ECU reset procedure, how to confirm reset

bmessina · Post by **bmessina** » 20 May 2013, 13:17

Hi,

I tried to reset my computer over the weekend, but I don't think it worked. I had the battery negative cable off for 3-4 hours while I was checking and re-checking somethings. Before I hooked it back up, I got in the car and applied the brakes a few times and moved the key to starting position a few times as well.

Hooked the battery back up and checked some readings via OBD before I started the car. Specifically, I wanted to see if my LTFT had gone back to zero. I figured it would if the computer had reset, but it had not. It was still at a +10 with the car off. Started the car, it stayed at +10 for a minute or so before it started adjusting. That it didn't change immediately when the car started is what makes me think that the ECU hadn't reset, it remembered that value like it's supposed to (except after a reset!).

What's the accepted ECU reset procedure for a '96? How can I confirm that it has been reset after?

Post by **JRL** » 20 May 2013, 14:12

Post by **JRL** » 20 May 2013, 14:21

You tape the two (removed) cables together, this is known as a hard reset.
(Have your radio code handy)!
Nothing bad happens, actually if nothing else only good happens.
This can reset some nasty stuff that otherwise can be hard to reset.

Leave them tied together for at least 30 minutes

taupehat · Post by **taupehat** » 20 May 2013, 15:01

Why do I get the feeling some censorbot is erasing the name of the cables? Either that, or poor bmessina is going to go nuts trying to find which previously-removed cable he should tie together, and by what magic (literally) that will reset the ECU.

Now I'm really curious what name the cables could possibly have to get such a response from the censorbot.

bmessina · Post by **bmessina** » 20 May 2013, 15:20

Battery?

taupehat · Post by **taupehat** » 20 May 2013, 15:32

bmessina wrote:Battery?

I'm pretty sure he's not recommending you tape the battery cables together!

Edit: I've just been informed that he may well have meant just that. Presumably after disconnecting them from the battery...

Best to let JRL get a chance to reply here, just in case there are some complexities you should be warned about.

bmessina · Post by **bmessina** » 20 May 2013, 15:53

Yes, obviously after they've been disconnected. I'm fairly certain that's what he meant, the battery cables. I think I've seen that mentioned someplace else before.

bmessina · Post by **bmessina** » 20 May 2013, 21:18

Did the 30 mins with the battery cables tied together, can't tell if it worked. LTFT was the same, so it definitely didn't seem to reset that. I pull that and put the spare ECU in, that definitely changed the trims at least (duh).

bmessina · Post by **bmessina** » 21 May 2013, 23:51

So after 2 days with the spare ECU, the trims are... odd. Running condition is basically the same (woefully underpowered, can't rev past 4kish, died after warming it up this afternoon) but the fuel trims look normal. LT is less than 1%. No codes, via generic OBD or an LED hack circuit. O2 sensor seems to switch like normal.

Here's an OBD log from my drive home tonight:

https://docs.google.com/spreadsheet/ccc ... sp=sharing