some times you get the bear....

Some of you may have read Dave Rock's post about the error in the WSM. I though, in my typical verbose story telling mode, I would post on how I found that error.

A couple of weeks ago Jeanne and I were out for our usual drive through northeast Connecticut. We stopped for lunch and then started home. A little way in to the drive home the car started missing and backfiring badly right around 4500 rpm. Back in the day we referred to this as breaking up. Below 4500 it ran smooth. So we continued home, short shifting with an occasionally push above 4500 to see if it would clean out. It didn't. There was no CEL, no SDL. Nothing. When we got home I immediately checks the codes from the ECUs. The car is an 95, 2.7 monotronic. Having read through the WSM I was aware that there are several codes on a .7 that do not turn on the CEL. But nothing. Just the flashing 4, 4, 4, 4 code on both sides indicating no errors detected.

Next day I did an ECU reset and took drove the car up and down the street. It started out fine, reving smoothly to past 6000, but as soon as I turned around and headed back it began breaking up again right around 4500. Checked the codes again, nothing.

Feeling this was ignition related I got out my spark tester and found that on the 1-4 bank there was an occasional miss on cylinders 2 and 3 at idle. The 5-8 bank was fine. So, that kind of ruled out the cam position sensor since it would affect both banks. I pulled the coils from both sides and measured the impedance of the primarys and secondarys. Both sides were identical and on spec. So, I took a shot and though I would try replacing the ignition module. Looking up the part, Ricambi said, "Call", All Ferrari Parts said $789. WTF!!! Doing a quick Google search revealed it was a standard Porsche part. NAPA had it for $250. But it gets better. FCP Euro, and mail order outfit in CT had it for $85, and they guarantee the parts they sell for life. (Side note: Why does a Ferrari parts house sell an $85 part for $789?)

Moving on, I figured that my local shop would charge more that $85 just to run a diagnostic, let alone the $250 to have the car towed there. So I ordered the module. Anyone need an ignition module? Yep, no change. Not the problem. Now I'm down to two items. It could be the RPM/TDC sensor or it could be the ECU itself. But if either was failing it should throw a code, and, again, there were none. But just to be sure I started the engine and checked the codes. Nothing but the NO ERROR, 4, 4, 4, 4 flashing away on both sides.

Then I had an epiphany. As many of you know, to stop the 4, 4, 4, 4 from flashing the ignition must be shut off and the car restarted. But I though, what if I just go out and drive while they are flashing, kind of like a PC in safe mode? I figured if something screwed up it might at least stop the ECU from flashing. So, out for a blast up and down the street and around the block, pushing the engine to 5000 so it was doing the nasty. At fist, nothing. But then suddenly the 1-4 ECU stopped flashing its "No Error" code and went out. I immediately pulled into my driveway and checked the codes. Magically, there it was, 4114, "TDC control unit recognition". That's Italian for "the ECU is loosing the TDC signal". And, yes, for some unknown reason Bosch didn't seem to feel that warranted turning on the CEL.

So the problem was the TDC sensor on the 1-4 bank. However, where was it located. On page C3 of the WSM it says it's the one hidden up next to the AC compressor where you can't get a baby's hand in there. On page C9 it says it's the one on the bottom that Godzilla could easily remove. Tracking the wires showed it was the position shown on page C3.

So the happy ending is that the part was replaced and the car is again running fine. Or should I say it made it up and down the street and around the block a few times getting up to 7000 rpm w/o any hesitation. I'll take it out for a longer drive today. And the TDC/RPM sensor? $232 from Ricambi, $195 from All Ferrari parts, $45 from Amazon, genuine Bosch part.

And just a closing note about why the code didn't show up at first. OBD I and II will erase a code (and turn off the CEL if lit) if the error that set the code doesn't occur again after a certain period of time or drive cycles. I can only assume that since when driving home, short shifting so that the engine didn't break up, the ECU decided that sufficient time had passed w/o a reoccurrence of the error and erased the code. But I'll never know for sure. Still, the self diagnostics ultimately worked as it should. Hurray!!!

 

Great explanation. Thanks for sharing!

