4.6 Stroker Build

[redrider2911]

So I built a stroker in my other Jeep about 4 years ago. It was the first engine I ever tore apart and do to some assembly issues causing major blowby I had to tear it back down and set the project aside. The last 1-1/2 years I have spent building up a new rig, 1998 XJ Classic. About 4" of lift, 37.5" KM2s, 5.13s, waggy width HP44 front with chromos, CTMs, and ARB, XJ44 rear with chromos and OX locker converted to air, linked front and rear on coilovers and a full exo cage.

I bought this Jeep for 500 dollars with a torn apart engine that supposedly had a bad rod knock. During the initial build up I dropped my tired 1991 4.0 in for the time being. I planned on slowly building a 4.6 stroker out of the 98 block and head while wheelin the crap out of the current engine. On a wheelin trip last saturday I found out that the 91 engine in the Jeep has a blown head gasket or cracked head. Instead of putting the time and money into the tired engine, I decided to do an impromptu stroker build. Im trying to keep this cheap as it is an unexpected expense.

The plan:
Jeep 4.2L 3.895" stroke crank - (already have)
Jeep 4.2L 5.875" rods - (already have)
EngineTech P1593 +.040 bore pistons, 1.581 pin height, checked to 14cc dish - (already have from last build)
98 XJ block milled .054 - (at machine shop now)
72-80 4.2L 9.594" Pushrods - (junk yard)
6-232-4 Compcam - (already have)
98 XJ Stock Lifters - (already have)
94-03 Pontiac Grand Prix Valve springs and Keepers - (junkyard)
98 XJ head with polished combustion chamber, intake and exhaust matched to gasket
EngineTech Reseal and Rering kit
Mopar/Victor 0.043" head gasket
.035" quench height
10.48:1 SCR
8.96:1 DCR
Accel 24lb/hr injectors for '96-'04 engines,

Any input is appreciated.
Thank you,
Kris

[redrider2911]

This is the jeep the engine will be going in.

[redrider2911]

Ordered everything I need for rebuild from FalconGlobal for 250 bucks!

Perfect Circle Moly Rings
King Rod Bearings
King Main Bearings
King Cam Bearings
Victor Heinz Complete Gasket kit with valve seals
Freeze plugs
Lifters

[SilverXJ]

Falcon is a good company to work with.

[redrider2911]

Yea. Thats what I was reading. I was mostly surprised because it would have been 350 for the same parts through Summit!

[redrider2911]

Silver, you got any ideas on junkyard injectors?

[JolleyRoger]

I personally have had bad luck with junkyard injectors and even "cleaned" injectors. I got my latest set new from rockauto for less than $180 after I decided this wasn't something I wanted to skimp on.

STANDARD MOTOR PRODUCTS Part # FJ475 {#53032145AA, 53032704AA, 53032704AB} New; Multi Port Injector; w/ O-ring

They seem to do well, but I have a FlyingRyan tune job as well, which seems to help.

I believe I went with these based off of Silvers recommendation.

Just my 2 cents.

[redrider2911]

Got a call from the machine shop yesterday. The 98 block is cracked so I'm either gonna have to find another one or pull the engine out of the Jeep. Think I know someone who has a 91 block I might pick up.

[redrider2911]

Engine is together and everything is good. Breaking it in with Rotella 5-40

Ive been beating on it on the way to work and back. I work in tieton so I do some nice pulls on the summitview grade there and back. Feels real good. Pulls through the whole RPM range. Doesnt seem to pull as much at high RPMs in 3rd gear though. I think the transmission will need rebuilt in the future. Its either that or im feeling the added wind resistance from the higher vehicle speed?

Got great oil pressure, always 50+.
Good temp always 200-210 (even with only the 1 stock electric fan that kicks on at 210)
She runs smooth. No predetonation (running Shell premium, havent tried ohers)
No pertinent engine codes. I am occassionally getting a code saying the Crank Position Sensor and Cam Sensor aren't synched. Maybe because of the aftermarket cam?
The DashCommand app says my long term and short term fuel trims are all the way up at 32%.
It also says my O2 voltage is at 0.00. Maybe its not compatible with its signal? I dont have the downstream sensor in and get a code for that but dont get a code for the front sensor.

