I think I am defueling at 24psi...

[TyCorr]

My stock php tunes didnt defuel, but set the SES light. My custim ones for stg II's didnt do either. No light, no defuel.

 

[jaybuller]

I guess I'm not defueling then just have the ses light..... No big deal at all to me.

 

[farmall99]

I get the light too at 24 but no defuel. On my insight, after it throws the light, it shows boost varying between 0 and 8ish psi until the light goes out and everything is back to normal. Whats up with that?

 

[yzrmbsg]

I get the light too at 24 but no defuel. On my insight, after it throws the light, it shows boost varying between 0 and 8ish psi until the light goes out and everything is back to normal. Whats up with that?

The MAP is trying to tell the computer to defuel, but your chip is overriding it. I'm assuming its just a glitch....?

 

[Charles]

The MAP is trying to tell the computer to defuel, but your chip is overriding it. I'm assuming its just a glitch....?

The Map sensor is just a sensor... All it does is report a voltage to the PCM based on input pressure. The PCM and it don't have any sort of power struggle or anything like that.

When the Map sensor reports a voltage equal to ~24psi to a PCM running a stock Ford calibration for at least _____ seconds the PCM will set a SES light and reduce power as it is programmed to do. If you simply change the parameter in the calibration of the PCM that explicitly tells it to set a SES and defuel when the Map sensor reports a pressure of _____ psi, then it will not happen.

The Map sensor is doing it's job, and the PCM has been instructed by the Ford software to reduce power and alert the operator that a problem is occuring via a SES light.

For years we solved the problem by disallowing the Map sensor to ever see this value, and that in turn kept the PCM from doing what it was told, setting a SES and reducing power.

The files I wrote for my 550 do not set the light, nor do they defuel thanks to a little tip from Matt at Gearhead. Those were the first files of mine that did not require a map sensor fooler.