We are having a rough idle problem with a mostly stock 89LX. All of the usual sensors have been replaced, ACT, ECT, TPS (replaced and reset over and over again), Oxygen sensors replaced, EGR cleaned, IAB cleaned, 10 pins re-bent and dielectric grease added. We got one code (can't remember the number right now) that indicated a low voltage from the mass air sensor (source voltage is good). So now we are down to the mass air sensor. It has been gently cleaned with a q-tip and alcohol a few times. Bottom line, has anyone ever sucessfully tested the mass air sensor ? Is there a chart available showing what values to expect with a voltmeter ? A search yielded very little info. Thanks.
Dump the codes and see what the computer says is wrong… Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. See http://www.troublecodes.net/Ford/ OR See http://www.dalidesign.com/hbook/eectest.html for more descriptive help OR See http://www.mustangworks.com/article...c-iv_codes.html IF your car is an 88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 88's except possibly the Cali Mass Air cars. Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test. Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes. For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart . If you get a code 66, then here's the MAF test proceedure Code 66 MAF below minimum test voltage. Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it. There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables. The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer. At idle = approximately .6 volt 20 MPH = approximately 1.10 volt 40 MPH = approximately 1.70 volt 60 MPH = approximately 2.10 volt Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms. There should be a minimum of 10K ohms between either pin C or D on the MAF and ground. See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif To clean the MAF, remove the MAF element and gently spray it with electrical contact cleaner. You can also use non-flammable brake parts cleaner (same chemical in a bigger can & cheaper too). Let it dry and put it back in. http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp
Thanks for the info. That was the code we saw earlier (66). The voltage read .86 at idle so, a little higher than the stated .6 volts . We swapped sensors with another car and did see a little improvement, but it's not conclusive. These gremlins are hard to reproduce sometimes.
Hey everyone, I'm BlackGT89's son. There is a little more to this story. Car had been runnning so so for a while. I cleaned the MAF sensor wire a while back and actually moved it a little bit. But, I didn't break it. Ran a little better after that. Fixed some more problems, but it still wasn't running right. After asking around, I was told that even bending the MAF element wire will ruin it. Now that your up to date. I tested the sensor voltage at idle. jrichker, I wasn't exactly clear on your instructions. Do measure the voltage across pins C & D? If so I got 0.77 volts. I then measure my dad's 73mm C&L meter. Got 0.90 volts. I then swap just the sensors between the two cars. Measured 0.84 with my dad's sensor on my car. I drove my car and the low speed bucking was gone and the throttle was much more crisp. My dad did not drive his car with my sensor nor did I measure the voltage of my sensor on his C&L. Finally, my questions to everyone who wants to help. Are these elements ruined if you bend/move them? Are remanufactued (autozone,etc) elements trustworthy? Is this enough evidence for me to bite the bullet (no pune intended) and buy a Pro-M 75mm Bullet? I know this is long but thanks for the help.
67coupe! Hey if you are in Tuscaloosa Now, can you call me (chris) at 292-1800? I have a quick question you may be able to answer? Thanks
cleck673, No man I'm in Huntville for the weekend. Are you in school at Bama? Did you have a question on your car? Later, Todd
Yeah, Having trouble with this 86 GT I bought. No, I live here. I go to Shelton though at night. I have to get this 86 gt out of the Bellsouth (my work) parking lot just in case we strike tonight. This is the thread I am seeking help in: http://forums.stangnet.com/showthread.php?t=490165
