ferrari 348 engine left bank exhaust is getteing red

What do the spark plugs look like on that bank? Are they at all fouled/black, or do they look the same as the ones from the other bank?

You did check the fuel pressure on both banks, right?

It sounds as though either too much fuel is finding its way into that bank or the timing is severely retarded, causing incomplete combustion and a rich condition in the catalytic converter.

I'm not 100% certain, but I think the 348 ignition timing signal is shared between the two banks, but it would be worth confirming that because incorrect timing could certainly be the cause. You might swap the ignition modules between the two banks-- it seems unlikely that one of those could cause this problem, but it's easy to try.

One possible cause of a rich mixture is a bad engine temp sensor, causing the ECU to think that the engine is at -40F (or whatever it's low temp threshold is) and to therefore richen the mixture. Here again, I think that sensor is shared between the two banks, but something worth looking into, just to make certain.

Just a couple of ideas to consider in the short term. I'll add to this if I think of anything else. Hopefully someone better versed in the specifics of 348 engine management will chime in with their thoughts.

Good luck, and please let us know when you find the root cause, as it may help someone else in the future.

 

Been a while since I looked at the 348 and Mondial T but just a couple of suggestions:

Have you tried to read any fault codes from the ECU (via test button)?

Also have you checked the other 2 ECU modules for the AFR/cat system?

 

Yes, the ignition modules should interchange with no problem. But something else just came to mind after reading 308mon's post. The 348 has an air injection system that pumps fresh air into the exhaust ports to help the converters come to operating temperature faster. It would not surprise me if there is a fault in that system and air is being injected into the exhaust on that bank even after the engine is hot. I suggest capping off the air line going to the air injection manifold on that bank and seeing if that solves the problem. If so, you can start comparing individual components to the corresponding parts from the other bank until you find the faulty component.

Hope that helps!

 

Not sure, but I think you might have to be subscribed to post pics.

I was almost certain that the problem was caused by a fault in the air injection system. Back to scratching my head...

Checked the manual and there are separate engine temperature sensors for each bank, so that is certainly a possibility. An open circuit or infinite resistance at the sensor will cause the ECU to think that the engine is completly cold and the weather is freezing, so it will richen the mixture accordingly.

Values for the temp sensor are as follows:
At 20C the resistance should be 2.5 k ohms, +/- 250 ohms
At 40C the resistance should be 1.2 k ohms, +/- 150 ohms
At 80C the resistance should be 200 ohms, +/- 40 ohms

You can check those values at the ECU connectors. The diagnostic proceedure linked below will give you the pin numbers.

Also, there are in fact two separate TDC and engine RPM sensors on that engine, so it might be worth testing those.

Did you check for trouble codes, as suggested by 308mon?

Other things to try include swapping MAFs, checking the throttle position sensors, and swapping the ECUs themselves. One of the nice things about that engine is being able to swap components from side to side as a means of testing them.

I PMed you links to the Motronic diagnostic proceedure and diagram for the 348 2.7 system in case you don't have them. They contain more details on checking the above. And I'll give this some more thought and see if anything else comes to mind.

Good luck and keep us in the loop as to how you're progressing.

 

Hemantha,

Once upon a time, we owned a Chevrolet Chevette. We were in the process of moving from Houston to Crockett, Texas, about 130 miles away. We towed the Chevette behind a rental moving truck. We left Houston right at sundown, so decided to turn the car’s parking lights on for safety. When we got to Crockett, the Chevette’s lights were out and the car would not start. The Chevette being a manual transmission car meant we could push-start it, which we did. I drove the car around the small town of Crockett for several minutes trying to charge the battery. The battery never got charged enough to run the lights, so I had to drive in the dark and very slowly because it would not go above 10 mph. I was driving around and around in a shopping center parking lot when my wife caught up to me in our other car and said, “There’s something glowing under the car!!” I looked and, sure enough, the catalytic converter was glowing a bright orange (I think you could read by it.). Apparently, the fuel system was dumping basically raw gasoline into the exhaust system and almost all of the combustion was occurring in the catalytic converter. How the car could produce enough power to move itself at all, let alone at 10 mph, is beyond me. I don’t think there was enough electricity in the battery to run the spark. The car ran smoothly. There was just no power. Ultimately, we had the voltage regulator in the alternator replaced since it was not recharging the battery.

Most of Ferrari’s engines seem to be two half engines turning a common crank, some even with totally separate ignition systems. I wonder if your sick bank is producing any power at all, and, if it is, that power level is likely way down. I cast my vote for little or no ignition in that bank and the good bank is just using the bad bank to pump raw gas into the bad bank’s catalytic converter. Most of the bad bank’s combustion is occurring in the bad bank’s cat and that is what is producing the glow.

Tom