Goz Posted March 7, 2009 Report Share Posted March 7, 2009 Hi, I have decided to get a custom exhaust, I was also hoping to get some high-flow cats fitted at the same time but it turns out I have pre-cat and post-cat lambda sensors :flush: What are the post-cat lambda sensors for, and more importantly can I get rid of them? Is it as easy as telling the ECU to ignore them using VAG-COM? Has anyone done this before? Thanks Goz Link to comment Share on other sites More sharing options...
A8_Tony Posted March 8, 2009 Report Share Posted March 8, 2009 Not sure on this one fella. There are a lot of people out there who've had custom exhausts fitted. Myself included. Who haven't worried about any sensors after the cat. What year/model is yours? Tony Link to comment Share on other sites More sharing options...
Goz Posted March 8, 2009 Author Report Share Posted March 8, 2009 Hi Tony, Its a 2001 S8. I asked a few places and they all said you can have the high-flow cats, but you will need a re-map because of the lambda sensor after the cat. Its a lot of money to do a new exhaust, sport-cats and remap all in one go. So I was hoping maybe there is a way to disconnect these lambda sensors without needing a re-map. then I can get a re-map later if I want it. Thanks Goz Link to comment Share on other sites More sharing options...
A8 Doc Posted March 10, 2009 Report Share Posted March 10, 2009 Or you can use spark plug extenders to mount them further out of the exhaust which works a treat. The americans love 'em. Link to comment Share on other sites More sharing options...
A8 Doc Posted March 10, 2009 Report Share Posted March 10, 2009 Or you can use spark plug extenders to mount them further out of the exhaust which works a treat.The americans love 'em. Here ya go the idea: How to install the spark plug anti-foulers to remove the ses or cel light - evolutionm.net Link to comment Share on other sites More sharing options...
Tobes49 Posted March 10, 2009 Report Share Posted March 10, 2009 Depending what ECU software the car running, You might be able to recode it to a 2 probe system. I did this with my S4 engine. Get someone to check with VAG-COM if you can recode the ECU to EuroII standards Link to comment Share on other sites More sharing options...
sutherland Posted March 11, 2009 Report Share Posted March 11, 2009 I asked about changing to sport cats on various forums, but didn't get any responses to my queries about the effect on post-cat lambda sensors, so I've decided to go ahead and get them fitted to my 02 S8 anyway and see what happens. I was told the same about remaps, but the exhuast place said they've done it on other 4.2 Audis with post-cat probes and it hasn't caused CELs. I am getting this done tomorrow so I'll report the results. It would be good to find out about recoding the ECU in case that is necessary--I do have VAGCOM. Link to comment Share on other sites More sharing options...
Goz Posted March 11, 2009 Author Report Share Posted March 11, 2009 Thanks guys, good info. I'm really hoping I can re-code it to a 2-probe system like Tobes suggested. In the meantime I'm going ahead and fitting the high-flow cats anyway like Sutherland. I'm booked in for Monday. I have also done some searching and asked the guys over on AudiWorld.com they came up with the spark-plug extender as well, but also this one: VWvortex Forums: DIY: Wayne Angle O2 Sensor Block 42 Draft Designs which I have gone ahead and ordered. but if I dont get a CEL, I'll be even happier. Sutherland let us know how you get on with your cats. Also, just to confirm, even if you get a CEL from the post-cat Lambdas, it doesnt affect engine running at all? They just monitor the operation of the cat? Cheers! Link to comment Share on other sites More sharing options...
Goz Posted March 11, 2009 Author Report Share Posted March 11, 2009 Here is the spark plug extender / anti-fouler post from AudiWorld forums incase its usefult to someone. AudiWorld Forums: possible solution for those running race cats or test pipes (provided by gesTTalt) Link to comment Share on other sites More sharing options...
sutherland Posted March 12, 2009 Report Share Posted March 12, 2009 Well, I've now got two highflow cats on my car (200cpsi not 100). So far it's going perfectly and the CEL is now staying off. It's also going more smoothly and sounds a lot better, but there's a reason for that--when he removed the left cat he discovered it had been smashed out so one side was de-cated. The noise I was hearing was therefore not a rattly cat, but an empty one resonating in a rather unpleasant rasp. I imagine the uneven backpressure may not have been helpful either. Link to comment Share on other sites More sharing options...
Goz Posted March 13, 2009 Author Report Share Posted March 13, 2009 thanks Sutherland, thats good news. Unfortunately I went over the top and bough 100cpsi cats, so I'm still a bit worried. I need to get myself VAG-COM soon. Link to comment Share on other sites More sharing options...
sutherland Posted March 13, 2009 Report Share Posted March 13, 2009 Perhaps even the 100cpsi will be OK--the CEL was not coming on immediately in my car even although the cat on bank 2 had been smashed out by some villanous traders in London. Link to comment Share on other sites More sharing options...
