fooling the map sensor

[bandit86]

looking for a fix on the web for a fix to my drastic FE reduction form 27-30 on the tps (according to sgII) I found this on the web for enriching the mixture after the engine is modified, could it also be used to lean it out for low speed driving?

Looking at this circuit, a plain variable resistor could be spliced in line of the 5v feed, hooked up to a microswitch on the pedal so that if the pedal is pressed more than a preset amount the resistor will be bypassed and the vehicle will function as intended, or kept lean as the driver saw fit.

[Joenavy85]

if you want to cook your engine, go ahead. i personally wouldn't mess with the MAP sensor to tweak the F/A ratio, no different than messing with the IAT sensor for FE. if you run too lean you'll burn pistons (one of the issues that NASCAR had racing at daytona this year), if you know the system intimately you can probably be able to adjust it and know exactly what the ratio ends up being, if not i wouldn't risk the engine for the potential benefit.

yes, it could work, but it's risky

[suspectnumber961]

With an 86 Nissan truck I found that by using resistance on the TPS and the CHTS I could lean it out...but saw no real mpg gain by doing so...some power loss...and might have been overheating it.

I put a bypass switch on the CHTS resistance so it would start in colder weather...and I could lean it out so much with the TPS resistance...that it wouldn't run.

I used small pots that I put into a panel on the dash...adjustable while driving.

This kind of thing might work if you had additional mods like fuel vapor or ????

And each vehicle is different?

http://www.nonags.org/members/nijqk/Sensor%5Fmods%2Edoc

[ATaylorRacing]

When raising turbo boost in the 80-90 turbo Dodges we'd put a resister into the map sensor wire so that it would not see how much boost we werre running and would not shut off the motor at about 14 psi....BUT, to run more than 14 psi we'd stick some extra cold start fuel injectors from a VW or Saab and have them hooked up to Hobbs pressure switches so as each higher level of boost was hit another injector would be turned on so there would be no leaning out and parts melting/breaking. A guy named Paul Smith had a woodie Dodge Caravan with a basically stock motor running in the low 12s while using a bunch of those injectors and pressure switches used in series!