MAP readings KOEO?

Turbo1dr

New member
What's the KPA reading of the MAP sensor suppose to be with the key on; engine off? I have one that's showing 54kpa. It has a 2 bar sensor but I thought it was suppose to read 99-103. Customer is complaing about low performance.
 

Turbo1dr

New member
Re: MAP readings KOEO?

You're thinking about BARO pressure...which is around 99-103kpa. Map sensors should display the same kpa reading until vacuum or pressure is applied to the port. Trouble is, the scan tool is displaying half of what it should read with the engine off.
 

Jimmy

Banned
Re: MAP readings KOEO?

You're thinking about BARO pressure...which is around 99-103kpa. Map sensors should display the same kpa reading until vacuum or pressure is applied to the port. Trouble is, the scan tool is displaying half of what it should read with the engine off.
Right on.

There are guys here that have forgot more than I know,so I'm sure you will get an answer.

Good luck.

You may wanna search around here a bit.
 

JSM

Active member
Re: MAP readings KOEO?

Your right should be near 100 depending on current weather etc.
 

sly dvl

Ya, it's got a Turbo
Re: MAP readings KOEO?

Whoops! Right you are. I forgot about the 2nd bar. Too many years working on N/A engines...
 

Turbo1dr

New member
Re: MAP readings KOEO?

BTW, this trunk was a stolen/recovery that had a campershell, regular S-10 wheels and hardly looked like a Syclone when the customer bought it. There's no telling what the number of the ECM/CalPack/Chip is actually in the truck. I'll have to do more investigating...
 

turbodig

Active member
Re: MAP readings KOEO?

What you're seeing is a bug... the stock baro routines don't always work correctly.

Pull ECMB, and re-try the key-on sequence... eventually you'll get it to read in the 97-100 area.

Basically, the ECM is looking for ignition voltage to be in a 4-9v range, which is only supposed to happen as you're turning on the key- ie, voltage is "coming up" to full system voltage.

The downer is that the same thing happens on key off. If the motor is running as key off is done, it can actually pull a bit of vacuum as the motor is still spinning.

The 54.x value is actually a default that gets used when the routine gets confused.

I've been working on this part of the code for quite some time, but I still don't have it quite correct.
Furthermore, I don't really trust the readings of the sensor when the voltage is less than full, so I'm not sure the key-on is entirely valid.

*EDIT* - rereading this again - You're saying *MAP* is at 54.x at key on? That would again point to a default, a dead MAP condition.
Alternatively, if you had a 3 bar sensor plugged into a truck with a 2 bar chip, you might see numbers like that.
 
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