ECU Reset - Why and should I?

[FORDavid]

I recently read the guide on how to reset the ECU. I have some idea of what it does but can someone give me an explanation as to the benefits of reseting. Is there any problem issues that can happen due to doing a reset?

Thanks in advance.

(thinking about reseting my AUII Fairmont Wagon)

[FORDavid]

anyone got an info on this? even just a link because search brings up nothing

[grandpa_spec_F6]

From what I hear (don't quote me on this) people have claimed anything from improved fuel economy to increased power to doing absolutely eff all.

Some on here swear by resetting the ecu regularly, others think it's as useful as hooker with buck teeth.

Edit: After doing it a couple of times to mine I haven't noticed any great performance or economy increase, just a reset fuel consumption and average km's guide.

[Jack91]

Id like to do it, but Ive heard for the first 100km's or so the car runs like a pig and stalls. I think a big highway drive after any mods would have the same benefit.

[Dave_Obsession]

Originally Posted by DAVO_XR

Id like to do it, but Ive heard for the first 100km's or so the car runs like a pig and stalls. I think a big highway drive after any mods would have the same benefit.

I had this issue - it's all about the ECU relearning the 'stall' points - where it needs to boost the revs when it's under extra load - use of air con etc...

So after you follow the standard reset procedure:

Originally Posted by www.aufalcon.com

- Reset Computer by disconnecting battery (Take off the positive terminal lead)
- When power is re-connected, start car and idle in this sequence
- 2 minutes idling with the transmission in drive and A/C on.
- 2 minutes idling with the transmission in drive and A/C off.
- 2 minutes idling with the transmission in neutral and A/C on.
- 2 minutes idling with the transmission in neutral and A/C off.
- Drive the car on the road, for at least 5 minutes under variable throttle positions.

What I found was that it took a couple of days driving (around 100kms) before it really settled down - whilst driving around, I found that the longer I was sitting at idle (at lights etc), it was almost like you could 'feel' the engine learning again...but obviously it's not healthy to let the engine idle for 20 minutes in one hit...

I had the engine stall on me a couple of times (while going around corners, which wasn't fun since the power steering and brake booster die as well - made for some hairy moments!), but generally the more idling you do, the faster the ECU learns where the idle points are...

I found when I did mine, suddenly the car felt a lot more responsive and smoother. Probably fair to say that the effects wear off once the engine 'relearns' everything, but FWIW, I reckon it's fine to do - especially after you've done any mods, should let the engine start afresh and relearn everything under the 'modded' system....

Reminds me, I should probably do mine again, hasn't been done since I had headers, cat and exhaust put in

[LukeyST]

Originally Posted by dave93761

- 2 minutes idling with the transmission in drive and A/C on.
- 2 minutes idling with the transmission in drive and A/C off.
- 2 minutes idling with the transmission in neutral and A/C on.
- 2 minutes idling with the transmission in neutral and A/C off.

How crucial are these steps? When i put my new exhaust on the other day i disconnected my battery (was off for a few hours) and for the first 50-100kms it did the usual idle fluctuation every time i went into neutral or put the clutch in. Do these fluctuations DEFINITELY mean that the ecu has been reset without the above steps?

[Highway]

I had a miss in my AU when I tramped it, so I just reset mine. and found it to drive a lot better then it did B4. still has the miss only sometimes now but I have only drove it for about 10 mins.. but is a big improvement on how the car was.

[Highway]

I just used my watch.. and let it run about 5secs over at the most and had no problems.

[19RIP]

Hi guys and sorry to dig up an old thread but looking at doing this to my AU Series III SR soon; its doing some crazy stuff.

When you say the car "learns" the driver/mods, is it better to drive it harder or more conservative ??

The reason I ask is because my mate had a Mazda MPS 3 and if the car was driven hard over this "learning period", the car had a more aggresive, sportier setting...

[FGII-XR6]

Originally Posted by 19RIP

Hi guys and sorry to dig up an old thread but looking at doing this to my AU Series III SR soon; its doing some crazy stuff.

