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PinkJeepGirl 07-15-2010 05:37 AM

Stroker Problem
so, Iím having a real problem here. My 4.6 was built last summer, renix motor with Lunati cam p&p head 2 1/2" exhaust. Ran all summer with small problems. With the advice from all here, I ran 24#er's. That made it run rich as hell and washed out the rings and bearings.

Now itís back from the builder with new rings, bearings, pretty much everything. I put new o2 sensor, e3 plugs, adjustable fpr, bored renix throttle body, and added an AEM wideband.

It won't hardly run so I put the stock injectors back in. runs better but still rich (black smoke out exhaust). The wideband says around 14 idle and maxes out the gauge when revving past 17, which should be lean. Fuel pressure at 35psi.

I got some rc9's, and then got a map sensor adjuster. New map sensor. Now with the map adj on 4.2, revving it up the afr goes to 14 but at idle its 10. Fuel pressure is at 37psi. This is all with the stock injectors now. Could I have one stuck open? The have 220,000 mi on them. it has always gotten bad fuel mileage, and when I got it it had been sitting for a few years.

Also a jeep guru told me that i might not have enough vacuum. He said it should be around 18in at the lowest. Its running around 12in right now. So i'm guess that could be a big part of my problem not enough vacuum, but i'm not sure how to get my vacuum back with out retarding the cam back, because i don't want to lose any low end torque.

What do I do? Hate to mess it up again. Anyone have any thoughts or input PLEASE tell me!
Please your help with greatly appreciated!!!!

Scottina06 07-15-2010 04:08 PM

Re: Stroker Problem
the fuel problem sounds like a bad injector...possibly clogged...or it could be a inline filter. heres what i found for a 4.6 stroker kit..what they recommend

Recommended parts for the Jeep 4.6/270HP long block

- 24lb fuel injectors

- 91 octane pump fuel

- 62mm throttle body

- Aftermarket header and exhaust

- Cold air intake

- DUI Firepower Ignition Kit which includes cap, rotor, Screamin Demon coil, Livewire spark plug wires (use your stock distributor.) This is not available for 2000-06 year models that use 6 coils.

- Champion RC9YC4 with gap set to .035".

- Valvoline 10/40 Conventional (Non-Synthetic) oil for break in (700 miles) we recommend using a Zinc additive with each oil change for the life of the engine. We also sell a Joe Gibbs Hot Rod oil for $75 a case that has high levels of Zinc present to get the job done even better.

- Wix or AC oil filter for a 4.0 Jeep (Do not use a Fram oil filter we have seen problems with them collapsing)

here is the site

The vacuum problem could be as simple as a collapsed hose. Check all the vacuum hoses and make sure they dont collapse easily when pinching it between your fingers. If it does.....get a new one.

Marlin 07-15-2010 04:34 PM

Re: Stroker Problem

PinkJeepGirl 07-15-2010 06:20 PM

Re: Stroker Problem
Thanks for the info. Just found out the cam is to big for my build, gotta pull it back apart and put diff cam in it. its taking away the vacuum causing it run rich at idle.

hemi.jon 07-15-2010 06:25 PM

Re: Stroker Problem
also look into dumping your E3 plugs..they are terrible! mine blew out in 2,000 miles. and i have herd of nothing but problems with them.

PinkJeepGirl 07-15-2010 06:26 PM

Re: Stroker Problem
yeah thats what we did get rid of them...we just tried it as someone said too...before we knew it was the cam we had no idea what was making it run rich. so we was trying EVERYTHING hahaha

Scottina06 07-15-2010 06:28 PM

Re: Stroker Problem
that will do it.....

scjeep4.7HO 07-15-2010 08:34 PM

Re: Stroker Problem
I melted my E3's!!!!!! get an adjustable fuel pressure regulator. sounds like a possible stuck injector. How big is you're cam?

If you see a AFR of 17 that is really lean, but you can't use revving it in you're driveway. That is not a good number, since there is no load in the engine.

PinkJeepGirl 07-15-2010 08:44 PM

Re: Stroker Problem
got the adj. fuel pressure regulator as well....and i know i can't go by the numbers while sitting in the drive way. But i'm not going to go drive it and wash the rings expensive of a fix each time. a buddy of mine and my bf is going to help pull the front off and change the cam..

scjeep4.7HO 07-15-2010 08:57 PM

Re: Stroker Problem
I have driven mine with a tune so bad mt wideband was maxxed out at 10 AFR and it was bucking and i didn't wash my rings. Granted I fixed it right away. turn you're fuel pressue down unti you get it to lean up enough to work with it. 35# is not a hole lot of fuel pressure. hows the timing?

PinkJeepGirl 07-15-2010 10:03 PM

Re: Stroker Problem
times fine, the fuel pressure is turned down. but i'm still not going to drive it until the cam replace. if then it still having the issue i figure my next step

Escape 07-15-2010 10:34 PM

Re: Stroker Problem
220,000 miles on the injectors is a bit much. I'd replace them.

What are the spec's on the cam?

Check out this article about cams.

You said you washed out the rings and bearings...Were the piston rings put on correctly (alignment)?

You want your AFR to be at 14.7 during closed loop operation. 12.2-12.5 during a open loop full throttle blast for naturally aspirated engines. When driving and then slowing down (letting off the throttle) the PCM will cut fuel to aid in deceleration. This will cause a very lean condition but it is perfectly normal.

What all did you do to the MAP and why? You shouldn't need to mess with this. This will alter what the PCM uses to look up it's proper fuel tables.

You said you replaced your O2's do you have a scanner with the ability to see your fuel trims? long and short term and also view your O2 sensor voltages?

All you should really have to do is match the fuel injectors with your new bore and stroke and your factory maps should be fine and well within the range the PCM can add/subtract fuel using the O2 sensors input.

As for your vacuum issues. Does this reading fluctuate or is it steady? Are there any leaks? How is the vacuum brake assist (brake booster) working? Do your breaks feel fine or soft/weak?

Cams are very very important check out your specs and make sure it is doing what you want it to do when you want it to do it. A badly chosen cam can make an otherwise powerful engine a complete dog. Choose wisely.

Have you sea foamed to check for exhaust leaks and clean the internals?

Have you tried your stock throttle body to rule it out of the equation?

Please post up the full specs on the build and everything you have done and I'm sure we can get it running strong for you.

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