No, it will not. The air that the AAR leaks into the manifold is metered air. In the 1.8, it is air that has already gone through the air flow meter and that the FI "knows" about. The FI will add fuel for any air that goes in that way.

In the 1.7 and 2.0, the manifold pressure sensor will see the slightly higher pressure in the manifold that is caused by the air that is going through the AAR. It will add fuel to make up for that.

As Miles said, it is just exactly like opening the throttle valve a little more than it is. (Ignoring the fact that opening the throttle valve from idle will take the FI out of "idle compensation" mode, which may change the mixture or may not depending on how the FI adjustments are set.)


It would be, but the "can" part of the AAR is not on the manifold side. I believe that there is no path for air to get from the hose fittings into the can, so there is no need for it to be air-tight.

However, I used RTV to seal around mine when I did this repair. Just in case.


Finally, the CSV is something that almost never opens up to squirt fuel. There are two things that must be happening at the same time for it to open. First, the starter must be cranking. The CSV gets its power from the yellow wire that carries the starter signal. That only has power when you have the key in the "start" position--when the starter motor is cranking. Second, the temperature must be "cold enough". Reports on how cold that is have varied from 50F to 40F to "lower than freezing". That's when the thermo-time switch closes, giving the CSV a ground path.

The CSV's sole function is to provide an extra shot of fuel to help the engine "light off" when it is very cold. It does not do anything for the mixture during warm-up, except possibly as a side-effect for a second or two.

--DD

dont you guys read the manuals? CSV is an independent circuit containing a thermal switch, an injector and teh power wire described by Dave above. Power is applied by the yellow wire when cranking, it goes to the CSV then to the thermal switch. the thermal sw completes the ground path when its cold enough

the AAR is also electrically isolated from teh injection computer, providing metered air when cold. It is an air valve that closes via a heater element in teh can . No air path to the valve section to the can. when the key is on, the heater gets power. It take 5 minutes to progressively close. hot engine block will also close it. EFI knows about the extra air (metered) L-jet runs like crap for 5 minutes without it. D-jet runs OK but needs a little foot action

fix it!

Did not know about the CSV power feed only during solenoid contact ... interseting. Then forget everything I said about rich start up with out the AAR. But if that is the case....why have a thermo time switch? Thermo yes for the "light off" but it takes minutes for the time switch to reach a temperature to remove the CVS ground path. Seems like an uneeded fuction if the CVS only squirts when you are turning the starter....again a function that is not needed? "Bad engineer" said the bean counter...

Go to the local pick 'n pull.
You should be able to find one on a bmw/wv or something that is the same.

I was told (not by Jeff) that our MPS could be found on other makes of cars also. Jeff Bobsley knows how/have the equipment to re-calibrate them

Check my web page for details on the D-Jet AAR. Is purpose is to increase the cold start idle to overcome higher engine friction (of a cold motor). Non-functioning AAR's can be repaired, as DD describes. If you remove the AAR, you'll probably have to use your foot to substitute for it, by holding the throttle open at idle for the first 5 minutes or so - not a big problem. Main issue is if you have to pass a visual smog inspection - capped-off hoses and ports don't cut it here.

The CSV turn-on temperature is lower than most of the estimates in this thread. I've yet to find one that opens higher than 30 deg. F. It's active only during cranking, too.

If you decide to get rid of your non-functional 1.7/2.0L AAR, don't throw it away!! Sell it on Ebay, they're NLA and are simple to repair, so some of us out here are likely buyers.

Agreed, so here's my mea culpa. I was aware of those things but obviously hadn't thought it through well enough. Thanks.

"Thermo-Time Switch" is the label it is given in the manuals, but it is actually a misnomer on all of the pre-75 cars. 70-74 TTSes do not have a heating element inside of them, so they are actually just thermo-switches. The 75-76 TTSes do have small powered heating elements inside of them, so they do have a timer function.

Not sure why, though... Maybe they figure that you only need that extra shot of fuel for 10 or 15 seconds, even if the engine doesn't start up right away??

--DD

Holy crap! Look what I started. And now I dont even think its the AAR thats causing my problems. Here it is. Starts on the first or second turn of the engine when its cold. It does however idle below 500 RPMS when cold. It warms up and the idle goes to where it should be at about 900-1000 RPMS. BUT, after its warm I shut off the engine for a few minutes try to start it and have to give gas or it wont even start. Engine cools and its all starts all over again.

I also had the valves adjusted and seems to be running hot now. Could they be too tight? Whats the normal operating temp on a 1.7. I have a laser temp gauge, pointed it at the block after it had been running for a while and it read 240. Seems to hot to me. What else can cause it to run hot? Bad head gasket maybe, but it doesnt leak oil. Does the fan run off a belt hooked to the crank, or is it hooked directly to it?

Apparently, in very cold climates, there were problems with severe flooding from the CSV, if the car didn't start in the first 10 to 15 seconds of cranking. The "time" function prevented the CSV from operating past the point of flooding.

The first part of what you describe (low post-start idle, going up to 1K when warm) sounds like a missing or stuck shut AAR. The second part could be a lot of other things: e.g. leaky injector, classic "hot start" problem, etc.

Have you tried starting it hot with a wide-open-throttle? Try this the next time it happens: without turning the key to the "on" position, depress the throttle fully (if you do this while the key is "on", you'll inject additional fuel from the action of the throttle position switch). Now, switch the ignition to "on" and crank the motor. If it starts up, then your engine is flooded prior to start or you have a very rich cranking mixture. Check injectors to see if you're pooling gas.

If the above is a no-go, then do what you should be doing, anyway: start from the beginning. Mechanical -> charging system -> ignition -> fuel supply -> fuel injection.... check them out in that order.

Thanks Brad, you mane a good teacher.


Miles