Help? We have a 1991 Ferrari 348. The right bank 1-4 is not running. It started running extremely rough. And is not driveable. We and to be towed home. The car has 30k miles. We pulled the connector to the right (1-4) coil pack and it many no difference in the way the engine rough running. When I did the same on the left 5-8 bank the engine died. This lead me to the conclusion the right bank was the cause of the rough running. I pulled a plug wire on the right bank to verify the spark and there is good strong spark. There is no CEL light on. This lead me to think it is a fuel issue. We checked the relays for the 1-4 injectors and the 1-4 fuel pump by swapping the right bank relays and the left bank relays and we also purchased a new bosch relay to replace the right bank fuel pump and right injector relay and still the right bank is not working. Any suggestion on what to check next? Thank you
Fuel and spark, but also they need to be controlled/coordinated correctly - timed. OP said he had spark on right bank, so fuel pressure or timing (ECU for RH bank is therefore a possibility).
Thank you for the help. What is the best way to check for fuel pressure? I was going to check the crank sensor as well. I did not think about swapping the ECU since I was not throwing any codes, but I will swap it and see what it does. Will post the results. Thank you again.
Take the airbox off and spray a quick shot of carb cleaner or starting fluid in the right side intake. If it takes off momentarily on all 8 cylinders then you know that the right side pump is probably not getting power or has an issue with being plugged etc. I think 348 fuse boxes sometimes have a problem delaminating and not powering relays correctly which could be killing your right side pump.
Yes, it was coking plugs. Had spark and fuel. No spark=washed down wet plugs. No fuel gives dry plugs. Different symptom. The OP must first determine if 1-4 has spark and fuel. Go down the ladder of diagnosis, so to speak. Follow the trail and you'll get to the end. Just poke around guessing and you waste time and money.
I was able to do some more testing. I started the car and loosed the fuel rail connection and there was fuel pressure to the fuel rail. I also sprayed starting fluid in to the right bank and it made the engine run alittle better for a few seconds. I also pulled the mass air slow sensors off and inspected them and they looked clean. Any suggestions?
Dave gave you a good advice about swapping the engine ECUs across sides. I had a similar problem caused by a faulty ECU. Also, it's a very cheap way to test some parts like MAFs, crank sensors or ignition coils, by swapping across sides.
Happened to me twice now since I put the Hyperflo cats on. If you are out on the road and half the engine goes down just disconnect the battery torpedo connector for a few minutes and reconnect it. Not sure what is causing the problem but at least it gets everything running back on 8.
Thank you. I'll swap ECU next. I disconnected the battery and reconnected it but no joy with fixing the problem. I thought that since there was spark coming from the distributed that the coil pack was good. Thank you all!
It's good to know that the ECUs are fine. Well, you have fuel pressure, and in your first post you said that you pulled a plug wire and there was strong spark, but did you check every plug wire? What I mean is, are sure that the right bank is completely dead? Maybe a faulty sparkplug or wire? However you can try swapping MAFs, crank sensors and coils too. It's easy and cheap.
I haven't seen any indication that you have pulled a spark plug to see if the plugs on the 1/4 bank are wet-fouled. You can have plenty of spark at the plug wire and no spark at all on the plug electrode itself. If the plugs on that bank ARE wet-fouled, you need to find out what caused that condition. Perhaps your OXY sensor has failed and put that bank into full rich mixture. In case you haven't ever checked the plugs, you should have a special socket for them in your tool kit.
Unplug the cat temp ecu, could be causing that bank to go in limp mode. I had it happen to me without throwing a cat temp light, was not easy to diagnose. Luckily the car helped me out by starting to flicker the light, but the bank had dropped out a couple of times randomly prior to that with no cel or temp light.
I dont know on 348s , but on 355s if you unplug either the TC or the plug for the Cat ECU itself it will send a 5V signal to the ECU which is a shut down level. Have you checked the voltage out put of the cat ECU to see if it is just sending out a voltage over 3V for some reason?
Depends on the year, on the 355's with 2.7 motronic if you unplug the cat ecu it just throws the SDL and doesn't shut down the bank. I'd imagine the 2.7 348's would be the same, not sure about the 2.5's. Solution to my problem was to just unplug both cat ecu's as I don't have cats anyway.