When you say the car "learns" the driver/mods, is it better to drive it harder or more conservative ??

The reason I ask is because my mate had a Mazda MPS 3 and if the car was driven hard over this "learning period", the car had a more aggresive, sportier setting...

drive it as you would normally drive it so it learns your normal driving style

[rowan194]

Does the SR have adaptive shift mode or whatever it's called? That's the transmission, anyway, not the ECU.

The main reason I do an ECU reset is to stop the car shuddering at idle and high load (eg in reverse at 0% accel, with rear demister and headlights on, then the A/C compressor kicks in and the whole thing shudders like it's about to stall). Over time, several months, the ECU seems to "forget" and the shuddering gradually creeps back in, so I reset it again. I've never noticed any change in fuel economy.

[rayhines]

I got a AU I 1999 Forte Wagon, converted to gas.
It was running rough and missing, so my gas guy diagnosed new plugs and leads and tweaked the computer settings. Seemed ok but on way home it backfired once. Then for next few weeks it would backfire at least once a day. Eventually it got a bit worse, missing, even on the highway, and to the point it almost stalled. I switched to running on petrol only, which was better, no backfire but after a while it also missed and ran rough occaisionally. I was thinking it may be electrical - like the coil pack arcing?

Went on holiday for a month and came back - the battery was flat. I charged it and started it on gas - it drove like a dream, no backfire or missing, smooth idle even with AC on. Conclusion - resetting the computer due a flat battery fixed all the problems! My mechanic had no idea about this, wish someone had suggested it months earlier, saved me running on petrol for a few months at more cost!

[auIILTD]

Originally Posted by rayhines

I got a AU I 1999 Forte Wagon, converted to gas.
It was running rough and missing, so my gas guy diagnosed new plugs and leads and tweaked the computer settings. Seemed ok but on way home it backfired once. Then for next few weeks it would backfire at least once a day. Eventually it got a bit worse, missing, even on the highway, and to the point it almost stalled. I switched to running on petrol only, which was better, no backfire but after a while it also missed and ran rough occaisionally. I was thinking it may be electrical - like the coil pack arcing?

Went on holiday for a month and came back - the battery was flat. I charged it and started it on gas - it drove like a dream, no backfire or missing, smooth idle even with AC on. Conclusion - resetting the computer due a flat battery fixed all the problems! My mechanic had no idea about this, wish someone had suggested it months earlier, saved me running on petrol for a few months at more cost!

You will probably find that your car will tend to go back to it's old habbits. Resetting the ECU does nothing more than erase the learnt long term fuel trims. These trims are designed to pull or add fuel to compensate for engine wear, changes in air flow - both intake and exhaust. Ideally, your trims should only be erased when you have made a change that will impact on the air / fuel flow through the engine - such as exhaust / CAI etc.

There may be other 'items' erased with a reset too, but I certainly are not aware of them, and I have not read of any in my tuning research.

Hope that clarifies a bit.

Cheers
Stu

[rayhines]

Originally Posted by auIILTD

You will probably find that your car will tend to go back to it's old habbits. Resetting the ECU does nothing more than erase the learnt long term fuel trims. These trims are designed to pull or add fuel to compensate for engine wear, changes in air flow - both intake and exhaust. Ideally, your trims should only be erased when you have made a change that will impact on the air / fuel flow through the engine - such as exhaust / CAI etc.

There may be other 'items' erased with a reset too, but I certainly are not aware of them, and I have not read of any in my tuning research.

Thanks for your comment Stu - You would not believe it, but yesterday your prediction came true, I started up and found the accelerator was lagging badly, I had to stamp my foot to get out of idle, which was rough, and soon experienced a backfire. When I got back from the shops, I disconnected the battery, reconnected a couple of hours later and drove to work with all running smoothly! I didnt drive in any special way as suggested earlier on resetting the ECU, the simple reset did the trick. It has taken about 2 and half months to revert back to problem running.

