Thermo Fan Switching On Causes Car To Stall

[aaron1259]

Just had a look at an R34 GTT and I am really liking the car and could be a winner as it is the first skyline I have looked at that is running coolant in the radiator.

Everything with the car looks ok, except when the car is idling and the thermo fan kicks in, if you dont give it a good rev the car will stall, he told me its to do with the tuning on the haltech ps2000 and that the tuning isn't compensating and giving a bit more fuel and air when the fan kicks in, is this an easy fix for a tuner?

[89CAL]

IF thats the problem it shouldn't be too much of an issue. But I find it weird that a tuner would let it go out with such a basic setting incomplete, not unheard of however.

First skyline that has actually had coolant in it? People cant spend <$100 on coolant etc?

Anyway. It may be a small issue with the tune or he may be blaming the tune when it is something else.

Realistically though it should only be tune, IACV or something along those lines. Its not something that would turn me off the car, but im not sure how mechanically minded you are. do you remember what the idle speed was off the top of your head?

[aaron1259]

I think it was about 800, give or take, also when you push on the brake on and off at idle the RPM would fluctuate (vacuum leak?), could this issue be related?

[89CAL]

Possibly. Or the altenator load is dragging it down because the tune isnt compensating. However I wouldnt think brake lights would drag it down that much

See if it does the same with headlights + rear demister. If not then quite possibly a vac leak. Should be easy enough to hear with the car off though. If there is no assitance in the pedal with the car off, then a leak seems quite likely

Edited December 22, 2014 by 89CAL

[jiffo]

Are you sure it's not the aircon cutting in and the thermo is wired to come on at the same time?

Can't imagine just the thermo load would be so savage to drop RPM instantly, there is a battery to assist after all.

[blind_elk]

Never had a car with thermo that couldn't idle when the thermo cut in - factory ECU or aftermarket ECU, or carbs.

[Dose Pipe Sutututu]

that the tuning isn't compensating and giving a bit more fuel and air when the fan kicks in, is this an easy fix for a tuner?

what the? no.. it's because the voltage is dropping and the tuner hasn't setup the injector dead times properly.. so when voltage drops the injectors are injecting the wrong fuel.. nothing to do with "giving a bit more fuel and air when the fan kicks in".. also you can adjust the idle motor duty cycle on electrical load OR power steering pressure switch input..

Easiest way is to use a diode and pass the negative trigger from the 1/2 thermo fans to the power steering switch input, then enable Power Steering RPM offset in your idle control.. add like 5 or so extra on the duty cycle then presto.

[Dose Pipe Sutututu]

Can't imagine just the thermo load would be so savage to drop RPM instantly, there is a battery to assist after all.

I actually had this issue with my old 180SX running a boat anchor RB20 with the battery in the boot... I had 3x thermos connected to come on all at once when the A/C is on and water temp passed 87 degrees. It was enough to make the car stall - so quick trick was to hook up a trigger from the thermo into the power steering input switch.. worked a treat

[niZmO_Man]

RB20s are cool little motors mmkay

[Dose Pipe Sutututu]

RB20s are cool little motors mmkay

I thought they were cool, till I tried to make it go fast..... wasted effort. It's like trying to make a RB25 go fast, hop into a V8 and you has a sads LOL

[niZmO_Man]

The trick is to make them sound better, not go faster .

[Dose Pipe Sutututu]

easy, gggggggggaaaaaaaaaattttttteeeeeeeeeeeeeeeeeeeeeeee LOL