I want to do a shake down run thursday or friday. I need to get my winch wired up and figure out my electric fan setup. I had to remove the mechanical fan to fit the winch behind the crossmember. Was going to work on an aluminum fan shroud at work today but found at the taurus fan I was going to use is also too big and doesnt fit between the hood and the winch. Will probably end up running 2 stock XJ electric fans for now.

[redrider2911]

So I went up wheelin this weekend and impressed a lot of people with the power I had available, most of those people running modded 350s. I do believe I need to look into overhauling the AW4 as it seems to be soaking up quite a bit of power, especially in 3rd gear. I need to get my tiptronic shifter set up so that I can control the shift points fully. The TCM is having a hard time deciding what gear to stay in: jumping from 1st strait to 3rd, down to second, then to 1st, and up to 3rd again.

I also used almost 18 gallons of fuel during a 12 hour wheelin trip. It was crap snow so constant higher RPMs were common. Then there was a lot of idle time waiting in line for others to make it over an obstacle. At the end of the trip I had to buy some gas off a fellow wheeler. It was regular 87 so I was a little worried. To my surprise I didn't get any pinging and the stroker still ran so so. I did notice a slight loss in power and strangely enough a little stronger fuel smell from the exhaust. I guess it is possible that the lower grade fuel wasn't burning as efficiently, leaving more fumes in the exhaust gases. Even then, the lack of pinging really surprised me at the higher altitude along with the compression ratio I am running that is higher than most.

[SilverXJ]

So I went up wheelin this weekend and impressed a lot of people with the power I had available, most of those people running modded 350s.

Nice!

I do believe I need to look into overhauling the AW4 as it seems to be soaking up quite a bit of power, especially in 3rd gear.

3rd is 1 to 1. It may drag the engine down a bit. Also, get in touch with Fringe XVO about an upgraded valve body http://www.naxja.org/forum/showthread.php?t=1089241

[redrider2911]

I think Im going to go through and modify my valve body and actual valves myself. Thanks though.

Strange thing did happen. The other day my fuel economy (according to the stock read out) went from 8-12 mpg on average to 16-22 mpg on average. I was super excited about this but started to wonder what caused the change. The Jeep is still running just as good as ever and still plenty of power. I hooked up my OBD2 Elm sender today and pulled up Dash Command on my phone and saw that my fuel trims are stuck at 0. Before they were both pinned to 32%. Anyone have any insight on this? Like I said, super happy about the MPG increase but thinking that there has to be something wrong.

Kris

[SilverXJ]

The stock read out is useless once you change injectors. The MPG readout is calculated on injector pulse width. Since you have larger injectors you are getting less than what the readout says.

As for why the fuel trims are at 0 I don't know. I would try resetting the PCM and see what happens. Maybe check on the elm again first to see if it wasn't some sort of read error.

[redrider2911]

I know its not correct any more but it should still be directly proportional. The change from 8-12mpg with 32% fuel trim compared to 16-22mpg with 0% fuel trim is consistent in its inaccuracy. lol Ill try doing a hard reset by draining the capacitors here in a couple hours. I honestly don't know if I want to do that though if my efficiency is gonna go back down; like I said, the Jeep is still running good and no pinging. I need to get a wide band O2.

[redrider2911]

So I was doing some wiring on my jeep and wired up a spare O2 sensor for the downstream and just let it hang in hopes that it would fix the fuel trims. While looking at the O2 sensor schematic I realized that I had wired the upstream O2 sensor improperly. I went back and fixed that as well and then started the Jeep. My DashCommand app showed that it was now reading O2 voltage but was not adjusting fuel trims, I assumed that this was because the Jeep was still in closed loop.

I undid the positive battery cable and grounded it for 30 seconds to reset the ECU, then took the Jeep out for a drive. No fuel trim adjustment, no fuel trim adjustment, then all of a sudden it went crazy. It was all over the place. The Jeep (which ran perfectly before) was now stumbling and would die at idle while the ECU was taking out as much fuel as possible to try and maintain a voltage in the mid 0.4 range; then it would realize it was too lean as it dropped to 0.2, so it would go way the other way. The only time the jeep seemed to run fine was with my foot in it probably 50% and at least running 3000rpms; then it would take off like a bat out of hell.

Pretty much my question is: is this expected for the first few key cycles while the ECU relearns its long term and short term fuel trims?

Thank you for any help, Kris