Hi, I need some help and I know this subject has come up before on this forum but I didn't seem to read any conclusion to it. A couple of weeks ago when the weather got hot I noticed that my car was sputtering hard and it wouldn't start. I did the paperclip trick in the DLC connector and it flashed code 13 and code 33 on the check engine light, which are the following:
13. Oxygen sensor signal stays lean during warm engine cruise
33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor)
I used the starter fluid trick on the vacuum hoses and found no cracks, we replaced the engine coolant sensor and now the throttle body sensor and after I let the car cool off for awhile I started up the car and it seems to idle fine between 600-700 RPMs and I let it run for about fifteen to twenty minutes and then I got back in the car and revved the engine near 4k RPM and it started to sputter again and then died. It flashed a code, this time just code 33. Apparently the new throttle body sensor got rid of the code 13 and we are now trying to find out what's causing the code 33. It only seems to do this when you give it any gas and the car has warmed up to 220 F. Any ideas as to how and where to start tracing this problem?
A guide I found on the firebird forum for code 33 (which I can't understand):
http://members.shaw.ca/corvette86/Code 33.pdf
Any help you can give me would be greatly appreciated! Thanks the link u posted wont help u here. your car has a map sensor (manifold absolute pressure) not a maf sensor (mass airflow sensor). heres what your map sensor looks like:
its on the passenger side of the engine compartment near the firewall.
the map sensor uses engine vacuum to send a voltage signal to the computer and its one of the inputs the computer uses to adjust fuel mixture. high voltage = low vacuum. if the voltage reading it sends is too high for engine operating conditions itll set code 33. thatll mess up the fuel mixture and cause the problems u got.
start by doing a good visual inspection. make sure the 3 wire connector on the sensor is clean and plugged in tight. check the wires for loose connectors or any damage. make sure the vacuum line on the sensor is mounted tight. check it close all the way back to the engine for any holes, cracks, breaks, etc. and make sure its securely attached at the source. it dont take much of a leak to throw the readings off so check it careful.
if all this looks ok u can check the sensor with a dvom and a small hand vacuum pump liike a mitey-vac. if u got these things and wanna troubleshoot it let us know and we can walk u thru it. DTC 33 MAP Sensor Circuit Error. Signal is high indicating low vacuum.
The ECM uses the MAP sensor as a measurement of engine load. Then the ECM uses the information from the MAP sensor to help determine the proper amount of fuel and spark timing to deliver. When the voltage is high this indicates a low amount of engine vacuum and higher engine load. Low voltage would indicate high engine vacuum and lower engine load. MAP sensors do fail, but GM sensors don’t have a high failure rate. It’s more likely that you missed a vacuum leak. The method of spraying vacuum hoses and connections with carburetor cleaner, starting fluid or WD-40 is not very reliable. The most accurate way to find a vacuum leak is with an engine vacuum pressure tester. Auto Zone (and similar stores) have a free tool loaner service. There you can borrow an vacuum tester for free. 4 Bolt Main wrote:GM sensors don’t have a high failure rate
but that dont mean they never fail. especialy one thats allmost 20 years old. with a code 33 id still start with a visual and then test the sensor. if it proves good then we can move on to other stuff. A Map Sensor in good working order should have an output voltage range of 0.5 to 4.5 volts.
When the output voltage is between 0.5 and 1.5 volts this indicates a high vacuum (low pressure) condition. Examples include idle or deceleration.
When the output voltage is between 1.5 and 3.0 volts this indicates a medium level of vacuum (pressure). Examples include cruising or slight acceleration.
When the output voltage is between 3.0 and 4.5 volts this indicates a low vacuum (high pressure) condition. Examples include hard acceleration or a mechanical failure.
