deliriousga

There was a disconnected plug in the front of the engine in my '87 S4. I connected it and a flap/vent in front of the fans started opening and closing continuously. I'm assuming it's supposed to open or close depending on the engine temp, but not sure. Does anyone know what it's for and what might need to be done to make it work properly?

Thanks!

Nicole

It was designed to optimize aerodynamics and engine temperature - it would be closed at low, and open at high engine and outside temperatures. It can help the engine to warm up faster, and save gas. However, it was a much underappreciated feature that was deleted from 1991 onwards. When it goes bad, many owners chose not to fix it - they either disable or remove it. I think that's sad, because it's one of those fascinating unique features of the 928...

okbarnett

The plug must be to the front flap. I think the problem with yours is the module with the big fins out in front of the radiators. It is probibly bad and causing the flaps to go crazy. You can replace it and should work fine. The flaps open and close to do several things. They close to prevent air from coming into the radiator so it can warm up quicker, they close at high speed to reduce drag and inprove aerodynamics. They open to allow cool air to cool the radiator when its hot.

Steve J.

Some have speculated that the flaps were added to achieve better drag coefficient numbers in the wind tunnel - a marketing ploy. They must not be that important if Porsche deleted them. I considered removing mine but I hate to remove anything from my car that actually works and has no problems...hehe.. If you can't fix them, you can unplug the flap motor or pull the fuse for the motor, then remove the rubber cover from the motor and turn the **** to manually open the flaps permanently, and replace the cover.

Doug Hillary

Hi,
I have been doing some tests on the operation of the S4 flaps. As Nicole quite rightly says they are not appreciated or their operation even understood by many owners. The same can be said for the 928's integrated cooling system too!

At some future point I will post here some "operational" data on this valuable feature
So far I can say that even though I live in the Tropics I would not operate the car for a long period with this feature inoperative

With the ignition off the flaps should be fully open. When running and with the bottom of the radiator (sensor is at front of radiator opposite the return hose) at 79C the flaps will open to 30% and the fans will too at half speed

My car spends a lot of time with the flaps at 30% even with an ambient of 34C

Regards
Doug

mpesik

As far as I'm concerned the flaps are a great protection device from road debris at speed! I was at the muffler shop and saw a 97 ACCORD on a lift;it has a horizontal opening somewhat similar to the 928-The whole front part of the radiator which was exposed was all damaged(crushed) by road debris!-ME

Nicole

Can they be retrofitted in my '91?

IcemanG17

My car came without a flap motor! The flaps work fine when you reach down & move them....the plug even looks good, just not motor to move them! I leave the flaps in the open position since I only drive in nice weather. One thing I noticed was when driving at high speeds (think over 130) the flaps will close on thier own, causing temps to increase (guess how I figured this out!), luckily for me I was watching the temps & quickly pulled over to fix it...but your right about the flaps protecting the radiator...there are some chips on the flaps, but not a mark on the radiator! I've been told to remove them, but since my car rarely runs above 1/2 I don't see the need for increase airflow. I just can't bare the thought of taking a hacksaw blade to my baby....Apparantly removing the flaps increases airflow to the radiator about 10%!
Brian

Nicole

I'm glad to hear someone has mercy with their shark...

IcemanG17

Nicole
On your thought of retroing your 91 to the flaps......probably not worth it....I doubt your car has the right computer to control the motor (the one on the passenger side near the door, ahead the amplifier + the little one under the hood) & then you'd need to get an older body part to mount the flaps & the motor, etc.....sounds like alot of work & the drag numbers I've seen are not any better for the cars that had the flaps? So unless you live somewhere really cold, its not worth it....but would be a cool project IMHO
Brian

Nicole

I'm not seriously considering a retrofit. It was more of a hypothetical question, as I really did not know how the flaps are managed.

In the late 80ies, Porsche began to eliminate underappreciated features, and I guess this was one of them.

Jim bailey - 928 International

I think Porsche may have learned that the flaps could cause overheating when they failed closed and it was very expensive replacing engines under warranty which overheated . Because we all know nearly everyone will "try to make it home" regardless of how many warning lights are flashing , what noises the engine is making........instinct takes over and they crawl back to the cave.....either go slow to take it "easy" or fast to get there "quickly".......but try to "make it home" . One local fellow hit a rock put a hole in the oil pan ........decided he should drive directly to the repair shop .....he made it several miles to the shop. Ruined the engine but made it to the shop! He did "save " a tow bill

IcemanG17

<<One local fellow hit a rock put a hole in the oil pan ........decided he should drive directly to the repair shop .....he made it several miles to the shop. Ruined the engine but made it to the shop! He did "save " a tow bill >>

Nice one! Sometimes you have to wonder
Brian

Brett Matthews

Interesting this. I have often found Rosy's flaps CLOSED, with the ignition off. I have seen 30% and rarely 100%. I'd have to say the system in Rosy works fine, as my temps never vary while on the road, city or hyway. I have THOUGHT about removing the flaps.......... But, once again, positive atributes are pointed out (radiator/condencer protectant), so it stays.

I'd NEVER take a hack saw to the car! C'mon now, what're wrenches for?????

Robert_H

Hack saw?... How archaic, use a Sawzall!