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I have just changed my map sensor to a 3 bar one. I unticked the map A selection sensor type flag and ticked the map B to change it to 3 bar which it did. My maps stayed the same but the car is running rich and my manifold vacuum is still 21 inches at idle. but the logging shows it has gone from 30% to 50% at idle. I measured the map output without the engine not running and it reads 1.77 volts. I would think that would be close. Am I missing something in another setting?

with the engine off and ignition on the map sensor should be on 100kpa, if its not then its likely out of whack

when you say 30% and 50% are you referring to 30 kpa and 50 kpa (as the map is not a percentage)

Ive posted one of jaymes examples of setting the sensor type to a new question near the top of the faq.

Charlescrown wrote:I have just changed my map sensor to a 3 bar one. I unticked the map A selection sensor type flag and ticked the map B to change it to 3 bar which it did.

actually just noticed this .... are you referring to map b or map selection b ?

Think you might be right. I just had a look at the map ign on not running and it's reading 113 kpa. So that's a substantial amount of error. Yes its selection B so that's correct and yest reading 50 kPa. My mistake. Is there any settings that can correct my map error or should I buy another one?

I used a 3 bar sensor off ebay in a car a while ago now. but it did sit pretty close to 100 kpa on keyon. are you sure its not a 2.5 bar sensor? is it a GM one?

No it's an ebay 3 bar special so most likely it's out of wack. I have another one on another car so will swap and see.

i've one from ebay and it was out then got another one free it was out too ... the error increases as the sensor heats up too!

Just tried the other map sensor and the reading is exactly the same. 113kPa key on engine not running. I also swapped the ecu as I had just changed it to try it out and still the same reading. Puzzling.

do you mind posting a copy of the bin in quesiton, we can check if its corrupted.

EDIT: Just checked... at keyon with my 3 bar its 99.8kpa