NC928S4

My 1989S4 continuously opens and closes the front louvres when sitting at idle warm or cold. They stay open for 5-7 seconds then close briefly then open for 5-7 seconds, and repeats forever. This was observed when trying to figure out why the air-conditioning compressor clutch does not engage. I will be performing Dwayne's latest HVAC lesson this weekend coming up but that is a different problem.

Any ideas what could be causing this? I disconnected the connector plug for now and they are wide open.

heinrich

Pull the fuse (50 I think) and then remove and discard the entire louvre mechanism -- it is unnecessary and heavy, and causes overheat at sustained speed.

Normal behaviour by the way -- if you are within the operating temp range of the flaps they will close and open when they sense temp change.

finally!

are you saying that REMOVING them will improve cooling? I ask as while that might seem the case to my logical mind it would seem that leaving with them locked in the open position would be beneficial due to the way the vanes direct air at the radiator..

True?

dprantl

Your 928 has been Ford Focused.

Dan
'91 928GT S/C 475hp/460lb.ft

heinrich

That is EXACTLY what I am saying.

NC928S4

With the connector removed the Vanes are wide open. The only downsides I assume are that the car won't warm up as quickly and will be marginally less aerodynamic at high speeds.

The alternator charging is totally steady without the Louvre motor cycling continuously which has got to be good for something.

heinrich

They have no effect on warmup. They affect 2 things:
1) .34 -> .32 Cd at speed when they close - negligible, and causes overheat
2) less cooling and air in your engine bay at speed

THere is a very large air hole that opens once you get rid of this silly thing, and you save a little weight and electrical complexity. Controller under passenger hatch release can be deleted as well and the power used for other things like an appropriate radar/laser system

Leon Speed

WSM has a testing procedure for the louvres.

JoeTaylor

The vanes opening and closing is indicative of the Porsche 928 mating season. You should have your car spayed and neutered! Haha....

SeanR

I'm of the opinion that if the system is working correctly, leave it. If it's not, take it out. The flaps were to help the engine warm up faster when it is cold out, and helps with the CD as it goes through the air. At least that is what I've heard/read.

Now, if mine quits working, I'm going to find out why and fix it. But that is just me.

Hacker, if you look at them, they direct the air to the radiator from the lower louvers.

NC928S4

Thanks Guys. I'll debug some more, I'd rather fix it. But simpler is better and the louvre operation looks like an interesting mechanism searching for a problem.

Cheers

fraggle

I vote for fix it because it is a cool feature of our cars initially, even if Porsche eventually binned it for cost and simplicity.

Nicole

+1

Removing is always a possibility, but it really is the easy way out... Later, some unsuspecting buyer gets the car, and next thing we know there is another PO-Hate thread here.

Yes, it may save weight. It probably costs just as much in additional gasoline from longer warm-up and lesser aerodynamics. Starting at around 60 km/h or 40mph, wind resistance becomes the strongest resistance an engine has to overcome. It quadruples at double the speed... and it's rather unlikely that gas will get cheaper in the future.

heinrich

By that logic Nicole, all other years 928 take too long to warm up, have worse drag, use more gas and are slower. Because the flaps came only on 87 models.

Nicole

89-90, actually.

Believe it or not, but they are making a strong come-back on newer cars. BMW 1-Series has them, at least in some models and markets, as do others. Expect to see more of this, as gas is getting more expensive, and both the EU and US are clamping down on CO2 emissions or gas mileage.