MDP questions? ?
 

Can the MDP sensor be used to monitor vacuum conditions?

I ask this because I cannot get a vacuum reading. Boost (MDP) in EvoScan reads in the 50s at idle which I know is incorrect because of the vacuum condition at idle.

I assume most of you will tell me to get the JDM MAP sensor and be done with it.

nope. i think all of our sensors are MAP only even the stocker. thats why the map to maf patch is really just a MAF emulator-this misguided me when i originally ported the stuff over.

would be great is there was a two way pressure sensor heh....

correct me if i'm wrong please.

EDIT: please do tell me there is vacume resolution on the JDM 3bar and i'm wrong. if so, i'm buying one right now.

^MAP sensors measure absolute pressure. From -14.7 and up. Meaning vacuum is seen as pressure by them. So yes there is vacuum resolution, if that's what you're asking about JDM MAP...

OP, stock MDP is a 1 bar, meaning it should show vacuum values.. Maybe Evoscan calculation/address is wrong?

what should the EvoScan calc be???

i never quite understood that. i *thought when the pressure between the vacume source and sensor equalized from negatives to 0psi, then the map sensor would report accurate values after that point to 14.7psi say for a stocker 1bar. i'm seeing this in my logs.

to OP, i get your same issue when logging the MAP with evoscan--i gave up a while ago lol. i'll check this out in detail again tonight.

thanks

atmo isn't 0v on the MAP sensor, its like 1.6v.

so anything under 1.6v is considered vacuum.

I dont know what formula to convert -psi into hg/mm (orwhatever vacuum is measured in)

1.6 on a 3bar MAP :)

i have the crappy usdm MAP. it's a hair under 4v or so it says lol.

i tried manipulting the cal tables a while ago to the usdm linear curve, but i still couldn't get proper vacume tunability [with bez's code]. i'll try again as maybe i gave up too quick lol.

Multiply psi by 2.036 (or to make it simple, just 2) to get in. hg.

My question still remains......what should the proper calculation be set as in EvoScan for reading the MDP???

depends on the MDP. what one is it?

Stock

The reason for my request is because I am working on the MAP to MAF patch. I have my car running pretty well but I cannot get accurate with VE if I don't have accurate vacuum.

what the 1bar version?

Yes.

I am also running the 94170015 with your 5.10 mods. You really are the man!{thumbup}

hrmm not sure what the scaling for the 1bar map sensor is. actually isn't it in evoscan already?

Thats the problem. I cannot get a vacuum reading. The Boost(MDP) setting in EvoScan never goes negative. At idle it hovers in the 30s.

just logged the MDP:

meh i guess it works lol.

one of the reasons i'm late/don't post logs/code all the time is the BS i went through to make this all align up.

See how the MDP is positive though? Shouldn't it be reading the negative vacuum condition?

the PSI identifier in EvoScan 2.6 is not correct i guess. should be like random_number_scaling lol j/k.

That is what I have been trying to get at. EvoScan does not read the MDP correctly....I think.

you should be able to edit stuff. you would have to have a another logging source to compare and then correct scaling values with. i'm not sure if someone has done this yet as i have not searched.

OT: thats how the map to maf values look when logged correctly. notice that the MAF is being used the whole time for this log as the value is always lower.

The proper eval in evoscan for the JDM MAP is
(obviously replace 14.3 with whatever you standard ATM is

Considering the JDM MAP is a 3 bar and stock is 1 bar, I'd assume
should get you pretty close. Then just log with the car off if you know your standard ATM and you should be able to adjust the multiplier accordingly...

Obviously please post the results if you get them.

If that doesn't help maybe looking at MRfred's "log a JDM map" thread can help. You could take a look at some of the values in the tables there to see if you are close.

That will get you pretty close for psi units.

This should be a little closer:

The stock MDP sensor is a MAP sensor as far as I can tell from my testing. The "14.5" value needs to get adjusted for your altitude. Higher altitude requires a lower value. There are tables on the internet to get the proper value for your altitude.

I adjusted Boost (MDP) in EvoScan to this 0.36*0.19347*x - 14.3

What other settings need to be changed in EvoScan....i.e. Gauge Min and Max, and Chart Min and Max?

Nothing else needs to be adjusted unless you plan to make output show up as a gauge in EvoScan.

Cool Beans ! ! THANKS

I will get to logging. Hopefully I can get the MAP to MAF to solve idle problems with hard intake pipes and big cams.

I am close.....so close.

IT WORKS ! !

I can now log vacuum conditions and boost up to about 2.2 PSI. This will help to try and get MAP to MAF configurations correct for idle with big cams and hard turbo inlet pipes.

THANKS a ton ! !