348 cylinder bank out

When you say ecu's, are you referring to the cat temp ecu's located behind the shock towers, or the ecu's behind the seats?

 

Try disconnecting the cat ecu's completely, and leave them unhooked, then start the car and see what happens.

 

Have you disconnected the cat ecu's completely yet? If not, go unplug them and then start the car.

 

I've never tried to troubleshoot this on my car, but if swapping the Ecus make no difference, that should mean it's not the Ecu itself (good!)..... (don't mean to step in on your help with this Brother here ernie). That likely means it's actually either a high catalytic converter temperature, or a faulty signal of some type on the bank that's cutting out. Do you get dash warning lights when it happens?

If the catalytic converter on that bank is not getting unusually hot, it's more likely a faulty thermocouple, Cat ECU, or intermittent bad electrical connection in those systems that sends a false signal to the main ECU (can cause the ECU to shut off that bank). Not sure if faulty O2 sensor or connections would also cause a bank shutdown... don't think so. Anyway, sounds like you should check connections at the Cat and Cat ECU .. clean them and then make sure they're attached properly. Good luck with the troubleshooting!

 

Just read closer that you don't have Cats!! Sorry about that ...I was just trying to rush through posts before getting back to work on the car. It does seem that the main ECU is cutting your bank out.. seems to be getting a false signal perhaps from the Cat ECU, which is why Ernie suggested disconnecting them (don't mean to mess up your help Ernie. If you still have the thermocouples connected up to the ECU, perhaps they could have gone faulty, or perhaps the connection has gone bad. I'm sure Enrie is correct... try to make sure the Cat ECUs are completely disconnected... and post any dash warning lights you're getting.

 

That's an easy one. You have an ECU relay that is failing. It is located in your passenger footwell. You can replace it (best option) or at least swap the left ECU relay with the right ECU relay to watch the problem switch banks.

Also, check that your CEL 1-4 and CEL 5-8 lights are illuminating briefly at startup. You may have missing or burned out warning bulbs.

 

Check engine lights not use on your car?????????? I thought that the Euro cars couldn't pull the codes but still got the light? Something doesn't sound right.

As for the problem being intermittent, the next time it gives you a problem turn the car off, open the engine lid, disconnect the catalytic converter temperature ecu for the bank you think wasn't running, then go start the car again. See if the bank will then fire.

What I'm getting at is that I think your cat ecu/s is the problem. When the cat temp ecu thinks that the cat is getting hot it will send a signal to the Motronic ecu to shut the bank down. Well since you have no cats it should never get an over heating signal. Sooooooooooo there really is no need for you to run the cat ecu's to monitor the temperature of pipe that won't over heat. Capiche?

 

No CElights on Euro cars (except maybe Swiss spec). To display the codes you need to fit a small harness/pushbutton (Farrari part) near the ECU and put bulbs in the dash.

 

"actuation of injection nozzles" sounds right.

As for the CELs, just insert bulbs in there...they'll start to work immediately if you have Motronic 2.7.

After an ECU relay goes out, your CEL will come on as your ECU turns back on (when the relay kicks in again). Just like at startup, your ECU will repeat its self-test.

And because a bad relay turns off (then back on) your ECU, your error codes will be lost...there won't be any codes to pull if you have an ECU relay problem. They'll be lost each time.