351 running horrible

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Dec 3, 2007 | 08:37 PM

oldgreenf100

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From: kansas city, Missouri

351 running horrible

about a week ago i swapped the engine in 1990 f150 m50d , a 351 for a 302 and after the big headache of getting it in there its not running to well, it does not like to idle when i first start it and it sounds like it is missing, i put new headers and dual exhaust on it and cant figure out how i should hook up the egr because the headers have the tube on the front for it( its plugged with a pipe fitting right now) but today it ran worse than ever, it had no power untill about 2500 rpm in every gear then it would take off after it hit 2500, right after i got the motor in it showed a check engine light but hasnt shown it since that night, im wondering if its because of the egr not being hooked up or if there are bigger problems, the motor is out of another truck and hasnt been rebuilt , i changed the pluggs and wires and it didnt help anything

Dec 3, 2007 | 08:42 PM

jroehl

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From: Lafayette, IN

Did you swap computers, too? The injectors have a different pulse width. And, did you swap around the plug wires? The 351 has a different firing order than the '90 302... One is 1-5-4-2-6-3-7-8 and the other is 1-3-7-2-6-5-4-8, but I can never remember which is which.

Jason

Dec 3, 2007 | 08:49 PM

oldgreenf100

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From: kansas city, Missouri

the donor truck was an 88 and i did swap the computers but i was not aware of the firing order being different, so do i need to swap the plug wires or injector wires?

Dec 3, 2007 | 09:00 PM

kcb37

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If you didn't leave the cap and plug wires on the 351 when you pulled it, and put the wires on for the 302's firing order. Then yes you do need to change the firing order.

Dec 3, 2007 | 09:04 PM

oldgreenf100

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From: kansas city, Missouri

all of the plug wires stayed on the 351 the only thing i changed between the two motors was the injector wiring harness because the 88 351 harness would not match the 90 trucks harness

Dec 3, 2007 | 09:11 PM

jroehl

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From: Lafayette, IN

Just because the engine light isn't on doesn't mean a code wasn't stored. Go to fordfuelinjection.com and poke around to find out how to pull your codes and let us know what you get. You have 2-digit codes. I'd double check the firing order, just for grins. Stuff happens.

Jason

Dec 3, 2007 | 09:17 PM

oldgreenf100

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From: kansas city, Missouri

i think ill use o'reillys scanner tomorrow morning when im pickin the parts i ordered. hopefully that will give me an answer, the motor ran fine in the other truck and nothing has been changed so id almost bet it would have to be one of the injector plugs unless something got sucked into it somehow wich i dont think happened because i was carefull to plug all hoses or openings when i was changing it, anyone got an answer about if the egr sucking in the cold outside air would be effecting anything?