F355 Isolating stalling problem...F 355 - Ferrari Life
 
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post #1 of 11 Old 03-30-2014, 02:19 PM Thread Starter
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Isolating stalling problem...F 355

I think the reason my car chugs and sputters when the fan kicks on is possibly related to an aging fan motor (drivers side)- pulling too much current from the alternator.

In order to isolate the issue, and before I buy a new fan...can I simply unplug the fan and see if the problem goes away? If I suddenly hit 190+ degrees, and no fan kicks on, and therefore no stalling...I would assume it is time to invest the $ for the new fan.

The stalling ONLY happens when the fan kicks on. Otherwise, idle is always smooth.

I will not keep driving if the temp gets too high, obviously.

Is this a good idea? I will be keeping a very close eye on the oil/ coolant temp if I unplug it.

Aside from overheating....can I damage the car by doing this? Should i suddenly expect a CEL or anything else I should know?

I want to buy this fan asap and get back on the road.

Thanks for your feedback, this forum is always helpful.
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post #2 of 11 Old 03-30-2014, 04:26 PM
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What you might be seeing is an instantaneous voltage drop from that fan kicking on, and one or both ECU's don't like the dip in voltage. Could also be affecting the injector & ignition performance.

Unless the fan motor is really dragging, and that's what's causing the heavy current and voltage drop, there may be some dodgy connections in & around the battery & alternator. It doesn't take much corrosion on a 12v connection for a bad connection to develop.

I'd either disconnect the fan for the test, or pull the relay for it, whichever is easier, but don't let it get overheated.

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post #3 of 11 Old 03-30-2014, 04:55 PM
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Quote:
Originally Posted by Ready321now View Post
I think the reason my car chugs and sputters when the fan kicks on is possibly related to an aging fan motor (drivers side)- pulling too much current from the alternator..
Ah, no...extremely doubtful. Simply stated, the car does not run off the alternator, but rather the battery. A fan motor drawing as much current as you hypothesise will blow the fuse long before the engine will sputter. Measure the battery voltage when the car sputters. I suspect that it is considerably below 13.2V....

For my money, I'd bring the car back to the dealer. I suspect that the charging system was not checked nor was any sort of quality check done. The fan issue should have been caught long before you ever saw the car.

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post #4 of 11 Old 03-30-2014, 06:35 PM Thread Starter
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Ok, I suppose this info just confuses me more, but at least we are getting somewhere.

The reason I thought it might be the fan motor is because of this quote I found on F-chat:

QUOTE" I recently had a 30amp left side radiator fan use blow recently. It did this once previously about 3 years ago. Knowing that this is not going to get better and according to others, is caused by aging fan motors drawing more start up current, and more current during operation. The drawing more current while the motors are running is a concern, since there is sporadic reports of melted 355 fuse panels on those circuits. Also, it can contribute to low idle and almost stalling of the engine when the fan motors cycle on, due to the current draw and extra load the alternator puts on the engine trying to keep up. (I have not experienced this) So if you have ever blown a radiator fan motor fuse, the cure is new fan motors."

This seems to be in conflict with the idea that the alternator isn't affected, but the battery might be more a part of it, or at least the connections. I am still learning obviously.

Hmmmm. Should I still disconnect the fan to isolate the prob or will that simply do nothing? Thanks in advance for any input.
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post #5 of 11 Old 03-30-2014, 06:44 PM Thread Starter
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Is it possible that the wrong type of battery is installed?
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post #6 of 11 Old 03-31-2014, 04:33 AM
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This seems to be in conflict with the idea that the alternator isn't affected, but the battery might be more a part of it, or at least the connections.
The alternator is affected as when the load on the battery is increased, its output must increase to keep the battery fully charged. That is the role of the voltage regulator. However, with a properly functioning battery and alternator, a current surge shouldn't stall the vehicle with everything else functioning, as designed.

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Is it possible that the wrong type of battery is installed?
Doubtful, as I presume that you got the car started somehow...

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Measure the battery voltage when the car sputters. I suspect that it is considerably below 13.2V....
I'm not arguing with you that the fan may be a problem. What I'm questioning is why is the vehicle doing what it's doing when a load less than 30 amps is applied? Between the AC clutch, heater motor and headlights, there are other electrical items in the car that too could eventually cause stalling problems. Although "throwing parts" at these cars sometimes actually fixes them, I'd want to know what the root cause is before I'd replace anything.

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post #7 of 11 Old 04-01-2014, 04:21 PM Thread Starter
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Well, bought a volt meter today so I can see what happens with the battery when the fan comes on. Does it mean anything if the driver's side fan seems to make this happen more, while the right side one seems to not make the idle dip much? Still not sure of the sequence of the fans, but it seems the driver's side turns on first but the right side seems to come on sometimes. Not sure how that works. Will test the voltage tonight.
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post #8 of 11 Old 04-16-2014, 08:29 AM
 
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Someone on the other site brought back a post from 2007 that includes one very creative owners ideas to address his particular stalling issue; hit the site, perhaps it will be helpful.

Thread is titled:
The 355 'spider' idle stumbling problem is solved!!!!

Grace and peace,
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post #9 of 11 Old 04-16-2014, 02:43 PM
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Why not just take it back to the dealer who did the major service?

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post #10 of 11 Old 04-17-2014, 02:54 PM Thread Starter
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Solved.

Quote:
Originally Posted by Ssnowball View Post
Someone on the other site brought back a post from 2007 that includes one very creative owners ideas to address his particular stalling issue; hit the site, perhaps it will be helpful.

Thread is titled:
The 355 'spider' idle stumbling problem is solved!!!!

Grace and peace,
I took his advice and concentrated on the blowback from the fan (left side). Instead of modifying the radiator with shrouds, I simply isolated the top air duct (behind the door, and now the top duct is for intake only, whereas the lower 3 are to cool the radiator. ) Ferrari made a mod to the duct for 1998 and newer 355's, and I more or less copied the mod, though they basically have 5 slots instead of four. Their mod allows less airflow to the intake, where mine allows slightly less airflow to the radiator which, in my opinion, runs relatively cool, as does the car. I have yet to go above 195 in this car, if that. We will see what a hot summer brings.

I used Duct tape, very durable plastic, which is almost impossible to rip by hand (an old drumhead from my DW drumset...very durable). I cleaned up the visual with carbon-fiber tape, and it looks great, actually.

3 test drives later, the car has yet to dog-out on me! Quite pleased.

Wasn't the fan or fan motor
Wasnt the fuses or relays
Wasn't the alternator
Wasn't the battery
Wasn't the charging system
Wasn't the sparkplugs.

It was the blowback of hot air... from the left side fan.
Go figure.
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post #11 of 11 Old 04-17-2014, 02:58 PM Thread Starter
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Quote:
Originally Posted by David @ FluentInFerrari View Post
Why not just take it back to the dealer who did the major service?
Good question.

It was a preexisting problem, and they know that.

They are 2.5 hours away, and my rims are taking a beating from straps, and I hate not seeing the car for 2 weeks, or having it on a flatbed for 6 hours (slow truck).

It would cost me a fortune in hourly diagnosis time at Ferrari rate$.

I have spent enough on this car.

I love the forum, and love it when I fix it myself for free.

That's basically it!
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