96 355 dropping a bank of cylinders.

Most likely cat ECU.It would randomly go into limp home mode. I had this problem on my 95 that I chased for two years off and on. Disconnected ECUs and never had a problem since. Don't know if you can just unplug on the 5.2 cars.

 

Also check out post by DrBob101 or contact him. I believe he knowledgeable in this area.

 

Emac. If the bulb is out or black tape over it, you have one less monitor to determine what's going on. You said the cel bulb was out so does that mean you took apart the dash pod? If you didn't I would suggest checking that and correcting it. Make sure you turn off the battery switch to avoid an airbag light.

If you are losing a bank 5-8 it is most likely the drivers side ecu/tc fault. The best way to accurately determine what's going on is to tap the output wire of the ecu and using a dvom see what the main ecu is responding to. If you don't want to do that then you are resigned to swapping things around until the problem goes away. With a functioning sdl you will then be forced to just driving and hoping it's fixed.

I would make sure the light is installed and not blocked out then tap the outputs and determine where the problem is coming from then fix/replace parts.

FYI. There is a current fchat member whose sdl system probably saved his car by functioning properly. I would not suggest disabling it. Simply unplugging the ecu does not disable it either.

Let me know if I can help.

 

Emac. If the bulb is out or black tape over it, you have one less monitor to determine what's going on. You said the cel bulb was out so does that mean you took apart the dash pod? If you didn't I would suggest checking that and correcting it. Make sure you turn off the battery switch to avoid an airbag light.

If you are losing a bank 5-8 it is most likely the drivers side ecu/tc fault. The best way to accurately determine what's going on is to tap the output wire of the ecu and using a dvom see what the main ecu is responding to. If you don't want to do that then you are resigned to swapping things around until the problem goes away. With a functioning sdl you will then be forced to just driving and hoping it's fixed.

I would make sure the light is installed and not blocked out then tap the outputs and determine where the problem is coming from then fix/replace parts.

FYI. There is a current fchat member whose sdl system probably saved his car by functioning properly. I would not suggest disabling it. Simply unplugging the ecu does not disable it either.

Let me know if I can help.

 

Unplug the cat ecu on that side and see if the problem goes away. If it does, swap thermocouples side to side and see if the problem moves or stays on that side. If it moves, you've got a bad thermocouple. If it doesn't, you have a bad cat ecu. I would replace if you have cats, if you don't I'd just unplug it and not worry about it.

 

Grab the green units. It's preventative medicine.

 

Earnest at this point I would run the positaps into your cockpit and monitor the voltages real time. Tap the signal wires, get 3 -6' lengths of 16/18g wire , terminated the ends with an insulated terminal, get your DVOM and drive around and check the voltages. You will know immediately where your problem is. If it is an intermittent TC connection your can prove it out by swapping that TC or just getting a new TC.

The other option is getting one known working TC and using it and seeing if the problem goes away.

Not a very elegant diagnostic method IMO.

Here is where you can get the positaps if you can't find them locally. Not many stores carry them.

Posi-lock and Molex Permaseal Connectors

 

Great web site Dr Bob, thanks for posting it.

 

Yes. Joe the guy who runs that site is a great guy and very knowledgeable about connectors and proper crimping etc. he has some good tutorials on that on there and has sourced crimp tools at good prices as well

He is a Jersey guy and a new proud owner of a red NSX so busy his chops if you talk to him. 😉

 

My SDL used to be present at startup, but would go away after driving and warming up the car. Thinking that heat was "curing" a potentially loose connection, I used contact cleaner on the 3 ECU's, and the problem seems to have gone away!

I would like to see if swapping the ecu's indicates anything in your case.

I have met up with BOB for cars and coffee before, and he has a very clever way to monitor his voltages, as described in this thread. Bob, hey buddy, did your SDL go away yet?

 

Good job! Gotta love it when it ends up being something simple like that.

 

That swapping of connectors must have been the last mechanic who did the major engine out. I did it once on my cars, very easy to do. I am never doing that again. I am extra careful around that neck of the woods now.

 

Chalk another one up to the Forum knowledge bank, this place is great. Glad it worked out for you.

 

Dear All,
First thank you for your good and valuable information which you are sharing, actually I started to have a problem on my car (5.2) last year after major service, its just that I don't feel the 375 HP from it ! Its feel like below 250 HP. I don't have SDL OR CEL, both lights are working.
Fuel pump pressure is normal, new spark plugs, new air filters, both engine banks are working. When I start the car initially, it will run normal but not 375 HP ! after couple of kilos driving, its goes buckling sound, bubble or like some electronic issue... when i accelerate, it doesnt accelerate normal and RPM moves very slow, please if you have any suggestions or advice, I really appreciated.

 

Classic. Just because there are receipts for a job does not mean a good job has been done. Add that to people who call a beltchange a major service and you got failing Ferraris that were "serviced."

 

so wait, I'm a little confused. If your ECUs were swapped why would that make the car run on 4 cIlinders? I have a P 1448 that pops up after every ecu reset...im losto...please educate me.