[me_sid]

Dadu thanks a lot for the useful bit of information, I will try it in my Baleno..

[Jr Godzilla]

The ECU reset as expalained by Dadu should be carried out each and every time you do a change, eg change spark plugs, clean carb, cleaning replacing sensors, pcv, replace timing belt, and anything connected to engine replacement parts.

Infact you will note that in all DIY articles the first step is to disconnect -VE terminal.

thanks dadu on point No. 5 & 6!!

[AbhiJ]

Great Thread.

So if I think that idling in my new car is a bit rough, can reseting the ECM help?

[dadu]

No harm in trying anyways, it doesnt bring any ill-effects.

Originally Posted by AbhiJ

Great Thread.

So if I think that idling in my new car is a bit rough, can reseting the ECM help?

[rks]

Originally Posted by dadu

These steps will properly reset your ECU, drive normally. The Vehicle will feel sluggish initially but will catch up once the ECU learning curve is over.

I have some doubts here regarding the ECU learning curve. I am using Speed 97 in my Santro for the past 20000 kms or so. I have read that modern ECUs (post ~1998) have the ability adjust the ignition timing for a high-octane petrol if the car has knock sensors. But the learning curve apparently will be slow, and the car has to be driven for up to 5000 kms before the timing adjustment is completed. If the ECU is reset, does it have to start all over again? My car is due for timing belt replacement at 80000 kms (now it has done 76000 kms) and I assume ECU will be reset then.

By the way, my car seems to have fully adjusted now to Speed 97. After my last service at 75500 kms, I have felt the need to ease off on the pedal on the Expressway, as the car races past the 150 kmph mark in many stretches. Sanjay Hyundai does an outstanding job of engine maintenance and their maintenance engineer claims that my car was tested up to 160 kmph on the Nashik highway.

[dadu]

Thats not true, specifically for the knock sensors(KS). The moment KS sends the knocking detection to the ECU the timings are reduced till the knock stops, thats why you see a loss of power if you keep the pedal pressed while its knocking. Its spontaneous.

Although the behaviour of the ECU LC is specific to the design by the manufacturer but generally there is no ECU learning beyond 100-200kms and then it tries to keep closest to the defined map in the ECU.

Originally Posted by rks

I have some doubts here regarding the ECU learning curve. I am using Speed 97 in my Santro for the past 20000 kms or so. I have read that modern ECUs (post ~1998) have the ability adjust the ignition timing for a high-octane petrol if the car has knock sensors. But the learning curve apparently will be slow, and the car has to be driven for up to 5000 kms before the timing adjustment is completed. If the ECU is reset, does it have to start all over again? My car is due for timing belt replacement at 80000 kms (now it has done 76000 kms) and I assume ECU will be reset then.

[rks]

Originally Posted by dadu

Thats not true, specifically for the knock sensors(KS). The moment KS sends the knocking detection to the ECU the timings are reduced till the knock stops, thats why you see a loss of power if you keep the pedal pressed while its knocking. Its spontaneous.

Although the behaviour of the ECU LC is specific to the design by the manufacturer but generally there is no ECU learning beyond 100-200kms and then it tries to keep closest to the defined map in the ECU.

The operative word here is "adaptive ignition timing" which at least some ECU's are capable of. See the following website:

Welcome to Land Cruiser Owners On Line

The higher the fuel octane rating, the less prone it is to detonation, hence the greater potential for ignition timing to be advanced further. – Again resulting in higher efficiency. However, we have no control over the ignition timing advance as it is adjusted by the engine management system.

In recent years, Toyota had been quite proactive in adopting advances in engine management and implementing them on the Toyota 4WD range. One of these advances was an ignition advance system that slowly advanced ignition timing to the point where minor detonation would occur and was registered by the engine knock sensors. The engine management system would then retard the ignition timing slightly and after a period of time without further detonation, slowly advance timing again. This ensures that the engine runs as efficiently as possible given the fuel quality available. The tuning industry’s term for this adaptive system is one that “runs on the knock sensors”.

This is not to be confused with less advanced systems that run a predetermined ignition advance map and use the knock sensors as a safety precaution to retard only when serious detonation occurred.
Prado petrol engines are equipped with adaptive ignition timing however the rate at which the timing advances is very slow indeed. In addition, if even minor detonation is registered at one part of the RPM range, the entire ignition map is retarded across the entire RPM range.

When high octane fuel is used, the likelihood of detonation is diminished and the engine management system can advance the ignition timing further than that with standard fuel. Resulting in higher efficiency, greater power and torque as well as reduced fuel consumption.

However, in the range of Prado petrol engines, the rate of ignition advance is very slow indeed. This means that one needs to run high octane fuel for many km before any change in performance or economy is fully realised. In the case of the 3.4L V6 in the 90 Series, 5,000 – 7,000 km and for the 4.0L V6 in the 120 Series, 3,000 km – 5,000 km.

Generally after one or two tanks full, the owner will give up and return back to standard fuel because he notices no difference – and does not realise that it takes so long. However if you persist, the benefits are real and quantifiable – more so in terms of fuel economy.

