[sai_ace]

Originally Posted by shyamhegde

Then remove the positive terminal also and try

Some of the basic type of keyless entry systems (mostly provided by dealers as free offer) tend to forget the key codes if battery is kept removed more than half an hour and needs to be re-programmed. So just have look on the user manuals before trying to keep the battery terminals disconnected for long hours.

positive terminal? but the instructions in this forum asks us to remove the -ve terminal. why is that so?

i will be checking this with my alarm guy though.

[shyamhegde]

Originally Posted by sai_ace

positive terminal? but the instructions in this forum asks us to remove the -ve terminal. why is that so?

i will be checking this with my alarm guy though.

I was just kidding. Sorry about that.
Check with the user manual, it might carry some inbuilt battery or so to keep it alive even when the battery terminals are disconnected.

[sai_ace]

Originally Posted by shyamhegde

I was just kidding. Sorry about that.
Check with the user manual, it might carry some inbuilt battery or so to keep it alive even when the battery terminals are disconnected.

thats ok. but the problem is..this is a used car, so i dont have any manuals with me - none at all.so was wondering if any of the experts here could shed some light .

[sanju.sreekumar]

I replaced my O2 Sensor on my Ford Ikon 1.6 today because it was damaged. But i do not see any difference at all. After enquiring with my mechanic he said that i need to run for around 50 kms before the ECU is rightly mapped. Is this the case?

[sai_ace]

Originally Posted by sai_ace

guys,

I dont know if I have missed anything, but when I remove the negative terminal from the battery of my Alto Vxi, the theft alarm siren goes off. As a temporary measure i have removed the siren plug, but can still see the alarm goes off.

what do i do for this?

sai.

any help from the experts?

[prithwi-81]

Most Modern ECUs have two feul and timing tables/tunes. One is the default stock tune which is on a erase resistant rom.

Next there is the LEARNED tune, which the car builds over a period of time based on a number of parameters. These can range from quality of Feul used, knock correction, driving style, ambient air pressure, etc... The car LEARNS these values over time and applies the respective correction factors to the stock tune.

In some cases this correction may improve performance, for example if the stock tune is for 85 octane fuel, and your put in 93 octane, the knock threshold of the car goes up, and the ECU will add timing, lean out the air feul mixture and your power level will increase. In some cases these corrections DECREASE performance, for example you drive in heavy traffic, and the car heats up and the ECU pulls timing, and adds feul to cool the mixture to prevent the car from knocking/stuttering.

Resetting the ECU as the thread states, clears or zeros out the learned table/tune from the ECU and the car returns to the factory tune and the learning starts all over again. Here is the kicker, clearing the table may increase power temporarily but eventually as you get back to your daily routine, the car will come back to the old power levels.

Now here is the CAUTION part. Not all car engines are made equal, two engines of the same specs from the same factory can have slight variations due to imperfections in manufacturing/processing/assembling. The ECU learns these variation over time and compensates the original tune to prevent your car from.. say blowing up/breaking down. For example, if your car is running a little lean on one cylinder, in the first 500kms the ECU figures this out and compensates for it by adding feul. When u reset the ECU it deletes this correction, and your engine may begin to have issues.

So if you are the recipeint of a slightly flawed engine,(believe me there are a LOT out there) and you reset the ECU, you effectively are back to square one and are increasing wear to your engine.

Bottom line, resetting ECU has its ups and downs, so know the risks before you do it.

[Rehaan]

Great post prithwi,

Originally Posted by prithwi-81

....So if you are the recipeint of a slightly flawed engine,(believe me there are a LOT out there) and you reset the ECU, you effectively are back to square one and are increasing wear to your engine.....

Thats something i had never thought about. (Though temporary).

Check this thread out as well : http://www.team-bhp.com/forum/techni...u-ecm-ems.html

cya
R

[im_srini]

Originally Posted by prithwi-81

For example, if your car is running a little lean on one cylinder, in the first 500kms the ECU figures this out and compensates for it by adding feul.

Hi Prithvi, a n00b question here... Short of having an O2 sensor in each primary, is this possible ?

