New Exhaust - warning light now showing?

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My exhaust valve emissions light has come on, anyone else experienced this problem?

I had a new back box and tail pipe fabricated onto the original exhaust, a stainless steel custom unit, about 2 months ago. Done about 300 miles since with no issues and yesterday the warning light popped up.

Display was error free and now I have this warning light on. Any ideas on how to get it sorted ?
 
Did you do anything to the catalytic converter? I have had a full cat system installed with straight pipes and a rear muffler delete and had no issues so far. send you send me a pic of the underside of the car and ill help you out best I can?
 
catalytic converter would be my best guess too. get a fault reader or ask someone to do it for you, the fault code might tell you more. If it is the catalytic system, I wouldn't wait too long to replace it (maybe with 200 cells sport cats?) because the stone in the catalytic converter might start to crumble and parts can be sucked up by the engine and you don't want that!
 
Could just be an unlucky failure of an O2 sensor (lambda).

Diagnostics will tell you


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Apologies for the delayed reply..

Thanks for the response though!

I'm not in a position to take a picture at the moment but ill try over the weekend.

In brief; the entire back box was removed and about 5 inches into the existing twin pipes, they were cut and have been fabricated into a new single pipe, a straight through stainless box, and then twin exit pipes.

Tbh I wasn't entirely happy, I wish I had gone for a proper aftermarket part for the z4 rather than a custom part. It sounds good but I'm not so keen on how it's been butchered on. I spoke to the fitting shop today (fastlane styling @ Romford) and they said they be happy to re fit the original part which I kept (luckily enough) and weld it back on using a coupe of sleeves.

What are people's opinion's ?


Cheers again for the help!
 
hmmmm.... I did the same to my previous Zed because most standard cheap backboxes have 1 entry and 2 exit or the other way around if you turn it over. First of all: it doesn't make sense why they would first weld a Y-shaped tube to be able to enter the backbox in the single pipe and to have a double exit. On mine they did the other way around and simply put a Y-shaped tip at the end. Makes more sense.

I noted after install that though it sounded great, I felt as if I had loss of performance at higher speed. Thinking of it, it makes sense too: you are reducing the pipe diameter from 2 to 1, thus creating more back-pressure, which is fine for low speeds but not at full throttle...

If you can change it, change it simply to a cheap backbox with 2 exits on both sides, that's what I did on my current Zed. It sounds great and I can really feel that the engine runs more smoothly, as if it can "exhale" better. Combined with a K&N filter in the original housing, the engine really runs great at any speed.

Anyway, it probably wont be the cause of the failure light, unless that the increased backpressure broke the lambda sensor, but I'm not sure if that is even possible...
 
Yeah I did think this when they showed me what pipes they had in stock and what they could do, but being the kid in a sweetshop that I am with car parts I went ahead it. Should have done my research and took it to profusion and paid a bit more.

Hopefully they can refit the old back box correctly and car will run as it should. Does make sense with the difference in pressure as you mentioned.

Silly me looks like I've wasted £180 incorrect parts :(
 
that's not as bad, it's a lesson we all have to take ;-)

I had my quads fitted with the right backbox for 500 euro all-in and it sounds/performs great, so no worries, there are options enough but indeed: do your homework or ask the forum for help ;-)
 
Whilst I was at the garage today I got a plug in done to find out what the error code was for my exhaust valve warning light. Mechanic said one of the lamda sensors had been set off and not to worry. He's cancelled the error warning (so light is out) and advised if it comes back on to change the sensor.

Still doesn't fully answer my question though; is the exhaust stopping the car from running as it should? I thought the sensor would be set off by the fuel/air mixture becoming too rich.

Tuesday I go back to the exhaust centre and thinking the just get them to put the original part back while I still have it. Just clean up the chrome tips beforehand and then replace the system later, when I have the funds to get it done properly :?
 
Someone will correct me if I am wrong but why would you waste more money on changing back the standard system and other tips? Did the garage tell you that the error might come from the backbox? If not, why not leave it as it is for now and save up for a better system later? I don't think it will damage your car, it will only decrease performance marginally at higher speeds. If you want to be sure: go back to the garage and ask them if it causes the error or not?

I had the exact same set-up on my 2.5i and ran it for about a year, never had issues.
 
Well plan is to save up for a better system at a later date. Garage that fitted the exhaust said they would put the old part back on for free due to the problems it's causing. The system they have put on includes the back box aswell, it's not just the tips. Plus I've gone off the look of the new tail pipes they just don't look right to me
 
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