is my map sensor bad?

[clubaudi]

i have a 2000 1.8t and i cant tell if my map is bad or not and i dont want to order one and it not be the problem. when it is pluged in the car idles crazy but when moving runs ok, when i unplug the sensor the car idles good but will not go into any boost without starting to misfire. i know that when it is unpluged it is leaning. i know someone knows or has had this problem before. please help

[walky_talky20]

Pretty sure you mean MAF? The air flow sensor in the airbox, right? If so, then yes. You probably need a new one.

[Seerlah]

I am guessing you meant MAF and not MAP sensor? A faulty MAF sensor makes you run lean, and also causes misfiring. When it is unplugged, the car will run (most times, but I have seen a few cases where it doesn't and the car dies immediately) but also runs rich. And during this time, you won't be able to make boost. You can drive with it unplugged till you get a replacement, but take it easy on the gas because you will be runing rich (possibility of fouling your cat converter and 02 sensors). And driving with it unplugged is not a good thing, for that very reason. But if you need your vehicle to get to and from work/school, you can do it that way till your replacement comes in. Actually, try to clean it with CRC MAF cleaner (found at Autozone) before ordering a replacement (and be sure it is a Bosch unit you replace it with if necessary). It could just be dirty and not actually faulty.

Edit: walky_talky20 beat me to it, and I added a bunch of stuff

[vortexjunkie]

It is your MAP sensor... Mine went bad and before i replaced it the car would idle fine the min you touched the gas and went into boost it would shudder and misfire and spit and carry on. also it would not make correct boost at all.. very low replace it for the 70.00 dollars it is and you will be fine...i just did this 3 months ago

[clubaudi]

i was talking about the map (boost sensor) and i know my maf is good. ill try and replace it and see what happens

[M-Hood]

It is your MAP sensor... Mine went bad and before i replaced it the car would idle fine the min you touched the gas and went into boost it would shudder and misfire and spit and carry on. also it would not make correct boost at all.. very low replace it for the 70.00 dollars it is and you will be fine...i just did this 3 months ago

But he said the car would idle bad and runs good when driving with the MAP sensor plugged in but runs bad when it is unplugged. It is always going to run bad when it is unplugged because the ECU is looking at the MAP sensor readings all the time and if the readings are off of what it is requesting it will close the throttle to 40%.

[clubaudi]

when it is plugged in it idles crazy and is really jumpy when you start off but when it is unpluged it idles good but you cant go into boost.... does it mean the sensor isnt any good or is there another problem with my car?

[FNK]

when it is plugged in it idles crazy and is really jumpy when you start off but when it is unpluged it idles good but you cant go into boost.... does it mean the sensor isnt any good or is there another problem with my car?

Try this,
Go in vag-com and clear your engine codes, even if there is none, this will reset the fuel trip and timing tables. Start the car again, the Ecu will relearn the base values. Drive for a few minutes without going in WOT.
If it still idle badly, the MAF appear to be the problem.

you can test it by logging the Group 002, (g/s) air intake read by the maf. I don't know if your car is chipped... Let's say you should have 170hp, multiply this by 0.8 and you should have a peak of 136 g/s of air. The MAF should read a peak value near this.