Robb

 

Great write up.

 

Amazing the savings you secured for both items with a bit of research. Top work.

 

Great work, John. Another example of how owners can inexpensively service their own cars.

 

Where did you find the parts so cheap...I checked amazon but says doesn't fit a 348?

 

I just googled the Bosch part number. It's clearly stamped on the parts. The ignition module for the 2.7 355 also fits all 348s and Mondial Ts. TDC sensor is for 2.7 and 5.2 355s.

I have a real problem with these rip off Ferrari vendor prices. The ignition module is just a couple of power transistors and maybe a few resisters. I could build one from scratch for $10 and when you consider you can buy a 55", 4k TV for under $500 you can see what a rip off $789 for the module is. Even $85 is a joke. Worth about $10. Same for the TDC sensor. It's just a coil of wire wrapped around a magnet. I believe these venders buy these parts directly from Bosch distributors and mark them up to or near prices for genuine yellow box Ferrari parts. Buy one from one of the vendors and see if it comes in a yellow box. But even if it does, Ferrari is just buying them from Bosch and repackaging them with a BS markup.

 

Thanks for sharing, glad you got it fixed.

 

Great job and write up. Now go plan a small block party to apologize to your neighbors for the 7,000rpm bonzi test runs up and down your neighborhood.

 

Yea, mothers running and screaming, grabbing their kids off of the street. Dad's drooling and thinking, I could have had one of those instead of the $50,000 SUV "she" wanted.

Come to think of it, it's a pretty strange neighborhood considering it's pretty much a run of the mill bedroom community. There is a guy up the street with a couple of old Maseratis and an old Healy; another guy with an 82 911 and an XKE, both in pieces, being restored; someone I don't know just bought an Alpha 4C; and there's a guy with a bus and enclosed trailer who races local NASCAR events on the weekends.

And, there was a block party today. 4th annual actually.

 

Great Job John...Thanks for sharing.

 

Nice work John. Great write up.

By the way, did you go to the Ferrari Challenge at Limerock?

 

Hi Jim,

No Jeanne didn't want to go and to be honest I was only passively interested. I may go to C&C tomorrow for a couple of hours up in MA with the 308. See the New England section for details.

 

So John

I got the reverse problem also on a 95 355. I have a CEL at idle and it goes away when I press the car hard. When the CEL is on, there is a noticeable but slight engine misfire. The spark plugs are fairly clean.

I pulled into the driveway and let it idle for 15 minutes hoping the CEL comes back so I can pull the code. It never did.

This is when you wish you have OBD2.

 

Sounds like a different problem. My car ran fine at idle and anything under 4000 rpm. But above that it was just POP! BANG! WAM! Nothing slight about it. But who knows with these cars.

 

What is the Bosch part number for the TDC sensor?

 

The TDC sensor for the F355 is a Bosch 0261210126. Not for a 348.

 

Here is a nice detail write up about the TDC sensor replacement on the 355

Love the 355: Angular speed sensor gone bad

 

That article isn't much help re: replacement. It just describes a possible diagnosis (guess) which was actually found to be incorrect. See Love the 355: March 2016 Ultimately it appears some of the high tension leads were the problem. Frankly, I'm not even sure this guy really solved his problem as further reading states that that the problem reoccurred later in the year. Initially he replace the leads on one bank, then when the problem reoccurred he replaced them on the other bank. What will he replace when it happens again.

As far as replacing the sensors:

Replacing the 5-8 sensor on a 95 is easy. Jack up the car. Remove the under tray. R&R the sensor directly under the toothed wheel. The 1-4 is a bit of a pain. You have to loosen the top two bolts on the AC compressor so belt tension can be removed. Then with the car jacked up and under tray removed, loosen the two pivot bolts that mount the compressor to the engine. Then slip the belt off the compressor pulley. Now remove the lower pivot bolts completely. Push the compressor away from the engine as much as possible and, if you have the correct tools, you can just get in there to R&R the 1-4 sensor. Then put it all back together again.

 

I had to drill out that allen bolt once, It was a royal pain. A 15m job turned into 4 hours.