Hey, anyone got any idea what I can check for? I replaced my MAF after it coded on me and I tested for voltage problems ( voltages OK ) and did a cleaning on the MAF sensor with no success. Still getting a P0102. I'm ready to return the new MAF sensor, but if I do and it codes on me still I will be where I am now. I'm a little suspicious that the MAF coding is what the computer thinks is wrong and maybe not the real issue. Is there anything else that can throw this code when something else is the real problem? Oh ya... 96 F250 4.9 2wd automatic.

 

Parts don't throw codes - only the EEC does, and you can't pick the name of a part out of the code definition and start repalcing things. Read the WHOLE definition, then learn about the system, then find out if the condition indicated by the code actually exists. There are at least 10 specific failures that can result in that code, and one of them is a vacuum leak. Did you check for that? Use a mechanic's stethoscope or 3' of garden hose to listen around the idling engine for a hiss.

 

Thanks for the reply. The first check I made was for a vac leak after the maf. Couldn't find one. Second was to clean the maf. Third was to test the voltages. The online link I was using didn't offer any other solution other than to replace the maf. Do you have a list link on those ten failures? Sure would help at this point. I was under the impression that there isn't anything to check after the throttle plate that could through this code.

The problem also comes and goes but never clears up completely.

 

This is just one step in a 19-step procedure to diagnose & repair that DTC, and you can see that it's a branching flowchart, so I can't post all 19 steps (some branches go to other procedures). But this should give you an idea of what you need to check:

Since you probably don't have a scantool that can read that PID, you can just measure the voltage directly with a common DMM.

Actually, ANY vacuum leak can generate that code - not just those near the MAF. And another possible cause for that code is contaminated fuel.

 

I'll run through the list you gave me and double check those on the list I've already checked. Will post back tomorrow. thanks again. Can a bad injector (P0302) contribute to the P0102 code in your experience?

 

I've never actually seen a Ford injector go bad, and that's not the definition of P0302 anyway. But P0302 should prevent P0102 from setting, at least temporarily. How long was it driven with the CEL on? List ALL the current DTCs.

 

Oh boy. Some time ago I had a bad intake valve on #5. In doing the R&R I had two pintle caps chip on me when I pulled the rail and slipped while leaning over the fender. My parts store had no line on new caps so I (at the time) replaced the two injectors. That's where the nightmare started. The injector supplier (Auto Line) insisted I had the right injectors even though the #'s didn't match. Yet I could not get the motor to idle good or perform well. 6 months later, numerous DTC's later. And all the tune-ups parts, and weeks of spare time later. I was at the top of my problem list again with no good results. So I pulled these two dam injectors and started running the numbers on the web. Turned out they sold me 232 V8 parts. Since that time I haven't been able to get a good injector from this company. 4 failures on #5 and now 2 on #2. They were all recons. I've given up on this supplier because they don't use industry approved electrical testing. They employ old Asnu cleaning machines, but refuse to buy the coil tester that works with the cleaners. I'm now just waiting for the Asnu distributor who runs his own shop to recon a full set for me. And yes every time I put in a fresh injector it ran good. Some ran for 2 to 5000 kms. before failing. Now I have just the one in #2 throwing P0302 intermintently. As for the P0102... it came on over the coarse of a day of running errands. I work the patch up north so working on the issue has been spuratic at best the last while. I realize that P0302 indicates a misfire, but with everything else working on the ignition. what else is left to throw this code other than the pcm? When I had #5 injector go this last winter I had #2 replaced as well because the warranty was up and the supplier tec wanted the two back for testing. Since the swap #5 is fine and #2 which was fine is now the problem. Go figure. And no I don't have any hair left. lol. My neighbour who runs his own shop scanned the unit (snap on) about half way through all this because I was convinced the pcm was the problem. He said it was fine. For the record; this is my first truck with all the computerization on it. And that I've had to do so much chasing on. Bit of a learning curve. But at least I know now what most of the sensors do.:-) As for your DTC question. I have a scan tool and clear the code(s) every time I've opened the hood and checked, tested or changed something. But The P0102 hasn't seen a full tank of fuel yet. Maybe 300 kms. And I buy only Chevron at one location. Been buying there for 20 years with never a problem. The P0302 only codes at low speeds/RPM. and not all the time. sorry about the book.

 

Do you still have the 2 original injectors? I'm pretty sure you can buy the pintle caps from Ryan.

http://www.fordfuelinjection.com/
http://rjminjectiontech.com/

Although these aftermarket injectors are the most likely cause, there are a few other things that can cause misfires, especially at low speed.
compression
plugs
wires
cap
rotor
PIP
ICM
misfire sensor fault (loose/damaged)

My engine is a '95, and I've never had to work on a '96 4.9L, so I'm not familiar with that particular setup (MAF, OBD-II) because it's so rare.