Goz Posted March 13, 2009 Author Report Share Posted March 13, 2009 good point! i didn't consider that. perhaps these post-cat lambdas are quite insensitive. Fingers crossed, will let you know when the new cats are in. Cheers! Link to comment Share on other sites More sharing options...
sutherland Posted March 16, 2009 Report Share Posted March 16, 2009 Perhaps I replied too soon. The CEL came on yesterday and VAG-COM gave fault of emissions beyond threshold for both cats, so it doesn't like 200cpsi cats either. I reset and since drove 40 fairly hard miles and so far they haven't come back on, but I guess they will. How do I recode to Euro II standards? I can't find anything precise for an S8 on the web. Does this affect other things like fuelling? Link to comment Share on other sites More sharing options...
Goz Posted March 20, 2009 Author Report Share Posted March 20, 2009 Hi Sutherland, I ordered a couple of these cat blocks 10 days ago from the US ($78 in total inc. shipping). They arrived on Thursday so I took them down to Hayward&Scott and they fitted them on whilst they where working on the exhaust. I picked my car up today from H&S, the exhaust is done and is really nice (sorry, forgot to take pics in all the excitement), I drove back home (about 35 miles), and so far no CEL light. Maybe its too soon to be sure, or maybe these cat-tricking blocks really work, I'll let you know if anything changes. Here is the site: http://www.42draftdesigns.com/faq.htm#test basically you just email [email protected] he makes them himself, he replied really qickly, within a few hours, and it only took 8 days for them to arrive. Although I would first see if someone with VAG-COM can have a look and see if your car can be programmed so it doesnt need them, thats the best and cheapest option in my opinion and as soon as I can get hold of a VAG-COM I'm going to do the same. good luck. Link to comment Share on other sites More sharing options...
sutherland Posted March 23, 2009 Report Share Posted March 23, 2009 Thanks Goz. I've actually got VAG-COM, but I cannot find adequate information on how to reprogram for a different emissions standard or to make it ignore the post-cat probes. Any help would be appreciated. Link to comment Share on other sites More sharing options...
Goz Posted April 1, 2009 Author Report Share Posted April 1, 2009 Hi Tobes, I got a copy of VAG-COM, and had a go at finding the emissions settings. I went into Engine > Coding and Engine > Basic settings, unfortunately I dont have a clue what I'm doing. Perhaps naively I was hoping there would be a field labeled 'Emissions'. Am I looking in the right place, what should I look for that would indicate Emissions can be re-coded? Many thanks Goz Link to comment Share on other sites More sharing options...
Tobes49 Posted April 7, 2009 Report Share Posted April 7, 2009 Hi Tobes,I got a copy of VAG-COM, and had a go at finding the emissions settings. I went into Engine > Coding and Engine > Basic settings, unfortunately I dont have a clue what I'm doing. Perhaps naively I was hoping there would be a field labeled 'Emissions'. Am I looking in the right place, what should I look for that would indicate Emissions can be re-coded? Many thanks Goz Can you please post your: Car year, Engine code and gearbox code the recode screen is the correct place but I cant match your coding. Link to comment Share on other sites More sharing options...
Goz Posted April 7, 2009 Author Report Share Posted April 7, 2009 Hi Tobes, thanks very much for helping me out. I almost changed the code to 05753 without checking if its valid (would it have done any harm even if it wasnt?) I think I found the engine and trans code by going into the adaptation screen: Model Year: 2001 (S8) Engine Code: AVP Trans Code: LBL Extra info (VIN + something else?): WAUZZZ4DZ1N011123 AUZ7Z0Y1748242 Cheers! Link to comment Share on other sites More sharing options...
Goz Posted April 7, 2009 Author Report Share Posted April 7, 2009 sorry, just realised, LBL is the file type extension, not the trans code, doh!! I will have a look for the trans code tomorrow. Link to comment Share on other sites More sharing options...
Goz Posted April 7, 2009 Author Report Share Posted April 7, 2009 I think the transmission code is 01L Link to comment Share on other sites More sharing options...
sutherland Posted April 8, 2009 Report Share Posted April 8, 2009 Goz This info should also be on the sticker inside the service book or the spare wheel well. Aren't the angle block things working for you? I just got mine from Wayne and had them fitted yesterday. Link to comment Share on other sites More sharing options...
Goz Posted April 8, 2009 Author Report Share Posted April 8, 2009 Hi Sutherland, Wayne's blocks are working just fine, I kept the trip meter on, so far over 400 miles with no CEL and thats on 100cell cats. I want the damn things (lambdas) removed because I want to put more silencers in after the x-pipe, the car drones at 1600 - 2000 revs at the moment, and if I can get rid of the lambdas perhaps I can have standard silencers fitted rather than custom ones. Also, I like the idea of simplifying the car electrically, so when the rear lambdas fail I wont have to replace them, I hear they are expensive. Also I just dont like the idea of anything cat-realated, if I could remove the cats too I would have. Link to comment Share on other sites More sharing options...
Goz Posted April 11, 2009 Author Report Share Posted April 11, 2009 Sorry Tobes, I got the trans code wrong. I looked in the service booklet as Sutherland suggested, and sure enough there is a sticker in there: Engine Code: AVP Trans. Code: EUU FBG Model Year: 2001 Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now