please help-unsolved problem

[rangerrager]

so guys i really need ur help ,a couple mechanics said they dont know what to do and neither do i . my truck runs OK when driving regular but the second i floor it the truck completly cuts out it doesnt stall just looses power completly and back fires out of the intake.

so far i have checked
the maf
tps voltage is fine at idle and at wot
i checked the resistance on all wires and its fine and checked plugs and they are are OK

i dont know where to go from here ..please help.
thank you to anyone who can help
ryan doyle

 

[KELLY88]

Is it an automatic transmission? If so it's probably not kicking down (downshifting) when you gun it like it's supposed to. Check that out. Otherwise it sounds like a fuel delivery problem.

 

[Stranger ranger]

my first educated guess would be the fuel filter.

 

[rangerrager]

ill check to see if it is not kicking down ,that does make sense .
and i didnt mention i changed the fuel filter last week im gonna check fuel pressure tomorrow any way tho..
any other ideas guys
im really stumped on this one

 

[rangerrager]

if it was a kickdown problem ,if i put it in the first gear selection(auto trans),it should not hesitate anymore because the kickdown doesnt engage in 1st or does it?
thanks for any help guys

 

[97ranger4x4]

Have you tried doing this. With the truck in Park, Open the hood and hold the throttle open so that it revs about cruising speed (2000-2500 rpms) and then push it wide open as if you were flooring the thottle. This will tell you if your transmission is a possibly culprit. If it still cuts out, then you know the tranny isnt the issue.

 

[rangerrager]

no it doesnt cut out when i do that ,,but that doesnt mean the trans is to blame it only does this under heavy load,meaning from a dead stop if i floor it

 

[rangerrager]

no one huh? this is gonna be a hard one

 

[ranger dude]

Check the fuel pressure. Hook a fuel pressure gauge that has a long enough hose to put it where you can see the gauge ( tape to the window or hook to the wiper arm ) while you drive the truck and check the pressure at the same time the truck looses power and starts back firing

 

[Nhaz]

If its back firing would that not mean its still getting fuel? I could be talking out my ass on this I will admit right away im not mechanic I fumble my way through problems half the time.

Since the truck is fuel injected and is pretty much computer controlled for firing the spark plugs. how does a engine like that dump enough fuel into the exhaust to backfire?

bad plug? bad coil pack that doesn't fail until its asked to perform a tad more?

could this be a failing sensor that isn't informing the computer that the engine is running harder?

 

[shadetree]

Check your camshaft timing. It may have jumped a tooth.shady

 

[rangerrager]

it backfire out of the intake not the exhast .....and im gonna try that the fuel pressure idea ..
thankyou
ryan

If its back firing would that not mean its still getting fuel? I could be talking out my ass on this I will admit right away im not mechanic I fumble my way through problems half the time.

Since the truck is fuel injected and is pretty much computer controlled for firing the spark plugs. how does a engine like that dump enough fuel into the exhaust to backfire?

bad plug? bad coil pack that doesn't fail until its asked to perform a tad more?

could this be a failing sensor that isn't informing the computer that the engine is running harder?

 

[sndslingr]

correct me if i am wrong but that truck should have a distrubtor could it be going bad? spark plugs not hooked up in the right order ? like someone said earlier timing could have jumped

 

[rangerrager]

no distributor on this truck but i triple checked all wires and they are ok..if it was the timing it would run rite alll the time it runs perfect untill i floor it from a stop.
thanks for the ideas guys keep them coming

 

[snake]

I have seen this problem on an older car with a distributor, coil and carb, and it was the coil gone bad. It would run fine until you TOUCHED the carb secondaries and then backfire like a sombitch. Also had a bad coil allow a car to run fine, but the second it was dropped into gear (automatic), it would stall.

I know this is electronic and all, but normally if it is backfiring (thru the intake or exhaust) it is firing at the wrong time. Check valve timing, firing order, and look hard at the electronic ignition stuff.