And just because you haven't changed gas stations, that doesn't mean THEY haven't changed. We have a lot more ethanol down here now than we did a few years ago, and it's wreaking havoc with older vehicles (like the '74 MGB in my garage whose head has been at the machine shop for a month), so don't cross fuel contamination off your list yet.

 

No, the supplier had a core charge so they went back. The replacements are Bosch, just reconditioned. But I have a full set coming from the fellow I mentioned earlier. All have been compared with a .5% flow rate difference. In talking with the owner/distributor he says its very common to see one of the four spray holes completely plugged. And that the coils most often have problems at low cycle rates. I've replaced the plugs twice. Second time being that I could see the difference in the manufacturing of the same Champion plugs from two different sources. The first being a High volume store. Are you familar with Canadian Tire? My parts store wasn't open at the time. Cap and wires are (new) good. I tried moving the wires and plugs around, but the misfire stayed on #2. As for the PIP... haven't done anything with it yet. I figure it should give me trouble accross the board so to speak. Yes/No? As would the ICM? The misfire sensor... Is it not the crankshaft sensor on this year/model that acts in this fashion? I here you about the fuel issue. But up here in Canuckland they have different formulas even for the change of seasons. I do have a raw fuel odor that isn't related to filling up. I was thinking from the misfire I'm getting it curculating back through the intake. Any thoughts? When I tested the maf circuit the ground was good. The power supply is the same as the batt. Key on power is good, and the run up test has good output as well, climbing and holding in relation to the TPS. I've called my mechanic neighbour to get a pro scan done to see if he can find what I can't. Will let you know, but still greatly appreciate any input you have.

Thanks.

 

UPDATE!!

My neighbour didn't have time today so I decided to check my maf power again and whata know.... no power this time. DEAD DEAD DEAD. Checked all that I could short of cuttin the wire harness open. Main power (labeled "A" on the plug) is gone. Guess when I checked it before is was just toyin with me. So PCM? Does this wire feed right into the ignition switch? Run through the headlight switch? AAAWWWGGGG!!! My haynes manual isn't the best in the wire schamatic department. And although I can find the MAP wires running from the PCM, there is nothing for the MAF. Makes no mention of the maf system in sec. 4 either. Seems it's just the "A" wire. Ground is good. Figure no sense wondering about C & D on the plug. Think I should try and chase the power wire back?

 

Haynes failed to revise their manual after '94 when Ford trucks started going to MAF, or after '96 when they went OBD-II, so you won't find anything specific to those systems in it.

The R power wire to the MAF is the same as every other R wire on the engine: injectors, emissions solenoids, HEGOs, FP relay, IAC, etc., and they all get power from the EEC PWR relay. So if the MAF doesn't have power, check any of the others. You did check it with the key in RUN, right?



BTW
An engine with a MAF has no MAP - they're mutually exclusive on Ford trucks (and most others).

For the fuel smell, check the FPR.



The PIP sometimes has a mind of its own, as do some ICMs. I'm not saying they're LIKELY - just POSSIBLE causes. The misfire sensor is on the crankshaft, but it's not strictly a CPS; more of a CSS.

 

Yes the key was on..lol. Made me go test it in the dark though. I tested the solenoid (IAC) on the throttle body and it has power. And the engine runs so I can assume the other sensors and relays are getting power. And yes I'm aware about the map versus maf issue. I mention it because I can find the R for the MAP on the schematic but the MAP has only 3 wires. I went through the fuse boxes earlier today as well. But I can't ID what the power is running through for the MAF. That's why I was asking about the ignition switch. Do you know what circuit the MAF runs through? Or does the power come direct from the PCM?

So is relay #1 (powertrain control system) the right one? Just found my Owners manual online and it has the power distribution box listed. And nothing else referenced on this circuit.

I swapped out relay #1 with relay #5 (spare) Made no change.

 

The MAF's R power wire is spliced to all the other R power wires that I mentioned, and yes: they get power off the PCM PWR relay. If it's not hot when they are, there's a break in it between the splice & where you're testing. Run a jumper (overlay) from any of the others back to the MAF.

This is an older layout, but the relays are the same as yours:

 

Thanks, I'll let you know how I make out with it. time to get even!!! MMMMHHHHAAAAAWWW HHHAAA HHHHAAAA HHHHAAAA

 

That could be part of the problem - you should be using Motorcraft or Autolite.