3.0 valves AGAIN

[Rearanger]

ill tell you what the ford place here told my buddy on his 04 when he burned his valves out. the tune on the newer rangers (99 up) is super lean and any exhaust modifications will burn them out. it causes too much exhaust flow and the temperature in the chambers goes into the exhaust ports and cooks them.

If there's "too much exhaust flow" then that means the extra air entering the combustion chamber will be detected by the O2 A/F sensor and the MAF and the "leaner" burn will be adjusted by the computer. I haven't seen anyone here prove with a dyno/exhaust gas analyzer all this "lean" burn is actually happening. If in fact the factory has "leaned" these engines so much that the coolant cooled valve guides burn out before the valves, then we'd see 100's if not 1000's of Ranger valve guide replacements. Are there?

 

[stmitch]

u sure that shit is cheaper? regular unleaded is 2.54 a gallon and last time i see e85 (when it first came out and they only had it at one gas station in baton rouge) was 5.44 a gallon. ive heard it is an excellent race fuel for high compression engines or turbo cars, wanted to try some in a few quads and see how it does.

Yeah. It's generally cheaper. Atleast around here. Usually around $0.30 /gallon less than regular unleaded. I recently bought a whipple, and plan to use e-85 whenever possible instead of the recommended 93 octane. The e-85 would be 105ish octane, and it should average about $0.50 /gallon less too. Thats a double bonus!

 

[rurouni20xx]

extra exhaust flow will scavenge the fuel charge out of the chambers when the valve is open during valve/cam overlap. in turn the o2 sensor will read rich from the unburned mix, and actually lean the cylinders out even more, watched it happen on a dyno with long tube headers/no cats on several engines. interesting to kno on the e85 thanx for the input.

 

[crf250r6]

i had my cats checked, at least tried, they couldnt check them cause of the rev limiter at 3,000 rpm, they said that wasnt normal that i have other problems but i thought it was. also i think my fuel pump is goin out cause if it sits for more than an hour i have to turn the key on a few times, will that cause it to lean out, the check engine light did start comin on after the fuel pump started doing that.

 

[Big Jim M]

If the fuel pump is up to snuff and only has a leakback into the tank, there shouldn't be a problem when the engine is running. I've had several that I had to turn the key to "run" for 5 or 10 seconds before hitting the start, just to get it running.
Big JIm

 

[crf250r6]

yea it seems like a leak back cause it doesnt cut out, i was just wondering cause my buddy has a older f-250 and they said it was running lean cause his fuel pump was going out.

 

[Big Jim M]

Makes you wonder just who "they" was don't it?
Big JIm

 

[crf250r6]

Very true, but I guess when he switched to the second tank it wasn't lean anymore, also when they did my heads they must not have the valve guides right cause one cylinder burns oil, could that make that cylinder run hotter or possibly plug up the cat on that side?

 

[Big Jim M]

YEp!

Very true, but I guess when he switched to the second tank it wasn't lean anymore, also when they did my heads they must not have the valve guides right cause one cylinder burns oil, could that make that cylinder run hotter or possibly plug up the cat on that side?

Plug up the cat? Quite possibly. Run hotter? Prolly not enough to measure. The oil burns at near the same temp as the fuel it is already burning.
Big JIm

 

[rurouni20xx]

it will carbon up the chamber and raise the head temperature. carbon buildup will cook exhaust valves and even wear on the top of the piston.

 

[Big Jim M]

Howdy 120 From some of your posts I surmise you were and psooibly still are into 2 strokers.. There is lots of differences between them and these automotive engines..ain't there.
Big Jim

 

[crf250r6]

One day while driving it started cutting out so I checked the plugs, one was covered in carbon build up so I'm asuming that's the one that's burning oil, it wasn't like that the first time I had this problem, just noting that since 120 was talkin about carbon.

 

[stmitch]

Why is your rev limiter @ 3000 rpm??? These engines redline around 5500 rpms. They don't even start to make any power til around 2500-3000rpms. I agree witht the guys doing the testing. There's something else wrong here.

 

[crf250r6]

no park or nutral the rev limiter is at 3000

 

[crf250r6]

Sometimes too when I start my truck it revs up real high, any thought on that, and what ever that is can that cause it to run lean