A problem is indicated when any reading is 0 volts or over 4.5 volts. So this car doesn't have a MAF sensor? I don't know much about cars but I'm trying to understand this. I've been told that I need a vacuum gauge so I'm gonna try to get that today, do you think that I should get a voltmeter too to test the output voltage of this sensor? I'm certain that I had the MAP sensor replaced in october of last year and then when the weather cooled back down the car seemed to run okay. nope, no maf sensor on this one.
if u did replace the map sensor last year it could be theres another problem setting the code. thats why i told u the first thing to do is a good visual check of the wiring and vacuum line from the sensor to the engine. check that vacuum line real close, even if u gotta take it out to inspect it up close. but before going farther then that the sensor should be checked and proved either good or bad.
u would need a voltmeter or better yet a dvom to check it. a dvom is a handy thing to have around cause theres lots of things on a car that u can check with it, not just voltage but resistance too. u could use a vacuum gauge with a tee fitting connected to engine vacuum, or just leave the sensor connected to engine vacuum. but a vacuum hand pump is more accurate cause when u use that your taking the vacuum lines and evrything connected to them out of the picture and just concentrating on the sensor.
let us know what u finaly decide to use and we can give u the steps for checking it out. If you would, please go ahead and give me the steps to use the dvom and the vacuum gauge. Thank you If you clear the trouble codes, by disconnecting the battery, does the MAP code come back? You can get that code if you happened to unplug the MAP with the ignition on.
If you disconnect the battery on one of those, the idle learn gets erased and could cause the engine to stall after it is started. There is a learn procedure. Something like let it idle in gear till the coolant fans come on, drive it three miles, click your heals together. ok, im gonna take it on faith that u did a good visual and the wires and vacuum lines are in good shape. right?
so. unplug the electric connector from the map sensor. turn the ignition key on. use the dvom to probe the 2 outside connectors on the harness. these are reference voltage (power) and ground. u should see right at 5 volts. if not theres a wiring problem between the connector and computer, or a problem in the computer.
turn off the key. plug the harness back in to the sensor. tee the vacuum gauge into the vacuum line running to the sensor. start the engine.
backprobe the center (signal) and ground wire on the connector with the dvom. the ground wire is black or black with a colored stripe on it. if u cant get the dvom leads into the connector u may need to stick a thin wire or bent paper clip in there and take the readings from that.
at idle the vacuum gauge should be around 18 inches and steady. if its much lower or the needle moves back and forth theres a vacuum leak somewhere.
with the engine idling and normal vacuum u should read 1-1.5 volts on the dvom. now slowly accelerate the engine. the vacuum should drop smoothly and the voltage should rise smoothly. by the time u get to around 2500 rpm the voltage should be around 4.5 or so.
if it fails any of these voltage tests the sensor is bad.
another thing to watch for as u do this, is as your revving it up if the voltage 'spikes' up higher and then drops back down, or drops way down, like to allmost 0 and then comes back up, that allso points to a bad sensor.
let us know how this turns out. if the sensor checks out good we need to dive in a little deeper. Thanks for getting back to me, yes, I did a good inspection of the wires and we disconnected everything from the map sensor and we had good vacuum when I put my finger to the hose. I got ahold of my little pocket voltmeter, do you think that would work okay? We went to autozone and the guy behind the counter suggested that we check the idle air control valve for carbon build-up so we grabbed a can of carb cleaner and hosed it out really good and there was a LOT of carbon in there so we cleaned it off and inside that valve til all the black was gone. I plugged the sensor back in and hooked everything up and let it warm up again, it died later but this sensor was red hot so we disconnected it and we are taking it to autozone to see what this guy says about it. But I'm going to try everything you said about the troubleshooting this sensor with the vacuum gauge and dvom. Thank you for your help Connie! Is the reference voltage at the sensor reading at about 5 volts?
Remove the vacuum hose at the MAP sensor and attach the hose from a hand held vacuum pump.
Turn the ignition key to on but do not start the car.
Watch the voltage or rpm. At 0 inches of Mercury (in-Hg) vacuum, you should be getting a reading from 4.5 and 5 volts, or an rpm of 300 to 320.