Or is it that the ECU detects an overall lean condition & richens up the mixture for all cylinders ? If this is indeed the case, is it better to have 3 cylinders run rich compared to one running lean ?

Thanks...

[prithwi-81]

Originally Posted by im_srini

Hi Prithvi, a n00b question here... Short of having an O2 sensor in each primary, is this possible ?

Or is it that the ECU detects an overall lean condition & richens up the mixture for all cylinders ? If this is indeed the case, is it better to have 3 cylinders run rich compared to one running lean ?

Thanks...

The answer varies from car to car. Most Japanese Imports have a one knock sensor and one O2 sensor for all cylinders. Depending on what inputs these receive, they add or remove feul to ALL cylinders.

Most high end german cars have an O2 for each exhaust runner. So they may correct individual cylinder a/f ratios.

Technically its BEST to have all cylinders run the perfect mixture. Having 3 cylinders run rich while one runs JUST perfect builds up muck on the pistons, cats, exhaust etc... Similarly having one cylinder run rich and the rest running lean will have similar effects on the knock threshold and detonation resistance of the engine. Most ECU's keep fluctuating between these two extremes.

I know my EVO can from the factory with a lean condition in cylinder 4. No way to correct it without a retune and even with a retune, it just ensure that the A/F ratio never drops to too lean by adding a little feul to all cylinders..

[the_maassk]

Background - I have an Aveo U-VA (10 months old). After 3 months of owning it, I changed to a K&N stock replacement filter. A couple of weeks ago, I switched to synthetic engine oil (Mobil 1) and also changed the spark plugs to iridium (don't flame me on the sparks, it is a courtesy from a friend who will take them back if I don't see a change in engine response). The car has done 8k on the odo till date.

Because it was a new car, I was extra careful in the initial months of driving and would not sprint it or anything. Over a period of time, as I got used to handling it, my driving style is a little aggressive now (not excessively aggressive though). Immediately after the engine oil change, I noticed that the engine load (as shown by ScanGauge) dropped by 2%. I was happy. However within a couple of days, the engine load value came back to original. I can feel the smoother idles and smoother running of the engine with the synthetic though. A new problem seems to have cropped up now - the car is a little rough when picking up from stand still. I often have those 'jerks' while picking up. Also, downshifting from third to second gear is not smooth at all! Unless my RPMs in third gear are down to 1k or below, the second gear jerks. So I am being forced to actually kind of 'lug' the engine in the third gear!

My question is this - because of my extremely conservative driving in the beginning, the ECU might have created its initial maps. With all the changes in the engine and my driving style, the ECU would try to learn those changes (but will be slow in relearning). Should I try an ECU soft-reset? What are the drawbacks of doing that? What driving pattern should I follow after the ECU reset?


Note from Team-BHP Support : Thread MERGED. Please use the search feature before creating a new thread on a topic that might already exist. Please continue your discussion in an existing thread. This will keep all the relevant information in one place and make it easier for readers in the future.

[prithwi-81]

The answer to your question is COMPLICATED.

First a few pointers on engine oil... DONT change to synthetic unless your car comes with synthetic OR your running a BIG *** TURBO on the car.

The Evo 8 i had earlier and the Evo X i just got both have HUGE turbos and hence come pre-filled with synthetic. The STI on the other hand has a slightly smaller turbo and comes pre-filled with regular oil. ONLY after I put on a GT30R did i switch to synthetic due to its high temp oil breakdown resistance and also did a FULL retune.

For an Aveo i cant even imagine why one would switch to synthetic oil, unless your living in rajasthan or ladak.

I'd suggest you switch back to the regular oil that your vehicle manual recommends. The synthetic oil is generally lighter than the regular oil that your car came with and is what showed up as a lightened load. Initially this may have been a kick, but all this time your car may have been misfiring, and the ECU had to do all kinds of ****(which usually means pumping in more feul) to keep the engine from knocking. THAT is why you felt your 'temporary' increase in power. Now while you were feeling the power, your ecu figured out the proper mixture of Air/feul to prevent the car from knocking and misfiring. Hence the load returned to normal.

