Tuning my pcm. - JeepForum.com
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post #1 of 16 Old 09-18-2017, 07:54 AM Thread Starter
xcaliber81
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Tuning my pcm.

My dad knows a guy that hooks up a laptop and retunes the pcm, i was thinking of doing this maybe this coming weekend anything I should know about this before I possibly waste money?

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post #2 of 16 Old 09-18-2017, 09:50 AM
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I'm pretty sure you would need a handheld tuner to allow you to take the custom written tune and upload it into your factory ECM. I'm unaware of any software that would allow you use just a laptop to write and upload a custom tune to a WJ.

Also, I'm fairly certain that only SCT has the ability to let a tuner write a custom tune for our ECMs, most of the other handheld tuners only allow you to use their in house 'canned' tunes.

You would also need to store a copy of the base factory tune, as there are times you may need to re-upload it to the ECM.

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It is what Jeeples has *PARTIALLY* stated.
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post #3 of 16 Old 09-18-2017, 09:58 AM Thread Starter
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Not sure how he does it but that's what I heard from a few guys he hooks into the obd2 off and makes changes. It takes about an hour
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post #4 of 16 Old 09-18-2017, 10:00 AM Thread Starter
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So would I be better off just buying a handheld tuner?
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post #5 of 16 Old 09-18-2017, 10:53 AM
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Quote:
Originally Posted by xcaliber81 View Post
Not sure how he does it but that's what I heard from a few guys he hooks into the obd2 off and makes changes. It takes about an hour
Right, it's the same basic process that a handheld tuner does.

As I mentioned, it depends on what tuning software he's using, as not all software is able to make changes to a WJ ECM. Plus without a dyno to run the vehicle on you're not really able to determine what good (or bad) the changes being made are doing.

For instance, you can make basic changes to timing and fuel, but you'll need to data log a few full throttle pulls to see if you're getting excessive spark knock which can cause detonation and damage the engine. This is ultimately where your 'tuning' is done. Ideally this would be done on a dyno as you'll be able to see the corresponding increase in power and your tuner will be able to see how the engine is responding to the timing and fuel changes.

I would be suspect of someone using a laptop, making a fuel changes to the timing and fuel tables/maps, and then turning the vehicle back over to the customer in an hour or so.

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So would I be better off just buying a handheld tuner?
Yeah probably, if only for the ability to securely store your factory tune and being able to data log full throttle runs.

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It is what Jeeples has *PARTIALLY* stated.
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post #6 of 16 Old 09-18-2017, 11:14 AM Thread Starter
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What is the best bang for buck tuner?
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post #7 of 16 Old 09-18-2017, 11:34 AM
slickstick55
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I am currently selling a WJ tuner (Flashpaq 3875) that can tune your jeep for both regular and premium fuel for increased MPG or HP gains (albeit very slightly). You can also clear engine codes and tune your speedometer for when/if you're lifted + larger tires! feel free to PM

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post #8 of 16 Old 09-18-2017, 11:47 AM Thread Starter
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Okay. Let me do some research 1st.
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post #9 of 16 Old 09-19-2017, 03:08 AM
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Thumbs up

x2000 on what Jeeples said. I come from the sportscar/sportbike world and this is how it's done, properly!

Quote:
Originally Posted by Jeeples View Post
Right, it's the same basic process that a handheld tuner does.

As I mentioned, it depends on what tuning software he's using, as not all software is able to make changes to a WJ ECM. Plus without a dyno to run the vehicle on you're not really able to determine what good (or bad) the changes being made are doing.

For instance, you can make basic changes to timing and fuel, but you'll need to data log a few full throttle pulls to see if you're getting excessive spark knock which can cause detonation and damage the engine. This is ultimately where your 'tuning' is done. Ideally this would be done on a dyno as you'll be able to see the corresponding increase in power and your tuner will be able to see how the engine is responding to the timing and fuel changes.

I would be suspect of someone using a laptop, making a fuel changes to the timing and fuel tables/maps, and then turning the vehicle back over to the customer in an hour or so.



Yeah probably, if only for the ability to securely store your factory tune and being able to data log full throttle runs.

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post #10 of 16 Old 09-20-2017, 10:40 AM Thread Starter
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So the 3874 will cost about 500$ or there about is the price worth it? Aparantly the performance tune is good for 13hp I think kolak said? Opinions from people who bought it would be sweet.

I do eventually want a handheld tuner there's no doubt about that.
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post #11 of 16 Old 09-21-2017, 11:44 AM
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The Tuner that I am selling (Same as the one you mentioned) did give a small HP gain, can't really give you a specific number. The greatest improvment for my WJ was with the improved/changed shift points. Before installing the tune, my WJ would shift erratically/hard. The tuner solved many of my issues in that department AND allows you to check/clear check engine lights another benefit of the handheld tuner. I also found out recently that I could use my 3875 tuner for my WJ and use it to clear engine codes on my brothers 2015 SRT Grand cherokee. Pretty nifty.
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post #12 of 16 Old 09-24-2017, 07:01 PM Thread Starter
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I ended up buying the 3874 from kolak today, super excited to get it and I'm gonna start running premium fuel to try and get the most of it lol. Doing a fair bit of highway driving too atm.
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post #13 of 16 Old 10-06-2017, 10:59 PM Thread Starter
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I got presents today

I'd love to play with it but sadly I'm out of town for 5 or 6 hours. Curious should I use the 87 octane tune 1st or drain my tank and go right for the 91 octane tune? I've never tried premium fuel in my jeep yet.
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post #14 of 16 Old 10-07-2017, 03:11 AM
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Nice! LMK how it does for you. And I've only used 91 Oct in my Jeep. Pretty much any of my V8s

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post #15 of 16 Old 10-07-2017, 02:04 PM Thread Starter
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Its not as big as I thought it would be lol, for some reason I was expecting a small laptop. Good news is I have no engine codes
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