JB flywheel+ac+stop light= stall... any ideas?

[dakon]

the 318is has a JB racing flywheel, and when the air conditioning is on while at a stoplight, the car will stall if you don't feather the clutch..


Does anyone have any experience with this? Right now the car is already idling high, around 1k rpm, and when you engage the clutch, the load on the motor seems to be to much, because if you are not careful the motor will stall out.


The only thing we can think of is the lightweight flywheel doesn't have enough mass to keep the motor a little extra rotational mass to keep it spinning.?


with the AC off the car is just fine.

Thanks for any help guys.

[318lotis]

i would call jb corporate and talk to a tech.. how do you like the the flywheel can you feel a performance differance?

[dakon]

i no can't not... i am 1000+ miles away from the car right now....


however, my buddy Dan said it was well worth the money, and the motor revs with no problem at all!..

all of our car's have light weight flywheels, they are very much worth the money.

[dvmotorsports]

The flywheel is too light.

Here are your options;
a. heavier FW
b. stop using the A/C (best option)
c. adjust your idle (worst option)

[dakon]

we were thinking about getting a chip with higher idle.... i live in TX, and when its 100 degrees for a couple months strait, not using the A/C is not really an option...

adjusting the idle up, will use a bit more gas, but... this is a 1.8L, so i would imagine it would still be at LEAST in the 20's for city driving?


Thanks for your reply Dvmotorsports, you verified what we were thinking..

[DesktopDave]

I've never done this myself, but I'd figure you could modify the mixture off the AFM to avoid a new chip.  I always go cheap first, no need to reinvent the wheel if you have a sticky sensor.  A lot of other people have done this without stalling at idle, so I'd bet it's something particular to this motor.  You might be able to fix it and improve fuel mileage at the same time.

Changing the clock spring pressure might help without the trouble of a new chip.  I don't think our AFMs have the old CO adjustment screw, so this might be your only workable option.  Alternatively (if the DME isn't adaptive enough to counter slight changes) you can adjust the throttle body stop or TPS slightly.  I'd also test the IATemp or CLTemp sensors to be sure they're working properly.  They each contribute to timing and mixture...that could be the bit that's stalling the motor.

I'll bet that a little dyno time could solve the problem too - see how the mixture changes as it stalls out.  If the car suddenly gets too rich it'll definitely snuff the spark plugs & stall out.

[gearheadE30]

Do you mean it will stall if you don't feather the gas? Feathering the clutch to keep it from dying doesn't make much sense...

[dvmotorsports]

we were thinking about getting a chip with higher idle.... i live in TX, and when its 100 degrees for a couple months strait, not using the A/C is not really an option...

I lived in the central valley in California for many years where we hit 100+ for more than 70 days a year. At times as high as 115f. I have never used A/C unless i'm in my wifes car. Do it for a day or two and you'll adjust.

On a serious note, Dave always over thinks things. But it's always for the better. So listen/read his suggestions and mill them over. And remapped chip just for an idle adjustment is a little much. I would personally just adjust my throttle cable if I had to go that route. I'm just trying to keep this as simple as possible for you.

***EDIT***
What is your idle at right now? You might be low to begin with, thus the motor falling on it's face.

[gearheadE30]

fwiw the motor should idle at 850ish rpm. With the AC on, it should kick into fast idle mode, around 1000 rpm.

I am very much not a fan of adjusting the throttle stop to raise the idle, fwiw. That opening won't adapt to different atmospheric pressures, humidities, temps, or anything and can cause a set of problems all its own, at least in my experience.

[supadave]

I lived in the central valley in California for many years where we hit 100+ for more than 70 days a year. At times as high as 115f. I have never used A/C unless i'm in my wifes car. Do it for a day or two and you'll adjust.

On a serious note, Dave always over thinks things. But it's always for the better. So listen/read his suggestions and mill them over. And remapped chip just for an idle adjustment is a little much. I would personally just adjust my throttle cable if I had to go that route. I'm just trying to keep this as simple as possible for you.

***EDIT***
What is your idle at right now? You might be low to begin with, thus the motor falling on it's face.

I lived in both Cali and Texas, Cali is nothing compared to humidity in Texas. I'll take a 100+ in Cali any day over 100+ in Texas.

[KenC]

Your idle should increase a little bit when you turn the a/c on.

Your RPMs dive too fast with the light flywheel and your ECU can't correct the idle speed quick enough. I have a 13lb 323 m20 flywheel. Overall, my pressure plate + flywheel is 1lb lighter than your set-up. Often at stops, my RPMs will dive to 400 or so, nearly stall, and then pop back up to 700. Even with the AC, it doesn't stall. You should try another ECU.

[dvmotorsports]

I lived in both Cali and Texas, Cali is nothing compared to humidity in Texas. I'll take a 100+ in Cali any day over 100+ in Texas.

As many times as I traveled through TX, I guess I failed to realize how high the humidity is.

[longtallsally]

dvm, you're out of your gord, and probably stink a lot too.    AC is not an option in Sally's world.

I suppose I'm with Dave, but I agree with most others that you need a chip mapped correctly to the setup at the least.

EDIT:  Ignore me, I thought you had a turbo and deleted a couple sentences...