Confused 9702
 

Hello all,
new to forum have a problem I need help.1997 E-450 box van 6.8 V-10 motor took a dump.bought a 2002 wreaked E-450 motor home 34000 miles started engine purred like a kitten.pulled it and installed it in my box van change PCM and oxygen sensors motor starts but idles rough and backfires,checked all vacuum lines and connections everything seems fine.any help would be greatly appreciated.

Thread moved, more V10 spoken here. Welcome to fte and good luck with your truck.

In order for this swap to work properly you'd need to change just the long block. Considering you're using two different year parts there is most likely wiring issues---Ford is famous for changing wiring harnesses from one year to another.

Ideally you'd leave every part of the engine management system in the box truck transferring sensors etc to the replacement engine.

I do wonder if the 6.8's arrived with the PI heads installed like the 5.4's about '99 or 2000?

Thank you,maybe I need to change wiring harness on engine to one off my original engine?

You should use ALL engine related electrical items off the 2002. Is there a chance that you flipped the engine harness and installed it backwards? in other words cylinders 1-5 connected to the wire harness plugs meant for cylinders 6-10? I'm not sure if that is even possible...probably not.

Your description sounds like cylinders are firing in the wrong order.

I have another thought. check the body harness where the engine harness plugs in, but on the inside of the cab. Is it wired exactly the same as the 2002 harness?

After reading jwa's post and yours I am thinking I need to change the engine harness from my original motor.really don't want to have to change body harnesses 🙁

Is the check engine light on? And even if it isn't have you scanned it for codes?

Double check things like the MAF part numbers. Do either one or the other have an EGR?

The 97 had a EGR but the 02 doesn't.check engine light is not on. Don't have a scanner but may need to get one.

You need the whole engine and intake, PCM, etc. from the 02.
02 is PI, 97 is not.
If that is what you did (original post is ambiguous about exactly how you did the swap) then you may just need an ignition tune-up or check to be sure the injector and coil plug connectors are clicked together and have good continuity on the wires.
Also check fuel pressure.

Also, I believe you may find that the transmission will have shift issues trying to use the old transmission with the newer PCM.

This is the cheapest way I know to scan PCM:
https://play.google.com/store/apps/d...g.prowl.torque

https://torque-bhp.com/wiki/Bluetooth_Adapters

Thanks for the info.So I have checked all connections and vacuum lines and after reading earlier post I think that it is a wiring difference.was going to change the engine harness but the injector connections are different which leads me to believe that there is a wiring issue, I still have the motor home so I pulled the engine compartment harness am going to change that also,then all connections will be original and yes I used the 02 transmission as well

Fuel issues and timing issues will also cause backfire problems as well as running rough. Krewat would be your best bet between the differences from 1997 to 2002. I know the heads are different, so I imagine the electrical components might differ, as well as the fuel and timing controlled by the PCM. Did you swap in the motorhome PCM?

Yes swapped out the the PCM and oxygen sensors.i am thinking has to be wiring issue so I am going to change the engine compartment harness then everything should be same as was in motorhome.

Update, no longer confessed.
thanks too all of you who responded to my post,after reading everyone's comments I came to the conclusion that I needed to change the engine compartment harness because there were different connections to the the fuel injectors then my original engine harness. Finished the swap today and motor purring like a kitten so hopefully this will help others doing this kind of swap.thams again for all your help.

Thanks for reporting back! :-X22