Cattman,

Have you changed out your battery recently? There have been cases where we have lost flashes due to a lack of power and the ecu re-setting itself. We do not put flashes on our cars with "kill switches" for this very reason.

I am not saying this is the case but I would be curious if you had.

 

I have the same LWFW and I haven't noticed any drop in performance. I find it engine speed gets up very quickly and revs a lot quicker when you are moving through the gears.

 

Another reason to use the OEM trickle charger.

 

Good point North

 

This isn't unknown - especially if you have some mods on the car. It's caused by the ECU not adapting properly; why, I have no idea. What you're left with is a car with the ignition timing backed right off - probably retarded 12 or more degrees. You will have lost about 40BHP and yes, can you ever feel it. The car is just an embarrassment - I know, it's happened to me! We found the problem (if not the reason for it) using my local independent's PIWIS tester.

Thankfully the cure is quick and simple. Disconnect the negative terminal of your battery and leave it disconnected for a couple of hours or more. What this does is reset your DME to factory and restart the fuel and timing adaptation processes from scratch. It is important to make sure you leave the battery disconected for an extended period of time. For some reason a quick disconnect doesn't seem to reset everything.

Once the battery has been disconnected for a couple of hours, re-connect and drive the car normally. You will get some warnings - PASM etc, but these normally reset themselves after a couple of hundred yards. If they don't reset then stop the car, switch off, leave for a few seconds and switch on again; the warnings will be gone. Your car should now be back to normal and will likely be quicker than it has been for ages.

Let me know how you get on

 

Thanks for all the helpful suggestions, folks.

I think I'll call my service guys today and run some thoughts by them. Maybe find a dyno somewhere in ATL this week.

If I follow Ian's advice, and disconnect the battery, I will most assuredly lose the flash, as Kerrigan says, is that right? I've not lost battery juice, not even once.

This is a sad mystery, hopefully to be resolved soon.
CATTMAN

 

Cattman,

Generally just unplugging or a quick battery swap will not be as bad as letting all of the residual or stored power be drained out of the multiple ecu's through out the car.

Sometimes to reset the ecu's you can unplug the battery and run a long screw driver between the positive and negative cable ( with out being hooked to the battery! ) to drain down the stored power. This action or the battery being unpluged for hours I feel could potentialy effect an ecu flash; if you did not have the software yourself like what Softronics offers.

Sorry you are having this problem, wish we had an answer for you.

 

Keep us updated Cattman! Hope you get it resolved rather soon.

 

I didn't not know you could loose a flash by having the battery disconnected??? I had a GIAC flash and during my SC kit install (3 weeks of no battery or trickle charger) I had to have that flash removed (taken back to stock) because it was incompatible with the new SC mapping..

Are we sure you can loose a flash??????

 

I have lost flashes in cars with the "kill switch" feature. I have not done a recent flash on an ecu since 2007. I have steered away from them because of not having the control of actually seeing what you get for your money. That is why I am very interested in the Softronic hardware, where you can control the flash and see things on your own computer.

We had a similiar thing with a SC modification in our shop where the battery was unplugged for months and the flash remained. So all I am saying is it is a proven possibility with the 997 learning ecu.

I do not want to create any alarm or panic but it has happened to two of our earlier cars that raced in the Koni Challenge with no other explanation than the flash was un-learned with extended periods of no power.

Once again though I am speaking of the early generations of these flashes.

 

Disconnecting the battery absolutely will not lose a reflash. The flash process writes data to non-volatile memory space on the DME chip and these settings are retained even during prolonged disconnections of weeks, months or more. The re-flash replaces the factory maps in the memory space on the chip. The factory program doesn't 'disappear' if you disconnect the battery so nor will the program (your custom map) that has now replaced it.

Go ahead and do the disconnect and all your troubles will be over in a couple of hours.

 

Interesting.

When an ECU is reflashed, data on the non-volatile memory of the chip (non-volatile = retains settings when powered-down) is erased and replaced with data from the tuner. This base data - all the fuel and timing maps and control data - is retained irrespective of the length of time the control unit is powered down. Non-volatile memory doesn't require power to retain data.

Once the control unit is in use, the unit learns to a certain degree. This is primarily from data it receives from the MAF and lambda sensors and the car's knock control system. The unit then creates a set of adaptation values that to a small degree tailor the base maps to the individual engine. This data - the adaptation values - is held in volatile RAM and is lost when the unit is powered down. As soon as the unit is put into use again, the adaptation processes start anew and another set of values is created and stored automatically. These values can be viewed with a PIWIS. The adaptation values are in theory constantly monitored and adjusted by the control unit.

I think what you will have lost isn't the base reflash - if you looked at the maps in the units' non-volatile memory they would be exactly as flashed - but the adaptation values. Running the ECUs again would have recreated these values over a few miles.

What's happened to Cattman's ECU is the adaptation process has effectively 'crashed' and gone to minimum values. Resetting the control unit will let it rebuild correct adaptation values for his engine

 

Ian,

I am glad you have chimed in because you obviously have a very good handle on the 997. I will PM you to speak more specific about the effects we have found with using a "kill switch" on the 997.

 

Kerrigan,
Perhaps you can share that information here- I know people are interested in understanding this.

Regardless, if I do re-flash, I assume it's best to find a local dealer so they can perfect it with my car on the dyno, rather than sending my ECU in to some tuner far away, is that correct?
CATTMAN

 

a dealer or good p-car car mechanic shop can reflash you back to stock ECU program as a starting place. I had to do that once when SG could not undo my GIAC re-flash. I went to an indy and they reflashed me back to stock. $210...