Car idle dips really hard when fan kicks on!

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3tc power
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Car idle dips really hard when fan kicks on!

Post by 3tc power »

Hello everyone! well like the topic says, my idle dips really low when my fan kicks on and sometimes it will stall if I'm sitting at a light. I'm sure my alternator might not be cranking the juice its supposed to anymore but is there a setting in tuner studio to prevent this dip when it sees an electrical load like the fan kicking on?

Thanks in advance
midnite88
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Re: Car idle dips really hard when fan kicks on!

Post by midnite88 »

If your using MS3 to control your fan, you can also check a setting that will idle the engine up right before the fan kicks on.
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Re: Car idle dips really hard when fan kicks on!

Post by 3tc power »

midnite88 wrote:If your using MS3 to control your fan, you can also check a setting that will idle the engine up right before the fan kicks on.
i'm not using the ms3. using ford taurus fan with volvo relay.
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Re: Car idle dips really hard when fan kicks on!

Post by arran »

increase idle richness may increase idle stability
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midnite88
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Re: Car idle dips really hard when fan kicks on!

Post by midnite88 »

Doesnt matter what fan and relay your running. If the ECU is telling the relay when to kick on you can make the ECU idle your engine up before the fan kicks on. Also, if you have a RPM row below you set Idle RPM, add a few degrees of timing. That will help more than adding fuel. Fuel will generally make you bog, timings increases engine torque to compensate for the extra load the alternator puts on the engine.
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luiz callegari
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Re: Car idle dips really hard when fan kicks on!

Post by luiz callegari »

I'm not sure but check the dwell time, battery correction and battery voltage (while the car is on) to see if your alternator is running ok...it looks like the fan is getting a good amount of power.
TerrenceLP
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Re: Car idle dips really hard when fan kicks on!

Post by TerrenceLP »

This is a 40amp fan and the draw is just that.

Use the timing trick to get close, but if you can wire in a Air Idle Valve then you can control idle when they kick on.

Also Check the alternator, get a true reading of how it is working.

I do recommend a 105 amp or better alternator, because the fan draws 40 amps [continuous] on high running at 14V ... not counting any other accessories like A/C, or audio systems.
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Re: Car idle dips really hard when fan kicks on!

Post by midnite88 »

If its a 40 amp fan, the influx current is probably close to 50 or 60 amps. That will certainly make any vehicle dip.
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Re: Car idle dips really hard when fan kicks on!

Post by wes kiser »

Use adaptive idle spark. This can work even with no actual idle airflow control.

Set the table such that when the engine is idling "on target," actual idle spark is 5-10 degrees lower than the "ideal" value. I define ideal value as the classic "peak vaccum" condition. for Most engines/families, this winds up in the 20-25 degree range.

When the engine is below target idle speed, rapidly feed in timing. As an example, assuming 25 degrees is that "ideal" number, I would idle "on target" at 16 degrees. At 100 rpm below target, I would enter a value of 21. At 150 rpm below target, I would enter a value of 25. If the engine is above target, I would pull even more timing.

I can't remember if the current firmware is setup with absolute timing values, or if the adaptive curve is a "delta" curve.

What will happen, is since you are running reduced idle spark, when "on target" it will take the engine more airflow to idle. Even if idle airflow remains constant, the instant the engine begins to slow down, the extra timing will have a substantial "impact" in catching the engine.

before the adaptive software feature was added, I did this via table switching at low throttle positions, and dedicated a timing table to idle.

People want to fix slow idle with air, but engines (particualrly ones with large cam shafts at low speeds) respond slowly to changes in airflow. We have to tell the valve to move. We have to wiait on the valve to move. We have to wait for manifold pressure to drop. We have to wait for the engine to induce the aiflow. All this can actually add up to a very real amount of time, particularly at idle when we don't get many cycles, and if your engine makes little vaccuum at idle (big cams), we have a very limited ability to induce much more air at idle anyway.
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Richard454
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Re: Car idle dips really hard when fan kicks on!

Post by Richard454 »

How do you have the fan wired? Do you have a nice large gauge wire running off the battery versus the alternator? If wired off the alternator- that could be your problem. The battery not only starts your car but also stabilizes surges- like when the fan kicks on.

Richard
3tc power
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Re: Car idle dips really hard when fan kicks on!

Post by 3tc power »

ok for starters my ECU isn't controlling the fan. my setup is a ford Taurus 2 speed fan, Volvo 2 speed fan relay and bmw coolant switch. i have this setup conneced to the battery since i could find a good 12v switch in my engine bay. i was thinking my alternator is just too weak and can't keep up. i just purchased a 130amp alter. and will install it first to see if it makes a difference and go from there. thanks for you input guys and i will keep yall posted
3tc power
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Re: Car idle dips really hard when fan kicks on!

Post by 3tc power »

so i added a 130amp alternator and ditched the factory crap and it seems a little better but still has a dip! i just adjust the iac idle to 900 rpm at the temp where the fan kicks on. seems to be fine for now but you can tell when the fan kicks on when the car is just sitting.

thanks for all your input guys! Msextra to the world! lol
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Re: Car idle dips really hard when fan kicks on!

Post by hessdawg »

These fans will draw 100 amps at start up then ramp down to 30-40
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Re: Car idle dips really hard when fan kicks on!

Post by Matt Cramer »

In that case, I suggest you change the fan control from a thermoswitch to ECU controlled so the ECU can know when the fan is engaging and increase idle air flow to compensate.
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3tc power
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Re: Car idle dips really hard when fan kicks on!

Post by 3tc power »

hessdawg wrote:These fans will draw 100 amps at start up then ramp down to 30-40
yes i know that when was researching these fans, but they work very well even with the 7mgte that i known to be a hard motor to keep cool with e-fans. need high cfm's on the mk3 supras.
Matt Cramer wrote:In that case, I suggest you change the fan control from a thermoswitch to ECU controlled so the ECU can know when the fan is engaging and increase idle air flow to compensate.


yes this is my next step!
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Re: Car idle dips really hard when fan kicks on!

Post by mickeymarrows »

Can't closed loop idle control be used to deal with this?
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3tc power
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Re: Car idle dips really hard when fan kicks on!

Post by 3tc power »

mickeymarrows wrote:Can't closed loop idle control be used to deal with this?
i never set up closed loop idle before. if you have some settings i can go off of, i wouldn't mind trying it.
muythaibxr
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Re: Car idle dips really hard when fan kicks on!

Post by muythaibxr »

Closed loop idle will help. You will still have a dip but tuned right it should recover. Using fan control's feedforward mechanism is still the only way to avoid the dip altogether.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
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Re: Car idle dips really hard when fan kicks on!

Post by mickeymarrows »

3tc power wrote:
mickeymarrows wrote:Can't closed loop idle control be used to deal with this?
i never set up closed loop idle before. if you have some settings i can go off of, i wouldn't mind trying it.
I'm still running open loop 'PWM warmup' but I intend to adopt closed loop in the very near future as my car has a compressor for the air suspension and when that kicks in, like yourself, it will stall the engine if I'm at idle. I'm relying on closed loop idle to prevent the stall, I know it will dip and I can live with that if closed loop will bring the idle back up...

However, whenever I look at the closed loop settings page in the manual it goes completely over my head!
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Re: Car idle dips really hard when fan kicks on!

Post by muythaibxr »

What do you not understand?
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
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