I recently started having a minor intermittent miss in my 99 V10. Didn't worry about it too much because it was barely noticable. I thought that when I have some time I will replace the Fuel filter, put some injector cleaner in the tank, and clean the throttle body. 108,000 miles on the truck now. Plugs changed at 95,000. O.K. So going on a trip this weekend, 100 miles one way, the miss started occuring again. On the way home, 3:00P.M. Houston Tx. 101%s F. the miss started getting worse. This started under slight load at highway speeds. It is now bucking and jerking at any speed when hot. Runs great cold for about 10 miles or so and then starts rearing it's angry head. Checked the DPF Sensor voltage, the EGR Valve, and both are OK. No check engine light. The miss is too bad to be only one cylinder. Acts like the old days when someone would switch the ignition wires on 2 cylinders after doing a tune-up. It just has to be an ignition, heat related, issue. Help! and Thanks!

 

maybe the fuel pump?

 

Well here are a few things to think about and look at
Cops going bad ?
Spark plug boots cracking alowing misfires?
Did you chk to make sure you have no antifreeze dissapearing from the coolant bottle?
Or bubbles in the coolant?

Take a fuel pressure reading from the fuel rail

Have you ran another tank of fuel through it yet?

Rich

 

Get the misfire counters read. Drive it for a while, let the miss happen for a while, and without turning the key off, get it read for misfires. Not just codes, but misfires.

That should tell you what cylinder has the problem.

Report back!

 

I had a problem similar a few months back, had it checked out and everything, no one could find it. I was doing some routine maintenance and cleaned the MAF sensor, it did the trick. Seems my K&N was over oiled and caused a dirty MAF, thus my problem was solved.

Good luck

bill

 

Thanks for your responses gentlemen. I have stopped at several shops and tried to get the misfire counters read, but the independents tell me that unless I have a Check engine like on, thier diagnostic equipment is of no use. They tell me that only a Ford dealer can check misfires with proprietary software from Ford that they pay to update on a monthly basis. Those poor independants. I just hate to have to go to our dealership and pay an arm and leg to have those professional liers give me a story. Can't even go into the shop and observe the procedure. I too have a K&N Filter and will check and clean my MAF Sensor next. Since I first wrote for help, I have further noticed that when the missing becomes acute, meaning bad shaking and loss of power, if I continue to hold the same throttle setting, most of the time the miss will go completely away for a few seconds and then come right back. Just like turning a switch on and off. Absolutely no miss and full power for a few seconds. If I nail it to the floor and accelrated for 5-10 seconds, power is normally restored and the miss goes away for a few seconds. Anyway, it never misses from a cold start for the first 6-10 miles. Maybe that MAF secsor is getting tricked. I will try it. Thanks again.

 

well your local independants don't have very good scanners then!
Because you can go to your local autozone and have them read for free
Thats if you get the right monkey to work the scanner.

we have found that being that these trucks are OBDI that a misfiring coil will take about 40% longer to tigger the cel light.This because within the computer the threshold to trigger is very big

But autoxray is a scanner capable of reading misfires

Rich

 

Thanks FortyFord. We will keep diggin. I will check out the scanner you refered to. This problem just has to be a sensor that feeds data to the PCM that tells it when to send primary signals to the COPs. OR......a vacumn-air problem that is out of sink with the variables of a particular running situation. The answer is going to be a very simple fix! It always is. I am going to hook up a vacumn T in the EGR line tomorrow to monitor how much vacumn is being sent to the EGR and when. If the EGR is closed during the misfires, then it has to be an electrical problem. Remember that the fuel pressure has to be good to run the engine from cold start and shortly thereafter to 100+ miles an hour without a bump. As you probably know, even at 275HP, this motor has alot of torque, (grunt), and can propel this heavy truck down the road. We just have to keep working on this until we find the logical answer. Thanks for your response. By the way Bill, I cleaned the MAF and Air inlet temp. sensor and no fix. I was really excited however, because I am running a K&N Air filter as well.

 

You may just have a bad cop breaking down do to heat
I'd be looking at the cylinder misfire counters thata are stored in the memory of the ecm.
If your boots are good also as was stated before it either cop or injector cicuit(highly unlikely though )

did you clean the maf with brakleen and let it air dry?
Rich

 

Just play musical chairs. Buy a good COP and rotate it through the lineup. You're eventually going to need it anyway, and this way you'll at least get some definitive answers!

 

BareBones-YOU ARE BRILLIANT! I went and bought a coil, put it in #1, fired the V-10 up and still missing. I read the ohm resistance of the primary, compared to the old #1 to make sure it was not shorted or open and went on to #2. An hour and a half later I was at number 10 and not very confident that we were getting anywhere. But........guess what?? It was number 10. Back of the motor and hotter than *(^^. Anyway, it is fixed. Thanks to all of you for your input into this problem.

One more thing. I am digging into this code reader issue. As I understand it, most all code readers will output missfire codes, IF, a check engine light is on. Mine light was not on. I have an E-Mail into tech support at autoxray.com to verify that their new 6000 model reader and interface to a laptop is capable of this kind of analysis work. If it is, it would be a steal at internet pricing of $399.99. There sure is a huge market for this kind of technology.

Thanks again to all.

 

I don't mind adding that in my opinion, that solution WAS brilliant! Some things are so obvious you don't think of them, or something like that!

 

My autotap that cost like $250 or so reads the misfire counters. Not sure about the V10 though, it might not, come to think of it.... it's like 5 years old.

 

Agreed! Good call BareBones and your reputation points reflects it!

 

Cekingsley i have the same truck as you. And at 78k is when mine happened. One COP underload was going bad. It did take a load under heat to make it happen. I agree with barebones. One of the easiest ways to diagnose it.