I recently bought an 02 f-450. It has a miss sometimes at idle, it is more noticeable when taking off from a stop and accelerating. The truck has 245k miles. I replaced the spark plugs with new motorcraft plugs and changed all coil boots with no change. All the coils ohm'd out ok, and have no check engine light on.

I bought an actron scanner capable of doing mode 6 to try to find the culprit. I thought maybe it just wasn't a misfire, but when I go to test $53 I can't even get it to show me the max or min numbers. I read the article on testing mode 6 and took the truck on a test drive and did 4- 60mph to 40 deceleration runs without braking, and the truck has 1/4 tank of fuel. Is there something else I need to do to get mode 6 to work? I tried out my scanner on my 00 f-250 with a 5.4 and it did the mode 6 test as it should on it. I appreciate any help! Ryan

 

If your truck is an OBDI (=not made for CA standards and other green state emission standards) , quite possible that is not available .
Check the emission sticker under hood and tells us if it is OBDI or OBDII .

 

Is the miss somewhat regular or all over the place?
From idle to "accelerating" how long into "accelerating" does it misfire?
Does your F-450 have an IAC valve and has it ever been cleaned/changed?

 

Check all the injector clips. They get brittle and do not make good contact. Try zip tying them on if any are broken.

 

Thanks for all the help guys! I checked the sticker on the passenger side valve cover and it says, OBDI certified. So I guess I may be out of luck on the mode 6 thing.

The miss is pretty intermittent at idle. Sometimes it sounds good, sometimes it just sounds like it misses one every once in awhile and sometimes worse. The miss is worst when taking off, lugging the motor, and accelerating. It shakes and stumbles pretty bad then. By the time I get up to 50 or 60 mph it seems to be doing better but that could just be because the truck is rolling along pretty good then.

I don't have any of the service history on the truck, but it appears most service was neglected. It does have an IAC valve, I got it off today and it appears very dirty and is probably the original so I have one ordered to pick up tomorrow. I checked all the injector clips and they all appear good, but I do have one coil that has the ear where the bolt goes broke off.

I'll let y'all know who's it does with the new IAC, I appreciate the responses!

 

My OBD1-based 01 F250 with the 6.8 works fine, I can and have read the misfire counters with Torque as well as another application/tool. Mode $06 applies equally for both OBD1 and OBDII calibrations, it's the same basic PCM hardware and software. They just calibrate out the stuff unnecessary to meet the OBD1 standard.

All you're doing when you read the mode $06 misfire data is looking at counters that the PCM is using as a scratchpad of sorts.

I'd find it quite unlikely that an 02's software capability would have regressed from an 01.

 

I will admit I'm not very good with figuring out everything on how to use my scanner yet. It is very possible it would do the mode $06 on this truck and I'm just not doing something right or maybe if there are more conditions that have to be met for it to register the misfires that they haven't been met yet. But just for information I plugged it in to my 2000 f-250 with the 5.4 and showed the misfire data in mode $06 on it just fine. I'm using an actron 9670. Thanks again for the replies!

 

With your mileage I recommend removing all 10 injectors and either buying new ones or some refurbished ones or send yours off to be ultra sonically cleaned.

I dI'd this to all 3 of my V10s with between 100K and 200k on the odometer. In all 3 cases there was at least 1 injector that was severely clogged and/or not functioning correctly.

This is not in my opinion throwing $$ at a issue. It is standard maintance at your mileage and to properly diagnose a fault this maintenance needs to be done......

Next I would confirm proper fuel pressure. A poor battery or alternator will cause a fuel pump to be low on volume and pressure....causing numerous issues.

Your issues sound like poor fuel pressure causing a injector that is dirty to missfire.

So check battery, check alternator, check fuel pressure, and replace injectors. Oh and put some new Denso or oem coils on it.

After what you have already done I think there is a 75% chance the issue is one I have stated.

That said to the point of your thread.
A $20 Bluetooth obd adapter and free Torque app should tell you which cylinders are misfiring.

 

Thank you for the reply! I have started the first stages of working on this list. I found a place locally that will flow test and ultra sonicallly clean the injectors for $10 each, so I guess I will get them out and get that done.

Since you mentioned the battery condition and alternator, my battery does run down and it has to be jumped off if the truck sits for a couple weeks. So that could be contributing to the problem. I will check the battery and charging system condition before anything else. I know I can hear a buzzing from the fuel pump while the engine is running, which is different from my trucks with the 5.4. I also got a new fuel filter to put on and will check the pressure. Thanks for all the help and recommendations, I'll keep y'all informed on if I make some progress! The new IAC helped with throttle response but not really with its missing problem. Thanks again!