Decat'ing my car

Pitbull said:
Sound advice? What if his car is still under warantee or something?

As for me being incorrect, that is very likely. I mentioned it because I had the exact same problem. It turned out that there was a problem with the air/fuel ratio. This cost me an arm and a leg to have it fixed at a dealership. After I paid the invoice the clerk said I could have had it changed via a normal Dyno tune.
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Fair point about the warranty. If it is under warranty though then he should take it in for this to be fixed under said warranty.

Also: OP mentions that it is intermittent which does go against my hypothesis of disintegrated cat (porcelain inner section) causing blockage. Unless it's a small blockage that shifts from time to time... the misfire is very telling here - who knows though, until the issue is fixed it's all conjecture.

Kind of tough to diagnose over teh webz ;)
 
Pitbull said:
Sound advice? What if his car is still under warantee or something?
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It is quite obvious that one should not do this when the vehicle is under warranty. Or make sure your stealership is friendly enough to overlook such things.



As for me being incorrect, that is very likely. I mentioned it because I had the exact same problem. It turned out that there was a problem with the air/fuel ratio. This cost me an arm and a leg to have it fixed at a dealership. After I paid the invoice the clerk said I could have had it changed via a normal Dyno tune.
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Err, dunno about you, but I don't trust ANYONE at a stealership, not a mechanic and definitely not a clerk!

btw, was it the MAF sensor that needed replacing?
 
Hooked up an OBD scanner at work, and got these results :

http://twofold.co.za/Emissions.html
http://twofold.co.za/Trouble_Codes.html

and :

capture.png


Not very helpful though.
 
Spoke to Sanjeev at Powerflow... said he'd need to decat and put in a mini-cat. Should set me back around a grand, and will take less than a day. A bit scared of the extra rumble it might make though. I'm dignified.
 
Tell him to do a 76mm downpipe aswell! You won't be disappointed. Which powerflow you using?
 
You are probably getting the error because of a faulty O2 sensor. Not sure if the warning will go away if you remove the CAT as I know that you will have to deactivate the secondary o2 sensor. It will be best to speak to some Peugeot guys on this matter. I know in my Honda you have to us eHonData to deactivate the sensor when decatting, or the same error will display on the dash...

But I say do it mate.... More power for you and will sound a bit better too
 
Rouxenator said:
A new O2 sensor should not set you back more than R1500 if I am not mistaken?
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Depends on type. Wideband heated (R2.5k+)/Narrowband heated(~R2K)/Narrowband unheated(R1k+). Most N/A vehicles run narrowband but lately the shift is being made to wideband, especially for performance N/A vehicles. Also depends if you buy OEM or after market.

I've seen OEM heated wideband sensors go for R4K.

Heated O2 sensors last longer (150K km+). Exposing a O2 sensor to leaded/LRP fuel or additives can decrease life significantly. For example running on leaded fuel a sensor that would have lasted 60K km will last 10K km.

Little interesting info (to some): Wideband can actually measure the O2 level whereas narrowband can only differentiate between lean/stoichiometric/rich. Hence a engine using wideband sensors can optimize fuel usage with incredible accuracy (and similarly reduce COs very dramatically). Diesel engines can ONLY run with wideband (since they always run lean).
 
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Mine was on the Astra's manifold so I'd guess it was narrowband heated. Replaced it at about 120,000km. At the time there was a significant price difference between the one for the 1.6 16v and those of the 1.8/2.0/2.2. Perhaps these were wideband?
 
I was quoted about 3K for the lambda sensor on my 2006 Astra 180. I went mini cat & banana branch route, there was nothing wrong with my sensor. My cat was up to shyte after 180 000km. There are actually 2 sensors on my Astra, one on the manifold on/before the cat, the second is under the car just after the cat. Anyone who knows the Astra 180 will agree with me how under powered the car feels (standard) I personally think they got the gear ratios way to wide for an 1800 engine with 17" 225 tires. Just the wrong combo. But having the branch with mini cat has made a huge difference, car is much more responsive, low down torque is so much better, and the engine revs very freely now. Still to pull away with the car, you got to keep the revs up a bit, especially with its stupid break hold on inclines....
 
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I have a feeling that after fitting the mini cat, the error message is gonna go away permanently but you the car is gonna still have a slight jerk or flat spot.

Reasoning: I think that your O2 sensor is faulty, causing the fuel mix to go off, in turn causing the error message regarding the cat (cat detecting too much unburnt fuel perhaps). When you switch off and restart, the EU is then recalculating air/ fuel mixture (perhaps allowing more air to compensate for the extra fuel). I might be way off but that's my opinion.

But as previously stated, just get rid of the OEM cat and go from there. You do get Bosch universal O2 sensors which are cheaper than OEM, but depending on the type your car uses and the type of Bosch sensor you getting, you might have to modify the connecting point on your branch/ exhaust (easily done at exhaust places like Powerflow).
 
@OP

I had exactly the same problem as you on my Astra 2.0 GTC.
I did a decat and a down pipe. Never had a problem again. A year later I bought the Astra OPC. On 7000km I did a de-cat and down pipe again with software. I then went on to remove the centre box too. To this day still no problems.

If I were you id do it. I replaced the 02 sensor and it never helped on the GTC.

Good luck
 
Mypro-D said:
If I were you id do it. I replaced the 02 sensor and it never helped on the GTC.
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Probably because the software was changed. O2 sensor plays a mayor role ;)

Do you have any idea how they dyno a car to change the software? Or even how a car's engine map is created? They put the engine on a dynamometer (engine dyno) or the car (road dyno). Before they start the process they put a wideband O2 sensor in the exhaust.

The engine is then tuned SOLELY based on the output of the o2 sensor.

You should by now realize the reason manufacturers started fitting them to cars. It's not just about emissions, it's about running the engine at it's peak by checking that the mixture is correct.
 
What worked for me on a Suzuki Jeep, Toyota MR 2 and a Mazda Mx 5 was to take out the cat and beat a long screwdriver through the honey comb of the cat and remove all the bits and pieces and replace the box, connect all sensors and Viola, fuel consumption the same a lot more power and can run on unleaded fuel, downside a bit more noise.
 
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