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I know this is discussed ad-nauseum; but...... I am experiencing the P0103 MAF high code. I have done the basics: cleaned MAF, checked wiring, checked for vac leaks, etc. My question concerns reading MAF ref voltage to PCM. They talk about the frequency being above 14,500 hz for x amount of time. I back probed the ref wire. At idle I get 4.20 volts, as throttle is pressed gradually it drops steadily (no jumping around) down to about 3.8 volts. I have done a voltage drop on the ground wire from the connector to battery negative and get .027 v drop; negligible. I also checked for voltage drop on ign voltage wire in MAF harness to battery positive and get .031 v drop, again well with in limits. My question is; can the reference voltage test from MAF to PCM be enought? DO I in fact need to watch frequency on the sensor? P.S. All grounds are clean (as indicated by virtually no drop on ground wire of harness.....). No other codes, drive ability is good as well as fuel mileage???
Ok, is this a replacement sensor ??…if not to check the signal wire (I think you referred to it as a reference)…with key on do you see 5 volts on the yellow wire…basically this is how you would check the signal wire for circuit integrity…the MAF has a body ground so I just use a test light or old headlight bulb connected to B+…if light is bright ground is good…so you did a voltage drop on the feed and it looks good…with the connector unplugged and back probing the yellow signal wire if you’re seeing 5 volts I’d do the old wiggle check and see if signal voltage changes…I’d also do this on the ground wire too…is this how you checked the wiring ??…looking isn’t good enough…you should also do a terminal tension test on the connector…if all this is good you probably have a bad MAF…if this MAF was changed and you bought it off EBay or Amazon that’s probably your issue…oh, and what does your MAF grams/second read at hot unloaded idle…should be no lower than 5.7 and shouldn’t read very high (over reporting).
Original sensor that has been cleaned. Signal wire has 5 volt key on. Rechecked ground circuit, has no voltage drop on that circuit. Terminal tension and wiggle test sat. Re checked the signal wire voltage while running. At idle 4.02 volts with steady throttle acceleration it decreased to about 3.81 volts. Is this correct? Also rechecked for vacuum leak (sprayed intake, etc. with brake cleaner) all sat. Also, I started the engine and while it was idling, I pulled the MAF plug. The engine had a very slight "miss" for just a split second but continued to run well even with throttle acceleration.... So is it safe to condemn the MAF? I realize I need a comprehensive scanner to monitor the functions; just trying to get this sorted before I get my hands on it....
I usually don’t read MAF voltage since it is a digital signal (digital square wave) which turns on and off so voltage testing isn’t real accurate…a DVOM’s refresh rate is not fast enough…instead I look at frequency with my lab scope or airflow with the scan tool in grams/second…if I can remember my LS3 at idle is about 2.4 volts…if wiring checks good get yourself an OEM MAF…not an Amazon or EBay special even if it is an AC Delco…to many junk counterfeits parts…and as I mentioned KOEO MAP/BARO should be around 101kPa at sea level…and I’m surprised you know how to do voltage drop testing…very few do.
I usually don’t read MAF voltage since it is a digital signal (digital square wave) which turns on and off so voltage testing isn’t real accurate…a DVOM’s refresh rate is not fast enough…instead I look at frequency with my lab scope or airflow with the scan tool in grams/second…if I can remember my LS3 at idle is about 2.4 volts…if wiring checks good get yourself an OEM MAF…not an Amazon or EBay special even if it is an AC Delco…to many junk counterfeits parts…and as I mentioned KOEO MAP/BARO should be around 101kPa at sea level…and I’m surprised you know how to do voltage drop testing…very few do.
I was able to scan. At idle I was getting approximately 8.2 grams and 4200 HZ.....numbers did change gradually wit throttle opening. I put an new delphi MAF (against my better judgement) and it made no difference. What's curious is that after clearing the code, as soon as you start the car code comes right back but no check engine light? Is it possible there could be a tune issue? I recently purchased the car and can not get any definitive info as to if it was tuned..... The only issue I have not been able to pin down is the effect of the AIR system. Like I said driveability is good, mileage is good; just keep getting seervice vehicle soon every time I start it!
If you’re seeing 8.2 at “hot idle” with no loads that’s a little high (over reporting) and normally HZ is around 3000…maybe a tune ??…I usually don’t mess with tuned cars so maybe visit a tuner.
OK scanned again for short term and long term fuel trims. I was consistently getting from 0 to -3.2 short term and basically 0 long term on a 20 minute test drive..... Also MAF was reading and responding to throttle. Also MAP sensor was reading well also (30 kpa @idle, was also varying with throttle). Scan tool shows no MIL light on (dash light out), no ABS,Traction, or any powertrain codes. The issue is that the DIC continues to show current and history P0103... As soon as I start the vehicle (after clearing codes) service vehicle soon comes up along with the code. Again any chance of a PCM issue?
Well here is a flow chart for an ‘03 since we don’t even know what year car you have…if you are 100% sure the circuit integrity is good and the sensor is good so yes it could be a bad PCM but they usually don’t go bad.
well here is a flow chart for an ‘03 since we don’t even know what year car you have…if you are 100% sure the circuit integrity is good and the sensor is good so yes it could be a bad pcm but they usually don’t go bad.
MAF/DTC Issue
