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post #1 of 25 Old 03-24-2019, 08:25 PM Thread Starter
Brianj5600
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4.0 EFI Tuning

When I first bought my 04 TJ I was very disappointed in the lack of power on the interstate. Until recently there was not much I could find on tuning for increased performance. I would like to encourage anyone that has been tuning stock ECUs/PCMs to share tips and tricks to help efficiency and performance. I am using Syked ECU Tuning and have just started. A thread in the TJ section turned into EFI tuning and it was suggested that this topic be started here to include other platform using EFI 4.0s. Here is what was started in the other thread.

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Originally Posted by Brianj5600 View Post
Ever since I bought my 2004 Rubicon in July 2018, I have been disappointed in power production. It was not an issue around town, 2 lane highways or on the trail, but found myself trying to keep up with traffic on the interstate with even the smallest hill. It got better when the heat and humidity gave way to much cooler air.

I hooked up a scan tool to see if anything was odd. I noticed that timing was low at cruise on level ground and went lower as the accelerator pedal was pressed further the timing continued to drop. When the skinny pedal was pinned the timing dropped as low as 16* btdc. I could tell little difference on the interstate between half and full throttle. It seemed like power dropped beyond 3/4 throttle. Any more power that could be made by more air going in was negated by reduced ignition timing. That 16* btdc above is roughly half of what I would think the motor needed.

After seeing this I started shopping for ways to tune the stock ECU. Most handheld tuners are not worth the cost for negligible at best gains. I will likely end up turbocharging my 4.0 before my trip out west this summer. I don't have a lot of EFI tuning experience but have tuned several cars, both N/A and power adders. B&G tuning software was the first I saw that supported my 2004 TJ. After more than 2 months of not being able to contact B&G I gave up. In the meantime, I saw another option, Syked.

I received my Syked hardware 2 days ago and installed my first modified tune today. Basically, I added 5* to the bottom right corner of the timing table. With the modded tune, on a road I have traveled many times, I can say it has no trouble accelerating on hills that it struggled to maintain 70mph before. There is more in it and I have started the next round of changes
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Originally Posted by Brianj5600 View Post
I finally took the time to test the stock tune vs additional timing. I did several 0-60 runs with each tune and with stock tune times were 14.15 to 14.20. Modified timing was 12.75 to 12.79. I was surprised at repeatability. I used obdlink lx for testing.

Those numbers don't really mean anything to me because the only time I have gone WOT was testing today. The difference in the way it drives is very noticeable. The difference driving back to back is significant. Less throttle results in more acceleration. I can now use OD on the interstate as long as the hills are slight or not very long. On flat ground I can cruise at 80 mph in OD with out a lot of pedal.

I'm going to try adding a little fuel and see if there is more power there. Test were done with 87 octane.

I'm also changing from 4.10 to 5.38 and will test that difference too.
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Originally Posted by Misfits View Post
Brian, I'm on HP Tuners because that's what I'm familiar with so I don't know if the Syked spark tables are laid out the same way. If it's the same layout, adding timing to the lower right corner is the high KPA pressure and High rpm range. The vehicle is designed to pull timing under these high load conditions so be careful. Remember you have no knock sensors (at least on 05 & 06 models), so the engine is unprotected if there's too much timing and it knocks. I don't know your level of experience with tuning so I apologize if you already know all this. As far as a sag in power at high speeds and hills, monitor your fuel system. You'll most likely find that it is switching to open loop under these conditions, (which it is supposed to do). The problem is there is an 8 second delay in the power enrichment for added fuel economy. So very basically, it calls for fuel and then waits 8 seconds to make sure you really want it ,( such as a sustained hill climb), before enriching. Find the delay and set it less or even zero and it will produce a very noticeable result without the risk of running too much timing. I'd be interested In comparing tuning notes if you'd like. Not many people are doing this.
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Originally Posted by Brianj5600 View Post
Thanks for the reply. I would say I'm more knowledgeable than the average enthusiasts, but far from a pro. I definitely have the hunger for more knowledge.

I wish HP Tuners supported my 04 because of the support and that I have several friends tuning with it. I think I can add a knock sensor if I can identify the pin in the ECU connector. There is a provision in the software to activate knock sensors, but no one has tried. A pinout on the Jtec ECU would be very helpful.

The tune I have in it now is basically blending from the factory settings in the column at around 50 kpa to 33 degrees at WOT above 3000 rpm. It is fine except on gear changes. Fallback on gear changes pulls back close to peak torque so I will be pulling 3 degrees. From the 33 at around 3000 rpm in my next tune.

Thanks for the heads up on power enrichment delay. A member on the TJ forum was talking about entering open loop quicker, but at the time I didn't understand. After reading your post it makes sense.

