F355 CEL/SDL after storage for nine months

Hi all, I hope someone has some ideas, or can point me to a good thread for my next steps.

My 355 has been mostly without issues. But, I am now getting CEL/SDL whenever I go over 2250 rpms. And the engine will not rev about 2250 rpms (unless engine is cold).

I have never seen this before. The only thing I have done differently, is the car has mostly been in storage for about 9-12 months. Meaning, I have started it, and moved it around the garage, but yesterday was the first time, this year, taking it out for a real drive.

This is what I have done so far:

I have read 10-20 threads about people having similar issues.

The following did not help:

I have reset the system a few times, by rotating the battery shut off, to off, then back to on. Then letting the car run for 10 minutes or so.

I removed the battery, had it tested, experienced NAPA person said it is “better than new.” Which is strange as it is from 2017, but I keep the car on a tender always. I have now put the battery back in.

I accessed the CAT ecus on both sides, and tried to clean the terminals (someone had found this helps).

I cleaned the MAF sensor (by removing that part of the induction system from the car), removing the screens on both ends. Then cleaning the sensor with CRC MAF sensor spray (someone had found this helps).

I have a pretty basic OBDii reader. It found no codes when I plugged it in this evening.

Possible hint(?), it seems when the engine is not completely warmed, it is possible to rev the engine higher, 5000 or so, with no SDL/CEL. Of course I am hesitant to push the engine very hard when it is not up to temp. But that is one interesting thing.

Bad gas? I normally put Stabil in the gas for storage over the winter. But is it possible I did not? Yes. I probably will try removing all the gas from the car. And replacing with new. But of the many threads I have read, no one has mentioned bad gas yielding SDL/CEL. But that is my current suspicion.

Any thoughts appreciated. Not sure why lack of use/storage would yield this problem? It doesn’t make sense to me that the headers are ruined, or the cats are plugged, or the ECUs are ruined? Which are some of the more common causes of SDL/CEL. They were all fine in the autumn-meaning the car ran great.

 

SDLs will only occur if the exhaust temperature is sensed to be too high. If the car doesn't show the fault when the engine is cold, it does sound like you have a real overtemperature problem (or a faulty thermocouple ECU is somehow adding temperature to normal exhaust temperatures).

It sounds like a bank is shutting down as a result of the perceived/real overtemperature. Just figure out which bank it is by using an OBD2 tester and/or a temperature gun (preferably both). If there is no detectable temperature difference between the banks (with the temperature gun), swap the thermocouple ECUs. I keep a spare thermocouple ECU on standby for situations like this (Technistrada make some aftermarket ones cheaper than OEM).

I had one bank showing hotter than the other and it turned out to be a combination of bad spark plugs and faulty/dirty injectors. Injectors don't like long periods of inactivity. Maybe try some injector cleaner?

As you say, it's not likely a cat has failed by storing the car.

 

Thank you for the ideas-I will try them today.. The OBD2 tester I had on hand, showed no codes-which is strange.

 

Could be that the cat ecus themselves might be bad? I had 1 or both fail on my 360. Sometimes they would let me operate the car somewhat normal for a bit before killing a bank


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Thank you, exactly, much appreciated. I replaced one five years ago or so, maybe the other has gone bad?
Qavion mentioned, in another older thread, this idea from Ratarossa, of bypassing the ECU, just for testing. Today’s project will be injector cleaner, and ECU testing.
17th min of this video https://youtu.be/5SKGpdNVEF8 Ratarossa shows two very useful things. First, if he disconnected the three pin connectors from the CAT ECUs, his car ran normally. Obviously this would only be for very short term testing. But also, he shows how to connect AA battery to check the system.
Middle black is ground
Green is 12v
Brown is trigger wire
So he ran
Red from 1.5v battery into trigger/brown
Black from 1.5v battery into ground/black
And his SDL and CEL lights went away. In the next video, I think I remember he figures out it is actually his CAT thermocouple that went bad. And he emphasizes not just throwing parts at the problem. But step by step.
But for today, I will do the injector cleaning, and his idea of playing with the ECU as described above, and in his video.

 

Note that the battery method (or dummy Thermocouple ECU method) is only going to identify the faulty bank. It will hide all temperature changes due to faulty Thermocouple ECUs, thermocouples, broken cats and faulty combustion. At some point you will still need to swap over components or use a temperature gun to narrow down the problem.

Technistrada sell cheap dummy ECUs or you can make one yourself from a diode and resistor. The battery method may be more convenient however if you can figure out a safe way of attaching the battery.

