Running on one bank after the red light comes on The car was cold so it's not a high heat cat Was running great yesterday Any ideas?
Doesn't running on one bank introduce unburned fuel into the exhaust? Then it hits the cat and you have a fire. I think that is one purpose of the "slow down" light: to let you know your cats may be on fire internally. Alden
If it's not actually overheating (check with an IR gun, they're cheap), then I'd suspect ECUs for Cats. Did you get a CEL? IF so, after you confirm no actual issue with temp swap the ECUs rom side to side, CEL should follow.
The engines fuel injection system and ignition system is split in two and controlled by to separate engine controllers. If one side quits and doesn't flow fuel, you wouldn't have any excess fuel in the cat. Other failures could give you different results. Is the Check Engine Light on?
If it was a cold engine, could it be the failure of one of the 2 ECU's for the cats? One of mine failed and one of the keys to diagnosing the problem was the light came on when the engine was cold, no time for the cats to warm up. A common 360 problem with age. Replaced both. Or maybe one of the Lambda sensors, the cables have been know to wear. In any event, take it to some one with an SD-2 for proper diagnosis rather than throw parts at it
This was a common malfunction in the 348. Fixed by the 355. The seals on the exhaust ecu would crack allowing moisture to condense inside, shorting the board. One remedy was to reseal them but you had to be sure they were completely dry so you didn't chase it. At my major service, I chose the "one and done" approach recommended by a certified Ferrari master mechanic. We replaced mine with the 355 vintage which have better Green silicon seals. No problems since. Only one brief light up but cleared immediately, probably after a cold shut down and restart.
Battery bad One cell died Each cell is 2 volts The car hates 10 volts Battery is 8 years old New Battery Runs 😀
John K, how did your mechanic rewire the 355 exhaust ecu for your 348? I am having intermittent sdl lights and have narrowed it down to the ecu. The 348 ecu part # 142581 is almost impossible to find and when you do find them they are close to 1000. The 355 ecu is much better price wise and also reading a few posts are much more robust. A picture would be nice. Thanks
Is the connector arrangement the only difference between the 348's cat ECU and the 355's (see attached photo below, with 348's version on the top, 355's on the bottom)? I think that might be the case, but not sure. If so, then an adapter harness could be made to allow the 355 version to be used. Another alternative might be to use a version of the microcontroller-based replacement I'm building for the 308/328 Jetronic cat ECU. The 308/328's original ECU doesn't output a voltage, as does the Motronic-version ECU, but I've designed my replacement to include that feature. I didn't think there was any market for it in the 348/355 world though, given that those ECU's are relatively cheap ($400 or so) and available. Image Unavailable, Please Login
Not sure of the number of pins the 355 cat ecu has but the 348 has a 2 pin connector from the thermocouple and a 6 pin connector to the wiring harness. It looks like all 6 pins are used. I'm not sure of the arrangement on the 348.
All the information I'd seen previously re. the 348's and 355's cat ECUs seem to show/indicate only a 4-pin connector, not 6 pins. I guess I've missed something.
