How long for your CIS to warm up? ['83 911 SC]

[VaSteve]

Ever since I changed the battery in the 911, it seems like the CIS takes longer to warm up or "settle in". (For those of you with Motronic, the car idles high (about 2K) for a while and then drops to the usual ~900 rpm).

Given that it's not terribly cold out, how long is it taking your cars to settle in? The other night, I drove all the way to Lowes (~5 miles) and when I came out of Lowes it still didn't seem warmed up. Seemed to settle in on the way back. I don't have a lot more data points, but it seems to be taking way more than it used to.

Any thoughts? I know the WUR is somehow electrical, but I don't think a new battery should affect it...should it?

[tdatk]

If it's below 50 mine takes around 5 minutes idleing in the driveway to slowly settle down. My fuel pressures are fine and if it gets above 50 it takes less than 30 seconds. If its cold outside, I could drive for miles and it would still be idleing ~1500 rpm's until the temp gauge gets above the thick white mark. If i shut it off, the cycle starts again.
HTH

[henrydbrown]

I recently replaced my WUR b/c it would not idle down. Now my specs are like Tim's above. When it is below freezing it may take 20 minutes to idle down, which seems to be too long to me. I saw an add in Excellence Magazine for an electronic adjustable WUR - I'd like one.

[Rick V]

Steve, check the 60deg switch in the right chain housing. It won't bring the 02 sensor online until the oil temp gets to 60deg. It is a on/off switch so I just grounded mine out, my system goes hot as soon as the car is running. No issues with "warming the car up"

[VaSteve]

Rick, No O2 sensor anymore. :) Thanks guys...I'll just keep an eye on it.

[Trak Ratt]

Steve, check the 60deg switch in the right chain housing. It won't bring the 02 sensor online until the oil temp gets to 60deg. It is a on/off switch so I just grounded mine out, my system goes hot as soon as the car is running. No issues with "warming the car up"Did the same to my '82. Read somewhere that it rich'ns the top end too for a little more HP down the front straight ;)

[GoThingNC]

Ths morning it was 30 degrees out (about 40 in the garage) and it took about 20 seconds for the idle to drop from 1,300 down to about 950.

[VaSteve]

Ths morning it was 30 degrees out (about 40 in the garage) and it took about 20 seconds for the idle to drop from 1,300 down to about 950.


Hmmm. Mine's never been that short. It usually revs up to around 1900 for a couple of miles and then drops to normal pretty quickly. Not progressively. Just drops and stays there.

I'll have to take it out again this evening to check on it.

[turbo23dog]

For what its worth, on my 80SC does not get that much of an increased idle on cold start during winter. It maybe gets to 1000 -1100 tops. Lasts for max of 3 minutes.

[VaSteve]

For what its worth, on my 80SC does not get that much of an increased idle on cold start during winter. It maybe gets to 1000 -1100 tops. Lasts for max of 3 minutes.


That was my recollection as well. It seems to be taking a lot longer than it used to. Maybe the mouse that was in the air cleaner came back and messed something up.

[}{arlequin]

like i said, you should not drive your good car some more. maybe more things will happen to it

[VaSteve]

Ever since I changed the battery in the 911, it seems like the CIS takes longer to warm up or "settle in".

I think the issue is related to the fact that the car ain't charging up.

http://dorkiphus.net/porsche/showthread.php?t=16509

[Cliff Claven]

steve i don't know but maybe you're getting extra air past the throttle plate. that's the job of the aux air regulator, to give you that extra air during warm up. you could remove the aux air regulator and test it to make sure it's closing properly with a 12 volt circuit. it should take maybe two minutes to close. you could also check the electrical circuit going to the aux air regulator to make sure it's functioning properly. if the circuit isn't working properly, the valve will eventually close as the result of heat from the case, but that will take until the car warms up. you can always just bypass the valve by blocking the line completely all the time, but then you'll have trouble starting, especially in cold weather. or you could live it or buy a new one. in warm weather it should work much better.

[William Miller]

Bingo Cliff.
The internal heater or the wiring to it could be bad.
The AAR is on the right side (looking from the back).
It does the same thing the "fast idle lever" used to do but automattically.
It allows air to bi-pass the throttle plate.
Sometimes they stick and can be cleaned up, but if the heating element is bad then its a typical replacement.

Jim Williams Rennlist page has full descriptions on function and pictures.


I think I have a spare in the attic if you end up needing one.
It came off the cab because someone in the past installed the wrong part.



The electronic WUR sounds very intresting.

[VaSteve]

steve i don't know but maybe you're getting extra air past the throttle plate. that's the job of the aux air regulator, to give you that extra air during warm up. you could remove the aux air regulator and test it to make sure it's closing properly with a 12 volt circuit. it should take maybe two minutes to close. you could also check the electrical circuit going to the aux air regulator to make sure it's functioning properly. if the circuit isn't working properly, the valve will eventually close as the result of heat from the case, but that will take until the car warms up. you can always just bypass the valve by blocking the line completely all the time, but then you'll have trouble starting, especially in cold weather. or you could live it or buy a new one. in warm weather it should work much better.

I'm waiting to do further testing until I get the alternator fixed. I think the issues may be related. I guess I should have tested the alternator after the battery swap.

I do recall it being a very short time to do it's thing. See }{, I do drive it enough to know something's wrong. ;)

[Cliff Claven]

you probably shouldn't run the car at all with a bad alternator.

[tdatk]

Guess I'll be checking my AAR...

[VaSteve]

I think the issue is related to the fact that the car ain't charging up.

http://dorkiphus.net/porsche/showthread.php?t=16509


I can only assume at this point that the computer was starving for juice and it wasn't reading the WUR properly. After swapping the alternator the car is operating properly now. Engine revs up to (only) 1200 or so and drops off dramatically after a couple of minutes. Man, this is a fun car!

[KFJ]

Hehe, computer that's a good one:). More likely not enough voltage to sufficiently heat the bi-metallic strip in the WUR and AAR.

[VaSteve]

The 83 models have a computer that works with the O2 sensor that adjusts for emissions, etc. Bill Miller probably understands it the best on the board. Then again, I have removed the O2 sensor anyway for my cat bypass pipe so maybe the computer isn't doing anything at all.

[William Miller]

WUR and AAR are completely independant of the O2 controller.
The only thing that it effects is the frequency valve.
Like the WUR, the frequency valve modify's the control pressure of the fuel distributer. WUR when the engine is cold and the frequency valve once it is warmed up.
I guess low voltage made the bi-metallic strips in the WUR and AAR warm up slowly, which is what KFJ was getting at.;)

[VaSteve]

I guess low voltage made the bi-metallic strips in the WUR and AAR warm up slowly, which is what KFJ was getting at.;)


Yeah, what Bill said. :lol:

Anyway it works great now. Saw Tito while I was out driving and he got a turn at the wheel. Good Porsche day. :D