I would love to compare notes. I'm going wheelin tomorrow and need do a few things to my Jeep today, so it will probably be Sunday. I would like to keep this in open forum for people to learn. Maybe start a new thread and divorce this from the previous BS. What part of the world are you in?
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Originally Posted by Newtons3 View Post
A couple of questions for you, just comparing notes.
How much timing are you running at a stabilized speed, 70mph, and at what RPM? What is your MAP reading? IAT? CTS?
How quickly is it pulling in from idle?
When does it begin to retard and how much?

I was about to tune mine when I discovered other issues. The cure of the other issues fixed the power problems I was fighting, so I've never made it to the tuning phase. Considering the PCM problem I've had for the las 3 mos., I may not.

We have use HP tuners also to datalog and access the programming to check.



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post #2 of 25 Old 03-24-2019, 08:34 PM Thread Starter
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Originally Posted by Brianj5600 View Post
This isn't my current tune but close. The bottom chart is factory settings.

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Originally Posted by Newtons3 View Post
sorry. Ignorance. I can't interpret that. I'm guessing the LH numbers are RPM. What is the top row? I'm also assuming the rest of this is a timing table? If so....I definitely have questions. It's the same questions I've been asking for several years.

Usually, when we're looking at HP Tuner, it come with one of the best tuners in the area and he just answers my dumb questions.
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Originally Posted by Newtons3 View Post
Also, why 33 degrees? Seems arbitrary.
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Originally Posted by Misfits View Post
Unfortunately that table doesn't look like the HP layout. Newton- that's how I ended up with the pcm from FS1. I'm not willing to flash my oem/FSEG unit. For what it's worth on my 05, the stock base WOT spark tables pull a couple degrees timing after 3400. IAT do come in to play has the pcm will retard up to 7 degrees at hot temps and MAP values over 55 kpa. I tend to focus more on the VE tables than timing because I don't want to run higher octane and when I'm running real hot when wheeling the stock spark tables can be borderline too much.
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Originally Posted by Brianj5600 View Post
The top row is torr. 760 torr is 1 atmosphere. 1kPa = about 7.5 torr. I hate torr.

33 was not arbitrary. Combustion chamber and piston top shape are key to combustion efficiency. The more efficient the combustion chamber, the less timing the engine will need. I probably gave the 4.0 to much credit setting wot timing 33 degrees. I'm guessing at it so I didn't want too much advance. I'm also guessing 35 is probably a better number.
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Originally Posted by Brianj5600 View Post
Misfits, I will pay attention to how much I am asking of the motor tomorrow. I will be surprised if I spend much time in the cells that I have modified. I have never looked at data when wheeling so I might be in for a surprise. I'll take my hand held with me and reflash to the stock tune if I see anything concerning.

Can you post a timing table and have you made any changes to the timing?
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Originally Posted by Newtons3 View Post
So....I'm ready for the hate and such....again. That's what I get every time this discussion is brought up.

This is not an argument, nor is it instruction. This is, hopefully, an exchange of information and a comparison of notes.

By my experience with the 4.0, over various years, the following is a collection of what I have recognized and observed on my own engines.
The 4.0 likes spark lead, generally it seems to be as much as a Chevy wedge and not as much as a Ford.
I like mine around 14's at a normal idle and I like it to come in pretty quick. I like it in all in around 2400 rpm. With a stock lazy cam the dynamic compression is low enough and the cc shape is not optimal so I have had almost no issues....ever....with detonation. When the engine is in poor shape, have had some instances of pre-ignition, but that was limited. I tend to shoot for 36 degrees, based on WOT at around 24-2600 RPM but have run at 38 with good results. I will add in extra at part-throttle situations to around 46'ish when cruising above 2600 and approaching 3000 but only if I have cats. Non cat, I never want to see over 42...no reason. My camshaft is quite fast on the opening ramps of the intakes and closing of the exhaust with wide LS angle, so my dynamic compression is a little higher than normal and I have had no issues. I find the IAT pulls timing aggressively and have solved that issues. I suspect it is one of the contributors to low power, sluggish, and dead spot complaints. Regearing affected my MAP readings, as expected, and helped the FI maintain the timing better. If.....if we program this thing. I will mimic what I've done with distributors in the past with really good results. That will be my starting point.

BTW, all my FI Jeeps have run on 87 octane with the exception of 2, briefly.

