Happy New Years FCat! I am having an issue I cannot diagnose. Go to start the Testarossa and it starts fine and idles normal, but after about 10 seconds the right bank, 1-6, starts sputtering. I’ve swapped coils, same issue. I turn car off and back on and again it starts and isles fine but then 1-6 bank not all are firing. I can feel cold air out of the right, passenger side, exhaust so the problem seems to be right bank based. Any ideas for me to try?
There is a relay in a metal box to the right side of the engine compartment under the fender. The relay has a fuse on it and if it blows it'll shut down a bank of cylinders. I think it's the ecu protection relay. I replaced my fuse with a circuit breaker and haven't had any issues Sent from my GM1917 using Tapatalk
Right side, access from the top. Just look under the right fender in the engine compartment. It has two big rectangular connectors attached to it. Sent from my GM1917 using Tapatalk
Actually sorry, wrong box. It's the one with the round connectors next to it Sent from my GM1917 using Tapatalk
The round connectors unscrew then pull out. If your connectors are bad it's not too hard to replace them. Sent from my GM1917 using Tapatalk
Just undo the bottom cover, and it's a silver and red relay inside with a fuse on top. If the fuse is intact then that's not the issue. Sent from my GM1917 using Tapatalk
Strange. It looks like that fuse feeds battery power to both ECUs. I wonder why it only shuts down one bank. Calling Steve M! Wiring diagram here: https://www.dropbox.com/t/T6aNCt6y86BAjqpF (fuse is in the lower right hand corner)
Yea it's hard to diagnose. I had it randomly blow at times on startup. Runs poorly but slightly drivable. I got pretty quick at changing fuses in parking lots. So I installed a small circuit breaker that auto resets. Sent from my GM1917 using Tapatalk
Before digging into the box itself, I'd recommend that you make a simple functional measurement to determine if the Protection Relay (and fuse) is working, or not, by measuring the voltage on the red wire at the water thermoswitch: Image Unavailable, Please Login If it isn't +12V relative to ground when cranking or running = try unplugging/replugging the two round connectors to wipe the contacts, and remeasure. If still no joy = that justifies digging into the box with the two round connectors to examine the fuse and make some measurements at the protection relay terminals to determine if the protection relay is bad or some of its needed signals are missing. If the fuse is blown, and blows again after replacement = your alternator is probably wacko. If it is +12V = your problem is elsewhere. I don't like the description of your symptom as starting well, running fine for 10 seconds, and then having a bad-running issue appear doesn't match any specific fault that I can think of. Is it able to rev up strongly (even if burping and farting)? Have you used a timing light or spark tester to confirm/deny if you are actually losing spark on the 1-6 bank (and it should run smoothly if only running on the 7-12 bank). Since you've already swapped coils and power modules, one other simple thing to do is just have a look inside each dist cap to see if there's anything horribly wrong (e.g. broken rotor, full of oil, etc.).
Since it runs well for a little while i would fuel starvation issues as well Sent from my moto g(7) using Tapatalk
I'd check the fuse on the protection relay. It's the easiest thing. Mine had a low lumpy idle and smelled rich as well. Sent from my GM1917 using Tapatalk
Damn, I was hoping that would have been the easy fix. Maybe remove the fuse and reseat it. I changed my relay just because. Good luck Sent from my GM1917 using Tapatalk
Where is a good positive to hook the timing light to in the entire bay? My timing light wires are long enough to go to battery.
Yes, that's not good . It might be getting enough fuel from the cold start injector squirts to run reasonably well for the ~7 seconds until the trouble occurs, and yours might be tweaked up rich enough to not be as bad as they usually are when the Protection Relay isn't working. When the Protection Relay isn't working the system runs very lean/misses (so pushes unburnt fuel out the exhaust) and usually won't rev hardly at all -- so still start with ruling the Protection Relay in, or out, as Michael originally suggested.
There isn't an easy one on the later TR with the later (not spade) coil connectors. On an early TR with the spade coil connector, terminal 15 of the coil would do. I had to make/add a long extension wire to reach the positive battery terminal on my 1991.