456 GT 7-12, 1-6, & slow down lights

I just bought a 95 456 GT, driving it back to my home the 7-12 light came on. a few days after I got home I went out to run some injector cleaner through the system, to see if that might help the lean running issue that I thought I had. The 7-12 light came on and off several times then the slow down light came on. I stopped and rebooted the system, did this several times then went to get gas only to find that the rear bumper had the paint burned off and the tail light melted! After reading all I could find here, I think that the problem is the cat. temp. ECU. I have pulled those ECU's off of my T/R and installed test pipes, and the car has run great for over 10K miles. My question is, can that be done with a 456 and would that not get rid of all this mess with lights as they have nothing to do with anything but cat. temperature. By some miracle, no fire, and no body damage, other than needing to paint the rear cover.

 

If the CATS are hot enough to melt paint, it's not the CAT ECU. You have a problem.

These cars are sensitive in this regard. I had a misfire and poor pattern from the injectors, as well as an air pump that was driving air to one side only. A lean condition can drive the CATs hot; if it were me (and I have been here...) I would change all the plugs, pull all the connectors you can see and clean them, and pull the injectors and have them cleaned.

Couple questions - does the car only do this when cold? Can you sense a misfire? Do you get the CEL before the SDL?

 

The car at times hits on all 12, then goes to 6. I pulled the plugs, and they are fine except you can tell that 7-12 was not firing when I shut it off, black soot. I think that the accumulated unburned gas in the cat. on the 7-12 side was ignited by the heat from 1-6 side. The car does not do this when cold, and there was no damage or signs of heat other than at the end of the tail pipe, even after pulling the cover, nothing behind the cover, and the cover only had burnt paint. The heat was from the burning raw gas in the cat.. I have been all over the bottom of the car, nothing. I have pulled the two fuel pumps and have found what you would expect, the donut is becoming soft "gooey" small bits of rubber in the can, and the star pad under the coffee can is in pieces. I went then to the fuel filters and found that they were probably original, all good things to fix, but I still think that that ecu is the culprit. The filters were black! I don't think they had ever been off! But back to my idea of taking the cat. and the ecu's out of the system, it worked on the Testarossa.

 

Check the relays that control the O2 sensors before you do anything else.
They are in the fenders, just behind the front wheels.
You'll see them as soon as you open the hood.

 

Hello Ferrari Chat
Crazy as it sounds, I am troubleshooting a 1-6 light for my sisters friend who has a 456...
lucky her.
But I digress.
This seemingly spot on thread turned up on a search. And well, I am "guessing" that a can of BG44k "may" fix this problem?? That may be too easy, but if not, maybe an injector cleaning and test?
I don't know a lot about this particular 456, but it is well maintained but not used a whole lot:/ That last part I could remedy
Anyway any other thoughts or suggestions would be appreciated. I will have a looksee at this car early next week.
Thanks very much!

 

I have done most everything you can, rebuilt pumps, changed fuel filters, plugs, cleaned injectors, cleaned electrical connections, the thing that cured the trouble light problem simply is NEW cat ECU's. The new design ECU's changed the car! My 456, which I just bought, has had a history of trouble lights for over 10 years, and various owners have spent an enormous amount of money on bogus fixes. I pushed testing out this problem enough to blister paint on the rear cover, don't go there, change the ECU's, simple to do, and not much money. $295.00+- each. The Ferrari 456 is a terrific car, and one day will be considered a classic, ENJOY!

 

By the way, it was during the time that I was running BG 44K through my car that I blistered the paint!

 

Hello. I've had a problem with my 1994 456GT cutting out cylinder 7-12 every now and then (maby 6-7 times the last 5000km's) but this weekend it does not seem to help only stopping and starting the car again. I also tried to change the left exhaust temp sensor ecu with the right one, but still my car was failing on 7-12. Is it a way to verify what could be failing, without just buying different parts and try changing them?

Also, does the car have some kind of diagnostic logging (obd -connection perhaps), or is the car to old?

Thanks,
Ronny

 

I had this same "mystery" problem with the engine banks and it was faulty fuel pump relays. My Ferrari dealer said the plastic covered relays break down over time and cause these intermittent problems. I have a 95 456GT

 

Some workshops have a Ferrari SD1-tester to read out the ecu's.

 

The only time my 456 showed "slow down" was when the ecu relays in the fender must have got damp. Try remove, dry, reseal (or more likely seal for the first time )and use. Cheap fix that may work for you.

 

I did the same with respect to the fuel pumps , lines , filters and bench tested the injectors. Ultimately, changing the ECU stopped any further nonsense with the SD lights.

Best

AK

 

I have a Ferrari 456 and I am trying to find the rear RH tail light. Does anyone know where to get one?

 

There are two(I assume) Hall-effect generators that
serve as a "crank angle sensor" near the back of the engine

In the 1995 6-speed, there are two (2),
one for the 1-6 bank, and one for 7-12 bank.

Although they have different part numbers,
they will interchange well enough that,
with the car lifted, they can
can be removed and swapped.

If the problem changes banks,
you have found an indicator.

These sensors are only
about $100 from RICAMBI.

I replaced BOTH of mine, and carry a spare..........

 

I usually step to the rear of the car,
and face the tag.

The tail light on a 456 is usually three (3)
feet to the right of the tag, and a little higher.

 

English may not be your first language - your reply is just confusing the one who posted.

By asking "where can I find", he is referring to where can he purchase a rear light...

BTW, I happen to have a spare one, send me a PM.