IRISH IS THE MAN!!!!

I sent a PM to Irish as follows:

-------------------------------------------

Hey, Irish..

I've been looking at 6SpeedOnline for an hour and I’m getting bits and pieces but I need to confirm something with you. Once I confirm it, I will post it so somebody else like me doesn't bother you with the same question.

I have an 07 DB9 Sport Auto (although from what I read, its the same procedure for a stick)

I am replacing the battery (what a shock eh?)

The "Coast Down Procedure" is:

1. Car needs to be at operating temp.
2. Drive car safely up to 70mph, with the a/c off, in "D"' or manual allowing car to reach 6th gear.
3. Once 70mph is reached, allow car to coast to 30mph, without hitting the brakes or turning the steering wheel more that 10 degrees
4. Repeat 2 & 3
5. Repeat 2 & 3
6. Repeat 2 & 3 (4 times total with no detection equipment)

NOTE 1: If you hit the brakes anywhere during the process, it will abort the sequence. That process won't count and you will need to do it again. With your experience, 4 successful procedures "should" relearn the sequence. You won't know unless AM dealer checks.

NOTE 2: With a battery replacement, you will need to reset radio pre-sets, window dip, and seat memory.

Do I have it right?

-----------------------------------

Irish replied:

Yep, that's good.. The coast down is actually called "Misfire Factor Corrections" ..attempts required depends on coasting speed, coasting on a flat grade learns faster, if on a upward/downward grade it will take a few more than normal to learn

Irish

 

just a couple of questions ,,,does this misfire relearn need to be done everytime codes or mil are cleared with an obd ii scanner, or is this for when battery has been disconnected ... and with manual gearbox when coasting down to 30mph does
car have to stay in 6th gear when accelerating up again, or do you do normal gear changes back up to 70mph....thanks for any more info
.

 

I think it is just for battery disconnect / replacement but wait for definitive answer from Irish... he is the man.

I don't think it matters either way for shifting.

I have an auto w/ paddle shifts and the transmission shifts as it likes in auto and will down-shift to prevent too low of RPM even in "manual" mode.

Again, Irish can confirm.

Richard

 

No they don't need to be learned after a code clear. But they will need to be learned after a battery disconnect. Unless you have a dealer who has saved them on the scanner and can restore them. Yes just leave it in 6th gear on the coast, then once 30mph is reached down shift to get back to 70mph.

 

What's the benifit of doing this? I have replaced my db9 battery and I find car stuttering at 38 MPG DOES THIS PROCEDURE HELP IT?

 

It will help to diagnose which cylinder(s) are causing the problem. Yes you should definitely do it.

 

How does it tell me which cylinder is/are causing problem? Can you please elaborate?
Thx

 

Mine's been idling rough but wasn't showing any misfires on the OBD scan. Thanks to the excellent write-up at aston1936.com I was able to see that the misfire correction factors hadn't been learned, so I got out on the road in the wee hours and got it done.

Now I'm starting to see an occasional misfire on the OBD scan, so new plugs and coils are definitely in my future. (39K miles)

 

Aaarrrgggg! or perhaps Aaiiieee! I'm keeping notes on all of the tips 'n procedures which are causing me sleepless nights at this point. As far as this battery swap / coast thingy is concerned; I have a new Optima Red Top in the garage which I want to install as soon as I get the V8V off the carrier. Can I changeover and not have to mess-up settings by keeping 12VDC on the cables from the 4Runner battery or charger...?

 

Hook up a battery tender while doing the battery swap and you should be fine.

 

Telum

Not that a lot of the new battery tenders / maintainers do not show any voltage unless there is a load. With no battery, no current

 

Use the cable designed for the specific purpose of battery replacement, and an appropriate voltage source, to supply voltage to the car while the battery is disconnected.

https://www.6speedonline.com/forums/...-my08-v8v.html

 

Can this Misfire Factor Corrections procedure be done by putting the rear wheels on jack stands?

 

I had that exact same question in my mind but than I thought it's unsafe if jack stand or lift fails and if you are at 70 MPH you have a huge disaster at hand.

 

Excellent point
The question then should be, "Although not recommended, can this procedure be done with the rear wheels on jack stands.