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Is my 4.6 getting it's full performance?

Posted: October 7th, 2011, 8:51 pm
by Geck_4.6
Hello guys! This is my first post here!

I'll start by a quick intro!
I'm Jeff from Lake Elsinore, CA. I owned an 87 XJ awhile back and came across a deal that i could not pass up!! It was a 1997 Jeep Cherokee for $1500. It had a k&n intake, roof rack with lights, HID Headlights with glass housings, Full stereo and brand new kicker speakers, Brand new 33" tires, Brand new Borla headers, SYE, New alternator, 4" lift with sway bar disconnects and i am sure i missed some!

On with the my question. I built a 4.6 stroker for it and It's bored over 30K. It has brand new Venom 24lb injectors and a map adjuster. I have a 2.5" 10 series flowmaster muffler
The full stroker costed me $2081.....Yes...$2081!! I got the hook ups lol

My Question: Have i done everything i need to do to get it's full performance? :huh:
Is there anything that i should have done that i have not done? We are still working out the little bugs! It seems to be running a little rich because it feels like it loads up with gas sometimes and it sputters. It also sounds like the timing gets out of whack when i am going 70+mph on the freeway. We have 5 volts over factory in the MAP adjuster so if i pull voltage out it's pretty much going to take it back to factory.

Any insight guys?
Should i have had the computer flashed?
I think if i bore the throttle body and get a high flow cat, that will benefit me well.
Any thoughts or suggestions will be greatly appreciated.
Thanks guys!

The stroker consists of the following:
4.2 crank (258) has to be shortened 1cm=0.393 in. depends on crank year
4.2 connecting rods
melling high volume oil pump
.020 king main bearing
.010 king connecting rod bearings
.030 silvolite pistons
.030 hastings piston ring set
king cam bearin
elgin performance cam
johnson hydralic lifters
engine pro timing chain set
exhaust valves
exhaust valve seats
valve springs
bras freeze plug set
victor reinz gasket set
resurfaced flywheel



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Re: Is my 4.6 getting it's full performance?

Posted: October 8th, 2011, 4:45 am
by SilverXJ
A 62mm throttle body, header (you already have), 2.5" exhaust, high flow cat and muffler should all help the stroker. Also, a wideband O2 sensor would be good so you can see what your WOT fuel ratio is like.

Re: Is my 4.6 getting it's full performance?

Posted: October 8th, 2011, 8:39 am
by Cheromaniac
Geck_4.6 wrote:We have 5 volts over factory in the MAP adjuster so if i pull voltage out it's pretty much going to take it back to factory.
The factory MAP sensor input is 5.0v so are you saying that you have yours set at 10v?

Re: Is my 4.6 getting it's full performance?

Posted: October 8th, 2011, 10:01 am
by Geck_4.6
Thanks for the input guys.

It's probably obvious that i am not the mechanic. The mechanic is my brother in law.
Yeah it is at 5v above whatever factory voltage is.

Re: Is my 4.6 getting it's full performance?

Posted: October 9th, 2011, 12:46 am
by Cheromaniac
I'd reset the MAP input back to 5.0v and if the engine runs lean, raise it in 0.2v increments until you find the sweet spot.

Re: Is my 4.6 getting it's full performance?

Posted: November 24th, 2011, 8:13 am
by carlitos
I'm the one who build the engine and we set up the map sensor adjusted at 5.5v (the smog emissions were better there ), the engine dose have a set is headers on it, But it dose seem it could be lacking some power