Now pump in 5 in-Hg of vacuum. You should now be reading around 3.75 volts, or an rpm between 275 and 295.
Now pump in 20 in-Hg of vacuum. You should now be reading around 1.1 volts, or an rpm between 200 and 215 rpm.
Post the above test results and we’ll instruct you further. he aint got a hand pump, but he does have a vacuum gauge, so thats why i gave him the instructions with the gauge teed into the line.
if theres steady 18-20 inches of vacuum at idle that pretty much rules out a vacuum leak, so itll work. he aint got a hand pump, but he does have a vacuum gauge, so thats why i gave him the instructions with the gauge teed into the line.
Thanks Connie. I realize that. I’m simply throwing out more data to see what sort of feedback I get. I’ll continue to do so until we can get something to work with. Since we don’t have the car in front of us I feel that throwing out data (till something comes back ) that we can use, is the least I should be doing. You know it goes with repairing anything online.
oenone,
BTW you can borrow a hand held vacuum tester and digital voltmeter for free from Auto Zone. Just go to any Auto Zone store and make use of their free tool loaner service. If you’re sure you have the proper amount of vacuum going to the MAP sensor, and you have made sure that the air duct is not loose or damaged, then the problem is either with the circuit (means wiring and includes connector) or a failed sensor. I don't have either right now, the hand pump or the vacuum gauge. But I'm going to autozone tonight before I go into work to pick up my idle air control valve and I will try to pick up the vacuum gauge and see if I can get some ideas from them too. I have checked all the vacuum lines and pulled off the little black hose and I got really good suction but bhis weekend I'm going to try to devote more time to it and I will post the results. Thanks guys!Car Repair Talk's forum.
13. Oxygen sensor signal stays lean during warm engine cruise
33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor)
I used the starter fluid trick on the vacuum hoses and found no cracks, we replaced the engine coolant sensor and now the throttle body sensor and after I let the car cool off for awhile I started up the car and it seems to idle fine between 600-700 RPMs and I let it run for about fifteen to twenty minutes and then I got back in the car and revved the engine near 4k RPM and it started to sputter again and then died. It flashed a code, this time just code 33. Apparently the new throttle body sensor got rid of the code 13 and we are now trying to find out what's causing the code 33. It only seems to do this when you give it any gas and the car has warmed up to 220 F. Any ideas as to how and where to start tracing this problem?
A guide I found on the firebird forum for code 33 (which I can't understand):
http://members.shaw.ca/corvette86/Code 33.pdf
Any help you can give me would be greatly appreciated! Thanks the link u posted wont help u here. your car has a map sensor (manifold absolute pressure) not a maf sensor (mass airflow sensor). heres what your map sensor looks like:
its on the passenger side of the engine compartment near the firewall.
the map sensor uses engine vacuum to send a voltage signal to the computer and its one of the inputs the computer uses to adjust fuel mixture. high voltage = low vacuum. if the voltage reading it sends is too high for engine operating conditions itll set code 33. thatll mess up the fuel mixture and cause the problems u got.
start by doing a good visual inspection. make sure the 3 wire connector on the sensor is clean and plugged in tight. check the wires for loose connectors or any damage. make sure the vacuum line on the sensor is mounted tight. check it close all the way back to the engine for any holes, cracks, breaks, etc. and make sure its securely attached at the source. it dont take much of a leak to throw the readings off so check it careful.
if all this looks ok u can check the sensor with a dvom and a small hand vacuum pump liike a mitey-vac. if u got these things and wanna troubleshoot it let us know and we can walk u thru it. DTC 33 MAP Sensor Circuit Error. Signal is high indicating low vacuum.