Now your car's current jerky reaction could be one of the two scenarios i'm going to state:
BEST CASE- Your car learned the new timings required to keep it from knocking. BUT The synthetic oil is not designed to slow down the crank as much as regular oil would, so your getting the knock while shifting up the RPM, as well as sudden load increases while shifting down also. Your essentially overspinning the crank. SOLUTION- Go back to regular oil, do a ecu reset and you should be fine. It'll be a little rough during the learn in period (roughly 500-1000kms).

WORST CASE- Your cylinders have built up sludge due to the misfiring. When you misfire due to ANY condition, the ecu's first reaction is to reduce timing (the spark comes on earlier and detonates the mixture before the compression stroke is fully completed). So now you have x amounts of air and feul but only y amount of feul gets burnt off, and rest is left as residue. Now due to the lighter synthetic oil your engine balance is off. Inertial of the crank/piston from the ignition phase is slowed down by the engine oil to ensure smooth compression. With a lighter than usual oil the engine inertia is not completely lost and hence even if the ecu pulls/reduces timing, the inertial of the piston causes all kinds of havoc during the ignition, potentially damaging your pistons, crank, bearings etc. Add to this the constantly buliding sludge in ur cylinders and you get the picture. This also explains your jerkyness.

SO.. get your car checked out. Pull out the ignition timing tables and knock correction tables (if you have the tools for it) or take it to a dealer for them to have a look. Have then pull the plugs and see the gunk buildup. Also switch back to the OEM oil.

Originally Posted by the_maassk

My question is this - because of my extremely conservative driving in the beginning, the ECU might have created its initial maps. With all the changes in the engine and my driving style, the ECU would try to learn those changes (but will be slow in relearning). Should I try an ECU soft-reset? What are the drawbacks of doing that? What driving pattern should I follow after the ECU reset?


Note from Team-BHP Support : Thread MERGED. Please use the search feature before creating a new thread on a topic that might already exist. Please continue your discussion in an existing thread. This will keep all the relevant information in one place and make it easier for readers in the future.

[the_maassk]

Woah ! You have scared the living daylights out of me man. Your opinion on synthetics is totally contrary to what almost everyone on TBHP suggests.

Does any of the oil gurus on the forum have a second opinion? I don't want my engine dying!

[sanjz]

Woah ! You have scared the living daylights out of me man. Your opinion on synthetics is totally contrary to what almost everyone on TBHP suggests.




Ashishbhai dont get too perturbed with all this technical jargon. All you need to do is just change the pump you get your fuel topped from. Its just a plain and simple case of bad fuel. See i was facing the same problem , and since we last met i have even had the ecu of my car remapped i am now developing a good 15% more power than my stock values, yet had this persistent knocking. Changed my fuel bunk and voila no knocking issues.The other white Getz also had same issues , Not anymore the knocking and roughness of the car is history now.

[the_maassk]

Thanks Sanjay! Although I did not change the petrol bunk I get a fill from, I did switch from Normal + System G to Speed on the last half tank (wanted to verify Vishal's claims about premium fuel). Could it be because of this change? Guess I'll go back to Normal + System G on the next fill.

So you had a ECU remap ! Hmmm. Where did you get it done...Vishal's? I have tried to hunt as much info as possible for a remap on my engine. Have not had much luck yet. I guess I'll wait for my FFE job before I think of a remap anyways.

On a seperate note - I am still thinking of an ECU reset. The only think I am worried about it the Autocop and how it will behave if I disconnect the battery.

[veishal]

Amazing aint it. Please remember yours in not the first car on synthetic oil, the rest of the premium fleet with much more power and torque to account for are running on synthetic for ages now in India. The knock in your car is purely fuel related and thats a very typical problem on account of the naptha being added at the refinery level in the fuels delivered in gujarat in the summers. Now this is done to compensiate for the volumetric losses due to vapourisation at the warehouse of the refinery. Naptha has a tendency to form hard deposits at the small orifices in the fuel lines including your injectors. To avoid this situation, either you use your car for a longer distance during the course of the week or use an additive with an octane booster to ease out the roughness in the idling. You still are not able to help this situation, please drive down here and i would get your throttle body serviced.

Thoda daaba ke gaadi chalao yaar, gala [throat] khol ke.