Maxima Forums - Maintaining ECM Memory

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Maintaining ECM Memory

Simple but elegant:

http://www.autosportcatalog.com/index.cfm?fa=p&pid=52

This might come in useful for those who have had their timing advanced.

Re: Maintaining ECM Memory

[QUOTE]Originally posted by y2kse
[B]Simple but elegant:

http://www.autosportcatalog.com/index.cfm?fa=p&pid=52

Hmmm. How does that work, do you plug it in before disconnecting the battery, seems like it could turn into a bomb if that's the case.

Or is there a small windows of time where settings are still remembered after disconnecting the battery, giving you time to plug it in?

Re: Re: Maintaining ECM Memory

[QUOTE]Originally posted by grey2002_ny

Quote:

Hmmm. How does that work, do you plug it in before disconnecting the battery, seems like it could turn into a bomb if that's the case.

Or is there a small windows of time where settings are still remembered after disconnecting the battery, giving you time to plug it in?

I imagine you'd probably plug it in just before you disconnect your battery. And if you did that, I doubt a 9V battery would produce enough amperage to turn your battery into a bomb. :eek:

Re: Maintaining ECM Memory

Quote:

Originally posted by y2kse
Simple but elegant:

http://www.autosportcatalog.com/index.cfm?fa=p&pid=52

This might come in useful for those who have had their timing advanced.

im having mine advanced later this week by a local performance shop. i spoke with a guy with a 2k who had his advanced almost 9 months and took it back in to check to see if it had adjusted. it was still at +1 from -2 or 18 from 15. The reason he came back in was that he had disconnected the battery while the car sat for a while. im not sure if anyone has had trouble keeping the settings. ill certainly post if my settings are lost.

Re: Re: Maintaining ECM Memory

Quote:

Originally posted by sloppymax

im having mine advanced later this week by a local performance shop. i spoke with a guy with a 2k who had his advanced almost 9 months and took it back in to check to see if it had adjusted. it was still at +1 from -2 or 18 from 15. The reason he came back in was that he had disconnected the battery while the car sat for a while. im not sure if anyone has had trouble keeping the settings. ill certainly post if my settings are lost.

Good info, sloppymax. My suspicion is that the ECM contains different kinds of memory just as a regular computer contains different kinds of memory. Some of its memory may be volatile and some may be non-volatile. If I'm correct, then settings programmable by a Consult are probably stored in non-volatile memory. That would mean that disconnecting the battery would have no effect on them. But some people may want to back up their ECM memory anyway just to be on the safe side. And $16.00 is a cheap enough price to pay to do that.

By the way, if your friend had his ECM adjusted from -2 to +1, his advance is not currently set at 18 degrees BTDC. Remember that a setting of 0 equals 15 degrees BTDC. That means that his timing was adjusted from 13 degrees (15 minus 2) to 16 degrees (15 plus 1). He can still advance his timing another degree and remain in spec.

Last but not least, there's an interesting note in the Electronic Service Manual regarding timing changes. It says that the throttle position sensor harness connector should be disconnected before advancing or retarding the timing. You guys with an ESM can check this out for yourselves It's on page EC-733 of the manual.

Re: Re: Re: Maintaining ECM Memory

Quote:

Originally posted by y2kse

Good info, sloppymax. My suspicion is that the ECM contains different kinds of memory just as a regular computer contains different kinds of memory. Some of its memory may be volatile and some may be non-volatile. If I'm correct, then settings programmable by a Consult are probably stored in non-volatile memory. That would mean that disconnecting the battery would have no effect on them. But some people may want to back up their ECM memory anyway just to be on the safe side. And $16.00 is a cheap enough price to pay to do that.

By the way, if your friend had his ECM adjusted from -2 to +1, his advance is not currently set at 18 degrees BTDC. Remember that a setting of 0 equals 15 degrees BTDC. That means that his timing was adjusted from 13 degrees (15 minus 2) to 16 degrees (15 plus 1). He can still advance his timing another degree and remain in spec.

Last but not least, there's an interesting note in the Electronic Service Manual regarding timing changes. It says that the throttle position sensor harness connector should be disconnected before advancing or retarding the timing. You guys with an ESM can check this out for yourselves It's on page EC-733 of the manual.

im glad you said something about disconnecting the tps harness connector because i have not seen anything concerning that. the guy i know isnt a friend, so ill let his timing stay where it is.:D can you give me a heads up on disconnecting the tps connector? im planning on taking it either wednesday or thursday. also, any idea why its supposed to be disconnected? thanks for the info y2kse.

Re: Re: Re: Re: Maintaining ECM Memory

Quote:

Originally posted by sloppymax

im glad you said something about disconnecting the tps harness connector because i have not seen anything concerning that. any idea why its supposed to be disconnected?

My guess . . . and this is only a guess . . . is that the position of the TPS affects timing. If I'm correct, then you probably want to set the base timing without allowing the TPS to affect it.

Thats a great idea!

NOTE: Your cars ECU holds the program info in an EPROM or PROM. They do not lose their memory when power is disconnected. If the memory would be lost, your car would never run agian after the battery was disconnected.

Re: Re: Re: Re: Re: Maintaining ECM Memory

Quote:

Originally posted by y2kse

My guess . . . and this is only a guess . . . is that the position of the TPS affects timing. If I'm correct, then you probably want to set the base timing without allowing the TPS to affect it.

ive got a haynes manual for the 4th gen, is there anything to disconnecting the tps and is it located in the same position as a 4th gen?

Before you guys disconnect the TPS harness connector, you may want to check this out:

http://forums.maxima.org/showthread.php?threadid=183297

I don't know if disconnecting the connector has anything to do with the problem my tech ran into, but I'll try to find out and let you know.