P0102 Code

bbayne35 · Aug 1, 2016

I have a 2000 GT that is throwing a P0102 code. I do have a service manual on CD and will look at the troubleshooting procedure, but I wanted to see if anyone has any advice here.

My idle has been fluctuating more than normal in the past couple of months. I have had a faulty idle air control valve in the past, and this seemed similar. A couple of days ago, the car started stalling when the rpms dropped to idle. This is exactly what happened in the past, and a new IAC valve fixed the issue. So, I bought a new one and installed it. I also cleaned the MAF.

Now, my car is not stalling, but it did throw the P0102 again and is running rough. When I attempt to accelerate, the rpms dip before they rise. Let me know of any recommendations for troubleshooting.

Thanks.

squeak93 · Aug 1, 2016

That's a code for a Mass air issue. Check for leaks and proper connections. If you have a buddy with a known working sensor that's the easier way to check for a functioning sensor.

bbayne35 · Aug 3, 2016

squeak93 said:
That's a code for a Mass air issue. Check for leaks and proper connections. If you have a buddy with a known working sensor that's the easier way to check for a functioning sensor.

Good idea about borrowing sensor, but I do not know anyone with a match. I did go through the service manual diagnostic routine for P0102, and it is telling me to replace the MAF sensor. I hope that solves the issue!

bbayne35 · Aug 5, 2016

I followed the service manual diagnostic routine for P0102. I have a Predator and was able to monitor the MAF V pid. It was showing .02V and not moving with the engine running. I even disconnected the MAF sensor while it was running, and there was no change in how the engine was running (which was rather rough). I followed the rest of the routine to check for power, ground, and any shorts, and everything else seemed normal. The service manual said to replace the MAF sensor. I ordered a new Delphi replacement sensor from Rock Auto and installed it last night. It started and stayed running. I know it has to go through a learning cycle, and while doing so, the RPMs were somewhat erratic (dropping way low (~250) before surging back up again). It never stalled. I took it for a drive and it drove fine. At idle, it was still a little unsteady, but it improved. I noticed a P1100 code on the scanner (mass air intermittent). I realized I never disconnected the battery after installing the new MAF sensor, so I did that last night. I started it this morning, and it appeared to be doing the learning cycle again. The idle is still a little unsteady. Do I just need to continue to drive it to get through the learning cycle, and will it eventually right itself? I briefly looked at the diagnostic routine for P1100, and that appears to check for loose wires. I have not done that in detail, but nothing looks out of the ordinary at the MAF connector or under the air filter. Where exactly does the MAF and MAF RTN wires route to the PCM? Any advice is appreciated.

jeno_labanca · Aug 5, 2016

You need to relearn or do the drive cycles first before going any further see if it clears up

Sent from my SM-N910T using Tapatalk

bbayne35 · Aug 8, 2016

I have driven the car 3 times (30 minutes each time). It seems like it takes 2 or 3 tries to find the proper idle. In other words, it will drop really low and then spike a couple of times before settling on 750 rpm. On my ride this morning, it actually stalled twice (in a row). I need to look up the drive cycle, but I was thinking that it would be through it by now. Is there anything else that could be causing the unsteady idle? TP sensor? The throttle body itself?

wmburns · Aug 9, 2016

Your idle will NEVER be right while there's a P0102 DTC occurring. This DTC means that the PCM is essentially working without the MAF.

As for other "possible" causes for an unsteady idle:

battery, alternator, charging system problem. Bottom line. Today's cars simply will not work right without a strong battery and charging system.
loose/bad PCM ground.
Short cycling AC (low on Freon).
Vacuum leak.
disconnected or leaking fuel pressure sensor (FRPS) intake vacuum reference line.
Bad FRPS
loose or worn throttle linkage.
Weak throttle return spring.
Misfire or ignition problem.
Weak cylinder to cylinder power balance.

Start with the battery. Why? Because if the battery is weak, this can cause the PCM to "forget" and have to re-start the learning cycle over again. Wash/rinse/repeat.

