I want to slow it down
On The Tree
iTrader: (11)
Joined: Jan 2011
Posts: 123
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From: The forsaken tundra of Minnesota
Setup your IAT to a parallel resisistor engaged/disengaged with a relay. Size the resistor to park you at the furthest right or left side of the IAT timing table. Subtract like 15 deg timing from that part of the table.
Should convert the car from a raging race car to a gutless turd with the flip of a switch.
Should convert the car from a raging race car to a gutless turd with the flip of a switch.
Setup your IAT to a parallel resisistor engaged/disengaged with a relay. Size the resistor to park you at the furthest right or left side of the IAT timing table. Subtract like 15 deg timing from that part of the table.
Should convert the car from a raging race car to a gutless turd with the flip of a switch.
Should convert the car from a raging race car to a gutless turd with the flip of a switch.
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.
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.
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.
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.
Last edited by NoGo; May 31, 2012 at 04:28 PM. Reason: being polite
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
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.
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.
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