stroker tuning

[scooter]

I'm finally finishing up my 4.6 stroker build for my 99 tj. I have a few questions.

First off, I'm using my original block in this build. It had a girdle from the factory. When I assembled the motor, the 4.2 rods hit on the girdle. In order to get the necessary clearance, I brought out the grinder and added washers. Now the girdle is hitting the oil pan. Is this thing really necessary? My machinist tells me to heat the pan and remold it to clear. My fear is that by heating the pan, it will make it weak and can be damaged in the woods (primary use).

As far as fuel goes, I'm going to use the 24# ford injectors. Do I need to upgrade the fuel pump? Adjustable pressure regulator?

Is a wideband o2 sensor necessary?
Will I need to replace the stock map sensor?

My machist also tells me that I will need to have my computer flashed. Is this true? I will be using an aftermarket cam.

If you guys think of anything I might be missing, feel free to tell me. Thanks in advance.

[Russ Pottenger]

The girdles are a pain to clear but I'd recommend doing the clearancing to the girdle.
The factory 4.0 and 258 rods are usually balanced really close. In a normal situation you just match balance
to the lightest rod. If i know it's getting a girdle I'll start grinding on the balancing pads right off the bat.
That will make it a bit easier when it comes the clearing the underside of the girdle.

As for the topside you can use something like a body grinder to make short work of it. If you spread machinists dykem layout fluid, that would help to show witness marks in the areas that need more material removed.


Russ

[SilverXJ]

Is this thing really necessary? My machinist tells me to heat the pan and remold it to clear. My fear is that by heating the pan, it will make it weak and can be damaged in the woods (primary use).

I would leave it in. If something is going to hit the oil pan enough to puncture it that little bit of stretch isn't going to matter.

Do I need to upgrade the fuel pump? Adjustable pressure regulator?

No on the fuel pump and the adjustable regulator depends on how you plan on tuning it.

Is a wideband o2 sensor necessary?

With out one you have little idea of where your AFR is.

Will I need to replace the stock map sensor?

No

My machist also tells me that I will need to have my computer flashed. Is this true? I will be using an aftermarket cam.

Depending on the cam you might not have to. A flash wouldn't hurt to make the stroker run optimal or get the AFR where it needs to be if. If you choose to go that route [email protected] is good.

[optmaxx]

I found this video.

http://youtu.be/AeC212hUrfI

[SilverXJ]

Not all 4.0L oil pans are created equal

[Rockhound]

The girdles are a pain to clear but I'd recommend doing the clearancing to the girdle.
The factory 4.0 and 258 rods are usually balanced really close. In a normal situation you just match balance
to the lightest rod. If i know it's getting a girdle I'll start grinding on the balancing pads right off the bat.
That will make it a bit easier when it comes the clearing the underside of the girdle.

As for the topside you can use something like a body grinder to make short work of it. If you spread machinists dykem layout fluid, that would help to show witness marks in the areas that need more material removed.


Russ

Hey Russ, I went with ARP bolts/studs, so I had to ditch the girdle. Do you think this was a bad idea? I race it.
Sorry for the highjack...

[scooter]

Thanks a bunch guys.

[scooter]

Is a pcm flash something that needs to be done in person? Sorry for the rookie question, I'm still learning. I've heard of people getting it done via email. But I'm a little confused on how to hook a laptop up to my jeep's computer.

[SilverXJ]

No. You could use either an SCT tuner or send him your PCM.

[Radioactivexj]

I got my stroker together and at start up and even after heating up it ran really rough almost as if a cylinder was missing. But the mechanic we have working on it told us after installing our AEM air/fuel gauge that it was running really rich and would require a PCM tune either from a tuning program he recently bought and is messing around with or he would have to take it to the dealer to get reflashed. Keep in mind i'm running a stock cam and neon injectors which should only be running at 24# not even .5 pounds more than the stock injectors. So it came across my mind as really weird I would need to get it tuned to even be able to run it seeing as most people have no problems at all after installing as mild a stroker build as mine.

[SilverXJ]

I got my stroker together and at start up and even after heating up it ran really rough almost as if a cylinder was missing. But the mechanic we have working on it told us after installing our AEM air/fuel gauge that it was running really rich and would require a PCM tune either from a tuning program he recently bought and is messing around with or he would have to take it to the dealer to get reflashed. Keep in mind i'm running a stock cam and neon injectors which should only be running at 24# not even .5 pounds more than the stock injectors. So it came across my mind as really weird I would need to get it tuned to even be able to run it seeing as most people have no problems at all after installing as mild a stroker build as mine.

There is definitely something wrong there. I don't think a tune will fix it. Where did the injectors come from? How old is your O2 sensor? Any codes?

[jeepxj3]

Are the rings even seated after 30-60 minutes runtime? Could that be causing it to run rich?

[Radioactivexj]

There is definitely something wrong there. I don't think a tune will fix it. Where did the injectors come from? How old is your O2 sensor? Any codes?

We ran it through the break in procedure figuring it would smooth out eventually, I even took it around the block a couple times but nothing really seemed to help. The injectors came from XJwonders on cherokee forum supposedly rebuilt and cleaned. After we recieved them we soaked them in seafoam until we installed them. The mecahnic even switched them out for the stock ones just to see if that was the issue and said it still ran just as rough. So I assume its not the injectors. As far as the O2 sensor I can't be exactly sure how old but we've never replaced them so I assume they are original. The downstream O2 is not currently plugged in because we didn't get a catalitic converter put back in but from what I read that should not give us any issues. Our code reader wouldn't read the Jeep's codes because it broke so I hope our mechanic checked the codes. So assuming that our upstream O2 is bad then that could be the cause of our issues?

[jeepxj3]

The downstream O2 is not currently plugged in because we didn't get a catalitic converter put back in but from what I read that should not give us any issues.

Maybe it needs to be plugged in?

[christuned]

I would suggest getting a hold of a scan tool that can measure fuel trims and other engine variables. The ecu is capable of trimming the fuel by over +/- 30% . Have you put a vacuum gauge on it to see how much you have at idle ? If you can get the scan tool check for trouble codes, and look at and post the following info, measure at idle and while holding the throttle to maintain 3000 rpm :

Fuel trim long term
Fuel trim short term
Map
Map volts
Throttle angle
Coolant temp
Air temp
IAC position

If the fuel trims are zero, then check the O2 sensor voltages.