AAR Revisited - Page 2

BeeBeeper · 02-13-2005, 12:36 PM

I am using a voltmeter with a red and balck pin lead.

The problem I am having.

The car starts up at about 2000 RPM's. I start driving it immediatley. Within several minutes , the car RPM's drop to about 400 and runs like hell, backfiring and not power. When the car warms up completely(first mark on Temp guage) it runs well.

I ma wondering while the AAR is open, the car is running okay, then with vacuum hose disconnetec on the WUR, the mixture is not correct and runs like hell until the whole engine is running okay and the vacuum hose on the WUR is not as important. Does this make sense???

Should I have voltage at the AAR plug with the key on???

Thanks,

Ron

boyt911sc · boyt911sc's Garage

Ron,

The WUR and AAR should have power when the ignition switched is turned ON. What is your fuel control and system pressures?

What model is your car? PM me at atd911@hotmail.com if you wish. I had similar experience before I converted my WUR to adjustable one. Good luck.

Tony

Elombard · 02-13-2005, 01:31 PM

I think the car has to be running.

I jumpered 12 v. to mine because I did not have voltage. You may want to try this test at some point if you verify you are not getting voltage. Just put it back togeter start the car and pull the plug on the WUR and look for voltage it will run kind of funky but it will run.

I bet the vacuum line was your problem. Might be no voltage thoug,

By the way the WUR and AAR get voltage from the same place so if no voltage to one probebly no voltage to the other.

BeeBeeper · 02-13-2005, 01:50 PM

I am in the process of putting everything back together and checked the voltage again at the wur and aar , nothing with the key on. After I have it together I will start it and check voltage on the aar and Wur.

I have a a 1982 SC Targa. See Picture below.

Since I have an A/C in the way, it is hard as hell to get that AAR out and in. I had to remove the injector on the #5 cylinder. After I check it running, I will let you know how it turns out. If that WUR vacuum hose is it, I will be happy.

I have not checked the fuel control and system pressure. I will also check this when I have it running.

Thanks,

Ron

Elombard · 02-13-2005, 01:51 PM

Pretty sure it does not have power with just the switch on now that I think about it. If you were sitting in the car with the switch on listening to the radio for 10 minutes with the car cold, then went to start it; the AAR and WUR would think the car was warm and it would not run right, especially if it was cold outside.... Maybe I am wrong.

You know what!!! the power to the two items goes through the relay on the back fuse panel. If the relay crapped out that could be your problem. Maybe try switching the relay from another source???

BeeBeeper · 02-13-2005, 06:03 PM

I took it for a run and adjussted the ait and fuel misture and it ran like a bat out of hell. Also no miss and started idling at 900 where it should be. One more problem as I was running it home, I got caught in a huge rain storm and had to stop at a light. I could not even see the front of the car hood it was raining so hard. I started from the light and it died when I turned the corner to go home. It is raining like hell now and will wait until it let up a bit.

I have never had this problem before. Do you think the distributor got wet. I need to go down the street and get it later when it stops raining.
Any suggestions??

Ron

Paulporsche · 02-14-2005, 07:08 AM

Ron,

Your distributor cap is a good place to check, as you have said. Also, check your plug wires and connectors.

Lorenfb · 02-14-2005, 07:19 AM

"Should I have voltage at the AAR plug with the key on???" - BeeBeeper

No! It gets power at the same time as the fuel pump, when the sensor plate moves, i.e. engine runs.

"Pretty sure it does not have power with just the switch on now that I think about it. If you were sitting in the car with the switch on listening to the radio for 10 minutes with the car cold, then went to start it; the AAR and WUR would think the car was warm and it would not run right," - Paulporsche -

Right on!

Elombard · 02-14-2005, 07:39 AM

I love it when its intuitive, I find that all over the Porshce - not so much on other cars.

boyt911sc · boyt911sc's Garage

Elombard/Loren,

You are correct about the voltage when the ignition is 'ON". There is no voltage reading. But the test I did was similar to fuel pump test set-up with jumper wires to 30 & 87A terminals at the fuel pump relay socket.

Without running the engine and ignition switch turned 'ON', you could test the fuel pump, WUR, AAR, and the thermo-time switch for voltage and ground.

I apologize for the confusion of my previous post.

TD

boyt911sc · boyt911sc's Garage

Please help us understand how the car will not start when the ignition switch is left turned 'ON' when listening on the radio for a period of time as an example.

As mentioned earlier, the AAR/WUR/FP don't get voltage at all when the ignition switch is at 'ON' position (no jumper). They don't get energized until starter gets power and the alternator starts to turn.

So how would these effect a start-up? Just want to know and understand the wiring diagrams. Thanks.

Tony

Elombard · 02-14-2005, 09:04 AM

No no what we were saying is...IF they did get power when the engine was on it would mess up a cold start.

the little bi metal pieces warm with voltage(and engine temp). The WUR pressure is altered as the strip warms and moves and tyhe AAR closes off the air bypass (choke) needed for colder running as the strip warms and pulls the door shut.

BeeBeeper · 02-14-2005, 10:29 AM

Whe the the car is running and you check the WUR voltage should it be consistant??? or should the voltage be moving around. When I checked my voltage it was ruuning all around the meter. Is this normal???

Ron

vizail · 02-14-2005, 11:08 AM

You can check air leack's by Spraying some Carburator and choke Cleaner. around the Intake manifold rubber's, Injectors, Intake Box, Acceleration Assembly etc. etc. But be advice.., check for Spark's around the Ignition and Spark wires. This procedure is detailed in the 101 911 Project Book

Vic

Bjornb · 09:27 AM

I was having cold start problems with my 911SC until I discovered that the air line from my AAR to my intake was blocked off. After unblocking the line my car starts up and idles at 900-1000rpm from cold to warm but the weird thing is my AAR tested bad when I ohmed it I got an open circuit which to my understanding should make it heat up and close too soon. I have not checked to see if it has power yet but I have a hunch that there is no power to it and that the heat from the intake manifold is warming it up enough to close off. Does this sound possible to any of you or do you think there is something else going on. I just thought that if this is possible then unplugging a non-working unit could allow it to function again without the element inside heating it up too fast. Any thoughts on this?

dickster · 02-17-2006, 03:56 AM

Great write up

Mysterytrain · 02-17-2006, 04:51 AM

wow, this is back again almost a year to the day!

Bjornb · 02-17-2006, 02:22 PM

I just checked and I do have power to my aar and when unplugged the engine continues to climb in rpm as it warms up so my theory was wrong

I still don't know how it could be working correctly with no resistance on the wires. But it does, and I'm going to leave it at that.

vizail · 02-17-2006, 03:11 PM

Let me tell you..!
"Gremlins " at work on this cars..

Vic

l_turn9 · l_turn9's Garage

Hi Gang,
I enjoyed reading all the great work ya'll are doing on the AARs and other stuff. It really makes this list worthwhile.
I am suspicious of my AAR and may take it apart using the info here. BTW, I did some searching and found the mid to late 70s VW Bus' use a similar AAR as the 911 - except it has a plastic body. It sells for $60 and I was considering buying one until I read about this rebuild.
MidAmerica Motorworks has them as PN 319-017. At least they look the same ;-)
Thx agn gang - (back to lusk mode)