TESTING A MAP SENSOR W SAFTEY PINS, VOLTMETER, VACUUM PUMP AND GAUGE (EASY FOR THE DIYer) SAVE $$

11:29 what says manifold absolute pressure higher than expected so it’s saying that inside the engine there’s a higher amount of pressure being detected could be a vacuum leak could be a stubborn valve it could be the timing anything that’s causing more air to come into the engine causing high pressure so what you want to first students you want to look at the map sensor you got to do it visually the very first thing you do is a visual so this goes here this is the idle air control valve all this right here this right here is a TPS the throttle position sensor this right here I forgot some kind of switch or a vacuum line that’s our vacuum line right there one over here this right here is what we’re after this is the map sensor first thing you do is check the map sensor all right what we’re doing is we’re checking the voltage signals from the PCM here’s the map sensor and what we have here is we have three safety pins this is called back probing we got three safety pins hooked up behind the connector going in to the terminals touching the sensor okay the sensor terminals this is our ground wire here right with a green stripe this is our signal wire the green one and this is our reference wire this is our yellow and red one on this wire we need 12 volts so I’m gonna go from here to the battery positive and we should have 12 volts on that right there Levin point eight that’s good because our battery’s low but don’t worry about the 12 volts that’s good though but on a normal battery you want twelve point six our battery’s low but no big deal now on this middle one I’m going to touch over here in here and we want zero point five the two volts okay and we are good right there we’ve got two volts there so now on this one five volt reference I’m going to come over here and touch the ground wire and the reference signal wire and we got five volts see the negative sign right there to the left of the numbers it means the polarity of the leads are reversed okay so all you do is this let’s eat that the negatives done okay we got five volts right there four point nine that’s good so so far we got a good signal coming from the PCM so all that’s good so far now let’s turn it on warm it up I’m selling something what I did is we took off the inlet air temperature sensor right here we took it out of the housing that way we don’t trigger this coat what we also did is we we block this here we’re not going to be me back in there anyway we’ve hooked up to the vacuum right here check this out this vacuum is going directly to intake manifold vacuum that what that means is underneath this throttle plate here that is intake manifold vacuum all right and look what we got here what we got here is picking into the mercury look at the red area it says late ignition timing I hope you can read that on their resume another we’re in a red area that means our timing is de tarded just like I suspected okay so I don’t think this map sensor is the issue but we’re going to check it again right now because we already checked it with the car off all right now I’m going out in the car warm up and we’re going to check the voltage as we move the throttle plate and as we move the throttle plate like this we’re going to decrease the vacuum on the inside of the manifold if I set watch here as you open up the throttle the backing decreases do that with him open thought over here so immediately the back end decrease so look at that look how low that is pretty bad here so so I put my hand over the throttle body I’m actually increasing vacuum see that I’m let off do it again I can actually cut the car off like this and the vacuum is created from the downstroke of the intake scope of the piston okay and that’s how you get

vacuum in the vehicle so but now I’m going to check the map sensor now we got the tar off the operating temperature right 270 degrees Fahrenheit there we go man just came on for now here we go we’re testing the map sensor while the car is on at operating temperature we have the ground wire and the signal wire hooked up and right now we’re at one point three folks in Stoughton here now look over here at oh wait wait look here first at the back engage and go what we got go all this now look at the back in game we have 15 inches of mercury now come over here at 50 inches of mercury we need to be at 1.5 volts one and a half volts now look at the ball to tip me we’re at 1.4 1.5 well pretty 0.5 that’s good enough as you can hear the fan just came on we’re at an operating temperature only perform this test when the cars warmed up how do you know when it’s warmed up when the fan comes on who add one point for all that good right now watch the meter look at our ranges here and we’re hooked up still we’re on the signal wire and the ground wire remember reference signal ground now watch coming up move the throttle I’m going to take this up to 20 inches of mercury and at 20 we need to be at 1 volt here we go that’s pretty good right there see the left the more I close the throttle the more the vacuum Willet Creek but close it go to the crease both over increase my snap it hold it pieces all the way up to the normal operating Onision is 18 is 23 inches of mercury okay we are way low look at it watch this let me warm up well we’re operating around 15 inches of mercury right now okay but now the computer is trying to compensate for the lake timing respond to adjust the timing back to where it needs to be but it can’t maintain that because we’re running ways to lead okay how do we know this give these marks these three right here this should be right here in line with these they should stay that but they’re not they keep moving they keep fluctuating back and forth let’s when I snap the photo but we need to figure out why does this car go haywire say our mantra trying to stay lined up with the pointer here stay out of time but we got an issue hood so we got some adjustments to do to the time you go I look at the gate I look back you do to kind of maintain everything trying to maintain this going to a message forty point seven two one air few races but it’s going haywire because we’ve got an issue just trying to keep up with eventually it’s going to find it that’s going to take a little while right now we’re running rich we’re underneath you want to risk you running me if you look over here look at the goose print with negative six the computer is trying to pull away hence the name Stram children trying to pull away junior from the system okay from the fuel injector that we’re running through it then we’re running to lead but one is to risk then we’ll run it to me off and on now let’s look at our goal to set up cmlc sensors watch this one can be haywire it’s supposed to be a normal way pattern like this what’s gonna happen begin spikes okay and this right here we’re running risk to link rip to me this to me lean down here one boat was riverboat then the higher the voltage the richer it is the now let’s go down to the else game okay and that’s what the surging is rich to lean which to lean computer trying to compensate it overcompensates in an undercover state back and forth off and on this did via eight this is yet 450 to