Headers on the 4.0 are generally a waste of effort as is most exhaust work, beyond quality stuff because the head is fairly restrictive. Once the head and camshaft to match are flowing properly, exhaust does matter, but not critically. No cars, racing style, does not affect the engine positively until nearly 4000 RPM, so cats are not a factor for anyone driving normally. Watch injector duty cycle if power goes up. I know the math, but 19 lbs/hr doesn't go very far when power increases are seen. I have upsized nearly every one of mine to 24 lb/hr and my current set up sees 29. CAI picks up nothing on a Jeep, even with a stroker. The two things that do work is venting the hood (huge!) and thermal wrapping the intake tube with radiant barrier (until your sitting still and engine bay heat soak wins out).

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post #3 of 25 Old 03-24-2019, 08:36 PM Thread Starter
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Originally Posted by Newtons3 View Post
I wasn't talking about your hate.

You have given me some ideas to think about on my project.

My outlook on timing is governed by observation and performance. When I don't start from a position of what already existed and just adjust for the situation, my results are quite a bit different than some others. When I put no emphasis on NOx emissions and cat efficiency and focus only on observable results of timing on performance, with deference given to detonation, I come up with something that often looks quite a bit different than what others run. I hope when this PCM problem I am struggling with now is put to rest, I can acquire a second computer to tune on and get back to my original goals.

We should move this discussion to another forum to get it to an engine specific audience and not model specific.

I have had a hard time getting information from even the racers or the stand-alone guys because the threads are interrupted by noise so a lot of people avoid the subject.
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Originally Posted by Misfits View Post
No hate here just genuine interest. I've been much more conservative with my timing. This is partial due to running 35's with 4.88 gears and the deep overdrive ratio of.69 on the 42rle. As many with this tranny and insufficient gearing know, it can feel like a dog on the highway and the rpms are relatively low and the calculated loads are high. Add a 90 degree day and AC load to this and this get even worse. Like you said IAT pulls quite a bit of timing and an intake wrap and aluminum heat shield between the tube and value cover allow me to run about 10* above ambient unless drawing and then everything heatsoaks. It's a noticeable difference. I do add timing to the lower kpa areas of the spark table where my jeep has the gears to support it. I also add a couple degrees advance to the light cruise portions as well. Graphing the spark table shows some peaks and valleys that can be smoothed by adding to certain cells. All in all the part throttle acceleration is more crisp as a result. As I mentioned before, reducing the power enrichment delay to zero and reducing the WOT pedal voltage to 3-3.2v made a significant change - particularly for my high load/highway speeds situation. A have a wideband so I'm able to log delivered AFR, but even without it, logging fuel trims and tuning the VE table helps as well. Again there are odd craggy transitions in the graph of the stock VE tables that can be smoothed with positive results.

Now you and Brian are going to make me go and scrutinize my mid to top end timing again! Like I don't already have enough to do on the Heap! Out of curiosity what are you running for a cam?

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post #4 of 25 Old 03-25-2019, 08:10 AM
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For the FI guys, if we placed an engine on the dyno and made a pull under full load, and established the spark lead to achieve the best results.....when we put that engine in a vehicle, why would we pull timing with no other alarms such as high IAT, CTS, etc.?

In other words, combustion chamber shape and size as well as compression ratio and RPM (and of course some other stuff), of a given engine will dictate how fast the flame travels and the gas expands. Once we know what the target is to achieve max cylinder pressure at approximately 17 degrees ATDC, why would we pull timing?

My questions are, of course, purely performance related and have nothing to do with NOx emissions and cat efficiency.
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post #5 of 25 Old 03-25-2019, 08:15 AM
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I guess my theory is that when we approach ignition tuning from the standpoint of modifying what already exists, we are possibly ignoring our goal. If all we are doing is changing the top RPM settings, we are adjusting in a seldom used area for the 4.0 in a Jeep. If we know where the best power is produced, and it is safe to run there with the fuel we are using, why are we pulling timing or adding excessively. A lot of the timing additions are there to add heat to he exhaust system which effectively kills power, responsiveness, and engine efficiency overall.

I have asked for input from racers and stand-alone guys, and even more advanced pre-emissions tuners with what they have been successful with. I have literally gotten no responses.

I think my starting point, if I built it from the ground up would be....8 degrees BTDC at zero speed with an idle-1000RPM setting of around 14 degrees. I would ramp up in a fairly linear fashion until It was all-in around 26-2800 RPM at around 38 degrees. I suspect that pinning the timing on the dyno, may show that 40-42 degrees may make more power. I would love to test that out. The whole time I would monitor EGT's at the exhaust flange and take spark plug readings religiously. Colder plugs are an option and do work well if pre-ignition becomes an issue. I don't think that will rear its head on stock engine, though.
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post #6 of 25 Old 03-25-2019, 10:05 AM
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4.0 EFI Tuning

Just a quick reply to your WOT dyno timing question. You're not crazy in your question if we are only looking for highest output at 100% load. Some race cars do it with fixed timing, no mechanical, vacuum advance or otherwise. I would love to see what the optimum spark advance for power is at WOT and a given rpm. The dyno is the best and probably only place to do it.

