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I just recently bought a 2007 f 150 lariat. At random times when the truck is stopped and i try to accelerate it will bog down and it will work its way thru it and then work fine. Some times when i come to a stop the engine runs really rough, and i can hear a knocking on the driver side top of the engine. it will eventually stop in a few seconds and be fine. It mainly happens after the battery is disconnected for a minute or after i tune it and the computer resets. The truck has 128000 miles on it. Ive read many different forums and cant really pin point it. Any help would be apreciated. Im thinking about starting with the mass air flow sensor throttle body cleaning.
Check your oil pressure at hot idle. If it's at or below 25psi you have problems. Did you buy it from a private party? Why are you disconnecting the battery so much? Even after you disconnect the battery it should not do this.
Even if the check engine light is not on it may still have trouble codes stored. Pull these. If it's shuddering that bad it should have thrown something.
Any codes? If you don't have a code reader or tuner that can read them, take it to a parts store; they will read them for you for free. Then simply put that code in the Google search box (or search them on this site) to obtain good info on what the problem is, and in most cases, what the suspect components are.
Cleaning the throttle body is a good place to start as well. You may have a bad COP (coil over plug), but this will most likely have a stored code to indicate that.
I'm a firm believer in not tossing parts at a fault; eventually you fix the problem, but it gets expensive.
Get the codes read, then post them here and/or search on them in Google.
Give an answer, they learn for the day; suggest a search, they learn for a lifetime.
Rocko1- I will check my oil pressure in a min. I usually dont disconnect it. I read some were saying disconnect it and try it but i think my tuner resets my computer any ways after a new tune is installed.
Bucko- there are codes. I recently tuned it before i posted here and havent drove it. Im bout to go for a ride and update you with the codes. Thats why I posted here to hopefully get it fixed without spending to much money.
not to scare you but i had same problem, ended up with flat cam and a bad valve. the roughness only came at start up and it would go away, im assuming the computer was adjusting for it and after time it screwed up the valve. my father n law is a mechanic and did all the work for me and saved me a lot of money only had to pay for parts and the machine shop.
Mine has the same "rough idle/engine shudder"....its been doing it for well over a year now, though it used to only seem to happen occassionally, when in gear at stop lights etc. Now it seems to do it all the time...even on cold startup, after the rpm start to come back down. It seems to be worse with the a/c off. There are no codes and I've had the plugs replaced but not the coil packs, fuel filter, cleaned MAF sensor and TB.
And lately the idle rpm seems to rise as much as 100 rpm when sitting at idle for over a minute.