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Engine Retune After Changing Exhaust


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Has anyone retuned their cars after changing their exhaust ?

I've got a Greddy exhaust and it sounded great however got a little bit drony when it hits 4th gear. I found it had a loads of torque in 1st and 2nd, but tends to lose momentum when in 4th. I pretty much got used to it. Then recently I sent my car to Lexus of Chatswood to replace the disc brakes and they apparently reset my engine / ECU and as a result , no more drone and power is even all through the gears !

I immediately felt the difference and couldn't be happier. Enquired with Lexus and apparently the engine had to re-learn ? (maybe someone can help explain) My engine was too used to just my F-Sport filter and after 100,000km+ it needed a reset to adapt to the new exhaust. (Didn't know there was such thing??)

Anyway, thought I'd share this with those who have modified their exhaust or planning to do so. Bring it to Lexus to get it reset !

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Just disconnect the battery for 15 minutes and don't worry about the dealer.

We used to do this in the Soarer club all the time.

Not sure if this will work on the IS, but in the Soarer you could just pull the DOME fuse for 15 mins instead of disconnecting the battery, and you wouldn't have to reset all of the crazy features which hate power failures.

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Thats really cool if what your saying is true platinum Jay,

But if battery reset is the same thing . . . . not as interesting and its being talked up at the dealer.. an ECU reset is achieved by battery disconnect yes . . .BUT is that what they did or did they initiate some other "reset"

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battery d/c is a common trick used by most Lexus tuners in the US for our cars as we dont have a proven standalone or piggyback ecu available for our cars

the reset does not have to be performed by a dealer it maybe done at home by disconecting the battery for a X amount of time

this allows the ecu to reset it's previous map settings and relearn the mods that you have performed on your car

ie. adding an intake will increase the amount of air going into the engine.

it will take around 3 full drive cycles with a few WOT sessions (wide open throttle)

you will find that once you have reset the battery your car will run different to how it was previously. most of the time it will be running rich.

once you have driven a certain amount of km's the car will have learned the new mods and adapt a new fuel and air mixture.

hope this helps

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  • 1 month later...

In response to what Atlantis said about his Soarer, does anyone know which is the corresponding relay for an IS250? I can't seem to find one that explicitly says 'ECU' or similar. Also, which one would be for the front cigarette socket? I'm not getting a voltage across it so it might be a blown fuse there =S

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ecu reset is simply done by pulling the negative terminal off the battery for 10-15 mins or so

i think the fuse box for the cig lighter is located in the engine bay passenger side

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I was hoping for names. How many fuse boxes are there? I see the one in engine bay passenger side but there aren't that many fuses in there.

I want to only reset the ecu and nothing else (from memory, I had to manually reset each window after the last time I pulled the battery)

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Ecu reset is as ilv1004s said. ( or positive terminal safer)

There are four fuse boxes. Engine bay has two. One non serviceable (by driver / owner) and one accessible. One in passenger foot well and one in drivers footwell. See your manual for these details and the details of the fuse ur looking for.

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Oh wow. It's probably in one of them footwell ones then. I have seen a few posts suggesting reset via fuse instead of battery, but mainly in gs forums. Was rather hoping that I can do something similar on an is.

Thanks lex51s

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On prior Toyota and Lexus ECUs (like the Z30 Soarers) all that was required was removing the EFI fuse for 30+ seconds to reset the ECU.

The benefit to this method over disconnecting the battery was that stuff like radio, mirror, seats etc memory presets are retained and you avoid having to reset power window limits etc.

Being able to reset it quickly without any tools was another bonus as it was something that was performed by some on a weekly basis....

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Yeah well I just got around to doing it (by disconnecting battery) with only half an hr towards bedtime. I think I got it disconnected for approximately 15 minutes. Hopefully it's enough to fully discharge any memory modules on the chip. The radio didn't reset (surprisingly) but I did get the power windows problem and had to initialize each one of them.

Do you think the ecu has been reset? Is there any obvious way to tell that the ecu has reset? I think the time was still correct.

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But nevertheless annoying. I was wrong. Clock was reset. Do you guys think it worked? Didn't notice much difference with performance. Perhaps my driving is too consistent? Lol

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only way you can tell that it made a difference is when you put it on the dyno

on our Last dyno run

a member with a is250 made power gains every run untill the 10th run

this was after a intake was installed and the battery was d/c for 10 mins or so

he took out the highest IS250 class!

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no battery was d/c'd while the intake was being installed

then after that dyno run

each WOT (wide open throttle) the car responded better

we actually saw the fuel curve changing every run when it was making power

from 107kwatw it made it self up to 120+ kw

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  • 4 months later...

Hi, I have just purchased a Greddy Exhaust. Can I ask whether you needed a new gasket to connect to the front exhaust system? Did you have any trouble fitting it? Any advice? Thanks.

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Hi, thanks for that. I have downloaded some instructions from the US forum which should assist. I do not have blue tips as I believe that is now discontinued. I think the polished tips are more to my liking though (personal). Thanks for the reply.

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