I swapped out my 96 f150 4x4 302 to a 351 with aode transmission existing. I'm still using the 302 computer,harness, mass air it all plugged into the 351. Trouble is I now have a rough idle and truck is rough running from engine especially when warmed up. What do I need to change computer, mass air to make it right? Thank you

 

What year is the 5.8?
Is it a stock 5.8?
Have you driven it around yet?
Hopefully you didn't use the flexplate that was on the 5.8(wrong offset) or the one that was on your 5.0(wrong balance)... and you bought a new one for a 351/AOD combo.

 

Yes it is a stock 351. 351 is a 96 as well. Yes drove it about 35 miles runs ok just a bad mis did some research on flex plate and 302 that came out and 351 was an exact match. No issues there. Qualified mechanic says it's the ecu as the ecu is for the 302 n now we have a 351 in there so I'm thinking of changing ecu from a 351 f150 . I appreciate your feedback n welcome more

 

The flexplate can't be right these two motors have a difference external balance requirements so I suspect what you think is a miss is actually the engine shaking due to the wrong flexplate balance weight. Your mechanic is also wrong the MAF EFI system in this truck will have no problem adapting to a stock 5.8.

 

Thank you for that input much appreciated. I'm going to pass that along and I believe your correct. That's an easier fix then computer wiring etc. driving me crazy. I do have one more question : on cold start up the truck works perfect not a single miss or shaking, once it reaches operating temp that's when it shakes or? If I step on the pedal harder it goes away. Does that make any sense. I appreciate your input. Thank you again

 

Also we did use the 352 flex plate so are you saying we should have used the 302 flex plate? Sorry for my lack of knowledge it's driving me crazy. Thank you

 

I just reread your first reply and no we didn't purchase a new flex plate for the 351 with the aode tranny. Seems this just very well be the mistake. Thank you

 

So does anyone know the correct part number for the flex plate I will need to match the 351 to an aode tranny in my 1996 f 150? Conanski thanks again for your knowledge And sharing.

 

I don't have a parts number but ask for a flex plate for an '85 crown vic with the 351 and AOD.

Also pull the codes to see if the computer has anything to say, if you accidentally mixed up some wires it should show up as a code.

Does the truck have dual front O2 sensors? If so is it possible you connected them in reverse.. left sensor to the right input and vise versa? If you get codes for O2 sensors that would explain it and would also explain why the truck runs better at cold start then when it warms up and goes closed loop.

 

Paul thanks again for your time and reply. Will do on the flex plate I do believe that's the issue. Yes I do have 2 -02 sensors up front and one past the catalytic converter. I'll check the codes and see if it comes up 02 sensors. Definitely buying that flex plate tomorrow and tearing out tranny again to put the correct flex plate in. Again thank you.

 

Anyone know the weight on this flywheel conanski is referring to? Is it a 50oz or 28oz or? I'm going to order the 1985 crown Vic with the 351 and aod trans flex plate and just double checking to make sure I get the absolute correct one. Thank you

 

It will be a 28oz flexplate.

 

I truly appreciate your knowledge. Thank you again.

 

So the one that was in the 351 already is 28 oz but was attached to the e4od and now its in the 351 and is attached to the aode trans in the truck. So even though they are both 28 oz, the one that was already with the 351 is different then the 1985 28oz flywheel from the crown Vic with the aod trans? Again sorry for all the questions conanski you have been patient with my ignorance and appreciate it.

 

Yes the front to back offset is different.