Hello, 2002 F250 5.4 V8. Recently swapped out my 200,000 engine for a 2006 engine with supposedly 40,000 miles on it. Well when I go up hills or even just accelerating the truck will studder a bit like its mis-firing. I would think its a COP but I did the unplugging of fuel injector test and they all seem ok. I haven't driven the truck very much since the swap...maybe 100 miles. I called the dealership and told them I just need everything gone over and diagnosed, they said no problem it'll be about $185 I asked how much time that included and she said about 2 hours. Do you think it would be money well spent or do I need to drive it a good bit more to let everything adjust properly? Also the only code it is throwing are O2 sensor codes.......thinking that may just be because it had about a 1/8th tank of gas sit in it for damn near a year.
Thanks everyone

 

If you have a code and you are a DIY, change the O2 sensors, My opinion anyway, Bad O2 will cause the problems you describe.

 

The code it was throwing was for the upstream + downstream O2 Sensors (I believe 4 on engine 2 had trouble codes) So you think this could cause rough acceleration and studdering? I never really knew what the purpose of the sensors were.
Thanks

 

They sniff the exhaust and compare it to what air is suppose to be coming in, if they throw a code it is usually for and engine A/F issue not the sensors themselves. Personally if you don't want to do it I'd go to an independent, the dealer won't be as knowledgeable on a 10 year old truck. Their bread and butter is 3-5 yr old warranty work and that is what they are trained for. Should also be able to get a free diagnosis from an independent.

Also a bit curious what a supposedly '06 engine came out of, they were all 3V's by then except for vans.

The actual code numbers would also help others on here give an idea of what may be wrong.

 

it could still be a bad coil. they will not throw a code if the coil is going bad and only occasionally misfires.. the computer will wait for it to just about fail completely before throwing a code.

 

The 2006 engine was from a van. I'll go back to Autozone and get another code reading....They say it will also read pending codes

 

Ok the code was a P0420, and I also had a P0125 for low cylinder head temp....but I put a 170 thermostat in versus the 195

 

In my experience, a P0420 will not cause a driveability issue - it just means the output of your two oxygen sensors is too closely matched, indicating that your cat converter isn't doing enough.

 

So, you're throwing a code for upstream and downstream O2 sensors?

If that is the case, those sensors are upstream and downstream of the catalytic converter. You might try disconnecting the exhaust ahead of the cat and seeing if the problem goes away.

 

170 T stat means it could run rich quite a bit, no reason to go below 195.

 

LOL. I've been at my dealership since 1992, and I am middle-of-the-pack as far as seniority. I still work on carbureted vehicles and throttle-body injection for cryin out loud.

Not as knowledgeable on a 10 year old truck? We've been working on them daily since they rolled off the line. It's not only bread and butter, but the gravy too. Only about 40 percent of the work I do is warranty work. Everything else is older vehicles, especially these days.

As for the op's truck and his problem, I would shop around for another dealer. Most will only charge one hour for a driveability checkout and that should be enough to get things rolling. The issue will be when it comes time to make repairs. If you replace the parts yourself, you won't have the ability to immediately retest with diagnostic equipment like the technician can. After they do the diagnostic and give you an estimate, I would explain to service advisor that money is tight and ask if it is OK to come in and talk to the tech for just a couple minutes to work out a game plan. Ask him how much he would charge to retest the truck after you make the repairs. I often do this for people for minimal charge, maybe a few tenths or a half hour, depending on what needs to be retested. Sometimes for free if they are a good customer or I think I can get them to come back for future work.