I have a 99 f250 v10. The engine started missing at idle speeds. So i discounted the mass air flow sensor and it smoothed right out. So i bought a new mass air flow sensor and installed then hooked it back up. When i started it up again it did the same thing. So i discounted the sensor again and the engine smoothed out again. Can anyone explain this to me?

 

clean the keep alive memory.. disconnect positive terminal on the battery and touch it to the NEG for about 15-20 min that will clean the KAM. try that. if not could be a problem with a dirty IAT intake air temperature sensor. since that works in part with the MAF. even though the MAF also has a back up IAT sensor.

 

I will try disconecting my battery like you said . do you know where the IAT sensor is located on the V10?

 

I'm no electrical engineer (but I will be a mechanical soon), but that doesn't sound like a good idea to me. Just disconnect the battery and turn your headlight switch to "On" for about 20 mins.

 

Wow what professional advice!
Wash the memory, throw money at it, guess.
Happy holidays.

 

. I did that and the check engine light went off but that was it. is there a IAT sensor somewhere.

 

I am missing something here I guess. Why disconnect the MAS, and where did that idea come from? And what's with touching the battery leads for 15-20 minutes? Never heard of either. Not trying to be sarcastic, just really curious.

 

I never heard of touching the pos to the neg either. Anyways My truck was running like crap. When the truck is at idling speeds or low rpm the engine revs up and down like im tapping the gas. I got the codes from the check engine light and it was p301 p304. Someone told me that could be from MAS sensor. So with the truck running i disconected the MAS sensor, right when i did that the engine smoothed right out and the truck ran fine. When i hook it back up the truck ran like crap again. So i bought a new MAS sensor and hooked it up but it did the same thing. I'm stuck on this one.

 

Dunno about putting the leads together for 15 mins. But Ive got to ask why do you turn the headlights switch on when clearing the ram?

 

It's been my very expensive experience that in situations like this it is a good idea to have it checked out by a pro. You end up spending more money on a possible fix, where as a tech may get it right the first time. Or maybe he has seen this problem before and knows right where to start. Just a thought.

Good luck.

 

Ya I know but when it comes to money Im a tight ***. I would rather spend my money on other stuff, like new tires. And I like to do the work myself so I gain something out of it. So I will try and get some input from people and keep tinkering around with it until either i find the problem or i get so frustrated that I take it to the shop. lol

 

It's just more Bum Gouge from Faster.


The reason people tell you to turn your headlights on is that it will drain any current left in the system and therefore clear the memory. HTH

 

What he said ^^^^

 

when you unlpugged the mas senser the computor goes into
failure effect mode usually called limp mode
p301 p304 are cylinder miss detetion code #1 #4
since it runs better in limp which is genrally a richer mixture
I would check for posible vaccum leak
maybe bad coil pac ?/plugs
mitch