MAP

[dirtymike]

anybody here know how to test a MAP sensor. Thanks Dirty

 

[RonD]

Just Google: ford map sensor testing

You need a Multi-Meter than can read frequencies, Hertz, Hz

 

[dirtymike]

Guess i better check my meters. Dirty

 

[RonD]

MAP sensors are not too expensive, even motorcraft brand($40)

But testing is best, and you should also have a hand vacuum pump with gauge, so you can test it, engine off, with steady vacuum source

Local airport website will have current barometric pressure at time of testing


When you first turn on the key the computer gets current barometric pressure from MAP, and that's the baseline pressure it uses in air/fuel calculations, this is mostly for elevation above sea level, i.e. is engine at 200ft, 1,000ft, 2,000ft, or 5,000ft(Denver) above sea level, this is a big deal for air/fuel calculations
So a "no vacuum" test is needed first, if that is off then MAP is bad

 

[dirtymike]

getting 5 volts and a good ground but the hertz are 2.55 and wont decrease once vacuum applied. Supposed to be 152 with no vacuum in KOEO mode. Odd I never had to change out a map. Dirty

 

[dirtymike]

getting code 1 and 34 with KOEO and 1 21 34 77 with KOER. Dirty

 

[RonD]

There is no "1"
1987 should use 2 digit codes, no "0's" either

List is here: https://www.therangerstation.com/tech_library/2digitcodes.shtml

21 means the 2 wire ECT(engine coolant temp) sensor is unplugged or failing
This has nothing to do with dash temp gauge, it uses a 1 wire ECT sender

34 is EGR code, does your 2.9l have an EGR system?

77 is a goose test code disregard

 

[Dirtman]

Not to highjack but since @RonD Is here. Is it safe to clean a map with MAF cleaner? Mines got gunk all over the bottom but don't wanna screw it up...

 

[RonD]

Yes, you could squirt some non-residue cleaner, like MAF sensor cleaner, into the vacuum port, then drain it and let it dry out a bit before using
Cleaning the outside is, of course, fine, and the connectors

There are 2 chambers inside with a diaphragm between them, one has the vacuum port, the other is sealed and has the pressure sensor electronics
Inspect for cracks in housing, if cracked its most likely bad/unusable

You would just be cleaning out the one chamber of dust so not sure it would do much??
But unless the diaphragm was bad it wouldn't hurt, and if diaphragm was bad then MAP was bad anyway, lol

 

[dirtymike]

Sounds like a plan. Ill pull her , clean and test again. Ill look at that temp sensor to. Dirty

 

[franklin2]

Code 21 can happen if you pull the codes before the engine is warmed up. The engine must be between 50F and 250F or the computer will set code 21.

The "1" was probably the factory fast codes going by.

If he has the EGR system my truck had, they are famous for the pressure sensor going bad. If everything is hooked up factory. If you have gutted the cat and have a straight through muffler on it, you will probably never get rid of the EGR code.

 

[dirtymike]

Yea i figured the code thing out, just trying to get to idle at a normal speed. It want to idle around 1000+, after warm up. Trying to clean the MAP sensor. Its the original. Its strange there's a part number on a sticker that reads E6EF-9F479-A1A and under the sticker is an embossed part number E7EF9F479A1A, no dashes. Dirty

 

[PetroleumJunkie412]

IIRC, there are two map sensors for 87 2.9... With and without egr. Egr sensor has a barometric pressure port on it, non egr does not.

I could and did run the baro sensor on my 88 non egr. Not sure if you can run the non egr sensor on a egr truck.

 

[dirtymike]

This 2.9 has the egr system

 

[PetroleumJunkie412]

Will need a sensor with baro port, then.