But when we factor in drive-ability, and varying MAP readings/loads, while "xx" advance is optimal at 100% load or 100KPA at a certain RPM, it may be too much at the same rpm with a lower load (think deceleration condition for example - or vacuum advance if your an old school dizzy guy like me!).

Also as a added thought,(and I'm just thinking out loud here), it might also be necessary to modify timing or even have a timing table because dyno runs are usually performed in a single gear such as 3rd on my 42rle where the ratio is 1:1. The greater mechanical advantage of the lower gears may affect the load seen at a given rpm.
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post #7 of 25 Old 03-25-2019, 10:30 AM
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One other thought is if you set your timing for optimal under WOT conditions, in a FI system this typically means you are under power enrichment fueling. So with richer mixtures you need more timing because of the slower flame spread. So if you set it for the richer WOT AFR, when you are not in WOT AFR ratios, there might be too much advance.
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post #8 of 25 Old 03-25-2019, 11:52 AM
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I have heard this in the past. In my experience, it only matters at the lower end of the RPM scale, but the difference is not great. I would love to test the theory. In the distributor world, my tuning for RPM has served me well. I will admit that when lower RPM's are utilized, especially on really sloppy low compression, big CC engines, a timing bump is beneficial. Those timing bumps, however are usually detrimental to throttle response....but on those big sloppy motors, you don't notice it. I do notice it quite a bit on more efficient engines.
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post #9 of 25 Old 03-25-2019, 11:52 AM Thread Starter
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Pulling timing from a dyno run vs in vehicles would depend on how it's dynoed as well as how the vehicle is used. Is it octane limited?

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post #10 of 25 Old 03-25-2019, 11:59 AM
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I guess my wish list for a future tune is as follows, but still evolving:
1. The ability to pin my timing where I want it without the unnecessary jumping around and non-repeatability.
2. The ability to actually set a curve without sort of setting a general "feeling" for how the timing is going to work.
3. The ability to advance by only a couple of degrees when MAP readings are steady and relatively high and pull that out as soon as they drop or a rapid change in TPS is seen.

My guy on HP says he can do all this.
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post #11 of 25 Old 03-25-2019, 12:12 PM
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Quote:
Originally Posted by Brianj5600 View Post
Pulling timing from a dyno run vs in vehicles would depend on how it's dynoed as well as how the vehicle is used. Is it octane limited?
I only use dynos as comparisons not for absolute measurement. I also only dyno on the fuel I will be running/racing. I dyno VERY few engines. I have used collaborative R&D dyno tests to help make decisions.

That said, the methodology establishes where the timing is best for a given RPM. We generally move 2 degrees at a time and change nothing else. How the vehicle is used....not sure what I think of statements like that. I think in my case I would establish that in this case, for me, I had an existing version of an engine and that I thought it could do better. Upon noticing how much timing got pulled from the lower end of my RPM range and how much it bounced around from really high to really low on the top side, I feel I could do better. Going back to all my other successes and ignoring the existing parameters....

I have not had octane become a factor on my 4.0's, yet.
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post #12 of 25 Old 03-25-2019, 04:14 PM Thread Starter
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I always used the drag strip to tune WOT using MPH as an indicator of positive or negative changes. I like that it tests all the systems at once. I have more fun going to the track than a dyno. I've heard several stories about people tuning using chassis dynos with power adders, breaking things once the car is on the road and has more load. Dynos have come a long way and newer ones load the car much better.

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post #13 of 25 Old 03-25-2019, 06:01 PM
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Not for me. Real world use is where my data logging comes from, unless I need a baseline. I've done my tuning on dirt tracks, drag strips, tractor pulls, etc. Dirt tracking we used back-to back lap time averages.
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post #14 of 25 Old 03-26-2019, 10:20 PM
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Have any of you had issues with a new tune causing high startup idle? I've made no changes to any idle settings, yet for some reason I get a 2k+ rpm cold start that immediately idles down to normal. I've even gone back and changed all timing/fuel settings below 1k rpm back to stock, same issue. Stock tune doesn't do this.
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post #15 of 25 Old 03-27-2019, 07:36 AM
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I have not officially tuned this Jeep. I have installed a couple of downloaded tunes to watch how the aggressive timing affects driveability. None of the stuff we installed (5 separate tunes) made any noticeable changes to idle.

I would like to raise my idle to 950-ish RPM.

I would like to have the ability to incorporate some of the stuff that is in my Focus RS tune. When you are engaging/disengaging the clutch the idle RPM's sit at 1200. Flat foot shift is nice.
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