Had an engine replaced (5.4) on my wife's expy a shop but when we got it back, the expy was running real rough and is backfiring. The guy at the shop said a Ford dealer gave him some additives to retard the cam? I took it back to him and he changed the oil and said to run it like that for a while to let the oil circulate ( he put thicker oil in before). Well the engine still runs rough ( sounds like a diesel engine at idle sometimes) and still backfires. Any suggestions? I think the shop is at a loss on this also.

 

did he get the firing order correct when he plugged in the COP's?

5w20 oil only. anything thicker can run the risk of engine damage.




also, Ford does not, nor will they ever give out additives. There are too many sensors that can be damaged. Your shop sounds quite incompetent to me.



have the guy check that spark plugs #7 and #8 are tight and not broken, check that all the sensors are properly connected.


he might have also forgotten to connect the CMCC on the back of the intake...or didn't connect the vacuum lines back there.

 

The guy said he put in 10w-30 the first time, then changed to 5w-20 after I told him what the mech @ a Ford dealer told me about the oil being too thick (after about 2,000 miles). I had put a scanner on the expy and it said #'s 1 through 4 were randomly mis-firing. It said probable cause was an open circuit. I told the mechanic that and he said he would check all the connections again. So far it's the same. He said to run the ride for a week with the fresh oil and see what happens.

 

and that is the part that bothers me alot. besides the fact that he put 10w30 in there initially

1. Ford has been using 5w20 as the standard oil since 1997-1998. All Fords except a few of the exotics (ie: diesel) run it

2. um...every single parameter of the engine operation is monitored and controlled via the PCM.


did your mechanic re-use your original components? or did he try to be lazy and use the complete longblock from the wrecked motor? Ford changes the electronics and wiring stuff almost yearly. They are almost the same from year to year...but things aren't always the same. The block itself is identical.


if it's a brand new motor, did the guy try to re-use your sparkplugs and COPs?













I hate to say this, but I really think you should let a Dealership look at it. Just based on what you've posted, I wouldn't let that guy work on anything I own. Or have owned. Hell, there is a damn cap with bright lettering that says 5W20 right on it. he had to remove that to fill it with 10w30 oil

 

Sounds like a botched rebuild. These engines don't backfire for no reason. Tylus is dead on.

 

The guy told me it was a new engine. Then he said he used the same heads, but the engine was the same year.

 

Make him fix it.