If the MAP sensor was bad wouldn't it cause the check engine light to come on?

Ron

 

Ron,

It's not about the sensor going bad, it's about the sensor not reading correctly anymore. Age + carbon build up makes the sensor inaccurate.

In the 1st Gen durango forum, another member tried the map sensor, he replied that it greatly improved his throttle response and more power and will check the final mileage after the first tank. He's happy with the new map sensor.

 

This gets interesting now, I've had my 2004 QC 4.7 4wd for two years now and have thought the mileage sucked. The best I got was 17 mpg driving like a little old lady on a 400 mile trip, and around town its 12 if I'm lucky. Truck runs just fine and even installed a kn filter and flowmaster 70, which didn't change anything. Is there a way to test it ? The truck has 30k on it, like to improve it a little before I head out west for vacation.

Thanks Ron

 

i just tested the sensor on my 3.9 v6, here are my findings..

5.14 volts from the pcm to the sensor, thats within range so its good

sensor reads 1.38 volts with the engine not running

sensor with engine running at idle is the same, supposed to be at least 1.5 volts

sensor with engine at wide open throttle is 1.7 volts.. supposed to be between 4-5 volts... will be ordering a new map sensor.. thanks for the insight, even us experienced guys learn new things.

 

You mean wide open throttle, not idle open throttle?

 

Well i guess you were both right seeing you posted almost indentical answers with in a minute of each other...

and what are you guys doing up at 3 am?

 

We have no life. lol

Just trying to help dodge owners improve gas mileage.

 

I bet there was no engine codes generated. lol

 

edited my first post, and no codes what so ever, i un plugged the sensor to test for the 5 volts, turned the ignition to run, without the engine running. didnt throw a code. started it up, threw a code for high resistance, something like that, didnt grab the code. cleared it (thanks superchips for this option). and proceeded testing it. otherwise no codes from daily use, nada.

 

Although I don't have a 2nd gen, since we're on the topic of MAP sensors, I went out and tested mine this evening. It read fine with the motor off, but with the motor idling, it was at ~1.12V. When I kicked it up to WOT, it peaked at ~4.35V, and when it was dropping back to idle, it was reading ~0.15V (although it drops fast, so that was a hard one to check). These aren't horrible readings, but they are at the very low side of the accepted range. What do you guys think, replace it or leave it?

I should also mention, the reason I checked it in the first place is cause my truck has a hard time coming back down to idle when I depress the clutch. It will try to stall and then "catch" itself. I have already replaced the IAC. It's been like this ever since I did the auto to manual transmission swap.