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Newest FNG with a 4.5

Posted: January 30th, 2020, 11:59 am
by WyoCherokee
Howdy folks. After lots of Lurking i finally created an account. Very active over on CF and CC.
Heres my build threads.
https://www.cherokeeforum.com/f46/proje ... er-231553/
https://comancheclub.com/topic/51825-pr ... ail-build/

After finding a broken piston skirt from an oil pump bolt, I decided to build a 4.5 using the guts from a friends old 258 YJ.

Currently running, but fighting a super lean issue. havent swapped in 24lb injectors yet, so hoping thats the issue. I will add soem more detail on the engine alter. but heres some teasers.

Re: Newest FNG with a 4.5

Posted: January 30th, 2020, 3:11 pm
by SkylinesSuck
Welcome! What size injectors are you currently using? If stock, I found your problem ;-)

Re: Newest FNG with a 4.5

Posted: February 5th, 2020, 1:32 pm
by WyoCherokee
SkylinesSuck wrote: January 30th, 2020, 3:11 pm Welcome! What size injectors are you currently using? If stock, I found your problem ;-)
Yes they are currently the stock 19lb injectors. In the process of getting the engine back in the truck, i was also selling my house and moving, so i just had to get it running to get it on the trailer and into my new house! I am thinking i will try these if i can find them FMS-M9593-A302. If not ill try the zj injectors 53030262. i have been researching and found though, that folks have used the 21lb 91-95 injectors at my renix 39psi. so im not sure what to use first. Go for the cheaper easier 21's and hope they are rich enough, or go for the 24lb Zj or Ford injectors and Hope they aren't to much. Allot of conflicting info out there.

Re: Newest FNG with a 4.5

Posted: February 18th, 2020, 7:37 am
by WyoCherokee
Ok tested 703 injectors to rule them out...still lean. next will be 24lb accell injectors :frustrated: . Need to grab a rail pressure guage to make sure im getting the full 39 PSI to the rail

Re: Newest FNG with a 4.5

Posted: March 30th, 2020, 8:06 pm
by WyoCherokee
Ended up going with the Ford ev6 24lb injectors. Made a huge difference, and I can actually drive it around town and down the highway. It still backfires around 2000 to 2200 rpms under light to moderate throttle whole just trying to cruise. If I floor it, it pulls hard and runs great. Need to check dizzy indexing, fuel pressure at the rail, and eventually a wideband or adjustable map. Was really hoping I would get lucky and not fight this.

Re: Newest FNG with a 4.5

Posted: April 1st, 2020, 11:49 pm
by SkylinesSuck
You didn't mention the backfire out the intake thing before. Yes, injector timing. And get a wideband.

Re: Newest FNG with a 4.5

Posted: April 7th, 2020, 1:28 pm
by WyoCherokee
SkylinesSuck wrote: April 1st, 2020, 11:49 pm You didn't mention the backfire out the intake thing before. Yes, injector timing. And get a wideband.
it doesn't backfire out the intake. only the exhaust. Just need some good weather to go crawl around outside and index the dizzy. I recently sold my house and moved due to a job change, so i no longer have my nice heated shop :frustrated:

Re: Newest FNG with a 4.5

Posted: April 8th, 2020, 7:57 pm
by WyoCherokee
Indexed the distributor, no more backfire. Need to check the plugs for rich/lean, and maybe I can go back to the 21lbers.
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