changing idle flunctuation

TomTomTom · 10 Jul 2007 at 12:56

Hi,
Anyone heard of being able to tune the engine's setup so that the idle rpm will not fluctuate in relation to whether the cooling fan is running? The reason I would like to do that is that my idle rpm's drop by as much as 200-300 rpm when the cooling fan goes off and that makes hill-starts more tricky. Basically, I'm on a hill, raise the clutch to just the right spot, then right before I manage to press the gas peddle the idle RPM happens to drop off just then stalling the engine (people behind honking, etc).

It's a new Mazda 6 2.0 liter and I've been wondering why I've had occasional difficulties with hill starts in my new car (never had that problem on manual before)... THEN I noticed the RPM fluctuation... did some experimenting and determined for sure that it's the sudden inopportune drops in 300 rpm's that causes the stalls.

So can the Mazda mechanics simply "setup" the engine to STAY at the higher rpm level @Idle regardless of the cooling fan running or not??

Thanks, it would be nice to know a little more myself before I go to the service place.

Cheers

Gaverick · 10 Jul 2007 at 13:03

Can you not just press the accelerator a bit to keep the revs up? :confused:

brendy · 10 Jul 2007 at 13:05

Dunno about mazdas but i used lemmiwinks with my revo stage 2 software and upped my revs by 40rpm so my harsher dogbone mount doesnt vibrate now. Before you could feel slight vibration through the steering, now its gone.
Ask your dealers if its possible then find someone on the mazda forums with the appropriate cable and software (again, if its actually possible)

[TW]Fox · 10 Jul 2007 at 13:05

Just learn some clutch control - the regular idle of your car is the lower figure, it increases to compensate for the air conditioning when its turned on (and, as a consequence, the cooling fan comes on).

TomTomTom · 10 Jul 2007 at 13:14

Gaverick said:
Can you not just press the accelerator a bit to keep the revs up?

Not while I have my foot on the break as I'm on a hill.

Xplo · 10 Jul 2007 at 13:17

Handbrake?

Gaverick · 10 Jul 2007 at 13:19

Lol yes, that lever down to your left is called a handbrake

TomTomTom · 10 Jul 2007 at 13:20

[TW]Fox said:
Just learn some clutch control - the regular idle of your car is the lower figure, it increases to compensate for the air conditioning when its turned on (and, as a consequence, the cooling fan comes on).

Like I said, I did experimenting with it. The lower rpm figure can barely hold the car on a very small incline... any more of an incline and it can only slow the sliding-back at best (and I realize that hand brake is needed in more extreme cases)

I've never remotely had a problem like this on other manual cars. I haven't driven manual for a few years before this car, but I'm not a beginner at it.

TomTomTom · 10 Jul 2007 at 13:20

Gaverick said:
Lol yes, that lever down to your left is called a handbrake

Read my above post.

TomTomTom · 10 Jul 2007 at 13:24

Anyway, I guess it's a little hard to believe that the lower rpm level is inadequate, but that's what's happening. I know how to hill-start on both small and big inclines and I know how to tell the difference. I'm well versed with clutch control. Just wanted to know if taking out the fluctuation is generally possible.

[TW]Fox · 10 Jul 2007 at 13:26

TomTomTom said:
Like I said, I did experimenting with it. The lower rpm figure can barely hold the car on a very small incline... any more of an incline and it can only slow the sliding-back at best (and I realize that hand brake is needed in more extreme cases)

You are going to have to explain more - what are you trying to do? Allow the idle speed to hold the car on a slight incline with your foot off the accelerator?

TomTomTom · 10 Jul 2007 at 13:27

brendy said:
Dunno about mazdas but i used lemmiwinks with my revo stage 2 software and upped my revs by 40rpm so my harsher dogbone mount doesnt vibrate now. Before you could feel slight vibration through the steering, now its gone.
Ask your dealers if its possible then find someone on the mazda forums with the appropriate cable and software (again, if its actually possible)

Thanks, hopefully they can do it then.

The variation is just so extreme in terms of available power that it really messes me up. I raise the clutch until I feel it catching just enough, then the next thing I know is it's not nearly enough because the revs went way down.

Thanks

L1J · 10 Jul 2007 at 13:29

Your car does not produce suffcient torque at low rpm to move your car up the "incline", hold it on the handbrake and give it more revs.

I havent driven many cars that will pull away from idle without any additional revs.

As Fox said other systems will put additional load on the engine, some ECUs do compensate for this by increasing the idle speed, so it might be something simple as the ECU not getting a signal from the AC or charging system.

Personally I think you need to adapt your driving style!

TomTomTom · 10 Jul 2007 at 13:30

[TW]Fox said:
You are going to have to explain more - what are you trying to do? Allow the idle speed to hold the car on a slight incline with your foot off the accelerator?

Exactly that. No one else in this thread does that? .... raise the clutch to catching just-enough (while foot on brake), then calmly move foot to gas pedal while car holds position. Works on most reasonable hills. I've always done that.

alexthecheese · 10 Jul 2007 at 13:31

I know de nada about cars, but it just sounds to me like either you're a bit crap with the clutch control, or the clutch is crap. I must admit it does sounds like the first.

alexthecheese · 10 Jul 2007 at 13:32

TomTomTom said:
Exactly that. No one else in this thread does that? .... raise the clutch to catching just-enough (while foot on brake), then calmly move foot to gas pedal while car holds position. Works on most reasonable hills. I've always done that.

Err... no?!?!

[TW]Fox · 10 Jul 2007 at 13:32

TomTomTom said:
Exactly that. No one else in this thread does that? .... raise the clutch to catching just-enough (while foot on brake), then calmly move foot to gas pedal while car holds position. Works on most reasonable hills. I've always done that.

Virtually no cars will do this! It's not what you are supposed to do with a manual car. You bring the clutch up as you apply throttle.

TomTomTom · 10 Jul 2007 at 13:33

L1J said:
Your car does not produce suffcient torque at low rpm to move your car up the "incline", hold it on the handbrake and give it more revs.

NO. Not move-the-car... just to hold the car in place long enough to get to the gas pedal.. lol

L1J said:
Personally I think you need to adapt your driving style!

it's worked on all other manuals I driven just fine. you'll even find that technique in a driving manual

brendy · 10 Jul 2007 at 13:35

For what its worth, the 20vt VAG engine can easily pull away from the steepest of hills on the bite point, it just keeps raising revs until it goes.

TomTomTom · 10 Jul 2007 at 13:37

[TW]Fox said:
Virtually no cars will do this! It's not what you are supposed to do with a manual car. You bring the clutch up as you apply throttle.

Well this is a surprise to me. It's what they teach in driving school and like I;ve repeated it's what I've always done. And for anyone else catching up, again yes I know about hand-brake on extreme hills.

Anyway, thanks everyone