See this thread for making a dummy ECU:

https://www.ferrarichat.com/forum/threads/simple-2-7-slow-down-ecu-replacement-only-for-no-cats.538719/

 

Thank you Qavion. I’m working on getting a temp gun, it is on the way.
Update: I disconnected the three pin connectors from drivers side ECU, passenger side ECU, and both of these ECUs. It had no effect on SDL/CEL, the SDL would blink continuously, and the CEL would come on, and the revs would be limited at 2250. This is a bit strange.
I tried the Ratarossa battery trick, on both 3 pin connectors, as described above (1.5 volt battery connected to 3 pin connector), and it did nothing. Same problem.
I will have to digest this…I was pretty sure the battery trick would at least bypass my problem/trick the system, and it hasn’t.
Siphoning gas from the car, is difficult. To use a fuel injector cleaner, need to start with empty gas tank. So I have the cleaner, just deciding how best to empty the tank.
Note, my car still has cats.

 

Interesting result, but perhaps not so strange. The ECU is not getting vital exhaust temperature information. With data from both sides missing, it is probably programmed not to shut down both banks, but gives you a car which at least runs.

Unless there was something wrong with the way you hooked up your batteries, this doesn't sound so good. It may indicate a wiring issue or ECU internal problem (both not unknown). All I can suggest is checking the wiring between the ECU and the thermocouple ECUs. More specifically:

1) Check for 12 volts DC on the Thermocouple ECU green wires (ignition on).

And with power off (preferably battery disconnected)....
2) Check that you have continuity between the engine block and the Thermocouple ECU black wires.
3) Check the resistance between the RH Thermocouple ECU purple wire and Motronics pin 15.
4) Check the resistance between the LH Thermocouple ECU purple/white wire and Motronics ECU pin 14.

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If you are getting an SDL with the battery trick, I can't imagine that fuel injector cleaning would help. The ECU should think that the temperatures are ok.

How did you keep your 1.5v batteries attached to the wires? Did you check the polarity was correct?

 

I used a single 1.5v battery. I attached a red piece of wire to the positive end, a black to the negative end of the battery, using 3m electrical tape to hold them in place. On the other end of each lead, I used a male disconnect, that I cut to form a pin (see image), that I crimped in place. I masking taped the battery to a nearby wire. Unfortunately both my multimeters are at my garage, which is inaccessible today. The battery was new, and I was careful to tape the pos and neg wires in place, but without a multimeter. I can not be sure I was getting the 1.5v? I will have access tomorrow, and try the experiment again.
I inserted the black negative wire into the center black wire of the 3 pin connector
I inserted the red positive wire into the brown (trigger) connector.
The good news and bad news, is that once the car is warmed up, the CEL/SDL/Rev limit kicks in right away. So testing is not 5-10 min. It is get in the car, put in gear, rev past 2250, and see what happens. Usually just 20 seconds, turn around, insert in the other 3 pin connector, tape in place, and try again. I guess I could try a battery in both connectors, so far, I have just used one battery rig.
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Actually, it's a 4 pin connector, but I understand.

Unfortunately, other than the wiring checks, I'm not sure where to go from here. Maybe check that the major earth for the engine management is clean/tight?

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Thank you Qavion. Everything seems tight in the engine compartment, including the major earth. I’m a bit surprised today’s experiments did not show me a direction. I tried the 1.5v battery experiment a couple more times, using another new battery, better connections, etc.I will keep thinking.

 

You may have multiple problems. If you have a problem on both banks (injectors or whatever), then I suppose the (single) battery method is not going to work.

You did say you cleaned the MAF, but did you try disconnecting it completely? Give the engine a few moments to adjust to the loss of the MAF. See if your SDL disappears.

 

Thank you Qavion.
I turned the battery off, using the switch in the front, then completely disconnected the MAF (meaning unscrewed it from it’s port the air intake, left the connector dangling safely) then I turned battery on. Let the car warm up/adjust. The CEL did not come on while driving (I did not rev the car past 4-5k, SDL still blinking etc, but it seemed fine), no sign of CEL.The SDL continued to blink, but maybe I need to clear that? No MAF = no CEL, but SDL still blinking.

I reconnected the MAF and I made another 1.5v battery pack. I turned the battery off, using the switch in the front. I installed a battery back on the black and gray leads of both 4pin connectors which normally attach to the CAT ECUs. I turned the battery back on using the switch. I drove the car with both 1.5 battery packs installed and same result as past few days. SDL blinking from startup, and CEL whenever I go above 2250rpms, and rev limited to 2250rpms.

I will have access to my multimeters later today to confirm that my 1.5 battery packs are putting out 1.5v, and will report back. But they are new batteries, tight connections etc. Maybe I should buy some pins instead of the male disconnects I am using and trimming (per Ratarossa). Maybe the way I am poking the leads in to the 4pin connectors is not working. But it seems okay.

 

Yikes. I only meant disconnect the electrical plug, but you proved that the MAF wasn’t the issue by disconnecting everything.

