MK5 Golf GTI
All Things Mk5 => How to Guides / Troubleshooting => Topic started by: Mk5_Jim on March 24, 2014, 09:38:14 am
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Hi guys so yesterday I removed my precat, all went well and took us 2 hours thanks to a very stubborn exhaust rubber!
Took it for the initial test drive and it felt no different really - maybe marginally louder. However after 15 minutes driving it started to feel odd. Under high load it would accelerate very slowly and it felt like it was cutting fuel. After another 10 minutes my CEL flashed a few times :confused: and went out so I pulled over and switched off for 10 minutes, turned it back on and no CEL after another 5 minutes the CEL was back but this time just on constantly (not flashing). The car feels fine under normal loads but anything above 4k and it just stops pulling?
Initially thinking maybe a worn cam follower and just coincidence in the timing of it or that I have damaged a lambda sensor. The first lambda right by the turbo was left on while we knocked the precat out as it was proving very tough to remove however I took care not to hit it or lean the chisel on it! Could the precat dust have got itself into the sensor?
The car is a 2007 57 GTi DSG with 67k on the clock and no other modifications. Any help would be greatly appreciated!
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The problem seems to get worse the nearer the redline you get, I've stopped trying to provoke it and am now driving it like a nun until I can get this sorted :sad1:
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Seen this talked about a few times after a pre cat removal.
When you removed the pre cat did you also make sure you removed the fiberglass/asbestos looking stuff that was stuck to the inner wall of the pre cat housing?
Sounds like a blocked main cat possibly?
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I've never heard this talked about after pre-cat removal? (at least not on this forum)
I think you need to scan for fault codes, it sounds like you may have damaged the lamdba sensor tbh :sad1:
Its like fitting a performance down-pipe, you shouldnt get fuel cuts as a result of it.
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Thanks for the replies, I made sure that I removed everything to do with the precat so don't think it could be a clogged cat. Starting to lean toward a damaged lambda due to dirt getting into it? I only suggested fuel cuts being the issue as the dsg fart between gear changes has also disappeared and under light acceleration the car picks up as it used to its only when using medium to full throttle that the lack of power is properly noticeable. I'm going to take off the MAF and see if it runs better or worse. Also might try disconnecting the battery for 15 minutes as some people have suggested this may help? Anyone know how much an indy is likely to charge me to just run a scan?
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Have you scanned it to see what the fault is?
Could very well be coilpacks or did you knock the lambda sensor...??
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Haven't had a chance yet. The car idles smoothly and doesn't feel lumpy, wouldn't coil packs do this?
I was very careful to avoid the lambda and definitely didn't hit it with the chisel but when getting my hands in there to remove the precat material I may well have bumped it with my hand?
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Haven't had a chance yet. The car idles smoothly and doesn't feel lumpy, wouldn't coil packs do this?
I was very careful to avoid the lambda and definitely didn't hit it with the chisel but when getting my hands in there to remove the precat material I may well have bumped it with my hand?
You didn't take the lambda out to hit out the material??
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Nope, seems stupid now I know. It was too tight to get off without the use of a blowtorch which we didn't have to hand, we just unplugged it and did my best to avoid disturbing it
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Nope, seems stupid now I know. It was too tight to get off without the use of a blowtorch which we didn't have to hand, we just unplugged it and did my best to avoid disturbing it
these sensor are very sensitive (mind the pun) but Yes, there is a very good chance you have damaged it as they are so delicate, even if you have got some dust or particles in it, it can cause loads of problems
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Ehhh :embarrassed: live and learn though ay! I'll get it scanned when I finish work tonight to double check, is it worth removing it myself and giving it a clean up with some WD40 and seeing if it makes a difference or is it more than likely going to be knackered? Thanks for all of the replies!
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Yeah scan it first, give it a quick clean (i cant 100% confirm WD40, but would think its ok), maybe use an air line / blower if you have one, if not may have to buy a new one.
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If you've knocked the Lambda sensor (which is what I suspect) you will need a replacement as it would be broken.
VCDS it first to be sure.
Mine came out with a spanner , it stuck in quite a way so no way of doing it without taking the Lambda out imo.
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I'll let you know what the scan shows and if the clean helps at all.