The 90 series Prado was introduced around 1996 and I am assuming that most modern ECU's, at least post 1998 or so, will have this capability of adjusting the timing for optimal performance (I did read that elsewhere but cannot recollect where).

There is no doubt in my mind that my Santro's performance has improved noticeably and I estimate the improvement in fuel economy to be between 0.5 to 1 km/lit. But whether this is due to Speed 97 or many other possible factors I am not very sure.

[dadu]

I had discussed knocking (wrt to timings too) in one of my threads, dont know if you read it.

Originally Posted by rks

The 90 series Prado was introduced around 1996 and I am assuming that most modern ECU's, at least post 1998 or so, will have this capability of adjusting the timing for optimal performance (I did read that elsewhere but cannot recollect where).

[rks]

Originally Posted by dadu

I had discussed knocking (wrt to timings too) in one of my threads, dont know if you read it.

Thanks for the link. It does confirm what I had expected regarding ignition timing.

[mdesai_1981]

hi guys i've got a 2005 chevy optra1.6 and i've done 28000kms on it. i bought it second hand at 13000kms last year and since then have changed the spark plugs, air filter and upgraded to castrol magnetec. so u think i should get my ecu reset as i havent done it. also should i get this done from a mechanic as i'm planning to go for a 2000km ride next week?

[dadu]

Follow Step 1 of Post #47 , then follow as below.

Step A - Ensure Ignition Switch is Turned OFF

Step B - Open the bonnet/ Engine bay and locate the Relay Fuse box (Its usually around the Battery).




Step C - Remove the Fuse Box cover by pressing the Clips on its sides(varies from model to model). On the underside of this cover is the Fuse Type layout. From the Fuse layout mark the position of the fuse marked as ECU or EMS or ECM (depending on manufacturer). It will usually be a fuse between 20Amp to 30Amp rating.




Step D - . In the fuse Box there is a supplied fuse puller, marked as red below. Pull that out.




Step E - Gently press the fuse puller on the head of the relevant Fuse, till it clicks and pull out the ECU/ EMS/ ECM fuse.




Step F - Wait for 1 min and then plug it back in gently with your hand using only your index finger for pressure, polarity does not matter with these fuses.

Step G - Replace the Fusebox Cover. Follow Step 5 & 6 of post# 47

The ECU is now reset. This method has an added advantage of not resetting any other electrical component settings like for the ICE, Power windows etc etc. An indication of the reset is that the digital clock part of your Odometer will be reset (if you have one).

PS: The pictures are used for illustration purposes only and might not represent the exact location of the Fusebox or the Fuse for your vehicle.

[KSM-Vtec]

@ Dadu - Thanx. Could you tell us the advantages of resetting the ECM. Just to give u a background, I have an OHC Vtec and had recently faced a prob with the CEL which is rectified now and she is back to normal. But otherwise ...what are the advantages of ECM reset?

[KSM-Vtec]

@ Domnic - Wanted to know why you want us to got for a fast spin?? Wont this reset to higher consumption of fuel, leading to lower FE? What happens if you got for a bumper to bumber city traffic drive? Or if you go for a low rpm slow drive on an open road?

Originally Posted by Domnic

* Now start the car and go for a fast spin for about 4 kms. The computer reads the extra airflow from the MAF then calculates for extra fuel and resets the map. The new variables are now stored. This works pretty good!. Ive seen major differences.

[Shan2nu]

I don't know how effective this really is.

Everytime i rip my car for 5 mins, the ECu gets charged up and the car performs brilliantly. But if i drive normally the ECU goes back into eco mode and the throttle response and acceleration bcomes a bit dull.

What is the main object of this ECU resetting technique? Coz i my car's ECU adapts to my driving style automatically.

Shan2nu

[dadu]

Once reset the ECU will put itself into 'agressive learn mode'. When it is in agressive learning mode, the ECU will keep pushing timing and fueling, until it starts to sense knocks, then it backs off. It does at all RPM's, under all loads. And this is done for its continous and non-continous monitors.

Eventually, it will have enough data and will exit the agressive learning mode. From there, it will still make minor adjustments based on the sensors.

Also read the thread fully, ECU doesn't learn your driving style so much, but of highs/ lows, temperature, air, etc which it gathers from the sensors.

Originally Posted by KSM-Vtec

@ Dadu - Thanx. Could you tell us the advantages of resetting the ECM. Just to give u a background, I have an OHC Vtec and had recently faced a prob with the CEL which is rectified now and she is back to normal. But otherwise ...what are the advantages of ECM reset?

Not exactly,read above. Unless you have a open map ECU, then its a different ballgame altogether.

Originally Posted by Shan2nu

I don't know how effective this really is.

Everytime i rip my car for 5 mins, the ECu gets charged up and the car performs brilliantly. But if i drive normally the ECU goes back into eco mode and the throttle response and acceleration bcomes a bit dull.

What is the main object of this ECU resetting technique? Coz i my car's ECU adapts to my driving style automatically.

Shan2nu