RPMs reving and dropping when steering wheel is turned
 

Do any of you guys have this issue, where your RPM revs up to 1-1.2k then drops back to idle when you turn the steering wheel in first gear with the clutch in? The car is stationary/not moving, it's just in gear with the parking brake on. Before the jokes come in, I am not stepping/tapping on the gas pedal at all. My foot is completely off the gas pedal/brake pedal. Just ebrake on and clutch in on first gear. It happened when I turn the steering wheel.

Edit: I am also not playing with the clutch. I like to leave my car in first gear when it's parked on any slight uphill, even if its a tiny bit.

Just a guess, but my first thought is that this is a normal response from the "system." Now that computers run our cars, practically everything is interlinked. The power steering is an electrical assist and when you turn the wheel it imposes a load on the system. At low idle rpms, the load might cause the engine rpms to drop too low. The computer would then raise the rpms slightly to adapt so as to avoid stalling under this load.

I have not noticed this in my car (but I'll have to try it), but I do notice in all my cars for many years that when the air conditioning kicks ON, the ECU raises the engine revs slightly to adapt to the additional load.

I notice that on our Mazdaspeed3, I just have to engage the clutch in 1st gear on a moderate incline going up my drive, and without any throttle application at all, the ECU will raise the revs and drive the car up the driveway without stalling and without any help from me. I just gently engage the clutch in 1st. Years ago, before computers (BC), doing that would stall an engine, but not now.

So, my guess is that this is a normal response to a sudden load on the system, the power steering in this case, at low rpms when the alternator is not putting out much "juice."

Well, maybe the ECU is thinking ....."hey, this guy is going to turn and he has the clutch pushed in and has it in gear ....... but he hasn't given it any gas ....so, let's help him out by increasing the rpms, so as he doesn'r stall" ..... :D


humfrz - :iono:

PS - I see old @Porsche is 6 minutes faster than I am ....:clap:

Completely normal for all cars with power steering. Old school way of doing it was a vacuum line from the intake to behind the throttle body with a valve that opened when the pump was loaded.


Now it's done other ways, but yes, it's to counter the load.

I'm going to test this again tomorrow morning. It didn't seem to have done that before though as I have parked uphills steeper than what I parked on when this happened.

I reckon that puts me a lap up on you, old boy! ;)

-Porsche (Who's in the middle of watching the Steve McQueen racing classic film: "Le Mans," which one can see on youtube.)

Do you want to drive the 917 or the 512?

Just you wait up till I get my engine swapped in my 512 ...... then .... MOVE OVER .... :burnrubber:

humfrz

What on earth is that thing?

Porsche made a flat-16?

And, umm... "Move over?"

Nuuuuuu...

You're going to have to get your nose well and truly up underneath me to take away the corner. :)

I reckon they did .... :confused0068:

http://commons.wikimedia.org/wiki/Fi...cyl_engine.JPG

I'm gonna slip that puppy into my FR-S ...... and call it the "Turbo Eater" ..... :D


humfrz

Oh yeah, well I'm gonna put a tesla motor in my BRZ

Ahh...

I see that it never saw use. Porsche decided, instead, to go with a turbocharged version of the 917 flat-12 for the car they wished to campaign in the Can-Am series.

In fact, that car was entrusted to Roger Penske and Mark Donohue.

It's debut race was at Mosport, Canada.

I was there at that race.

(Maybe someday I'll buy a film scanner and dig out all of my old slides from those days. They were wonderful days, the "golden age of motor-racing." :) )

That new Can-Am Porsche was visibly faster than the two McLarens, but it was weird, because it sort of whooshed away with the turbo, very unlike the thundering, chest-vibrating roar of the big, normally aspirated V-8s of the rest of the cars.

If any of this interests you, I would encourage you to read Mark Donohue's account in his most enjoyable autobiography "The Unfair Advantage." It's back in print again, if your library doesn't have it. It's worth reading.

While the rest of us will quickly call you ... dead. :D

But, I imagine that would apply to all of us. Not picking on you, my friend. ;)

Besides, no Porsche engines allowed in the 512.

Don't forget the fire extinguisher! :D

I like how this thread turned into a @humfrz vs @Porsche thread