T4MO engine dies when fan comes on

TT331FB · 04-17-2007, 03:26 PM

Hey experts, I need some input.

As long as the fan stays off, my car idles great. I have the idle at 800 RPM, and its stable. ICS is about 25% duty cycle.

What happens, about 7 out of 10 times, is right when the fan comes on, the engine stalls. 2 out of three times, the ICS will catch the engine, run rough a few seconds and then get back to a stable idle. 1 out of 10 times, the engine rpm will hardly vary as the fan comes on. I have data logged this and see nothing else unusual going on. FYI, ICS goes from 25% to 32% when the fan comes on, if the engine hasn't stalled.

I have tried setting the ISC RPM for HS fan add to 40 and it made no change.

Is it possible that something is failing in the ingnition when the voltage drops as the fan comes on?

This is a '94 with the electronics fender mounted, not on the distributor.

Thanks,
Eric

QWKSNKE · 04-17-2007, 04:28 PM

Is the fan going to immediate high speed?

I think either it is a faulty fan (pulling to much current on startup) or something in the charging system is failing and can't keep up with the voltage spike from the fan starting up

TT331FB · 04-17-2007, 04:54 PM

Quote:

Originally Posted by QWKSNKE

Is the fan going to immediate high speed?

I think either it is a faulty fan (pulling to much current on startup) or something in the charging system is failing and can't keep up with the voltage spike from the fan starting up

I'm not sure but I think it starts slow speed. I can tell when it goes high speed as the voltage drops. The fan is the second fan I have installed and the first fan did the same thing.

Wasn't there some recall about these fans or relays?

Eric

QWKSNKE · 04-17-2007, 05:27 PM

Isn't their a control box of some sort mounted near the radiator? (its been a while since I owned a sn95 50. based car)

TT331FB · 04-18-2007, 08:00 AM

Quote:

Originally Posted by QWKSNKE

Isn't their a control box of some sort mounted near the radiator? (its been a while since I owned a sn95 50. based car)

I tested the fan last night, it runs at low speed. It seems to be fast for low speed but its working OK.

I started a new thread . Take a look.

Eric

04-17-2007, 03:26 PM	#1
TT331FB Member Join Date: Aug 2005 Posts: 53	T4MO engine dies when fan comes on Hey experts, I need some input. As long as the fan stays off, my car idles great. I have the idle at 800 RPM, and its stable. ICS is about 25% duty cycle. What happens, about 7 out of 10 times, is right when the fan comes on, the engine stalls. 2 out of three times, the ICS will catch the engine, run rough a few seconds and then get back to a stable idle. 1 out of 10 times, the engine rpm will hardly vary as the fan comes on. I have data logged this and see nothing else unusual going on. FYI, ICS goes from 25% to 32% when the fan comes on, if the engine hasn't stalled. I have tried setting the ISC RPM for HS fan add to 40 and it made no change. Is it possible that something is failing in the ingnition when the voltage drops as the fan comes on? This is a '94 with the electronics fender mounted, not on the distributor. Thanks, Eric __________________ TT331FB - T3/.6/.63 turbos, Spearco intercooler, 302/331 Mexican Block,AFR 185 heads, 80mm MAF, 75mm TB, 50# injectors, Tweecer, Track Heat intake, Comp cams roller blower grind, MSD BTM, DIY-WB, Yokogawa video display,T-56 tranny, 9" 3.5:1 Traclock, 4x disk brakes, TCP most everything, shelby roll bar. First fire up 2/14/2004.

04-17-2007, 04:28 PM	#2
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Is the fan going to immediate high speed? I think either it is a faulty fan (pulling to much current on startup) or something in the charging system is failing and can't keep up with the voltage spike from the fan starting up __________________ 2009 Porsche Carrera S 2008 ///AMG C63.. Eurocharge Tune. RIP 2019 AMG GLC43..wife's 03 F250 SD.. Edge Evo, AFE Stage 1 CAI 08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's 01 Cobra vert... wife's I need a new toy

04-17-2007, 05:27 PM	#4
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Isn't their a control box of some sort mounted near the radiator? (its been a while since I owned a sn95 50. based car)