[DreFromTheBay]

i had a 351 put in my 88 5.0 GT but the computer wont compensate for the bigger engine and i had to disconnect the O2 sensor to keep it running, any ideas where i went wrong?

[BWAL]

i think you need a new computer

[DreFromTheBay]

well i think that might be a problem, because i dont know all the specs on this engine yet, it runs good but i'm gonna have to deal with a smog check soon

[OTreborO]

Originally Posted by BWAL09 i think you need a new computer

+1 for new computer

[ryans88gt]

88 is a speed density computer, you need to upgrade to mass air or you'll blow it up from running too lean.

[DreFromTheBay]

do they have a section here on how to do that?

[ryans88gt]

Buy a mass air conversion kit....instructions will come with it. Basically you replace the computer and add a mass air sensor in the intake plumbing. It isn't a hard install, if you are mildly competent at following directions it shouldn't be a problem.

They run around $500 for the cobra kit from ford racing for a recalibrated computer, mass air meter, and they used to come with 24 lb injectors too, not sure if that is still the case.

That should fix your problem, in the mean time don't drive you car like that or you'll blow it up.

[DreFromTheBay]

ok the guy who helped me gave me a little more info, my 88 mustang has MAF already but he he doesnt think that the engine is a 351 because it has a different firing order, since the engine is more powerful do you think the problem is the small MAF sensor, because with the O2 sensor unplugged it runs good, i'm lost

[JBIGBOOTSY]

pull codes

[zero]

Originally Posted by DreFromTheBay ok the guy who helped me gave me a little more info, my 88 mustang has MAF already but he he doesnt think that the engine is a 351 because it has a different firing order, since the engine is more powerful do you think the problem is the small MAF sensor, because with the O2 sensor unplugged it runs good, i'm lost

ford made two different firing orders for the 351W.
one is for the m code motor which was the 4bbl version in early years
1-3-7-2-6-5-4-8
one is for the h code motor which was the 2bbl version.
1-5-4-2-6-3-7-8

it could still be a 351, just a different one than you thuought. easy way to tell, measure. there are two different deck heights for the 351 though... i think one is 8.2 and one is 9.5 but im sure im wrong about the 8.2. if you want to be thorough in your identification, take off your heads and measure your piston width. as for your other problem, a new maf and a computer will clear things up. a 351 eats more gas than a 302.. so naturally the 302 computer is going to starve it.