Thread: sputtering while accelerating

I have a 2001 Ford F1 50 at first it was misfiring on cylinders one and two I replaced the spark plugs and changes the coils and now as I accelerate truck starts to sputter

What engine do you have?

So u have a scan tool?


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If so. Does it have mode 6 data on it?


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It's the 4.6 and I have a diagnostic tool. It showed me a code for misfire so I replaced the coils and spark plugs I'm thinking it's the egr valve

I don't think it's the EGR valve, because when I put my new exhaust on my '05 4.6L it killed the EGR valve. The only thing it did was throw a code and maybe give me a little less mpg's for a bit. But if it wasn't for the code, I probably wouldn't have even noticed it.

Wen EGR valve hang open. It's usually due to the EVR passing vacuum to the valve. U can see if there is vacuum on the green EGR vacuum hose at idle. But I don't think that's it


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I'm stumped. Could the fuel filter cause this?. It really does not have a good exhaust. It leaks really bad. It's mainly when it gets warmed up. When I first start it in the morning and shortly after take off its fine.but when it warms up it starts acting up. It has random misfires now different cylinders. I'm used to foreign cars haha this is my first American truck

Sorry you're having issues with your first American truck, but it could be a few things. To be honest with the misfires on multiple alternating cylinders it could be the fuel system. I'd run some fuel system cleaner through it, I recommend Lucas or Stabil, replace the fuel filter, and see if it persists. If it does, then I'd change all the spark plugs and COP's. But do the stuff with the fuel first.

Ok. A few things to look at.

On heavy acceleration look at your 02 voltage with your scan tool. On WOT it should be over .88V or 880 mv. If it's not than this means one if two things. There is a miss or it's runing lean during the acceptation. See if you felt a miss or not. That can help u determine. U can also replace the filter for save measures. Next. Check back pressure. Easiest way is to get the DPFE hose that is hooked up closer to the exhaust. There is two hoses on the EGR tube. U want the one closer to the exhaust header not the motor as there is a restricter. Now hook up a pressure gauge and do a some snap throttles. In neutral snap the throttle to WOT and record your peak back pressure reading you don't want more than 6 psi. ( rough spec ) if you do your cats may be restricted. Another thing to look at is your spark plugs. If they been in there for awhile the plug gap could have grown. Install new plugs if it's been awhile.


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Okay, sputtering on acceleration could mean timings off, not enough fuel pressure, maybe another coil is bad and some other stuff. What i need to know is does it only do it on take off 0mph-up or does it do it when you hard accelerate at any speed?