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Old 07-30-2012, 12:59 AM   #1
turbofreak79
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ok so i was talkin to one of my buddies at auto school and i was askin if i could get a little more power outta my 2.5i and he said i could if i did a few things. one of the things that caught my attention and was seemed really easy was trickin my ecu by puttin a resistor in my signal wire from my map sensor to the ecu to make the ecu seem like the engine was getting more air, in which case it would add more fuel. the only problem is a Map sensor reads in a range of voltage which is 0.5 volts to about 4.5 volts, and the map sensor has a fail safe programmed into it. this means that if the map sensor is off by 0.25 volts (plus or minus) that the map sensor would fail. so my question is does anyone know how small of an ohms resistor i need so that the fail safe does not activate.

thanks for you help also
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Old 07-30-2012, 09:50 AM   #2
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That will not work for a couple reasons. First is that the EFI system on all 2.5i's is MAF based. So the MAP and MAF would be sending "conflicting" data so to speak. Second is that adding fuel would probably actually hurt power, especially top end, as the stock tune is on the rich side in most of open loop already.

I would ask your buddy how he expects more fuel to increase power of there is not also more o2 to support combustion?
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Old 07-30-2012, 04:54 PM   #3
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Whats the AFR under WOT. Have you used a wide band for that
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Old 07-30-2012, 06:11 PM   #4
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Quote:
Originally Posted by RaceFaceXC
That will not work for a couple reasons. First is that the EFI system on all 2.5i's is MAF based. So the MAP and MAF would be sending "conflicting" data so to speak. Second is that adding fuel would probably actually hurt power, especially top end, as the stock tune is on the rich side in most of open loop already.

I would ask your buddy how he expects more fuel to increase power of there is not also more o2 to support combustion?
I was under the impression that some of the early phase 2 2.5liters were MAP based. Is this incorrect?

Regardless I agree more fuel wont help without more air.
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Old 07-30-2012, 07:11 PM   #5
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Some of the previous ej n/a motors were MAP based but no 2.5i (2005 or newer I know for a fact is MAF, besides 2012 which I just dont know much about. ) has ever been MAP based in the US/Canada
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Old 07-30-2012, 07:17 PM   #6
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Quote:
Originally Posted by turbofreak79 View Post
Whats the AFR under WOT. Have you used a wide band for that
The ECU OL fuel maps on my 07 calls for mid 10's AFR near Redline @ WOT and on the typical switch to OL (~3000 rpm) call for high 12's IIRC. Others with 05 and 06 have verified similar findings on their same tables. I would strongly suspect the 08-11 would be similar since the design, power and efficiency have remained mostly the same.

My CL2 measured high 9's near redline on stock tune w/ a rescaled MAFv for a hybrid intake.
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Old 07-31-2012, 01:28 AM   #7
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Quote:
Originally Posted by RaceFaceXC

The ECU OL fuel maps on my 07 calls for mid 10's AFR near Redline @ WOT and on the typical switch to OL (~3000 rpm) call for high 12's IIRC. Others with 05 and 06 have verified similar findings on their same tables. I would strongly suspect the 08-11 would be similar since the design, power and efficiency have remained mostly the same.

My CL2 measured high 9's near redline on stock tune w/ a rescaled MAFv for a hybrid intake.
What did you use to find this out.
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Old 07-31-2012, 02:31 AM   #8
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Note im not tryin to argue with you im just curious about whats happening and what goin on cuz i know very little about this. So sorry if i seem like an ass i dont mean to be
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Old 07-31-2012, 03:03 AM   #9
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Originally Posted by Tomato_88

I was under the impression that some of the early phase 2 2.5liters were MAP based. Is this incorrect?

Regardless I agree more fuel wont help without more air.
You cant really add more air. But you can make it flow better if thats what you mean. But i think that even the stock tune can be altered a little bit to make it perform better i mean almost ever car with a stock tune and get more out by adding a little bit more fuel
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Old 07-31-2012, 04:02 AM   #10
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Quote:
Originally Posted by turbofreak79

What did you use to find this out.
I'm not exactly sure what you are asking but I used Rom Raider ecu logger/editor to look at the rom and as I stated in the past you quoted, I used my innovate motorsports CL2 WB to log actual AFR.
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Old 07-31-2012, 04:06 AM   #11
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Quote:
Originally Posted by turbofreak79

You cant really add more air. But you can make it flow better if thats what you mean. But i think that even the stock tune can be altered a little bit to make it perform better i mean almost ever car with a stock tune and get more out by adding a little bit more fuel
Altering the MAP signal or any amount of "tuning" will not change flow or v.e. of the engine. If you do increase how well the heads flow by physically changing something you are effectively adding air (and o2). The EFI system should measure that increase in air via the MAF and add fuel accordingly.

With that said, the 06-11 ecu can benefit in some ways from a "tune" to the dbw throttle tables, the CL/OL delay, MAFv (rescale) and timing advance to clean up some knock. Leaning the OL fuel a bit in the right places helps top end noticeably but a WB is a must to do the latter.

Last edited by GrundleJuice; 07-31-2012 at 04:14 AM.
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Old 07-31-2012, 04:53 PM   #12
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Quote:
Originally Posted by RaceFaceXC

I'm not exactly sure what you are asking but I used Rom Raider ecu logger/editor to look at the rom and as I stated in the past you quoted, I used my innovate motorsports CL2 WB to log actual AFR.
Yeah i was wonderin what kind of program you used haha sorry my bad. So there is a program out the for n/a subies
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Old 07-31-2012, 09:38 PM   #13
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Originally Posted by turbofreak79

Yeah i was wonderin what kind of program you used haha sorry my bad. So there is a program out the for n/a subies
It's a free open source ecu logger/editor. It just happens to support many of the n/a USDM ecu's from 05 to 09, but not all of them. You can DL it, get a tactrix cable, pull your Rom image and see if your Rom ID is supported on the supported ecu list. There are a couple other editors that are also open-source and free.

I strongly suggest not editing/flashing your Rom/ecu until you have a very good idea of what you are doing. It is possible to turn out into a paper weight
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Old 07-31-2012, 11:20 PM   #14
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A very expensive paperweight.
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Old 07-31-2012, 11:55 PM   #15
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Sounds like your friend needs to stay in auto school. That idea is as scary as using an eBay ecu chip lol.

The 2.5i's are not built to be a race car by any means. And without a proper tune even a cold air intake can cause issues.

There is the whole engine management and tuning forum here which has some good info if you want to read up and see if it interests you. You will learn a lot
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Old 08-01-2012, 03:19 AM   #16
turbofreak79
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Quote:
Originally Posted by RaceFaceXC View Post
It's a free open source ecu logger/editor. It just happens to support many of the n/a USDM ecu's from 05 to 09, but not all of them. You can DL it, get a tactrix cable, pull your Rom image and see if your Rom ID is supported on the supported ecu list. There are a couple other editors that are also open-source and free.

I strongly suggest not editing/flashing your Rom/ecu until you have a very good idea of what you are doing. It is possible to turn out into a paper weight
well thanks for the info. im actually in class right now and we just went over pcm tuning and we get to out and tune the car while using a load cell dyno. im totally excited cause i find this stuff very interesting.

thanks for the help with everything.
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