>>>
P0102 - Mass Air Flow (MAF) Circuit Low Input

MAF sensor disconnected
MAF circuit open to PCM
VPWR open to MAF sensor
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
MAF circuit shorted to GND
Intake air leak (near MAF sensor)
A closed throttle indication [throttle position (TP) sensor system]
Damaged MAF sensor
Damaged PCM

bbayne35 · Aug 10, 2016

Thanks wmburns. I failed to mention in my third post that after I did the diagnostic routine for P0102 and replaced the MAF Sensor, the MIL turned off, and the P0102 went away. The idle is still unsteady though.

I will take a look at the battery, but both the battery and alternator are relatively new, and the connections are in decent shape. I will check my manual for the location of the FRPS and see if everything looks ok. Is there some type of test or PID I can monitor to evaluate the FRPS? I will double check the throttle linkage as well.

bbayne35 · Aug 10, 2016

The battery seems fine. If the FRPS is the fuel rail pressure transducer that is located on the fuel rail on the driver's side, then it appears to be ok visually. I checked the throttle linkage, and the throttle cable seems to have a good amount of slack in it. However, I was monitoring the TB on my last drive, and it did show WOT when I floored it. The hose that exits the rear of the throttle body is in bad shape. It is one of the only ones that has not been replaced on my car. It appears to disappear down into the passenger wheel well. Where exactly does that go?

bbayne35 · Aug 10, 2016

I followed the hose off of the back of the throttle body, and it leads to the evap canister purge valve in the passenger wheel well. As I mentioned, that hose is in terrible shape. I have removed it and will try to get a replacement for it tomorrow. The outside of it was crumbling as I was handling it.

I connected my scan tool and see that it has a P1100 code (mass air intermittent). It is not turning on the MIL, but the code is there. I looked at the diagnostic routine, and it is saying to check the MAF sensor wires. I will give that a shot, but when I did the P0102 diagnosis, the MAF wires seemed to pass the tests.

I will report back after I replace the evap canister purge valve to intake plenum hose.

bbayne35 · Aug 11, 2016

I replaced the evap canister purge valve to back of the intake plenum hose. The idle issue remains unfortunately. Any advice is appreciated.

wmburns · Aug 12, 2016

Focus on the MAF. Everything else is just a smoke screen until the PCM has a solid MAF signal. Since the MAF is new. Look for a wiring problem to/from the MAF.

bbayne35 · Aug 13, 2016

OK. While going through the P1100 diagnostic routine, the service manual says with key on engine off, wiggle the MAF Sensor wires to see if the voltage goes outside of the .23 -4.6 V range. With key on engine off, the MAF voltage is showing 0 V and does not change with any wiggling. The last time I checked with the engine running, the MAF voltage was in the acceptable range. So, with key on engine off and a MAF voltage of 0, what could be the problem?

wmburns · Aug 14, 2016

Are you still getting a P1100 DTC? Is this an after market MAF? Is it over sized or larger than stock? Is it "indexed" differently than stock?

Note, if the wiggle test does not produce changes in the MAF signal with the motor off, then likely the problem isn't a loose wire right at the MAF.

bbayne35 · Aug 14, 2016

Yes, the P1100 is still there. It is an aftermarket MAF, and it is oversized (80 mm from C&L). I do not think it is indexed any differently than stock. FWIIW, my intake setup is a C&L air filter, 80 mm C&L MAF, C&L inlet tube, Accufab 75 mm throttle body and C&L intake plenum. I have had that setup for 10 years.

bbayne35 · Aug 26, 2016

I just wanted to post a follow up on this issue. You can see the details above, but the P0102 code pointed to a bad MAF sensor, which I replaced with a non-Ford part from RockAuto. I was still having idle issues though. It turned out that the non-Ford MAF sensor was no good (at least for my set-up). I ended up installing a good Ford MAF sensor, and that did the trick. I think the lesson is to stick with Ford parts when it comes to sensors!

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