Aux air regulator problem on 2.0???

[malpais]

I just got my 76 2.0 running, but idle is high...If I pinch either hose (from cold start injector to AAR or from AAR to intake), the idle drops to near zero. is the temp sensor or injection wiring bad? How do I trouble shoot.

Thanks, Gordon

[3D914]

Gordon,

Welcome to the challening world of 914 ownership. What they lack in servicability (finding parts, if they still exist), they more than make up for in drivability and fun.

You don't mention what the idle setting is, but at startup it should be in the 1100rpm range for a cold start. By crimping either one of the hoses you're cutting off the by-pass air required at startpup - since the thottle valve is closed.

Here's how it works.

The Aux Air Regulator is full open at startup, to allow air to bypass the closed throttle valve until engine temp reaches 122 deg, at which time it should close (the manual says completely, but I have heard from others and seen on mine, that it still allows a small amount of air through). You can pull this easily when cold to see if it is open or not, and again when engine is warmed up to check its status when hot.
These are no longer available for the 2.0 liter, so I had to soak mine (which was locked only partially open) in machine oil for a couple of days, but it did the job.

The only way I know to test the cold start valve is to disconnect the electrical lead to it. If engine function remains the same for cold starts, then its likely the culprit. This isn't definitive, but I'm still looking for another test method for this one.
Another check I would make in relation to this is fuel pressure. Make sure you're getting the required 28psi.

Another factor is to verify there are no vacuum leaks, and that the hoses are connected correctly. You can go to Pelican Parts Technical area for a diagram on the vacuum hoses.

Hope this helps!
PS: A Clymer manual for the 914 can prove a useful assistant.

[pbanders]

As 3D914 says, your AAR is stuck open. Even if the heater element is not working, the engine heat eventually warms the bimetallic strip enough to close the AAR. This part is NLA, you will need to repair it yourself. Do a search on this list, I think Dave Darling described a repair process in a posting. Note in advance that repair of this unit can be a PITA.

3D914 commented that his AAR doesn't close completely. When an AAR is working properly, it closes completely once the engine is warm or it has been sufficiently warmed by the heater.

Regarding the comments from 3D914 on the CSV, be aware that the CSV doesn't activate until it is rather cold, at least 32 deg F and below. Additionally, even if the temperature is low enough for the thermo-switch to turn on, the CSV is only activated during cranking. Testing the CSV is accomplished by removing it from the intake plenum, hotwiring the fuel pump relay, and hotwiring the CSV to turn on while the business end is directed into a jar. Note that the spray pattern of the CSV is different from that of a port fuel injector. The CSV delivers a mist, while the port fuel injector delivers a spray. The mist improves the distribution of the fuel to all four cylinders.

For more information on the AAR or CSV, check my web page.

Brad Anders

http://members.rennlist.com/pbanders/djetparts.htm

[Dave at Pelican Parts]

In general, there are two causes of a high idle in a D-jet car. One is over-advanced ignition timing. The other is air leaks.

Air leaks can be from "ambient" air into the intake system somewhere (vacuum hoses, manifold, etc.), or they can be internal to the vacuum system (an AAR that is stuck open, a Decel Valve that is leaking, etc.).

If pinching the hose to the AAR comes close to killing the motor when the car is cold, that's fairly normal. If it does that when the engine has warmed up, then the AAR is indeed stuck open.

How high is the idle? Does it change when the engine warms up?

Another good D-jet page (but much older) is Kjell Nelin's D-jet Guide http://www.914fan.net/djet.html .

"Re-building" the AAR involves large implements of destruction like hammers and chisels. So be certain yours is dead before you try to "fix" it. Just like the Head Temp Sensor, it is easy to mess up a part that is hard to find. (In the HTS' case, the part you can screw up is the cylinder head. BTDT.)

--DD