Your battery test setup should be fine, but check the battery voltage anyway. The only thing left now is checking the wiring from the Motronic ECU to the Thermocouple ECUs as mentioned earlier. You will need a long piece of wire to run from the cabin to the thermocouples and a short piece of fusewire or lockwire to probe the Motronic ECU connector sockets (as your multimeter probes are probably not thin enough). You may need some short pieces of wire with alligator clips on them to join the wires and test leads together if you run out of hands (or just join the sections of test wire together by twisting the wire conductors).

With the Motronic ECU plug disconnected, also check for bent pins on the ECU and on the two smaller connectors in that area (white one and semi transparent one).

I admire your dedication to this faultfinding.

 

Thank you Qavion. Somewhat of an update:
I used an OBD2 scanner to clear codes which have accumulated over the past few days.
Those codes were
P0336 Crankshaft position sensor A circuit range/performance
P1396 DTC definition not found
P1445 DTC definition not found
P1449 DTC definition not found
P0102 Mass or Volume Air Flow sensor A circuit low

Clearing these codes, at idle, the flashing SDL no longer occurs, and CEL is not there.
But, again, when I go past 2250rpms, SDL and CEL come on, revs are stopped and then the lights both go off. If I stay below 2250 rpms, no lights.

I used a temp gun to look at bank temperatures. Now remember that I can only push the car to 2250 and then revs stop. So if one bank was firing poorly, not sure we would see it much as the engine shutting down hides the difference.
Drivers side valve cover 194
Passenger side valve cover 210
Drivers side cat 260 but variable toward higher
Passenger side cat 309

When I scan the car, after it has bumped off 2250 and SDL/CEL come on. There are no codes. Which I think is strange.
Maybe my crankshaft position sensor is not working?

Qavion, I will think about your idea of testing the Motronic ECU to Thermocouple ECUs. Electrical stuff is a bit daunting for me. So…I will have to work up to that.

Remember: The care seems to run normally, revs smoothly to 4-5k, until it warms up. All the above is once is warms up

 

Anyone who can wire up a battery to the thermocouple ECUs should have no problem checking the wiring

1) Check the volts and earth at the Thermocouple ECU on the green and black wires with the ignition on.

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2) Check the resistance of the purple (or whatever colour) wire.

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The hard part will be getting the plug off the Motronic ECU. You may need to dismount the ECU from the firewall to prevent damage to the crumbly soundproofing.

P1445 is the thermocouple ECU signal "range/performance-plus/min/max" (no side specified): check wiring, check TCU and thermocouple
P1449 is the left bank thermocouple ECU signal "range/performance-plus/min/max": check wiring, check TCU and thermocouple

These signals may have been triggered by things being disconnected or by faulty components/wiring.

A common fault, but I've never heard of these symptoms before. If you have access to the underside of the car, check that the sensor plug is clean and the wiring undamaged. If you had a completely faulty sensor, the car wouldn't even start. The fuel pump wouldn't be activated (during starter cranking and afterwards).

 

Let me answer some specific question.

How to empty the gas tank: Remove the panel under the gas tank (the big panel). Get large buckets to cover what amount of gas you have in the tank. Remove the brass drain plug at the bottom of the tank. Big mess ensues.

On to your problem. You are looking at the symptoms and not looking for a cause. It is hard to troubleshoot a car from a distance. I think you have a rich running bank 2, which is a real problem that is causing the real SDL. Start looking at spark plugs, ignition module, spark plug wires, injectors.

Also don't ignore that MAF error code.

 

Spot-on analysis - That said, If the car has factory/original Cats the lining can become brittle and collapse which obviously will not pass the exhaust gas through properly which will cause the ECU to trigger due to temps. I had that happen. And this can be exacerbated when the car sits because when it is driven frequently the lining heat-cycles frequently and stays more malleable - when it sits for a long period it does not heat and "drys" out - then when you start it up again it re-heats and can cause an issue. I had my AD check and sure enough the right-side Cat was rattling from collapsed lining - replaced and no CELs/SDLs.

To your last paragraph, I recently had to let the car sit for a few months - When I drove it it was absolutely perfect for a while then I had a VERY quick SDL flash and could feel the car go into limp mode - then it cleared and all was fine - then did it again - cleared. Oddly, I was taking her in for an annual anyway so had it checked - they could see the brief code flash in the OBD and put in some infector cleaner - I then filled her with premium Shell gas - no issues since.

Good luck and hope the posts help - As you are no-doubt aware, 355s are hyper-sensitive to any condition that can cause operation outside of VERY tight temp parameters so the slightest thing (random sunspot activity, bad mood, Covid, etc. <kidding obviously>) can trigger an ECL/SDL - usually it is something minor but the suggestions provided should help narrow it down.

Cheers

 

The MAF was completely disconnected and the engine running during faultfinding. It's not surprising that the MAF was showing as an error. Anyway, it can't be a MAF as it was completely disconnected and the defect was the same.

