F355 CEL/SDL after storage for nine months

Yes. That's the other thing I was thinking. Open loop >>> Good. Closed loop >>> Bad. What happens in closed loop that's not in open loop? When does cat temp signal enter the picture. Like Ian has stated, it looks like the main ECU is getting a bogus or not signal from the cat ECU and your battery tests seem to confirm that. Not of much help, I know. Hope you get it sorted.

 

Let me give you another clue. On a 5.2 F355 with OBD2, once a SDL light is on and the CEL code is logged, the SDL will stay on at the next time the engine starts up. You have to clear the OBD2 error code before you can do more trouble shooting.

As for the 2250 rpm limit, I have no idea.

 

Weird. Does this apply to flashing and steady SDLs?

 

Sorry, I should have been more specific. The RH Thermocouple ECU is connected to pin 15, the LH Thermocouple ECU is connected to pin 14. Your OL (open circuit) and zero ohms sound correct. Unfortunately, in light of Mitchell's (Yelcab's) information about latched SDLs, this puts us back at square one. The problem may indeed be a crank sensor or other issue.

Not knowing that SDLs are latched, I think I led myself down the wrong path Well, it seems to be latched in your case only on start up, then it starts afresh until the problem re-occurs. This is starting to make more sense. If, say, the crank sensor is malfunctioning at higher rpms, then perhaps fuel scheduling is being messed up and the SDL is being triggered. Why the ECU is not generating a fault code, I don't know. Perhaps it needs x seconds to confirm a fault. The very specific rpm seems strange, though.

For future reference, resistance checks should be done will all power off the circuits (probably best with battery off, too, when disconnecting the Motronic ECU plug).

 

Or maybe it isn't.

With the double 1.5 volt battery bypass and the messages cleared, there should be no new SDLs. Unless SDLs are also triggered by non-exhaust-temperature related issues, this still points to an internal ECU fault.

Can the exhaust bypass thermocouple system trigger an SD light with an rpm limit?

 

This is what I would do if it were my car.

Clear all error codes using OBD2 scanner.
Start the car, monitor all three analog signals from the three Thermal Control Units to see what voltage they are. Leave the car idling, wait for the SDL to come back, see which TCU is causing the high temp signal.
Meanwhile, read the Long Term Fuel trim, Short term fuel trim, and O2 signals of both banks pre/post cats to see if they are within operating range. Is one bank way different from the other?
Using the scanner, monitor engine temp and compare against actual engine temp
Using the scanner, monitor RPM signals and compare to actual signal (you might need an oscilloscope)

Depending on what the data above say, I might decide where to go next. I realize that you are getting a lot of different suggestions, and it might be difficult to do all of them. You have to pick and choose.

 

+1

Sent from my moto g power using Tapatalk

 

We’re certainly in new territory here and the potential to learn new things is great.

We know that we can’t use the battery trick for the exhaust bypass ECU… but will the battery trick on this ECU simply generate a fault message and not produce the 2250rpm limit when the engine is warm? I’ve never heard of exhaust bypass experiments causing rpm limitation. @Carmellini tried a range of dummy resistances/voltages, but, AFAIK, all he got was fault messages. Also, I can’t say I’ve heard of bank shutdowns or rpm limitations when you accidentally swap the leads on known good (exhaust bypass and RH cat thermocouple ECU’s). @Pespi10 maybe you could try the battery trick on the exhaust bypass TCU just to see what happens?

Given that there was a crank sensor fault, maybe it would be a good idea to order one of those.

Does your OBD2 reader show exhaust temperatures?

 

To be honest, I wouldn’t get your hopes up on the crankshaft sensor being the cause. The crankshaft sensor provides tachometer information for the instruments. You don’t seem to be having problems with your tachometer.

When you say your engine won’t go above 2250, do you mean that throttle control is normal from idle to 2250? i.e. Pedal input vs rpm increase is normal in this small range then any further pushing of the pedal produces no further increase in rpm?

 

Can your OBD2 scanner read the throttle position sensor?

 

I did think of the TPS, too, but wasn’t sure how the engine would respond to the loss of TPS data or with faulty TPS data:
If the throttle is physically wide open, the MAF would be sensing high airflow. At some point, would the ECU say that this combination of faulty throttle position and MAF airflow is impossible and would put on the CEL and the SDL? Or does the ECU keep adding fuel to match the strange MAF/TPS combo, causing a cat temperature issue?
But the latter doesn’t explain why you’re getting an SDL even with both cat thermocouple TCUs being bypassed.

My current shortlist is:
1) Undocumented logic of SD lights (allowing, say, exhaust bypass temperatures or faulty MAF/TPS values to put on SDLs with the engine warmed up).
2) Faulty Motronic ECU.

We still can’t be sure if the fault is linked to closed loop operation. It could simply be something on the engine heating up (or a relay/wiring overheating). Also, the WSM says that, at wide open throttle, the engine reverts to open loop operation.

Some folks recommend BlueDriver scanners, but I haven’t had any personal experience with these. Like yours, my scanner is surprisingly basic.

 

Looks like your throttle position sensor is bad. Absolute angle is "4"

Image Unavailable, Please Login

Your absolute angle readout is not even moving out of the idle zone.

I guess you could confirm this by taking resistance measurements across the pins (TPS connector disconnected):

Image Unavailable, Please Login
OEM part number is 158170, but according to this chart, you have options:

Image Unavailable, Please Login

 

I guess you should probably change the crank sensor for 0336, too, but it would best to change one thing at a time (as you won't know what fixed the problem).

Did the BlueDriver give a description of 1396? It's not on the Ferrari list.

 

If you change your TPS, is there anything on the BlueDriver which gives you an ECU reset. Learned parameters are not reset with a battery disconnect on the 5.2 car. Usually only a Ferrari SD tool can do this.

Perhaps BlueDriver owners can tell you how to use Freeze Frame. There is a YouTube video on this, but I don't know if it will be of any help



It only seems to be triggered at the moment the CEL comes on.

 

Quote: "So whether I was at 2000, 2500, 3000, 4000 using the tach**, ATP was always at about 2.5%. Not sure if this means anything."

It absolutely means your throttle position sensor is bad, or the wires going from the throttle sensor to the ECU are bad. This is your main problem. Fix that first.

 

Image Unavailable, Please Login

 

From memory, I think you just squeeze the metal clip (i.e. push towards the front of the car) and pull on the plug.

As well as resistance checks on the old TPS, you can check for 5 volts DC (with the ignition on) on the plug (between pin 1 and 2). i.e. on the engine harness side of the plug. Pin 2 should be the earth.

The TPS mount may allow slight movement (to help set up the relationship between the throttle shaft and the TPS). The yellow paint, if disturbed, will show that someone has removed the TPS. Anyway, do your best to remove the paint from the bolts. It may be best to use a ratchet/socket to remove the bolts, rather than risk damaging the screw slot.
The new TPS may just be plug and play. One it has been installed, you can check adjustment using your Blue Driver.