The ECM uses the MAP sensor as a measurement of engine load. Then the ECM uses the information from the MAP sensor to help determine the proper amount of fuel and spark timing to deliver. When the voltage is high this indicates a low amount of engine vacuum and higher engine load. Low voltage would indicate high engine vacuum and lower engine load. MAP sensors do fail, but GM sensors don’t have a high failure rate. It’s more likely that you missed a vacuum leak. The method of spraying vacuum hoses and connections with carburetor cleaner, starting fluid or WD-40 is not very reliable. The most accurate way to find a vacuum leak is with an engine vacuum pressure tester. Auto Zone (and similar stores) have a free tool loaner service. There you can borrow an vacuum tester for free. 4 Bolt Main wrote:GM sensors don’t have a high failure rate
but that dont mean they never fail. especialy one thats allmost 20 years old. with a code 33 id still start with a visual and then test the sensor. if it proves good then we can move on to other stuff. A Map Sensor in good working order should have an output voltage range of 0.5 to 4.5 volts.
When the output voltage is between 0.5 and 1.5 volts this indicates a high vacuum (low pressure) condition. Examples include idle or deceleration.
When the output voltage is between 1.5 and 3.0 volts this indicates a medium level of vacuum (pressure). Examples include cruising or slight acceleration.
When the output voltage is between 3.0 and 4.5 volts this indicates a low vacuum (high pressure) condition. Examples include hard acceleration or a mechanical failure.
A problem is indicated when any reading is 0 volts or over 4.5 volts. So this car doesn't have a MAF sensor? I don't know much about cars but I'm trying to understand this. I've been told that I need a vacuum gauge so I'm gonna try to get that today, do you think that I should get a voltmeter too to test the output voltage of this sensor? I'm certain that I had the MAP sensor replaced in october of last year and then when the weather cooled back down the car seemed to run okay. nope, no maf sensor on this one.
if u did replace the map sensor last year it could be theres another problem setting the code. thats why i told u the first thing to do is a good visual check of the wiring and vacuum line from the sensor to the engine. check that vacuum line real close, even if u gotta take it out to inspect it up close. but before going farther then that the sensor should be checked and proved either good or bad.
u would need a voltmeter or better yet a dvom to check it. a dvom is a handy thing to have around cause theres lots of things on a car that u can check with it, not just voltage but resistance too. u could use a vacuum gauge with a tee fitting connected to engine vacuum, or just leave the sensor connected to engine vacuum. but a vacuum hand pump is more accurate cause when u use that your taking the vacuum lines and evrything connected to them out of the picture and just concentrating on the sensor.
let us know what u finaly decide to use and we can give u the steps for checking it out. If you would, please go ahead and give me the steps to use the dvom and the vacuum gauge. Thank you If you clear the trouble codes, by disconnecting the battery, does the MAP code come back? You can get that code if you happened to unplug the MAP with the ignition on.
If you disconnect the battery on one of those, the idle learn gets erased and could cause the engine to stall after it is started. There is a learn procedure. Something like let it idle in gear till the coolant fans come on, drive it three miles, click your heals together. ok, im gonna take it on faith that u did a good visual and the wires and vacuum lines are in good shape. right?
so. unplug the electric connector from the map sensor. turn the ignition key on. use the dvom to probe the 2 outside connectors on the harness. these are reference voltage (power) and ground. u should see right at 5 volts. if not theres a wiring problem between the connector and computer, or a problem in the computer.
turn off the key. plug the harness back in to the sensor. tee the vacuum gauge into the vacuum line running to the sensor. start the engine.
backprobe the center (signal) and ground wire on the connector with the dvom. the ground wire is black or black with a colored stripe on it. if u cant get the dvom leads into the connector u may need to stick a thin wire or bent paper clip in there and take the readings from that.
at idle the vacuum gauge should be around 18 inches and steady. if its much lower or the needle moves back and forth theres a vacuum leak somewhere.
with the engine idling and normal vacuum u should read 1-1.5 volts on the dvom. now slowly accelerate the engine. the vacuum should drop smoothly and the voltage should rise smoothly. by the time u get to around 2500 rpm the voltage should be around 4.5 or so.
