figured if I had a stock pic of an s4 engine with everything hooked up right I could do it. I found out that the line from the mainifold near the firewall was plugged in to thermal wax and constantly sucking in unmetered air and once blocked that off my idle was perfect.

RotaryRocket88

iTrader: (7)

FSM pages 4A-55 to 59 have diagrams that'll show you. Basically, the rear nipple on the thermovalve connects to the UIM, and the forward nipple connects to the double throttle diaphram. There is also a check/delay valve in the line to the double throttle diaphram.

Blackfc3srx7

iTrader: (1)

Thanks I have Haynes but its hard to see. Its strange cause if I connect the last nipple to the uim then it just draws in air from the outside. I guess maybe the thermal wax is bad? I have that disconnected and it idles good once warmed up a little, better than before and I get a more accurate Afr on my wide band.

RotaryRocket88

iTrader: (7)

If you don't have the line to the double throttle connected, it'll suck outside air once the thermowax softens, but other than that, it's supposed to be a closed system.

With both vac lines connected, is there vacuum from the little filter on the end of the valve? I'm not sure what it's even there for, but there may be a check valve on the end to vent off any positive pressure.

Blackfc3srx7

iTrader: (1)

Hmm makes me think the thermal wax is bad. I have it completely warmed up and it is supposed to close the end off so that there is no outside air entering. The system makes sense now that I look at it. When hard the vacuum line off the manifold is sucking outside air in to raise the throttle at idle. Once the was softens it closes that leak at the end and then the vacuum is closed and now your idle drops. Correct me if I am wrong.

I have both lines hooked up. The other one is going to the double throttle pot. I am wondering if the check valve is going the wrong way on that?

RotaryRocket88

iTrader: (7)

I think you're mixing up the thermovalve and the thermowax. The thermowax softening opens the thermovalve and also rotates a cam that presses against the primary throttle plate. The ~1500 rpm cold idle is due to the cam, not the thermovalve. The valve is just for the double throttle. And it's not supposed to suck in any outside air, since that air would be unmetered (didn't get measured by the AFM). If yours is sucking outside air in, there's a problem with it.

The check/delay valve should have the arrow pointing towards the thermovalve.

Blackfc3srx7

iTrader: (1)

Alright that was my problem. The valve was pointing the wrong way. I will test it out tomorrow when I cold start it. Thanks for the help. I just gotta get my cruise control working now and everything is good for a long trip. Trying to get good for possibly driving to Seven Stock.

Blackfc3srx7

iTrader: (1)

Alright so I have everything hooked up right. However there appears to be a vaccum leak or air beinng sucked through the end of the thermovalve when it is running. It appears that everyone dtches the whole setup when that happens. Any thoughts on what to do so I can drive when cold?

RotaryRocket88

iTrader: (7)

Bypass the thermovalve alltogether, and just run the vac line with the check valve in it directly from the UIM to the double throttle diaphram. I doubt you'll notice any difference from the stock setup.

Also, do you know if your double throttle diaphram actually works? With vacuum applied, does the arm pull in on it (throttle plates closed)? The reason being, I know mine never worked on my NA engine, and I've seen plenty of others that didn't either. If yours isn't moving, there's no point in keeping the vac routing at all. You could just cap the vacuum source on the UIM, and be done with it. The outer set of secondary plates default to the open position when the diaphram fails.

Blackfc3srx7

iTrader: (1)

The double throttle diaphram is working when vacuum is applied. The thing I keep running into is that once I start my car it won't idle until warm or idle and sort of hickup then die. It I have those lines capped off then it doesn't sound like its misses but can still die if I rev it up to 3 grand. So its that possibly a thermal wax setting problem? It should still idle if its cold with out the double throttle diaphram right?