SXE10 ECU

[circuitR]

Heya guys,
I was wondering if someone could help me.
It seems that my Altezza dos'nt like running on anything less than 98 Octane. Even when I am running on 98, It feels like a dip in power just before the cam overlap. It's more noticeable when running on 96.

I spoke to a guy and he recokons you can reset the ECU by unplugging the battery over night and then the next morning you let it idle for 30mins while the ECU re-calibrates itself. And this will help with the octane issue.

I was wondering what you guys think.

[CozmoNz]

badluck dude, your problem dosnt lie with the ecu, but the fact that your running it on fuel that its not designed for.

Minimum of 100 octane . (revhead will be in here soon).... and im sure hell explain how the ecu works etc.

could try running 98 + some octane booster, and see if shes any better?


a few guys on here hate the stuff, others love it, so it just depends how you go...

[RomanV]

Have you driven any other Altezzas to compare?

Perhaps its time for a general service, eg. replace spark plugs, oil, coolant, etc. etc.

Or if you are convinced that it is a fuel issue, try running some octane booster perhaps... Is it worse when the engine is under load?

And BTW, the power bump at that RPM isnt due to the cams, its everything else (intake manifold etc.) coming into their efficiency range that they're tuned for, resulting in a bump in power.

Altezza motors have VVTI (Which adjusts the cam angles) As opposed to VVTLI (Which adjusts cam angles, and has two cam profiles, like a VTEC engine)

[dodgy]

Also could be your knock sensor if it was running ok previously. if its reading wrong, then it would be thrown into retard .

[circuitR]

Thanks for the prompt replies guys.
I did not think of the knock sensor. I might have a look at that in the weekend.
I have talked to a few people about octane booster and like Cosmo says, some like it and some don't. I guess that's another thing to try.

I might even get my hands dirty and check the plugs.

:RomanV: Thanks for explaining VVTI, I did not realise it was only cam angle adjustment.

Thanks for the help guys.

[RomanV]

Does your car have any mods?

Especially the intake?

Putting the air flow sensor in a larger diamater pipe could have unforseen consequences....

[circuitR]

The only mod is a cat back Apexi exaust.
It did originally have a TRD panel filter, but it was pretty stuffed. So I replace it with a factory one.

[Mr Revhead]

check ya timing

resetting ya ecu is a myth. the maps are programmed into it and the ecu will run as close to those as the sensors allow. they do not self programme.

it doesnt have a removable silencer does it?

also check plugs and leads

[jasestu]

resetting ya ecu is a myth. the maps are programmed into it and the ecu will run as close to those as the sensors allow. they do not self programme.

Are we sure it's a myth?

When in closed loop, the ECM modifies the final injection duration based on the oxygen sensor. These minor corrections are needed to maintain the correct air/fuel ratio. However, if more correction than normal (as determined by the ECM) is needed, the ECM will use the fuel trim strategy to compensate. Fuel trim allows the ECM to learn and adjust the injection. - http://www.autoshop101.com/forms/h44.pdf

Some talk on these forums here: http://forums.toyspeed.org.nz/viewtopic.php?t=31221

Also some discussion on the Altezza forum from this post onwards about the ECU 'out-learning' aftermarket piggyback units.

[Mr Revhead]

then why do they need piggy back ecus in the first place?
why do you need a fancy ecu when turboing etc?

and if they can adjust themselves in such a way, why do they need resetting?

[jasestu]

Valid points. From the sound of it they can only 'learn' within a certain range, so that's where piggy-back units come in - they can push it beyond the stock units defined max and min points.

As for why they need resetting if they learn, from what I've read it appears they learn quickly when they have a blank slate (i.e. after a reset). Once they've reached a steady state and you change something (e.g. intake flow) it takes much longer to adjust. The claimed benefit of resetting is to allow the ECU to re-lean the new environmental conditions.

The only evidence I myself have seen to suggest that learning occurs is that after resetting the ECU the idle speed changes (sits higher than normal initially). If I were to turn my car off (when hot) wait 5 minutes and then start again the revs would come to rest at about 500-750 rpm within 15 seconds. If I were to do the same, but reset the ECU during the 5 minutes the idle revs would sit at 1000 or over, and would only come down to the 500-750 mark very slowly (several minutes), and I think only after taking the revs above 3000 first. The revs appear to drop down in blocks until the ECU 'learns' the minimum rpm at which the engine can stay running.

[MikeMan]

then why do they need piggy back ecus in the first place?
why do you need a fancy ecu when turboing etc?

and if they can adjust themselves in such a way, why do they need resetting?

This does happen BUT there are limits on how far the fuel and ignition maps can be moved by the trim adjustment and most systems will only allow EXTRA fuel and less ignition timing to protect the engine from a lean or detonating state.

It maybe as far as 15 or 20% but that is not enough to compensate for a decent flowing turbo which is why you DO need an aftermarket ECU for serious mods.

[Mr Revhead]

yes, within small limits...... like i originaly said. but it will continue to alter itself within those parameters for the best possible tune. within its own limits. so "resetting" it wont achieve bugger all. certainly not in this case where it appears to be a mechanical problem

other than internet forums there is nothing anywhere about resetting ecus except for clearing faults.... no factory info and no one anywhere has ever privided any dyno info to suggest it. iv done a few runs in a dyno while swapping ecus around, and there was no difference from the first run with the ecu just plugged in, to the 3rd run with the same ecu having been in it the entire time.

now back to the original question....

another forum member has contacted me with a similar problem, and we have had a few cars in here with the same issue....
unfortunatly the customers havnt left the car with us long enough to solve it, but the thinking is its a failled vvt system. on the mechanical side, like a pully as all the electronics check out. however we havnt been able to confirm that yet