TBE + Up-Pipe, Retune necessary on Bugeye WRX?
 

Hey guys,

Got an October '01 WRX - Bugeye.

Looking to do the Full TBE Exhaust and Up-Pipe. I have heard that it is pretty much essential once completing this modification that the car is retuned, either re-flash factory ECU, Piggy Back or complete replacement ECU.

I have done my shopping around, and have been hooked up with a reputable contact who is involved in a fair bit of WRX/Liberty racing/performance/rally aus. He is able to hook me up and fully install a good quality custom TBE and up-pipe for a very nice price.

I have asked him whether or not a retune will be necessary, as I may get boost spikes, run lean/reach etc etc. He said he'd ask a few people and get back to me. Well he got back to me next day and said it wouldn't be necessary.

He said at the end of the day, the intake is all a 'closed system', and that the 02 sensor would natively provide the correct fuel/air mixtures regardless of fitting a TBE, and i shouldn't have any driveability issues. After hearing this, i am curious as to why everone mentions that an ECU upgrade is required?

Is this some form of scam? Is it said because it's not *absolutely* neccessary, but is generally a recommendation to get the most of your newly installed modification? Perhaps a safety-net to ensure that the motor is not damaged. I have heard that the 06 WRX definitely needs a tune afterwards.

Looking for some good feedback!

Cheers,

RichX

If you fit a full TBE system to a 02 Bug eye, the ecu will detect irregular signals from the two O2 sensors on the exhaust.

The reason is that there is one o2 sensor before the cat on the down pipe and another o2 sensor after the cat. there is also another cat after the second o2 sensor and before the first on the up-pipe.

The ecu expects to see differing signals from these two o2 sensors.

When you get a full 3inch TBE the cat on the down pipe is usually removed, so the two o2 sensors will end up detecting the same levels. This throws out the ECU which is expecting differing signals and causes it to go into limp mode.

Limp mode reduces your boost to default wastegate actuator setting and retards the ignition timing. The result is a very sluggish car.

You will need at minimum a re-flash of your stock ECU in order to make the most of your new TBE system.

You can still drive around on limp mode for a little while, but it is not recommended.

That is indeed a concern.

I have asked some other people to --> [url]http://forums.nasioc.com/forums/showthread.php?t=1121556[/url]

They seem to think otherwise .. I cannot get a rock solid answer to my question. :(

Just keep in mind that ADM, JDM, and USDM cars often differ in the way the ECU is set up from factory.

will not "need" one but it will make the car preform better.

I fitted a 3in TBE and VF30 with no ecu change to my MY01. Got sluggush off boost preformance, a massive hit of torque from 4000-5500 then not much more.

top end went from being able to hit 210 stock to not being able to run past 190.

Considering the relatively cheap costs of a Verso tune re-flash of your ECU, you may as well do it. The benefits definitely outweigh the cost and the difference after a tune is vast.

[QUOTE=Mister Two]If you fit a full TBE system to a 02 Bug eye, the ecu will detect irregular signals from the two O2 sensors on the exhaust.

The reason is that there is one o2 sensor before the cat on the down pipe and another o2 sensor after the cat. there is also another cat after the second o2 sensor and before the first on the up-pipe.

The ecu expects to see differing signals from these two o2 sensors.

When you get a full 3inch TBE the cat on the down pipe is usually removed, so the two o2 sensors will end up detecting the same levels. This throws out the ECU which is expecting differing signals and causes it to go into limp mode.

You will need at minimum a re-flash of your stock ECU in order to make the most of your new TBE system.

[/QUOTE]

Okay, i understand everything you've said. So you're essentially saying, you're not actually getting a retune, you're disabling/hacking the 2 02 sensors so that they read different signals as they would normally without the TBE.

Basically, yes, you re-flash the ECU with certain flags turned off so that it doesnt crack a spaz when it sees o2 signals its not used to seeing. But while your there, you may as well tighten up the AFRs and give the boost settings a little push.

If a high flow cat is icorporporated in the system then you'll be ok as the second O2 sensor will pick up that the cat is working as it should be

ok.. lets put some of these myths to rest.

1) Installing a turbo back exhaust will make your car flow better
2) Because of the increased flow, the ecu will need some modification to account for the extra flow
3) Boost spikes generally are not encountered provided you're using a decent dump pipe that is not obstructing the wastegate (assuming your boost control solenoid is also working).
4) Stock Ecu's have two modes of operation.. Closed Loop and Open loop.
5) During closed loop the ECU will try and retain a cruise AFR of 14.7 assuming no-one has fiddled with it.. YOU CAN ALTER THIS!
6) During open loop the ECU is not using the 02 sensor to make active corrections, its dumping in fuel as per instructions.
7) Some Exhaust installer are lazy and dont put the dump pipe EGT back in (for whatever reason) and this is one reason you see a CEL light come up
8) If you remove cat's from the downpipe the stock EGT sensor might get a little more toasty because of the extra heat it may/may not see. (which again can be corrected directly from the ecu) IMHO its better to do this correction then fudge it with a dodgy resistor mod.
9) You may throw a cat efficency CEL because of the modifcations (again correctable)
10) MY01+ car's have two 02 sensors.. one is a semi wideband and the other is narrow band.. front o2 sensor is generally accurate to about 12.2-12.0. Saying that dont rely on it as i've seen a few that have been WAY off.
11) Limp mode is only activated when the ecu is seeing HEAPS of det, generally an exhaust will not send it into limp home mode unless someone's wired something up REALLY wrong.