Ok my friends,

A couple days ago on the way home I went to pass somebody, when I did the truck started bucking and cutting out like I hit the rev limiter or speed limiter (it was around 3200 rpm's and as soon as I get back below 3000 rpm's it stops..) I can get up to 80mph or better as long as I do it slow..

Now for the things I've done:

1.Checked the computer, No codes..Reflashes in case program got a hick-up.
2.Checked fuel pressure. (65psi) Ford says 50-70psi.
3.Changed out coil pack.
4.New set of Motorcraft plugs
5.changed the TPS.
6.Pulled off the cam sensor cap nothing broke, shaft felt good and tight.
Still doing it!!! Rechecked codes, Nothing!!

Need some help guys, I'm at witts end!!!

Thanks Shawn

 

fuel filter...

 

No, less then 6months old and already checked fuel pressure...

 

Have you check for a vacuum leak? Air, fuel, spark. got to be one of the three you checked fuel and spark so only thing left is air!

 

Pulled air filter off, also checked the MAS. The intake air pressure / Temp and A/F ratio all checked ok.

 

I try and change mine every 3-4 months. Always dirty when I do. It's a $10 part. Change it and rule it out

 

Lets break this down to the basics, you say you have checked your plugs, coil, fuel pressure, tps etc. Did you do this when truck was under a load or just idling in your driveway. Can you check to see if the computer is giving full spark advance under load. What is your compression ratio? spark plug gap? coil output?
You can get full fuel pressure with a dirty filter if the pump and fprv is good at idle but it may be pressure maybe dropping under wide open throttle and heavy engine load. When was the last time you bought gas? Was it any good,did you get some water or dirt in the fuel, how much fuel in the tank? it could be a lot of things but it has to be related to one of the three basics.
Buy the way nice looking truck checked your profile!

 

According to the the livewire I'm getting full spark and load. Gap on new plugs is .044 because of factory coil, will regap when put screamin coil back on.. Gas was today 93 oct. same place 1/2 tank incase I have to drop tank... Haven't done a comp. check yet. Fuel pressure held at 65psi all the way to the park rev. limiter.I have also driven truck after each change of item.

Truck drives and runs great, even above 80MPH. But the minute you hit that 3000rpm to 3500rpm ranger it goes nuts bucking and cutting out. It reminds me of a new truck and you hit that 101MPH mark and it starts busting up till it back 99MPH..

 

Ok so your running a tuner, and it is between 3000-3500 rpm that you have the problem. Can you see your advance for that rpm? fuel map? Just to go back to basics have you done a wiggle test on your wiring? Does the engine smooth out after 3500rpm and start running right?

 

Will check tomorrow to see if it reads those, Might have to see if I can data log them. Checked all plugs I could think of, (ias,tps,injector plugs,coil plug,computer plug and ground wire,ect..) No haven't made it above 3500rpm's, what ever it is very violent when it starts.

 

Good morning,
Was thinking about your problem some more and still have a couple questions. I am not familiar with your setup other than what has been written here. So you say your air-fuel is right. What are you reading it with is it a regular 02 sensor or a UGO wide band.
What in your engine management changes at or above 3000rpm that can cause this type of effect.
Is it losing power then picking it up losing etc. You say it is very violent,3500 rpm is to early for valve float so I would rule out a mechanical issue.
Can you run the engine with out the SCT to see if it will run above 3500, replace the MAF with stock?

 

Good morning!! yes it is stock 02's. Not sure about program changes above 3000 rpm, My tune guy has fail to return any of my phone calls or e-mails as of this point. Yea, I could put stock MAS and tune back on. Just got off the phone with jegs they want $115.00 to put a gauge in cab (fuel pressure).. Checking on a set of wires and filter this morning also.. Will get back after I try the stock parts..

Shawn

 

Ok, stock MAS and stock tune... Still doing it!!!! Was able to check LTFT and STFT both were running in the .98-1.00 range which is good.

 

I would say it sounds like it is not your tune, could be something to do with fuel or timing. I would lean more towards timing, I am not at all familiar with the 3.0 do you have both crank and cam position sensor. I would check all my grounds for engine sensors i.e. maf crank position cam PCM power relay could be a high resistance only effecting when a big load is placed on it.

 

Well it looks like "Defeat" I'm going to wait till next Friday and take it to the rip off experts AKA Local Dealer and see if they can tell me something.. It's either going to be the Injectors or the Computer at this point I think..

 

Have you tried injector cleaner, you can get a pressurizes can for about 17 dollars and then a clamp on freon tap some imaginative plumbing and build a pretty cool injector cleaner.
http://www.amazon.com/3M-Universal-I.../dp/B0015PKNK6
http://www.etoolcart.com/cantapr-12r...oilcharge.aspx

 

Well update time!!! Went and saw a guy this morning who a guy at work told me about, told him all the things I had done and were I was at. He said well you've covered the basics pretty good, go ahead and change the fuel filter because you already have it. Then if it still does it. Unplug the cam sensor, it will still start and run. might even throw a light and code and see if it still does it.. AND IT DIDN'T!!!!!!

Now just got to buy a cam sonsor. Whats the best one to get and the ones to stat away from????

 

Cool glad you figured it out!