could go with some help please. Had a bank go down last year and replaced both crank sensors and that seemed to cure it, other than the odd hiccup at start up. Recently though I get a bank going down after about 15 -20 minutes running. Turning the ignition off and back on clears it and no more issues for the drive. Doesn’t happen every time out though. Anybody have any ideas what this would be about? Thanks.
Had exact same thing and it was my cat temp sensors. If I shut the car off and restarted it was fine until it randomly did it again.
Do you run cats? I have bypass pipes and it happened a couple of times. SDL would come on. Unplugged both TCU and haven't had the problem or SDL ever since.
Both come on, 1-4 goes out quicker than 5-8. Only stays on a second or two. (De catted with test pipes)
I'm out for a good run next weekend, so will unplug the TCUs and see what happens. I was thinking of wrapping the test pipes, would that make any difference?
If it is your problem, it is common those TCU go bad. Easy to check, just unplug and see if problem goes away.
The SDL system serves a vital purpose *if* the car is fitted with converters, but since yours no longer has them the TCUs serve absolutely no purpose. You probably already know this, but for the archives only two nuts secure each TCU-- they're small; 6 or 7mm heads IIRC. Once they're off you can remove the mounts simply by removing the fasteners for the coil/ignition plate, which covers the screws for the TCU mounts. Once the mounts are out of the way there's more airflow to the coil heat sink. Be sure to mothball the parts for the next owner. I asked here about sourcing connectors to use to seal the TCU connections but apparently those were bespoke for the application and no one has yet found a replacement. So I coated the terminals with DeOxIt, stuffed plastic wrap into the connector housing until it covered the terminals, and then sealed them with black silicone adhesive. That way they can be returned to service easily in the future. Rehung the connectors on the factory tabs so only a 348 purist will notice anything is missing. No more SDLs and no CELs as a result of the removal, and probably an extra ~lb removed from the heavy end of the car. Total win. Have you managed to resolve the problem yet and if so, was it the TCU?
Going for a good run on Sunday, but today I unplugged the TCUs and started her up. Both SD lights stayed on. Car ran, but the SDs stayed on. Plugged the TCUs back in and the SD lights went out as normal. So my car doesn't seem to be behaving like mentioned in other posts?! Will see what happens Sunday, but if I get the same issue, I'll replace the TCUs and go from there.
The results seem to vary from car to car. Lots of reading here: https://www.ferrarichat.com/forum/threads/348-sdecu-pinout-wiring-diagram.537300/ How many wires do you have on your TCUs plugs (or SDECUs as some like to call them)? When you say you disconnected the TCUs, did you disconnect the upper plug (going to the SD light & ECU) or the lower one (going to the temperature probe) ...or both?
Thanks for that. So previously I just disconnected the TCU from the Exhaust ECU. Result SDL lights came on and stayed on, engine ran. I've just (benefits of working from home) disconnected the Exhaust ECU from the harness. Result is SDL lights don't come on at all, even at ignition on stage (they use to pop on for a few seconds then clear), engine ran. I will leave them disconnected for the run Sunday and see what happens. TCUs have two pins. Other thread is interesting (thank you), if some bits a little beyond me, or requiring some time to digest. I take it the TCUs monitor the temp in the pipes to ensure they don't get too hot; presumably for when/if the car had Cats so you didn't damage them. Do they have a secondary function as I note the various parts diagram show the TCUs on a variant of the non cat pipes, so are they also associated with mixture control or something?
Ive had a very intermittent drop of a bank for some time. Normally pull over and restart and it will be ok all day and may not happen again for many drives. When I disconnected the cat ECUs from the loom it seemed to make it worse. It will idle all day like that but after driving a few miles it dropped a bank and would not clear even after stopping and restarting. Reconnecting the system again restored me back to 8 cyls and Im now back to the occasional drop. Very odd. Im doing an engine out service this winter so intend to remove, bench test and possibly repair the cat ECUs if at fault. I can live with it for now. I read that disconnecting wouldn't be a problem but it is for me. Maybe I'm missing something. Im running test pipes so the system is really redundant. Thats my experience. Will be interesting to see what happens when you drive yours. N.
Yes, by removing the upper plug, you are removing power from the SDECU and it's ability to illuminate the SDL. However, the engine Motronics ECU may identify the disconnected plug as a fault. What the Motronics ECU does after this may depend on what type of engine management system you have. It may or may not produce a check engine light (e.g. on my F355, it would probably illuminate the Check Engine light, if not on the first drive, perhaps the second). The 348 experts can probably clarify this. Yes, quite a bit of that is beyond me, too When you say you have two pins, I assume two pins on the plug (connector) going to the temperature probe on the cat. If you only have two pins/wires on the other plug, I'd be worried. 348 SDECUs have up to 6 pins (and sometimes 6 wires) on the other plug.
Update. Disconnected the exhaust ecus. Did about 200-250 miles today. No problems at all, with some spirited driving and some stuck behind the 40mph club drivers. Will put it on the job list this winter, will pull the tcus and give them a clean, wrap the pipes in exhaust tape and see what happens. Don’t want to just replace the tcus as they aren’t cheap. Very hot here and my headlining came away by the rear screen, so need to find the posts on how to get that out. Think the old glue just gave up!!
I just fixed my headliner. If you have any questions about it, PM me. Sent from my iPhone using FerrariChat
