Replacing MAP sensor in vain attempt to improve MPG?

anewman

I have done everything else possible that may improve MPG, for example replacing air filter, spark plugs, ensuring thermostat and temp sender work properly, keeping tyre pressures checked etc etc. There seems to be the odd report or two that replacing a MAP sensor, even one that the car's ECU believes to be functioning perfectly and does not complain about, can improve MPG.

For example,
http://dodgeforum.com/forum/1st-gen-durango/201704-poor-gas-mileage-and-loss-of-power-solved.html

I was considering giving it a bash hoping the £50 sensor might pay for itself eventually, even if any MPG benefit is relatively small.

Any thoughts?

Flying-High_2

Depends what car.... but split vac hoses can cause all sorts of running problems... between airbox throttlebody etc you end up with unmetered air etc and can send it loopy. Trace All the vac hoses etc for splits and swap out for decent silicone stuff available cheaply off ebay.

Temp Sensors also give bad MPG as they'll tell the ECU to over fuel as they cant read any temp think its cold.

anewman

ISTR spraying carb cleaner around the intake can help identify leaks too as the engine tone/idle will change slightly as it burns the carb cleaner it sucked in.

I believe MAP sensors have some sort of temperature sensor integrated too.

Gloomendoom

What kind of car is it?

Flying-High_2

anewman wrote: »

ISTR spraying carb cleaner around the intake can help identify leaks too as the engine tone/idle will change slightly as it burns the carb cleaner it sucked in.

I believe MAP sensors have some sort of temperature sensor integrated too.

Some do have a Thermistor in... I'm not quite 100% how or what this sends to the ECU but obviously Intake temps would be measureable...

Yeh carb cleaner can show up leaks as it'll suck it in but not always... Best to physically check I'd say..

*** Edited for me being dumb.... Err it will send the Intake temps to the ECU... far too long a day......

anewman

2002 Fabia 1.4 mpi. It's based on the old Skoda 8 valve pushrod engines and was deprecated due to being unable to meet future emissions requirements. Get around 35mpg on average. Official figure is 39.2mpg combined so I guess in the scheme of things I'm not doing too badly. MPG is on a downward trend, also not unexpected at this time of year.

Gloomendoom

The tests that produce the official figures are in laboratory and not the real world. I don't think you are doing too badly and I seriously doubt changing the map will be cost effective... although they do degrade over time.

frothey

changing the way you drive will have more of an effect than changing bits 'n' bobs. going to meetings I invariably get around 37mpg out of my car, coming back I get around 28mpg! It's not just about how quick you go, doing 70 isn't necessarily bad - it's how you get from 0 to 70*, and how you maintain the speed.





*notice I said 70, as we wouldn't go at more than 70 would we, it's illegal..... lolololololololol!

skiddlydiddly

I didn't think a MAP sensor had anything to read the temperature as its just measuring air pressure.Do you mean MAF?They can get little specks of dirt on them which can throw out readings.I clean mine every so often with carb cleaner type products.

Flying-High_2

Some MAFS are have a thermistor built in so they can read Intake temps instead of having another Intake temp sensor further down the tract... I'm not 100% MAPS do... Infact I'd go with they dont as they work differently and they'd have an intake temp sensor.

The MAP sensor sends a signal according to engine vacuum, or pressure.... hence the need for good breathers/vac hoses....

only_mee

Seen a few lately that the dash is reading 90 deg but the actual temp is 75-80 somewhat lower than 90, so the car is not at it's optimum temp.
If you can get it on vag com and monitor the coolant temp it might show less than the 90.