Greg Fell

iTrader: (9)

the diesel guys use EFILive to do this. there are some pretty trick setups where you can have a 5 way switch, and its a different load per setting. they also make 2 way switches.

MikeyZ

iTrader: (20)

if he cant handle the power why are you letting him drive a rocket? buy him a civic and save somebodys life...

charchri4

iTrader: (11)

Wouldn't the computer also change the fuel mix by doing this?

white01ss

iTrader: (37)

Yes this will work but is a horrible way to do it. It will cut power across the entire throttle range but the air and required fuel is mostly the same.

For example, to cruise 40 mph the vehicle needs to make 50 hp at 12% throttle. Lower the timing and now it makes 25hp at 12% throttle so it'll need another 12% just to keep that speed. You just cut your mpg in half. Also, other tables such as fuel enrichment/engine protection may get activated with the elevated fake IAT which will further waste fuel and dirty your plugs and oil.

The best solution is some sort of physical throttle stop on the actual throttle pedal. All he needs is 15-20% pedal which would keep him out of trouble. There may be a way to do this in the tune as well.

Whatever you decide to do I hope you share your results. Good luck!

Technically yes. Some fuel may get pulled by o2 trims but I would not expect by much.

NoGo

iTrader: (2)

If the car is open loop SD it will create a noticeable shift in fueling. To the cold side the table it would make it richer to the hot side it would lean it out. Closed loop or with MAF it will just be a blip and should get quickly situated by the STrim/Ltrim. Sure, some of the transition fueling will change.

My TA (which is open loop SD) ran for a while with a nitrous timing circuit. The switch moved the IAT from ambient to -32 deg. On an 80 deg day, if I hit the switch it only moved fueling 0.5 A/F points or so. The only place I really noticed it was at idle. Other than that, the car drove much the same.

So does it shift the fueling...maybe. But if it does, its not enough to matter to a kid who shouldn't be driving that fast anyways.

NoGo

iTrader: (2)

Changes are isolated to higher g/cyl cells, so no affect on highway driving etc...

As far as the protection limits that's not an issue and the reduced timing will not dirty your plugs and oil. These cars run just fine with a handful of degrees pulled out of the timing table.

white01ss

iTrader: (37)

You're right. The lower fueling part of the IAT reduction table doesn't pull timing at all. I still have a valid point, but you are more right than me!

Someone needs to check the truck's tune and log it while cruising to see how much (if any) timing is pulled and reduce those light throttle areas. After pulling up some old logs I found that if my car had such a switch that it would start pulling timing around 55 mph, but this car and it's driver are not the most fuel minded so the truck's spark reduction speed is likely much higher.

Thanks for being polite!

From IAT Table:
g/cyl Max Retard
0.20 0*
0.24 -1.4*
0.36 -5*
0.76 -8*

Avgs from various logs:
mph throttle g/cyl
30 5% 0.15
40 8.7% 0.18
45 9.9% 0.20
50 10.5% 0.23
60 12.5% 0.28
75 18% 0.37

NoGo

iTrader: (2)

Personally, if I was doing this, I would adjust the stock timing IAT table in the column that the relay pushes the IAT on to negate any timing pull below 0.6 g/cyl (or somewhere around there).

That way it stays isolated pretty much to roll-on and WOT.

I agree though, that this is the ghetto way of doing it. A better solution would be some sort of valet program or something.

This way works though and only costs a few bucks for a relay and a resistor if you know what your doing.