Where in a 87fsm does it mention resetting the ECU??

I might be the cause of the remarks about the series four not having any memory. I've yet to see a thing about it in the manual. Ever.

There is one wire to the ECU that is a constant 12v 23hrs a day. It's the BTN fuse. So if there is such a thing as erasing the memory on a series four, it would seem you could pull the BTN fuse and do what ever you do then reinstall it.

By the way, I pulled the BTN fuse a few weeks ago and started the engine and idled it. Saw nothing peculiar at idle. Did not drive it though. Might do that. Aw heck, why not, it's a nice day, just some other items related to lights that won't work. I'll get back later.

 

I drove without the BTN fuse in the car. Drives normal. Except I put the car in cruise, worked, then stepped on the brake pedal. OOOOps. BTN feeds brake switch so no stop of the cruise. Key off, then restart while driving. Killed cruise.

One thing of note though. AS I pulled out of the driveway and went down the street, my ECU code led gave me a 02 sensor light. That's normal for my car when cold. Step on the pedal removes the light, then when warm it goes away all together.

So BTN has nadda to do with codes on a series four. Has a bunch to do with the brake switch though. humor.

I'll settle for Icemarks explanation of the BTN fuse.

 

The only injectors firing while cranking are the primaries, and they're buried deep under the inlet manifold. So you must be unplugging the secondaries, which don't fire until after 3800rpm. Besides, even if they were firing, if you've read the posts above you'll realise unplugging any injectors is totally unnecessary. There are much simpler and quicker ways to unflood the engine.

 

Maybe I'm remembering that from the S5 FSM. Anyway there must be something stored in the ECU, even if we don't know what it is. Otherwise there's be no need for a constant battery supply. I leave mine connected for the whole 24...

 

i thought the injectors that you could see above the manafold are the primary injectors i guess mine must be really messed up because all mine fire and not just two of thats what i just thought thanks for the info.