Looken for any suggestions on my issue, its a stock 96. What i need to know is if i check my voltage on the harness at the "b" terminal and it is .89 volts at idle, and does fluxuate with throttle movment. should it hold a higher voltage if i hold it at a higher rpm????????? also from what i can find online the voltage should be 1.5 v to 2.1 v at idle. is this right and does anyone have a better way of testing the map sensor to trouble shoot???????????
and if i pinch of the vacum line with it idleing the voltage doesnt change, which i thought was kinda strang.

thanks in advance

Typical Readings:
Sensor output voltage range is 0.5 to 4.5 volts.

Output voltages between 0.5 and 1.5 volts indicate a high vacuum (low pressure) situation, such as idle or deceleration.

Output voltages between 1.5 and 3.0 volts indicate a medium level of vacuum (pressure) such as a cruise or slight acceleration condition.

Output voltages between 3.0 and 4.5 volts indicate a low vacuum (high pressure) situation such as hard acceleration or a mechanical failure.

Any reading of 0 volts or over 4.5 volts indicates a problem.

Copied from here: http://autorepair.about.com/cs/troubleshooting/l/aa042603a_06.htm

thanks wagonwes, thats what i used to get where I am, that info on that site is very helpful.

I was hoping that the other issues noted above might get some answers aswell,

Should the volts hold high with the rpm

When I pinch the vacum line the reading doesnt change, is that normal.

Oh, sorry.

Higher RPM means less vacuum, so that translates to more voltage, you are correct. When you pinch the vacuum line (I assume you mean the one going to the MAP sensor), you will be containing whatever vacuum you were at right before the pinch. So if you were at 50 kPa steady, and you pinched the line, it should stay at 50. However, this is not a very accurate test because you will have a hard time pinching it COMPLETELY off. A better test is to make sure it does not fluctuate that much at idle (maybe like .3ish volts max).

makes sense, my voltage does rise with the rpm but if I hold rpm the voltage drops back to th .89 volts. Which I assume is not good.
and the voltage does hold steady at idle. With all this being said, in ur opinion is the map sensor good or bad????

thanks

They are not too expensive, I would just replace it. Before you do though, make sure you get a steady 5 volts from the reference.

steady 5 volts. Will try getting a new one, soon. Don't get my licence back for a couple of weeks. Thanks for ur help.

Tim Clarkson wrote:makes sense, my voltage does rise with the rpm but if I hold rpm the voltage drops back to th .89 volts. Which I assume is not good.
and the voltage does hold steady at idle. With all this being said, in ur opinion is the map sensor good or bad????

thanks

It should, the same thing will happen when you drive. The voltage goes up because you put a load on the engine. But if you hold it there, you'll eventually start pulling less vacuum because the load from accelerating the engine is gone. This is what you're seeing at idle.

What problem are you having with your car that you think is caused by a bad MAP sensor?






i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

If the car is under an extremely light load, like when it is sitting in a driveway in neutral, the "load" will even out in less than a second or two. I believe he is saying it goes back to .89 after more than two seconds, which is a problem. It should NEVER be at .89, unless it is at idle speed.

Also, the sensor should read fairly stable at idle. Within a .5ish volt range.

ha guys, my originall prob is posted under maintenance
96 sunfire hesitation/bogging. it is a big list so it might be easier to look at it there then re type it....lol. id have to recheck the voltage again. but im pretty sure it was coming back to .89 right away at idle not load.....its a standard....but at increased idle it goes back to .89 volts...................

if u could check out my other post and give me ur thoughts that would be great

thanks wagonwes and SHOoff

for any one tht might want to know i solved my problem, it ends up that the valve seals r needing to b replaced, a bottle of barshal no smoke / stop leak has stoped the bogging problem till i can takle the job, since its not all that easy.

im still thinking that is running rich tho?????? a little bit of black smoke when u stomp on it at higher rpms....... so now that the other issuse is out of the way im hoping it will be easier the trouble shoot this part, any new ideas....lol


thanks in advance for new help and hanks for all the help on my now old problem

Oxygen sensor maybe? Bad fuel pressure regulator?

i am going to a buddys place this weekend that has a obd 2 scanner to check for codes. i have no cel on but that dosent mean anything. also i forgot to plug the o2 sensor in one time and was a little baffled that the cel didnt come on. ?????????? is that a sign of something ??? the fuel pressure regulator isnt leaking as per testing suggestions on hear. any other way to check???

There are quite a few things that can cause black smoke. Bad ignition componenets, fuel pressure, blockage in the airstream, bad air filter (potentially), etc. If your friend has an OBD 2 scanner, you can kinda check things out. And which O2 sensor was it that your left unplugged? Depending on how long the vehicle ran, it is possible that you caught it before a functionality test.

well made it thru the weekend, and back to normal life...lol it was the post cat o2 sensor. plugged in the obd2 and there was no codes, not sure if he checked for stored codes or not. would the come up or do u have to look for them. i want to borrow his scaner to do some poken around if his is capable.