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Old 07-24-2013, 12:57 PM   #1
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Reprogramming ECU to turn off O2 Sensors

I've deleted my cats with a test pipe and the shop is telling me that I need to reflash my ECU with the cats deleted. Does anyone know of a company I can send the ECU to?
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Old 07-24-2013, 02:15 PM   #2
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97-99 or 00-04? You don't have to reflash ECU when you delete cats. You can tune an ECU to make more power, however many people including myself are content with just the increase from removal. Are you getting a check engine light? You can flash it or just add some 02 sensor extensions to remedy the problem.

Edit: It looks like your car falls in the 97-99 range judging from you car pics. You would probably be throwing a check engine light then.

Last edited by Kenny Boxster; 07-24-2013 at 02:18 PM.
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Old 07-24-2013, 02:25 PM   #3
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97-99 or 00-04? You don't have to reflash ECU when you delete cats. You can tune an ECU to make more power, however many people including myself are content with just the increase from removal. Are you getting a check engine light? You can flash it or just add some 02 sensor extensions to remedy the problem.

Edit: It looks like your car falls in the 97-99 range judging from you car pics. You would probably be throwing a check engine light then.
I have a pretty strange problem. I removed the cats and the car ran fine. Then after making a different repair I unhooked the battery and reconnected it and the car started misfiring on all 6 cylinders. Both Porsche shops I've taken it to have told me that the problem is the removed cats and that I have to do something with the rear o2 sensors. And yes the check engine light is on.
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Old 07-24-2013, 06:37 PM   #4
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That is certainly strange. Dunno if a misfire and the cats missing could be related, or coincidence. Haven't heard of that on the forums, but is there a way to find the codes?
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Old 07-25-2013, 03:54 AM   #5
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Its reporting a misfire on all 6 and a code for e-trottle relay which is odd since its a 97
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Old 07-25-2013, 06:00 AM   #6
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Both shops are mistaken because the o2 sensors aft of the cats only sniff for emissions and don't affect mixture trims. I would disconnect the batt again for one minute to reset the DME and see what you get. Is it possible you crossed the pos/neg terminals and fried your DME?
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Old 07-25-2013, 06:17 AM   #7
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Both shops are mistaken because the o2 sensors aft of the cats only sniff for emissions and don't affect mixture trims. I would disconnect the batt again for one minute to reset the DME and see what you get. Is it possible you crossed the pos/neg terminals and fried your DME?
No the cords don't reach. This happened once before a month ago and I towed the car in and it was diagnosed with a bad air/oil separater. After the fix it ran, then once I dissconnected the battery again..same thing all over again. I've dissconnected it numerous times and connected them to discharge and capacitance..no luck. Very odd problem. Are you sure the aft O2's don't effect mix?
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Old 07-25-2013, 11:25 AM   #8
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Any shop with a PSTII or Piwis can flash it with a "ROW" tune.

It turns off the secondary 02's and does away with the secondary air pump.

Topless is correct, just HANG THE secodary 02's under the car in clean air. They are looking at CAT efficiency. Plug them back in and leave them in the trunk somewhere.. seriously.. plug them back in and let them *see* clean air.

They are heated, so secure them so they don't touch carpet. Up against plastic is fine.
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Old 07-25-2013, 11:32 AM   #9
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I would just do a RoW flash and then you can completely remove them, along with all of the secondary air injection guts.

This has the other nice benefit (at least to me) of being able to start the car without depressing the clutch.
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Old 07-25-2013, 11:33 AM   #10
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I have bypassed all my cars at the ECU lol

I actually forgot that the ROW tune removes it lol
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Old 07-25-2013, 03:43 PM   #11
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Any shop with a PSTII or Piwis can flash it with a "ROW" tune.

It turns off the secondary 02's and does away with the secondary air pump.

Topless is correct, just HANG THE secodary 02's under the car in clean air. They are looking at CAT efficiency. Plug them back in and leave them in the trunk somewhere.. seriously.. plug them back in and let them *see* clean air.

They are heated, so secure them so they don't touch carpet. Up against plastic is fine.
There's no way this could resolve the missfire problem right. I just pulled the codes again and now it's also reporting o2 faults on all 4, I guess that's a side effect of the misfires.
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Old 07-25-2013, 04:17 PM   #12
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How far is Richmond from Charlottesville? Ex factory tech has a shop there.

I'd love to hear from these techs at your local shops why its misfiring because of the CATS.. LOL

I'd actually use the words "shut up" in front of adults.. lol

Was there *anything* else done that you are neglecting to tell us?

I mean **anything** done to the car??
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Old 07-25-2013, 09:07 PM   #13
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Then after making a different repair I unhooked the battery and reconnected it and the car started misfiring on 6
What was the other repair?
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Old 07-26-2013, 03:17 AM   #14
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Thanks so much for your help.

Full story
1) Car refused to start, just clicked. The battery was old so I just went ahead and replaced it (never jump started the car)

2)with the new battery it started but misfired on bank 1

3) I towed the car in and they told me the AOS and oil fill tube failed so I replaced them

4) I got the car back and it didnt red line and still ran rough. They told me the variocam was bad and I had a bad cat.

5) I replaced the cats with test pipes and it ran great but wouldn't redline

6) I replaced the variocam and the car ran but wouldn't redline. I tried disconnecting the battery to reset the ecu and ended back at step 2). Except I now have a misfire on all cylinders. By the way steps 1-6 are over 3-4 weeks, only 1 week spent out of the shop.
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Old 07-26-2013, 08:39 AM   #15
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Dude.. (SoCal term for cool guy)

Please get your car out of that shop that has NO clue about your car..

Here is the MAP to Charlottesville:

Kenny Shreves runs a shop there and is a factory trained Porsche tech who happens to be a PRO race mechanic for teams like Flying Lizard, Park Place and many others... He is VERY VERY good at what he does. I'm glad to call him "FRIEND" and I don't mean facebook "friend"

All it takes is for this *shop* to leave a ground wire off for the coil packs and you will have a ton of weird ass problems.

https://maps.google.com/maps?saddr=Richmond,+VA&daddr=Charlottesville,+VA&hl=en&sll=37.269174,-119.306607&sspn=11.653767,21.687012&geocode=FXXTPAIdcGti-yntyZlXCRGxiTHFPELibT7Yvw%3BFfpHRAIdeopS-ymPpFDqLYaziTH8dIvDlvCGkA&oq=charlo&t=h&mra=ls&z=10
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Old 07-30-2013, 09:05 AM   #16
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Problem resolved! It was the mass airflow sensor. I haven't picked the car up yet but I'm told its running great. Thanks again for everyone's help. Luckily I didn't replace the ECU like the other shop was telling me to do YIKES! Pays to get a second opinion I guess.
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Old 07-30-2013, 09:28 AM   #17
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Glad to hear you got your problem resolved. Man, that sensor must be really bad to cause such misfire. Had a bad sensor once and only symptom was couldn't go past 5k rpm.
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Old 07-30-2013, 11:41 AM   #18
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Kenny, I would think that depending upon the amount of oil in the throttle body from the blown AOS, the MAF sensor could indeed be that bad!

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Old 07-30-2013, 05:09 PM   #19
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Kenny, I would think that depending upon the amount of oil in the throttle body from the blown AOS, the MAF sensor could indeed be that bad!

Brad
That was my first thought to. Especially after a failed air oil separator but that was one o te first things I checked. I pulle the mass air out and there wasn't a drop. Who knows, something tells me there is something else
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