if it fails any of these voltage tests the sensor is bad.
another thing to watch for as u do this, is as your revving it up if the voltage 'spikes' up higher and then drops back down, or drops way down, like to allmost 0 and then comes back up, that allso points to a bad sensor.
let us know how this turns out. if the sensor checks out good we need to dive in a little deeper. Thanks for getting back to me, yes, I did a good inspection of the wires and we disconnected everything from the map sensor and we had good vacuum when I put my finger to the hose. I got ahold of my little pocket voltmeter, do you think that would work okay? We went to autozone and the guy behind the counter suggested that we check the idle air control valve for carbon build-up so we grabbed a can of carb cleaner and hosed it out really good and there was a LOT of carbon in there so we cleaned it off and inside that valve til all the black was gone. I plugged the sensor back in and hooked everything up and let it warm up again, it died later but this sensor was red hot so we disconnected it and we are taking it to autozone to see what this guy says about it. But I'm going to try everything you said about the troubleshooting this sensor with the vacuum gauge and dvom. Thank you for your help Connie! Is the reference voltage at the sensor reading at about 5 volts?
Remove the vacuum hose at the MAP sensor and attach the hose from a hand held vacuum pump.
Turn the ignition key to on but do not start the car.
Watch the voltage or rpm. At 0 inches of Mercury (in-Hg) vacuum, you should be getting a reading from 4.5 and 5 volts, or an rpm of 300 to 320.
Now pump in 5 in-Hg of vacuum. You should now be reading around 3.75 volts, or an rpm between 275 and 295.
Now pump in 20 in-Hg of vacuum. You should now be reading around 1.1 volts, or an rpm between 200 and 215 rpm.
Post the above test results and we’ll instruct you further. he aint got a hand pump, but he does have a vacuum gauge, so thats why i gave him the instructions with the gauge teed into the line.
if theres steady 18-20 inches of vacuum at idle that pretty much rules out a vacuum leak, so itll work. he aint got a hand pump, but he does have a vacuum gauge, so thats why i gave him the instructions with the gauge teed into the line.
Thanks Connie. I realize that. I’m simply throwing out more data to see what sort of feedback I get. I’ll continue to do so until we can get something to work with. Since we don’t have the car in front of us I feel that throwing out data (till something comes back ) that we can use, is the least I should be doing. You know it goes with repairing anything online.
oenone,
BTW you can borrow a hand held vacuum tester and digital voltmeter for free from Auto Zone. Just go to any Auto Zone store and make use of their free tool loaner service. If you’re sure you have the proper amount of vacuum going to the MAP sensor, and you have made sure that the air duct is not loose or damaged, then the problem is either with the circuit (means wiring and includes connector) or a failed sensor. I don't have either right now, the hand pump or the vacuum gauge. But I'm going to autozone tonight before I go into work to pick up my idle air control valve and I will try to pick up the vacuum gauge and see if I can get some ideas from them too. I have checked all the vacuum lines and pulled off the little black hose and I got really good suction but bhis weekend I'm going to try to devote more time to it and I will post the results. Thanks guys!Car Repair Talk's forum.
Pre：cant figure out whats going on Next：93 ford ranger 2wd voltage problems
2003 Nissan Sentra Screeching
failed my state emissions test
1999 Ford Explorer door lock problem
2004 ford taurus serpentine belt problems
1994 dodge shadow wont start
Replacing Fuel Filter in Saturn SL - Question??
96 Neon Lower Idle Issue
New Distributor and no spark 1993 GMC Yukon
Car Parts: Air Conditioning System / Body / Lighting and Signaling System
OBD-Ⅱ Trouble Codes:OBD-Ⅱ Trouble Codes
P0108 | P0135 | P0171 | P0174
P0300 | P0320 | P0325
P0401 | P0420 | P0430 | P0440 | P0441 | P0442 | P0455
links:Car Logo / Autoi / Car Repair Talk's forum / Car Specifications