The cats, MAF or poor gas are not causing the SDL... The SDL is present even with both thermocouple ECUs bypassed. The 1.5 volt batteries should simulate a normal temperature signal. Therefore, only wiring or a Motronic ECU fault can cause the SDL.

The 2250 rev limit is puzzling. It doesn't sound like a single bank shutdown (due to a cat overheat signal). Since a wiring fault on both banks is unlikely, the symptoms seem to be pointing to a fault common to both banks (e.g. a faulty Motronics ECU).

 

Hmmm - Interesting - Well it is obvious you are darn good at methodical troubleshooting If I missed it in the thread apologies but what year is your car? i.e. 2.7 or 5.2?

 

Thanks all for your help and ideas. The car is a 1997, 5.2. I am trying to think what could cause this fault to happen over time-meaning the car ran great for ten years, and now this? That’s what made me think of the gasoline/fuel filter(?). I did have a CEL/SDL (I forget the exact symptoms) very early in my time with the car, and replacement of the driver’s side ECU fixed that. The car was not limping etc then. Just a light on the dash.

Qavion
Battery is 13.16v, measured at the positive lead near the passenger side shock tower, that one labeled +, and a ground
With the ignition on, but the car not running I checked:
Driver side ecu black and green = 12.33v
Passenger side ecu black and green = 12.33v

About your test of the nonblack/non green wire, we will call it brown.
I removed the motronic unit from the wall and disconnected that multi pin connector (mpc)
I connected a long wire from the brown socket of driver’s side 4pin ECU connector to one lead of the multimeter set to ohms. The other lead of the multimeter, I gently touched first socket 14 and then socket 15 of the motronic mpc.
With the car ignition on, but car not running these tests gave me an 0L reading, which was a bit of a head scratcher.
I think it was socket 15, but honestly, I was running out of time, and the 0L reading had me wondering if I was doing things right. So one of the 14/15 sockets gave me an 0L reading on ohms on the multimeter. I think the other socket, 14, just gave me a reading of 0 (not sure).
I decided to put everything back together, but now I understand how to get that MPC off the motronic, and everything would go much faster.
I think I will have time tomorrow to try MPC sockets 14/15 again with both the driver’s side and passenger side ECUs

Very minor side point. I finally had access to my multimeter yesterday. This allowed me to confirm that my 1.5v battery with test leads attached, for plugging into ground and brown 4pin connector of the ECU cable, was indeed putting out 1.5 volts. So our experiments where that 1.5v battery was plugged into black and brown sockets of the 4pin ECU. I am pretty confident that should have been an okay test.

Very strange to me that the 1.5v battery experiment did not allow me to trick the system into running “properly.”
Very strange to me that the car runs 100% until it warms up, then SDL/CEL/rev limiting.
And now that I have cleared some codes that have accumulated. No codes show up. And I see no lights on the dash, but when I hit 2250 RPMs, SDL/CEL come on and the car is rev limited. So I can drive the car at 2200 rpms and everything looks fine. But anything over that, lights/rev limits. If I then drop below 2250rpms, the lights go out and the car drives okay.
Could it be a fuel starvation issue? Meaning the filter is plogged?

 

What happens at 2250 RPM? Does it just not rev when given throttle or does it start to break up like hitting a rev limiter?

 

Well it does both of those things. If I give it throttle, it will gain speed/rpms to 2250, then it’s like a rev limiter hits. Revs drop down, independent of throttle position. SDL/CEL come on higher than 2250, the engine slows, but then the lights go off and I can creep along at 2200 rpms with the dash looking normal.

I’m starting to worry I sent Qavion/you guys down a misleading path. For a couple days, I had a blinking SDL from start up. And all of the above behavior. But after clearing those codes, yesterday, I have no lights at startup, and the SDL/CEL just come on when I hit this rev limit, then the lights go off if I drop below. So are SDL/CEL really a diagnostic of anything? Or are they just a symptom of the car engine “stalling.”

And remember, everything seems completely normal in the five or more minutes it takes for the car to warm up. Before warm up, the car revs freely, and seems fine. After warm up, can not go above 2250 rpms. I’m starting to think the car is hitting some rev limit at 2250, SDL/CEL come on, almost like the car is stalling? But when then the engine recovers, lights go off, and I can creep at 2200 or less.

Once warmed up, I can not get the car above 2250. Doesn’t matter throttle position.

 

All I can offer is a similar experience several years ago where my car would hit 4500 PM and it was like a rev limiter. If I kept on the throttle, it would just break up. Easy off a little the RPM would drop below 4500 and it was fine. No codes, no SDL, but my car is a 2.7.

Problem turned out to be a broken connection to the RPM sensor. Apparently at 4500 RPM some mechanical resonance would cause the break to open up.

Probably unrelated to your issue.