Decel valve removal?

[Tiramisu]

My '74 914 will not idle unless the Decel valve is clamped off from the manifold. I have heard this device is not needed. Can I plug the hoses and remove this device without issues?

Thanks

[scotty914]

well you can remove it but there are 2 schools on it

one go ahead and it will help with engine breaking for auto x

two (mine) no it leans the engine out and i think it can cause forced leaks in the valve seals and such by drawing tooo much vacume in the intake, also it can force leaks in the intakes too

i ran mine with out one for a while and if i coasted down with the clutch out then stepped on it it blew some smoke

[Tiramisu]

Well the high idle is not due to the Decel valve..I like an idiot had the wrong hose clamped off..was the other device located next to it..cant remember the name. I thought I might have a leak at the oil cap so I put some gasket sealent up in the top of it. Still high idle. Then I found a kink in the oil breather line..gonna fix that now..dont think its gonna make any difference. I reset the timing at 27 BTDC just to make sure it was not a timing issue. Any other ideas?

[paulhagedorn]

The "thing" next to it, I believe, is the AAR. Aux. Air Regulator. It is connected to the FI brain. It can cause problems at cold or hot, yes. Take it out and pour alcohol in it and swirl it around. It might help free up the parts inside.

Paul

[Tiramisu]

Paul,

I think the AAR is the culprit as you suggest. Now the AAR is supposed to stay open for 5 minutes to warm the car up then close right? I just ran the car for a few miles and the idle does not drop after 5 minutes...then i clamp off one end of the AAR and.. boom..idle drops to 900.

Can I remove this device? I dont see the need for this and it sure would free up the hose spaghetti bowl in the boiler room..i can warm up the beast with the gas pedal..

[Dave at Pelican Parts]

Can I assume you have a 1.8, and not a 2.0, in your 74?

The AAR is needed, otherwise your engine will not idle when it is cold. (RPM will be very very low and the engine will want to stall.)

New ones should still be available. But first, make sure the wires are hooked up to the AAR. Check for +12V on one of the wires when the fuel pump is running--easiest time is when the engine is running.

If it's plugged in and getting power, it's frozen. Some Liquid Wrench might free it up. Or you might be able to open it up and twist the rotary valve until it frees up.

Good luck!!

--DD

[Tiramisu]

Dave,

I have a 2.0. The AAR is definetly stuck open. I drove the car about 10 miles..then pulled off the AAR hose..it was still sucking. I plugged the line with a bolt and the idle dropped to 900. Last nite I sprayed in Liquid Wrench..maybe that will work. If not I will take it out and check the power as you mentioned.

I started the car just fine with the AAR plugged off..just had to keep the gas on for a few minutes..and it was cold this morning..about 31.

Thanks all,

MM

[pbanders]

Originally posted by Tiramisu
Well the high idle is not due to the Decel valve..I like an idiot had the wrong hose clamped off..was the other device located next to it..cant remember the name. I thought I might have a leak at the oil cap so I put some gasket sealent up in the top of it. Still high idle. Then I found a kink in the oil breather line..gonna fix that now..dont think its gonna make any difference. I reset the timing at 27 BTDC just to make sure it was not a timing issue. Any other ideas?

The device right next to the decel valve on a 2.0L is the MPS - clamping off the line to it simulates full-load (WOT) conditions and gives you a very rich mixture.

[pbanders]

Originally posted by Tiramisu
Dave,

I have a 2.0. The AAR is definetly stuck open. I drove the car about 10 miles..then pulled off the AAR hose..it was still sucking. I plugged the line with a bolt and the idle dropped to 900. Last nite I sprayed in Liquid Wrench..maybe that will work. If not I will take it out and check the power as you mentioned.

I started the car just fine with the AAR plugged off..just had to keep the gas on for a few minutes..and it was cold this morning..about 31.

Thanks all,

MM

Yet another AAR problem. Here's what the little bugger looks like inside (see diagram below). The rotating valve can become clogged or jammed with crud over the years, preventing it from rotating open or closed. Be careful about pouring vast quantities of solvents into it! As you can see, the solvent has no place to leak out of and you can crud up the bimetallic coil or even end up with a little grenade if your heater coil is defective. I'd suggest removing the unit from the car, and spraying in a volatile cleaner while holding the unit at an angle to permit the cleaner to drain out of the intake or outlet port. If that doesn't work, get your vice and chisels ready, and do the Dave Darling repair on it !!

[Tiramisu]

Paul,

Yeah..I should take it off..need to check the power to it anyway. I was worried about putting that oil in there..im still in one piece so it didnt blow up..yet.

Brad,

Yup..I had the MPS clamped at first..car ran like crap of course. I had to refer to Daves Hose diagram to see what the hell I was working on.

Thanks,

MM