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  #1  
Old 03-12-2016, 12:00 PM
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Stock ECU and exhaust modification

Hi everybody

How much exhaust modification can the stock ECU cope with before it will become necessary to for a custom tune.
I currently have hi flow cats in place of the "pre-cats" and two small glass packs with a j-pipe on the standard pipe.
Next up will be true dual 2 inch pipes with glass packs.
Will I need to tune?
I have not heard of anybody in SA that can tune my Jeep model.
Cheers

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  #2  
Old 03-17-2016, 11:25 PM
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Re: Stock ECU and exhaust modification

Hallo, anybody out there?
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  #3  
Old 03-18-2016, 07:17 AM
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Re: Stock ECU and exhaust modification

Yeh, iīm here, but donīt have an answer for you.
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Old 03-18-2016, 08:02 AM
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Re: Stock ECU and exhaust modification

Hi Frango, Now I dont feel so lonely anymore. Just a thaught, Why are you the only one always answering technical questions? Are the rest of us just here because we have questions?
Back to the origanal question. On the other forums the guys are always tuning after modifications, I even read the claim that you will loose performance by fitting a freeflow exhaust without tuning.
I saw a plug and play system on the net "bully dog" does that widen the parameters that the ecu can self tune?
As you can see I am a keen "how does it work?" enthusiast.
Looking forward to chat again.
Cheers for now.
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Old 03-18-2016, 06:59 PM
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Re: Stock ECU and exhaust modification

I donīt know, but there are not so many enthusiast on here I believe, most only come with questions and problems. I try my best, that's all I can do.
I donīt know much about tuning, so wonīt be much help here.
Maybe that you can contact some tuner in the USA via internet and ask him your questions.
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Old 03-18-2016, 11:41 PM
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Re: Stock ECU and exhaust modification

I will probably have to follow that option. I must confess that I am learning a lot about jeeps since I bought mine two years ago. How is it that you have so much knowledge of the wj, are you a mechanic or just an enthusiast? I am an enthusiast and have had a thing for v8 engines al along. In SA they are not an everyday sight so I have been rebuilding old C10's etc. The Jeep is my first modern v8. Therefore all the questions.
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Old 03-28-2016, 11:22 PM
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Re: Stock ECU and exhaust modification

On the 2003 4.7 HO Overland I have the o2 sensors are before and after the small cats in the Y pipe. Once you are beyond the last o2 sensor there is not any thing the PCM can monitor. So you can do what ever you like with the exhaust pipe with out affecting your PCM.

Hope this helps.
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Old 06-11-2016, 09:33 AM
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Re: Stock ECU and exhaust modification

I have read on other forums that the standard ecu can only cope with small changes and that more changes can lead to an actual loss of power as the changes you made is outside the range of what the ECU can compensate for. Is this true for my Jeep?
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Old 06-13-2016, 01:30 PM
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Re: Stock ECU and exhaust modification

Quote:
Originally Posted by 8isgreat View Post
I have read on other forums that the standard ecu can only cope with small changes and that more changes can lead to an actual loss of power as the changes you made is outside the range of what the ECU can compensate for. Is this true for my Jeep?

The WJ HO's have a ECU already modified for high output. Not many people have been able to tune them. However there is a very good tuner called Hemifever, which you can look up, that has had success with them.

That being said, the 4.7l HO is pretty good right from the factory.Even though the exhaust is larger than stock, a lot of people replace it with a 3 inch single exhaust after the y pipe with a flow through cat and low restriction muffler with good results.

This exhaust ,or any past the O2 sensors, does not affect the ECU.
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