EFI tuning? What can you do with stock ECU

[Tom86]

Hi everyone,

I was wondering what does the Mechanic actually do or check when they "Tune" your engine?

My 4agze on a stock ECU in the sprinter is running a little rough at the moment and if I was to take it to the shop. What can they do that I can't do myself at home to make it run good again? I'm I right to say that with stock ECU you're limited to playing with the timing and the TPS? or is there more to it?

Tom

[thechuckster]

factory ECU is not programmable - all you can do is set the timing wrong or change the spring tension in the AFM (if the ECU uses one - and it's a bad thing to do anyway). Changing TPS position will do nothing except get wrong idle and trailing throttle behaviour.

[Turdinator]

What a mechanic refers to as a tune up is usually just check the plugs, change the oil, check the timing and check for fault codes etc. Not tune the ecu.

[Ta22boy]

As well as clean out the throttle body, check leads for resistance to check if they are ok...but really thats about all, if your car is still running bad after that, start checking your ignition, and fuel...and you'll prolly find your problem...

Cheers
Scott

[mikie_121]

I heard that some ECUs also compensate for a wearing engine. Like they retard timing slightly etc. to try and keep an aging engine running ok. When i had my 3sge done they had to properly reset the ecu.
Or i might be regurgitating BS.

[celica_john]

resetting a 3sge ecu is done by pulling out the efi fuse for 15 seconds.

autospeed have done articles where they've added a turbo to a car originally n/a and used the ecu. from memory they disconnected the oxygen sensor and used a rising rate fuel pressure reg

nothing goes past a good aftermarket computer and a good ecu tho!

[Turdinator]

I heard that some ECUs also compensate for a wearing engine. Like they retard timing slightly etc. to try and keep an aging engine running ok. When i had my 3sge done they had to properly reset the ecu.
Or i might be regurgitating BS.

I believe that the ECU learns when you have bad fuel that causes knocking and retards the timing.

eg If you bought a car with a 3SGTE from somone who never used premium fuel the ECU would run the engine with less advance even if you start putting optimax in all the time. But if you were to reset the ECU and run it on optimax you would see an improvement as there would be more advance.

[Mr Revhead]

resetting is a myth
the ECU is constantly making adjustments within its preset parameters.

they only time you need to do it is to clear stored fault codes.
its not a magic fix to make your car go faster when youv fitted a pod filter.

[JustCallMeOrlando]

That's not entirely true, but it is dependent on the ECU. I've not looked recently at any current Toyota ECU's, but I can't imagine they're terribly dissimilar. Subaru ECU's since the mid 90's at least will limit performance based on an initial knock level that it determines once the ECU is first turned on (i.e. after being reset). This value only slowly goes up in periods without knock. Many people have had good results by resetting the ECU with a fresh batch of 98RON and some octane booster. Because the ECU controls boost pressure and timing, it makes a difference.

Of course a 4AGZE ECU isn't that smart

[Lachie]

I believe that the ECU learns when you have bad fuel that causes knocking and retards the timing.

eg If you bought a car with a 3SGTE from somone who never used premium fuel the ECU would run the engine with less advance even if you start putting optimax in all the time. But if you were to reset the ECU and run it on optimax you would see an improvement as there would be more advance.

I dont think thats right. My understanding has always been that when the ECU keeps advancing the timing until it picks up knocking on the knock sensor, then it retards the timing, but this is not permanent. If you put in a higher grade fuel, the knock will not occur until the timing has been advanced more, so the ECU will run this timing.

This means you will always run at max timing for the fuel you are using. It also explains why my car makes more power by simply putting in 98RON fue, without having ot reset the ECU

[Mr Revhead]

that is my understanding and experience as well.

[Turdinator]

I stand corrected. My knowledge about ECUs learning comes from when i was into nissans. Toyotas must be different. Appologies.

[Nim]

It's the same with Honda Fuel Injection. If you run a better fuel, the car will start to re-tune itself. Apparently it takes about 1-2 tank loads before it's finished re-tuning itself for the new, better petrol. For any Honda with the PGM-FI anyway.

[EldarO]

it "learns" by itself, but to quicken the speed at which it learns, you reset it.

Elmo.

[Nim]

it "learns" by itself, but to quicken the speed at which it learns, you reset it.

Elmo.

I can't speak for a Toyota, but I know for PGM-FI this isn't a good idea. It takes longer to re-tune itself from a re-set than it does just by changing the petrol.