I would like to know what Ford engineers have to say about this issue?

cheers,
Ray

[Lajon]

i have a 99 fairlane.. i have changed the air filter to a pod, have had the transmission serviced with a shift kit installed, changed the fuel filter and changed my diff fluid which i'd say hadn't been changed in a looooong time.... is it worth resetting after all this work? i'm also putting on a set of 18 inch rims..should i wait till these are on?

[auIILTD]

Originally Posted by Lajon

i have a 99 fairlane.. i have changed the air filter to a pod, have had the transmission serviced with a shift kit installed, changed the fuel filter and changed my diff fluid which i'd say hadn't been changed in a looooong time.... is it worth resetting after all this work? i'm also putting on a set of 18 inch rims..should i wait till these are on?

Lajon, read my post above. Resetting the ECU simply erases long term Fuel trims. Your Pod filter, yes will have an impact, but as for the other stuff - no. Reset your KAMS (keep alive memory) based on change of engine breathing alone.

Gents, this thread should be called reset Long Term Fuel Trims, not reset ECU, as long term battery disconnection as far as I know only erases LTFTs (or KAM). I am happy to stand corrected by someone else more in the know.

[FGII-XR6]

it also resets learned transmission data and DTCs that may have been transient faults but remain active

Originally Posted by auIILTD

Lajon, read my post above. Resetting the ECU simply erases long term Fuel trims. Your Pod filter, yes will have an impact, but as for the other stuff - no. Reset your KAMS (keep alive memory) based on change of engine breathing alone.

Gents, this thread should be called reset Long Term Fuel Trims, not reset ECU, as long term battery disconnection as far as I know only erases LTFTs (or KAM). I am happy to stand corrected by someone else more in the know.

[AUFanboy]

Originally Posted by auIILTD

Lajon, read my post above. Resetting the ECU simply erases long term Fuel trims. Your Pod filter, yes will have an impact, but as for the other stuff - no. Reset your KAMS (keep alive memory) based on change of engine breathing alone.

Gents, this thread should be called reset Long Term Fuel Trims, not reset ECU, as long term battery disconnection as far as I know only erases LTFTs (or KAM). I am happy to stand corrected by someone else more in the know.

There's also adaptive idle control - the ECU will remember how much it has to open the IAC valve to maintain idle speeds under different conditions. This corrects somewhat for dirty IACs, throttle bodies dirty/not set quite right etc. This is why (combined with fuel trims) they often idle like crap after a reset. But yeah I agree, lots of vodoo around the ECU resetting thing! It definately won't make the car go faster.

[Lajon]

before i changed the fuel filter the car was saying that that I'm using 14.2L per 100kms... if i reset the ecu do you know roughly how many i need to drive before it will give me a new accurate number?

[ICF67]

I havent been able to read all the comments, but what about te process in au3 xr6 manaul? all comments i seen seem to be auto related

[Maka]

Originally Posted by ICF67

I havent been able to read all the comments, but what about te process in au3 xr6 manaul? all comments i seen seem to be auto related

Hi & welcome to AFF ICF67, while its a good idea to reset the ecu in AU's, please be mindful a few owners have disconnected their battery & ended up having some issues with their AU2 & 3"s smartshield security system which cost them some good $$$ to fix.

If you dont want to chance it, your ecu will still learn any new parts installed after a few days anyway.

If you do put the new parts in, drive it in all variable conditions still - part to full throttle & air con on at idle & all through the rev range for a little period of time, your ecu will pick up the changes.

Let us know how you go one way or the other, good luck!!

cheers, Maka

[Oxmate]

I have a BF XR6 and my ECU is over heating is there away to fix this? The problem i have is the only error code that comes up is P0420 for the catalyst. I also just newly bought a trans coolant box. I issue's are it drives good cold but when it gets to a certain heat it jumps in and out of limp mode and when that starts happening i go to stop (brake) and the engine stops. I restart the car it idles good put it in drive and it cuts out again. I did a test waited till this happened again and poored cold water on the ECU untill it was cold and the problem went away.