Anyone know what the normal PCM parameters are for 2004 Wrangler 4.0 42RLE?

[Woodrow]

...At idle, timing adv. ranges between 7.5 - 14 degrees, most of the time, and goes to around 34 or higher when i give it small amounts of gas. A couple of times it remained at 27 while at idle. Other times it will hit 0 when i let off the gas. The bank 1 stft (short term fuel trim), O2 numbers, are relatively numerically close to their bank 2 counterparts; I don't see any drastic differences, and the numbers are pretty low both in both pos and neg ranges. That said, I have never looked at the live data before so I have no idea what's normal and what's not.

I'm looking for someone who knows what the numbers should be, and would be willing/ able to help determine/diagnose the issue(s). I cant find anyone where I live who can do this. I am more than willing to pay for the services.

Much appreciate any help/advice.

R

Disclaimer: I'm no tuner and I bought, not built the Golen 4.6 stroker in my '97. I'm using the stock PCM and tune.

One thing that jumps out at me are your spark advance numbers. I dyno'ed mine and some of the data is here: https://wranglertjforum.com/threads/woodrows-97-green-tj-moderate-build.51602/page-5
I think 34 degrees is a lot of advance. 26 or 27 at WOT is more the mark I've been told by both a tuner local to me and @Flyin' Ryan Performance.

 

[Geeknahalf]

cant beat the I6 reliability, 250K miles on it and only a burnt valve. Like to see an LS do that..

Don't get him started,,,,



I'd guess it would be but you could contact Comp just to verify.

I'll ask all the obvious. Are all your O2 sensors good? IAC & TPS & CPS? Did you hook back up all your grounds? Made sure you had tightened down all the nuts and bolts to each ground? These are the things that caused others issues after doing an engine swap.

Have you checked for vacuum leaks? Intake manifold leaks?

No worries, ask all the obvious questions you want!
I replaced all the O2 sensors, crank/cam/TPS/IAC. Didn't replace the AIT and MAP, not sure why- but I will just because.

I did find a few grounds that needed to be fixed during the swap, and checked the wiring harness as well (vigorous manhandling) looking for any other issues but didn't find any. No vacuum leaks that I could detect. Will recheck the intake this weekend as its time for the post initial assembly retorquing of all the bolts.

 

[Geeknahalf]

It sounds like a fuel problem to me. Did you install different injectors or are they stock? Monitor your long and short term fuel trims when it is running rough. I don't like to see any of the fuel trims more than 10% positive or negative. Ignition timing at idle is going to jump all over the place as it helps to control the idle speed. When you are accelerating lightly it should smooth out and be 20s to 30s depending on load and a bunch of other things. Most of the other parameters are common sense. Temps and pressures should be reasonable values. Map sensor should be close to 95kpa koeo, and go down when at idle. Usually below 40kpa or so, but that depends on vacuum. Tps should read sub 20% or so closed and go up to 75-100% at WOT.

I'm pretty sure that's the same cam I have, and it's not that aggressive. I also have the Edelbrock head and the torque tube header. It ran fine with no stumble.

Hi Jezza, thx for the help.

I am running aftermarket 4 hole 24# ford injectors. The stroker kit is from Clegg, its a stage 2. The assy was balanced at purchase.

I'm not sure if the scanner I have does %'s or not, I'll look and see what measurement system its using and post the numbers over the weekend.

thx again for all the help everyone, it's greatly appreciated!!

R

 

[OldBuzzard]

O2 sensor brand?

 

[Geeknahalf]

O2 sensor brand?

Walker, from O'rielly's. Usually had good luck with them, but then again I don't have anything to compare to

 

[OldBuzzard]

NTK/NGK and Mopar (made by NTK/NGK) are known to work well in TJs, and pretty much every other brand is known to work poorly if at all.

This thread has a lot of good info. I think there is a link in there somewhere to a video on why these specific sensors are needed. Only 37 pages to read through.

 

[OldBuzzard]

Ha! Found it, very first entry.

WARNING! Aftermarket Oxygen Sensors (Chrysler/Dodge/Jeep part 1)​

 

[Rickyd]

Disclaimer: I'm no tuner and I bought, not built the Golen 4.6 stroker in my '97. I'm using the stock PCM and tune.

