HELP 360 Slow Down Light when Cold ? not ecu's or thermocouple ...NEED BIG HELP !!!!!

You probably got them so. Good shots of Spider location at posts 15, 16 & 17 if any doubt.

 

Yes, the only reason I put my photos is because the ground points are slightly different on coupe than on spider...

I will try the other side as well... And then back to the dealer...

Keep fingers crossed !!

 

These are the ground points for the motronic. You should also check cat computer earth points, there is a rivet-nut in the chassis that can break loose. You need to take the rear section of the wheel housing our and it is visible close to the exhaust bypass valve.....
Also worth measuring exhaust temps, if one is above 250' at cold start you could still have a cat computer issue. If this is the case swap it across banks and carry out another cold start temp test.

 

Thanks Eddie for you help !

I found this diagram with the engine wiring of the 360. It mentions "Earth" for 11L and 34L.
Is this what you are referring to ?

I stick my iPhone and took a picture of the right side. Next to it you can see exhaust valve. This must be it.
It seems to be screwed tight in place, a little rusty though.

I think I can unscrew it, clean it and tighten it again without removing the wheel housing.

What do u think ?
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Yes, those are the ones! Also check cat control station plug, you will have 12v and an earth (which goes to the aforementioned earthing point) there is also a signal return to the motronic (middle pin iirc) which you can put a scope into and measure the signal from the unit.if it does, just try swapping cat computers across the banks and see if the reading moves bank too...

 

Thanks Eddie for you help !

I removed, cleaned and re-tightened the ground points on the left side , see 28L and 34L.

The one the right side 11L was very tight, but the tool could not fit to remove it.
However, I checked for tightness and it seemed fine.

I reset power and drove the car.

After 5 minutes I got SLOW DOWN again and the engine again was on 4-cylinders.
After switching off/on the engine 2-3 times, I got CEL.

Now the car drives normal, but the CEL is constantly on.

It could be the cat control station, but since I don't have ECU diagnostic machine to check error codes and see which bank is giving the problem, I guess I will have to visit the dealer.
I will suggest to them to swap the 2 cat control units and see if the problem switches cylinder bank.

If one cat control unit was bad, would the SLOW DOWN signal be all all the time ???

Let's hope it's not a bad catalyst.
The car only has 27000 Km and it has always been properly warmed up and top grade fuel has always been used.
The exhaust temps, I put my hand and both seem the same... (not very scientific test...)
No, Catalytic converter glow and night, just around both rear thermocouples / lamda sensors during warm summer nights, which has always been the case...

Could it be any white exhaust muffler material blocking the catalytic converters ???

The exhaust on my car is OEM but from a higher mileage car (I sold mine, put Tubi, remove Tubi due to excessive noise, and put back friend's high mileage OEM exhaust... no problems so far)

Thanks !

 

MD, if you haven't already diagnosed this, everything you need to know about how to test (and temporarily bypass if necessary) the Cat ECUs is here in this excellent thread started by FBB ......

http://www.ferrarichat.com/forum/showthread.php?t=328364&highlight=SDECU

If you don't have glowing cats then you almost certainly have a faulty ECU or a faulty Thermocouple. The hardest part of getting to grips with this problem will be taking the side guards off the engine bay. The rest is very simple if you follow the above thread carefully.

 

I have the problem of SLOW DOWN at start up. Dealer told me I needed a new "computer" and are replacing it.

 

Again sorry for bringing up an old thread but I am not sure I understand this fix. I have a 2000 360 coupe and the slow down light is coming on. With the suggested fix, am I just to locate the exhaust ecu and ground point, look for any loose connection and put back together? Again, I am sorry to ask but this seems so simple.

 

SOLUTION FOUND !!!

Hi , just an update...

The problem was the exhaust ECU on the right bank... Over time these small green boxes go bad and they need replacement... I was told to replace the thermocouple cable / sensor too...

Total cost was about 200 Euro for exhaust ECU and another 180 Euro for cable with temp sensor...

I was told that pretty soon I will have to replace the left side too...

Guess I will wait till the problem arises again, before I throw money on more parts...

 

Good stuff.

Agree your observations about replacing perfectly fine parts also.

 

After fixing the SLOW DOWN on my 360 by replacing the exhaust ECU module, something strange is happening sometimes.