800 millivolts this is after the computer compensated for everything we’re running good this is the downstream multi sensor now we’re back clean it’s going lean then it’s going up to where it needs to be at okay six seven eight hundred even 450 sometimes the six to eight hundred millivolts is what you’re looking for on a downstream motion sensor now suppose to the upstream right here now the street we got the wave pattern waiting so now we’re looking for a normal wave pattern we still have an issue that’s not a normal wave pattern that should be fluctuating between 200 and 800 millivolts right there but with a smooth way now what you want to do is you want to disconnect the map sensor believe the connector hooked up right here all right leave the pins in there because it’s still going to check for voltage we have the ignition in the on position and we got it out now okay so now what we have here is a vacuum pump she’s going to hook up the vacuum pump to the map sensor and these right here are the readings that we’re going to go off of okay now we have the terminals hooked up to the voltmeter and we’re going to check the voltage as we apply vacuum okay go ahead and take it up to five okay look at the five we need to be at 2.5 volts as soon as she gets it to five okay what are we at 2.5 right there at 5 inches of mercury right there well vacuum okay same thing now let’s take it up to 10 so she’s going to take it up to 10 and we need to be at what 2.0 okay we’re at 2.0 all right 2 volts that’s 2 volts so now we start she’s gonna take it up to 15 now what we need to be at 1.5 volts we’re at 1.5 volts right there so now she’s gonna take it up to 20 Oh 20 we need to be at 1 volt and we are right there 1 fault unfortunately my vacuum gauge is messed up and it can’t hold that anymore because it’s old but so what look at where it look what look we’re at we’re good to go right there we can’t take it up to 25 because the seal in here won’t hold that vacuum okay but try it anyway 25 we need to be out half a volt can we get it up there that’s the question oh we can’t but no big deal we’re good so this map sensor is good to go we have the bolsa okay 25 we need to be out half a volt fan right there we’re good to go so there we go right there that map sensor is good sometimes when you get a cold that will not be the problem sometimes so you have to learn how to inspect each component if the computer sets that code for that specific sensor so don’t just go change the sensor because if you change this sensor right here you’re going to have the same exact issue and that’s what you call just throwing parts at the car okay yeah that’s guessing never ever ever ever guess you don’t have to yeah you will waste a lot of money I did that I did that when I first started mechanics in 1991 guessing and wasting money I blew a lot of money don’t ever do that so that’s how you handle that that’s how you figure out if you have a bad map sensor all right that’s how you test a map sensor right there do not just replace it just because you get the code P 11:29 or P 11:28 gonna waste your money like that that’s how you do the test and it’s that simple you can go get this FAQ engage go to your local swap meet and go finally I got two of these but my other ones broke and I got them both from swap meet a long time ago this one oh all my stuff but they still work this is old school treat that works here’s the scale this is for 96 – I believe in my worked up to 2005 Honda Civics or maybe a little less than 2005 but this is a 2001 I’m a sip this scale right here this range for the map sensor this works you need a multimeter or voltmeter same thing need to get them a meter this is another meter did I have but I prefer to use that one because I like that one the most this is one from Harbor Freight you can get these free if you look in your Sunday paper right sometimes they have coupons that allow you to get these for free if you buy something look for the coupon but you don’t want to wait and pick this thing for like five bucks man five or six bucks I think it is you’ve

never even four bucks but use this to your Vantage vacuum pump another another tool from the swab unit anyways that’s how simple it is to test the map sensor it’s that simple make sure if you get a meter make sure you’re able to change the leads on the end with this cheap Harbor Freight one you’re not able to change the leads on the end but what you can do is you can change the wires you can change the wiring so that you can take these off like that alright or same thing with this one that’s what we did here I got the alligator clips on this one so that’s what you want to do you want to get the right tools for the right job you do not want to guess you do not want to assume I always tell you guys you stay solid stay strong those of you who believe in Christ for those of you have faith in God keep your faith strong or let nothing move you all right keep your head solid stay strong out there in Jesus name and in Jesus mighty holy name keep smashing on it don’t ever give up get out there and go get get after