Fan Kills Engine

[88GreenVN]

I have made a graph of the data from Winaldl when the car engine quit.

It looks like the fan relay droped the voltage and the engine stoped. I roll to a stop. Slip it out of drive hit the starter - engine starts and off we go.

Can the drop in voltage kill the engine?

 

[HDT_aero]

interesting does the fan still work??

 

[HDT_aero]

also was this a once off or is it a repeat offender

 

[88GreenVN]

The fan still goes. Car has been stalling every week after the DFI fryed itself 3 months ago. I looked at the event data and the graph is the result.

I have just replaced the relay and will go for more tests later tonight turning the a/c on and off to see if I can get it to do it again.
Still have a ruff idle.

 

[mouce]

That's a strange one though, because it's on the second fan request that the voltage falls through the floor. I'd say that it's only part of a much larger problem.

Have you tested the alternator? Because for a voltage drop to happen like that...it makes me think that the voltage regulator is having issues. Just a thought.

 

[88GreenVN]

New alt about 3 years ago. but yes thinking its the alternator.

 

[mouce]

It would be nice to know just what did trigger the voltage dip like that though...because looking at it, when the fan relay switched it only dropped a bit (nothing too drastic), then all of a sudden the SECOND fan request killed the engine??? WTF?

Is is possible that there's a strange earth leak, or even a short in the fan motor? That would create a voltage dip, although that should blow a fuse somewhere.

Another possibility is that there IS something dodgy with the charging system, I know that when I grab my high-beams, the system voltage hits about 11V for a split second before the alternator can compensate for it (I love having the voltmeter in the cabin).

Try placing as much 'instant' load on the electrical system as possible using something other than the fan...try your high-beams...they put more load on the system than the fan does (or at least they should). Also...just to be a little nastier, turn on the rear window demister too (that sucks a bit of juice). Test that out and see what happens.

 

[88GreenVN]

On the chart the first fan call kills the engine. Revs hit 0. Car rolls to a stop (bus stop) slip into park and start the engine first kick.

I've looked back over the 3 data sets I have recorded and when the volts hit 11 the engine stalls.

I changed the fan relay and did the same drive test loop and the volts were stable. I turned the a/c on and off 20 times during the drive with no effect on the volts.

The problem would appear to be the fan regulator, (replaced now) the fan itself or the alternator (new 2004).
I'll do the same test loop tonight with the a/c, rear demister on and some high beam too boot.

 

[VN_Luke]

dodgy earth somewhere?

fan relay is triggered by computer earthing a pin on the relay....?

dfi module not earthed properly?

 

[88GreenVN]

Dodgy earth? Well I've been over the car for the past 3 months looking for the stalling fault. I'm not saying its not a bad earth or connection (the oxy sensor connector was bad) I'm just hoping the relay was bad. I think I have tracked it to the fan system/alternator. The earth for the DFI is good, the earth by the battery is good. Is there any more earth points I should check?