Jay, it does sit quite far in but you can get around it without having to knock the sensor, the hardest it will have been knocked is potentially with the back of my hand as I pulled some of the precat stuff out. Obviously it's not a good idea to leave it in but as usual being too keen to get the job done quickly has resulted in it needing to be done twice and potentially at some cost to myself haha :fighting:
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Lamda sensors are very delicate things and even over tightening them can cause them to break. They are sensitive to knocks and vibrations so there is a chance it has fractured the sensor on the inside. Hope you get it sorted soon :happy2:
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Unfortunately the scanner I used was pretty basic and just gave the codes 7E8:Engine & 7E9:A/T. Reset the codes and the car drove exactly the same, managed to get the lambda out and gave it a good clean (it was filthy). Car felt like it drove a bit better initially but soon reverted back to being seriously under powered and as it got hotter it got worse. I nursed it home and noticed a quite deep noise coming from the exhaust near the front. Absolutely clueless really but would it make sense that the lambda being broken and the codes being reset has caused the car to run rich and in turn clogged my cat? Pulling at straws here to be honest and think I will just get it into my local indy as soon as poss.
As always any help would be greatly appreciated.
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...same thing will have happened that happened to mine. The garage who performed the work forgot to remove the ceramic 'sleeve' inside the pre-cat, which following re-assembly, broke up and partially blocked the exhaust flow which in turn caused severe power loss and threw the CEL.
Time to take it back off and have another look in there!
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:signIWS: Didn't notice any ceramic sleeve so must've left it in there! I'll whip it off tonight and see what I find.
Note to self - Don't rush and work in the bloody dark :signLOL:
Cheers for the help everyone :grouphug: I'll let you know how I get on
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Mine was low on power, threw up code for boost control range not reached, changed the usual things, dv, n75 valve, checked for boost and vaccum leaks, all ok. I noticed there was a different smell from the exhaust and there wasn't as much pressure from the exhaust. I fitted a full milltek from turbo back and the car now goes like a rocket.
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Mine was low on power, threw up code for boost control range not reached, changed the usual things, dv, n75 valve, checked for boost and vaccum leaks, all ok. I noticed there was a different smell from the exhaust and there wasn't as much pressure from the exhaust. I fitted a full milltek from turbo back and the car now goes like a rocket.
Sounds like a knackered cat, the restriction in mine felt so bad this morning that I have opted to walk home from work tonight and not move the car till I can get it over a pit - scared of doing any harm to the turbo! I have a friend who has one but he is away till the weekend, don't much fancy trying to get it done on axle stands in the dark! :stupid:
I also know of a miltek decat downpipe going rather cheaply which is looking more and more tempting by the minute :signLOL:
Probably a long shot but if anyone knows of someone with ramps or a pit in East Sussex that fancies some money chucked there way and all the takeaway food they can shake a stick at let me know!
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:signIWS: Didn't notice any ceramic sleeve so must've left it in there! I'll whip it off tonight and see what I find.
Note to self - Don't rush and work in the bloody dark :signLOL:
Cheers for the help everyone :grouphug: I'll let you know how I get on
Neither did the garage that did mine :mad:
They took it all back off and removed what they could, but sadly the damage had been done and some of it had worked its' way down into the main cat. The power loss still remained slightly after they had removed what they could.
The solution in the end involved a Milltek turbo-back system with 200 cell cat :happy2:
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Yeah I am beginning to fear the worst! Might have to leave the car for the rest of this week and get a milltek downpipe on this weekend :laugh:
Only decided on doing the precat mod as it seemed simple and effective - what an ordeal it has turned into! My fault at the end of the day, should've been more careful and triple checked everything :stupid:
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Neither did the garage that did mine :mad:
They took it all back off and removed what they could, but sadly the damage had been done and some of it had worked its' way down into the main cat. The power loss still remained slightly after they had removed what they could.
The solution in the end involved a Milltek turbo-back system with 200 cell cat :happy2:
Out of interest how long did you drive yours for before they took it back off and removed it?
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Neither did the garage that did mine :mad:
They took it all back off and removed what they could, but sadly the damage had been done and some of it had worked its' way down into the main cat. The power loss still remained slightly after they had removed what they could.
The solution in the end involved a Milltek turbo-back system with 200 cell cat :happy2:
Out of interest how long did you drive yours for before they took it back off and removed it?
About a week... was hellish!
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About a week... was hellish!
That must've been horrific! I have done about 15 miles since it got bad on Sunday, might get lucky and the cat will be okay but I think a milltek downpipe is the only answer!