[Did a search for this before posting, plenty of threads on CAI mods etc but did not see this particular mod. Pls move or delete if already exists and I missed it.]

Was just wondering if anyone's tried this particular mod - varying the signal from the inlet air temperature sensor to make the ECU think the air is slightly colder and thereby advance the ignition timing; this would potentially allow some power gains from higher octane petrol.

http://www.autospeed.com.au/cms/A_110896/article.html (scroll down just a bit)


So what, I wondered, would happen if I altered the signal the ECU saw from the intake air temp sensor? Since the lower the intake air temp, the greater is the engine’s resistance to detonation, if the ECU was convinced that the intake air temp was actually lower than it really was, it could be expected to run more ignition timing advance. That could in turn well suit the higher octane fuel.

I'm not even sure where the inlet air temp sensor is on 3rd gens. Is it integrated with the air flow mass sensor?

Any thoughts? Anyone done/tried this?

Cheers,
Aj

Yep, part of the MAF sensor.
I'd just buy a SAFC w/timing change to alter it...

Thanks. An SAFC sounds expensive though. If I can easily identify the air intake temp sensor, adding a series resistor along the lines described in that article will cost me a couple of dollars at most. I guess the real question becomes, will the Magna ECU sufficiently advance the timing so that an actual gain can be felt when using higher octane fuel?

Also, I have no real idea if all air intake temp sensors work the same, i.e. colder = more resistance, hotter = less resistance which is true for most semiconductors. Easy enough to experiment and measure if I can isolate the temp sensor from the rest of the MAF sensor.

I'd spend $500 and get a custom tune done on your ECU. Then you can add timing, take out/add fuel, do whatever the hell you want, and do it safely with zero guess work! That's just me though.....if your going to do a modification, do it properly.

I've been boggling over this for a couple of months also. All this effort to cool the intake air when its unsure if the MAF/ECU compensates for increased air temps - from things like heat soak applied to the actual air or the heat soak to the MAF itself. Over cooling either way could cause the ECU to enrich the mixture maybe? Just a theory. I've read about ECU's kicking into "lean burn" on some cars and it involves hotter intake air temperatures.

Here's a chart, created using EVOScan data logging software, from a short drive in my Magna. I have refined version of the "snorkle mod" on my intake. From what I can gather cooler air doesnt effect the timing advance. Timing advance appears to be controlled by things like throttle position and calculated load (not shown on this chart). Cooler air MAY affect AFR - dropping to 12.9 as the intake air temp' drops... could be a load thing to.

http://i.imgur.com/xM3hO.jpg

I've also tried to insulate the MAF but didnt see any dramatic changes. This was prior to me learning about things like "lean burn"... and since reverting back to the theory that the engineers at Mitsubishi are probably a lot smarter than me, and I shouldnt f#$k with things too much.

I am still keen to try running heatshields around the intake and MAF though.

;1356358']I'd spend $500 and get a custom tune done on your ECU. Then you can add timing, take out/add fuel, do whatever the hell you want, and do it safely with zero guess work! That's just me though.....if your going to do a modification, do it properly.

Fully agree with you on that! Just can't afford the $500 or so for a ECU reflash right now. One of these days...

Here's a chart, created using EVOScan data logging software, from a short drive in my Magna. I have refined version of the "snorkle mod" on my intake. From what I can gather cooler air doesnt effect the timing advance. Timing advance appears to be controlled by things like throttle position and calculated load (not shown on this chart). Cooler air MAY affect AFR - dropping to 12.9 as the intake air temp' drops... could be a load thing to.

Thanks for the detailed reply. Must get me one of those EVOscan cables + software soon. I know there's a few threads with info on which to buy etc.

Looking at your chart though it does seem to me that there is a relationship between the intake air temp and the amount of ignition advance. Do you see it too? Every place in the chart where the air intake temp dips, the ignition advance peaks.

I've read somewhere that the ECU will retard timing if the intake air gets too hot, but it won't advance timing if the air gets colder, instead the ECU adds more fuel for the denser air (more oxygen in cold air).

But the best thing might be to get a AFR kit and experiment (doing it without knowing if there's an impact on AFR might result in wasted fuel or a toasted engine)

I've read somewhere that the ECU will retard timing if the intake air gets too hot, but it won't advance timing if the air gets colder, instead the ECU adds more fuel for the denser air (more oxygen in cold air).

But the best thing might be to get a AFR kit and experiment (doing it without knowing if there's an impact on AFR might result in wasted fuel or a toasted engine)

Thing is a wideband kit will set him back $250 anyway. I still say saving for a tune is a better idea. And you are right, it will pull timing when the air gets hotter.

I've read somewhere that the ECU will retard timing if the intake air gets too hot, but it won't advance timing if the air gets colder, instead the ECU adds more fuel for the denser air (more oxygen in cold air).

There is a specific table for this purpose in the stock Magna ECUs that I have examined, but none of the stock ROMs I've looked at apply any adjustment to the timing regardless of intake air temperature. One of the things SKR do as part of a reflash is to change this table to retard timing when IAT climbs, to minimise the chance of detonation.