I am driving the car and as I shift (revs drop) and I get back on the gas pedal there is a slight hesitation an then power comes back on...

Is there a chance that I might need to change the left exhaust ECU ??? Could it be that the left side is "weak" and it is cutting power for some reason ??

There is no SLOW DOWN or CEL right now...

Thanks for your reply !

P.S. I do remember my mechanic saying that I should replace both sides, because the left side was weak and would fail pretty soon, but I didn't see any reason since there was no error in the car...

 

Hi MD,

If you check out the SDECU thread I think the answer is in there..... that the SD ECU has three states only, normal, slow down flash and slow down (solid) + fuel cut.

So, it seems me to me that no, it's unlikely that the other side is misbehaving.

It's possible you're looking for problems at this stage and imagining things or perhaps that you now have an unrelated problem in another area.

Best!

 

What you are describing is one of the symptoms of a failing MAF sensor. Usually also identifiable with rough "gargle" at cold start.

 

Thanks Greg , Eddie !!!!!

You guys are amazing !!!

I will look into it...

The funny thing is that it seems like all components in a Ferrari are engineered to last exactly 10 yrs or 25000 km !!!! LOL

My car was built on April 2002 and all the problems started January 2012 (28000 km) !!!
Before that I only had to deal with regular maintenance items...

Just out of curiosity : I was under the impression that the Lamda oxygen sensors adjust air-fuel mixture and the MAF is used just for checking purposes...

How do you know which one is failing ???

Is there going to be a CEL when it eventually fails ??

Is there any test to figure if that's the case ?

(I've seen people on this board talk about disconnecting the cables on the MAF, but is it safe for the engine ?? What happens then ?)

 

Don't run it with the MAF's disconnected.
You need to put a 'scope on the signal wire at the MAF plug and look at the output pattern and voltage; you should see close to 5volts at idle on a good one, bad ones tend to run about 3. Test both sides.
When they go bad you don't normally get a CEL, but if you look at the long-term fuel trim it will be really high on the affected bank. When they get really bad, the upper limit of the fuel trim gets breached and it logs a fuel adaption error.

 

Just to make sure I don't make any mistake, out of the 5 pins which one is the signal wire and which the ground ?

Based on some research I did on Bosch MAF the middle one is the ground (number 3) and the last one (number 5) is the signal ? Right ?

Looking at the way it is installed on my car which one is the number 5 pin ? The one closest to the car cabin or the one closest to the rear bumper of the car ?

Many Thanks !!!

 

Pin5=signal. The wire color is Brown with a green tracer.
IIRC look at the right hand MAF, the clip is underneath, which would make pin 5 nearest the bumper.

Make sure you use an oscilloscope and not a voltmeter on it!

 

So, new update...

I couldn't find an oscilloscope to test the MAF sensors, so I just replaced them both with new...

Their price was very cheap and I figured that they were 10 yrs old and would need replacement sometime soon...

I reset ECU by disconnecting battery.

I didn't see very much of a difference...

The car performs alright... No hesitation, but sounds and seems to be maybe a little lean on fuel...

The interesting thing is that when I start the engine it sounds very strong !
After a while the revs drop (normal) but is sounds like one bank is running lean... (my guess)

No CEL whatsoever...

When I drive and come to a traffic light, I switch gear to neutral and coast to a stop, the revs will fall to 800 and come back to 1100. Sometimes they might fall to 500 before they come back to 1100. New clutch and bearing, so it's not transmission related.
Idle is a little strange as if one bank is lean ...

Check video on unstable idle after coming to a stop.
http://youtu.be/6vrQFWZ1qrY

Any ideas ?
Could it be oxygen sensors or leak in intake manifold ?

Thanks !

 

People have posted that when their "slow down" light comes on they lose power. I have a 2000 360 Modena and when it comes on I don't seem to lose any power. Doe's this mean anything? Is this bad or good? I've cleaned the ground points but the light still comes on but again no loss in power? Is this normal? Anyone's help is appreciated.

 

There are two stages to the Slow Down protection circuit - when EGT exceeds 900 Celsius then a flashing Slow Down message is displayed. When EGT exceeds 940 Celsius then SLOW DOWN message is lit continuously and the Motronic shuts down the side of the engine affected (the CEL light is also lit but an error code is not stored).

 

^^^^^^^^ What he said!

 

I wonder if your problem is eventually sorted out, what was the cause and fix?