F355 ECU issue

Author
Discussion

priley

Original Poster:

505 posts

195 months

Friday 3rd June 2016
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One of my ECU's has developed an intermittent problem, dropping a bank on the side that it's fitted. My garage has sent it to two companies neither of which has been able to identify the problem or fix it. Can anyone offer any help or suggestions-other than buying new-please?

tomtom

4,225 posts

237 months

Friday 3rd June 2016
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Are you absolutely sure it's the ECU? How do you know? I assume your car is a 2.7 if you mention 'one' of the ECUs.

My car would intermittently drop a bank. I replaced coil packs and checked plugs, messed around with the exhaust ECUs etc and was getting very frustrated with the mystery. Finally, after an evening with a multimeter, I eventually traced the problem to a fuel pump relay.

HardtopManual

2,545 posts

173 months

Friday 3rd June 2016
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By "ECU", do you mean the small amplifier circuits that the cat thermocouples connect to, by the right rear wheel? Or are you talking about the actual Motronic boards?

If the former, I had this problem with mine some time ago. I bought a new part but now keep it as a spare. The fix for the "broken" one was a night in the airing cupboard and a good smidge of silicone sealant in a crack that had developed in the potting.

priley

Original Poster:

505 posts

195 months

Friday 3rd June 2016
quotequote all
Yes, the motronic boards. The car was in for a belt service and after mentioning the intermittent dropping of a bank the coil packs were replaced as a precaution. Since putting the engine back and test driving the garage has traced the problem to the ECU's and one in particular as it will drop the bank for the side which that one is connected to.

priley

Original Poster:

505 posts

195 months

Sunday 5th June 2016
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Sorry folks, just bumping this back up in the hope that someone can help. Does everyone just buy them new (in a pair at £2k each!) from Ferrari if theirs go?

FezSpider

1,067 posts

239 months

Sunday 5th June 2016
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You know what, i have very rarely heard of 355 ECUs blowing. Knowing this the first thing i would do is contact eurospares or any 355 breakers and buy a used one. Being that its a rare occurrence that they go, i think you would be good mate.
Even scan ebay because there are sone good breakers out there like a seller called steve strange, he sell some good 355 parts.
There is nothing i dont know about the 355s, i have owned mine for 12 years. I have done everything to them from engine rebuilds to suspension rebuilds. Last year my ABS master cylinder valve went, do you think for one minute that i spent £5,000 plus ferrari tax for a new one? Or do you think i spent £500 for a good used one? Like your ECU this was also a rare thing, so i knew a good used one would do the trick, and it did. Next month i am at the classic lemans then another 6 days in the italian alps and maranello, with full confidence smile
If your guys have traced your problem to one of your ECUs, just do it. Get ya car back on the road mate, its summer smile

Cerberaherts

1,651 posts

148 months

Monday 6th June 2016
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I agree. I've seldom had issues with the motronic units unless aggressively jump-started. Much more common causes are;
1. Connector for crank sensor, corroded pin/plug full of oil
2. Cat control station loss of reference voltage due to damaged connector
3. Pins backing out/bent on either of the two plugs that thread through the bulkhead to the ecu.
4. Faulty injection relay

tomtom

4,225 posts

237 months

Tuesday 7th June 2016
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You could try to borrow an ECU if you can't find one from a crashed car but I'd be reluctant to buy a brand new pair. I've also bought parts from Eurospares before and had good service but they're not always much cheaper than new.

I bumped into an old friend in the pub over the weekend and (unprompted, but reminding me of this thread) he was telling me that he'd also had issues with his 2.7 dropping a bank. His was one of the exhaust sensor/ECUs cracking as above...

priley

Original Poster:

505 posts

195 months

Tuesday 7th June 2016
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Many thanks guys. I'll direct my garage to this thread and post any developments.

phib

4,488 posts

266 months

Tuesday 7th June 2016
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Forgive me for being thick ... But if this is the units behind the rear wheel then I had a similar use a few years ago , if it's not ignore me !!

If it is these ecu's have you driven in the wet recently ? If you had take the ecu's out and dry them out properly ( a boiler room for a few days should do it)

You will probably notice that that the sealant has shrunk and water basically gets I and throws lights.

I dried mine out the resealed with silicon sealant and hey presto no more issues !!

Pretty silly place to put ecu's just behind the rear wheels !!

If it's not this at all just ignore me, I have had a glass or two !!

Phib

PAUL500

2,763 posts

253 months

Sunday 12th June 2016
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I know of a pair of 2.7 still sealed challenge 355 ecu that are available, they will run a normal 355 just have a few mapping tweaks and rev limit upped I believe. PM me if interested.

tomtom

4,225 posts

237 months

Friday 17th June 2016
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Any update priley? I'm interested to know what the root cause was.