One thing that jumps out at me are your spark advance numbers. I dyno'ed mine and some of the data is here: https://wranglertjforum.com/threads/woodrows-97-green-tj-moderate-build.51602/page-5
I think 34 degrees is a lot of advance. 26 or 27 at WOT is more the mark I've been told by both a tuner local to me and @Flyin' Ryan Performance.

A friend of mine who uses hp tuners told me the same thing. Lots of advance for emissions reasons. Some day I'll get a spare pcm and have him put a non california() certified tune on it.

 

[Geeknahalf]

NTK/NGK and Mopar (made by NTK/NGK) are known to work well in TJs, and pretty much every other brand is known to work poorly if at all.

This thread has a lot of good info. I think there is a link in there somewhere to a video on why these specific sensors are needed. Only 37 pages to read through.

Ordered all new NTK O2 sensors and a new Mid pipe with all 3 cats. Started to smell a hint of rotten egg on the way to work this morning, (not sure if it was me or the jeep) so I figured WTH, might as well since I'm ordering parts anyway.

Will post scanner numbers this weekend once I find unit of measurement its using.

Thx again everyone!

 

[Jezza]

Hi Jezza, thx for the help.

I am running aftermarket 4 hole 24# ford injectors. The stroker kit is from Clegg, its a stage 2. The assy was balanced at purchase.

I'm not sure if the scanner I have does %'s or not, I'll look and see what measurement system its using and post the numbers over the weekend.

thx again for all the help everyone, it's greatly appreciated!!

R

Yeah, going from 19lb/hr to the 24lb/hr is a 26% change. That's entirely enough to make it run poorly. It probably needs a good tune. You could also put the 19s back in it and see if it runs better.

 

[SkylinesSuck]

Sorry I'm late to the party. Got a lot going on ATM. I have a '98 so not apples to apples, but I doubt your cam is causing the issue. I've known several that ran cams that were supposedly too big for the stock PCM with zero issues. If course getting it tuned is what you want to do, but there is little point if you have an underlying issue that needs fixing first. I like the idea of swapping in the smaller injectors for just some daily driving and trouble shooting.

 

[Geeknahalf]

Sorry I'm late to the party. Got a lot going on ATM. I have a '98 so not apples to apples, but I doubt your cam is causing the issue. I've known several that ran cams that were supported too big for the stock PCM with zero issues. If course getting it tuned is what you want to do, but there is little point if you have an underlying issue that needs fixing first. I like the idea of swapping in the smaller injectors for just some daily driving and trouble shooting.

No worries, appreciate the help. I would swap the injectors but they're gone unfortunately. Going to swap the O2's and see how that affects the stft numbers and the timing. Guessing those are the numbers I'm supposed to be really paying attention to? The new parts should be here mid next week.

 

[Jezza]

No worries, appreciate the help. I would swap the injectors but they're gone unfortunately. Going to swap the O2's and see how that affects the stft numbers and the timing. Guessing those are the numbers I'm supposed to be really paying attention to? The new parts should be here mid next week.

Look at the ltft and the stft for both banks. If they are close to each other say 5% or so the oxygen sensors are fine. Record what the ltft and stft values are from startup to driving.

 

[Geeknahalf]

Look at the ltft and the stft for both banks. If they are close to each other say 5% or so the oxygen sensors are fine. Record what the ltft and stft values are from startup to driving.

Will do that this weekend, thx for the info

 

[Geeknahalf]

I’m gonna ask a stupid question, but I have to ask only cause I have very little experience with computer controlled vehicles:
Would being a tooth off on the cam sync cause this issue?

On known on carb and dist vehicles it would run… like crap but it would run. Is the pcm able to compensate enough only to run like it is?

Hope that makes sense.

R

 

[OldBuzzard]

If you're talking about timing chain, not OPDA, the computer can't compensate for a cam opening and closing valves out of sync with the pistons going up and down. If the computer gets crank and cam signals, it will try to make it go, but ignition timing and fuel injection will be way off. I suspect it would be a whole lot like the carb/dist engines, running really crappy, if it will run at all.

 

[Jezza]

If the cam sensor is off too much it will throw a code. I thought you said you syncd it. What process did you use to sync it?

 

[Rickyd]

If the cam sensor is off too much it will throw a code. I thought you said you syncd it. What process did you use to sync it?

A plastic thingamabob

 

[Geeknahalf]

A plastic thingamabob

That pretty well sums it up

 

[Geeknahalf]

I know the timing of the crank cam gears is ok, was just wondering if the pcm had the capability to compensate for the cam sync being a tooth off