2005 Ford Sport Trac 4WD Auto on column 1639001 original mi(garage kept I bought it in 2016 w/ 54897mi on it never leaked,ran like a kitten.
I have check engine light on as of May 2020 with142000 miles on it. I’ve changed everything coil,plugs,wires,upper oxy sensor,Maf sensor looked for vacuum leaks etc... I was told by a honest mechanic,that he checked it out n what he thinks it maybe is rear timing belt tensioner(which would involve pulling engine. Front right would be easy (but Ford engineers messed that up).He said I could probably drive it for another 20,000 miles as long as I don’t beat it. I don’t beat none of my vehicles ever. He’ll im almost 67 was brought up right with mechanically inclined dad! I since put an cheap code reader on it it reads PO302(13) idk if I’m reading it right. 4.0 SOHC V6 engine it runs rough until I pick up rpms on it.When light blinks it goes slower but picks up after a few seconds. What could it be?
by the way thank you for your service and dedication. Sincerely Mike
pScotty I have a Ford Sport Trac 4WD Automatic trans w/1639001 original mi on it when engine light is blinking the rpms drop. I’ve cleaned n changed everything coil,plugs,wi res,oxy sensor(forward) maf sensor,air filter,oil change I checked for vacuum leaks. I even had an expert Ford mechanic (he hates Ford,the company that is) he’s started his own buisness. All the people swear by him. Apparentley he deducted it was the rear timing chain tensioner of which is poor design. You can access front right but will have to pull engine to replace rear one...he charged me 40$ it apparently is poor design what do you think it is? He said he’s seen them go 20,000 miles more if I don’t beat(which I don’t) I hooked scanner to it it’s showing PO 302 (13) it idles rough but is ok when I drive it, 4.0 SOHC eng what could it be
by the way thank you for your dedication n service. Sincerely Mike
Please don’t double post. Thanks.
It could well be the tensioner, still, feel free to have a browse through this, since you have a misfire code -
https://carkiller.com/scottykilmer/qa/misfire-4/
Hi Mike,
Is there any rattling upon startup? That is also a sign of a loose timing chain.
PO302 is just a random misfire code, so it does not necessarily mean a bad timing chain. (but the 4.0s are known for faulty tensioners, at lest in the early years)
Also generally if it is misfiring due to the timing to have slipped, since it is an interference engine, the valves and head will get damaged.
Also the misfire doing way at higher rpms can mean multiple things, one can be bad compression and if you don't have blowby into the crank case it can mean the valves are already bent. But it can also just be dirty injectors.
What light are you referring too?
