GolfGTIforum.co.uk
Model specific boards => Golf mk4 => Topic started by: D1andonlyantman on 05 November 2013, 05:59
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Hi. I recently bought a gti 180. Not in bad nick but it has an exhaust warning light on. A mechanic friend of mine had a look and said something has broken off of the cat and that's why it's showing the warning light (I can't remember exactly what he said). I wanted to get a catback exhaust anyway but he said because of the dodgy cat I should replace the whole system. The bit I'm not quite sure about is if I should be looking for a whole system or if I buy new headers/downpipes and the catback part to complete it? I had a look on eBay and there were hardly any full systems so I thought I might be looking for the wrong thing
Thanks
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Also if I do decide to change the whole exhaust system would I need to adjust the fuelling? I know it would be ideal to adjust it to get maximum power but would I NEED to or do cars have the right sensors to adjust it automatically?
Thanks again
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The big question is do you have a 'friendly' mot centre that would turn a blind eye to the emissions? If you fit a decat you might also have issues with the engine management light coming on due to the decat.
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To be honest I don't even necessarily want a decat exhaust, I'm just pretty sure my car is down on power and it's probably because of the exhaust I reckon, so I basically just want to ditch my standard exhaust for one that isn't gonna throw error codes or cause power loss. I know a faulty MAF can cause problems so I replaced that which fixed my TC which wasn't working but didn't help performance. Basically half way through 4th at around 125 the car has no pull anymore and I'd need a runway to get anywhere near top speed. Other than for economy 5th and 6th are useless at the moment
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Basically half way through 4th at around 125 the car has no pull anymore and I'd need a runway to get anywhere near top speed. Other than for economy 5th and 6th are useless at the moment
:grin: Make sure your oil pump is working good.
Out of curiosity, is it a standard 180 you have?
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Yeh standard 180. It still has some revs to go in 4th so I'm not just beating the sh!t out of the engine hoping for too much power. If I change to 5th there's even less. I probably will mod the car more for performance further down the line but right now I'm just trying to get it running how i think it would have out of the factory and I can't see it being like this to be honest, especially because of the exhaust warning light
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Yeh standard 180. It still has some revs to go in 4th so I'm not just beating the sh!t out of the engine hoping for too much power. If I change to 5th there's even less. I probably will mod the car more for performance further down the line but right now I'm just trying to get it running how i think it would have out of the factory and I can't see it being like this to be honest, especially because of the exhaust warning light
Reason I ask is, 125 in 4th (4kish revs) doesn't sound right to me (standard anyway).
I have a AUQ, and usually, sits around 80mph @ 4k revs in 4th gear if I can recall. :grin:
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Is the oil pump part of the water pump on these and if not, are they known for failing?
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Is the oil pump part of the water pump on these and if not, are they known for failing?
Seprate pumps. You can take the sump off and clean the pick up pipe. Assuming the oil pump is in good nick.
Personally, if your not sure of the history of whats been changed i.e. the oil pump, I would refrain from doing 125 in 4th :grin: for the time being until you get the pressure checked or even have it replaced.
I got my timing belt and water pump done last week. Oil pump and pick up pipe is at the end of this month. Once I have done this, hopefully my worries of planting my foot will be long gone.
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Is the oil pump part of the water pump on these and if not, are they known for failing?
no its not part of the water pump and you would already know if your oil pump was not working right so i wouldnt worry about it :smiley:
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Ok thanks. Bringing it back on topic, the easy of putting this is saying I cannot get my car to redline in 4th. Is that normal? I realise peak hp where I'd want to change gear is probably a little bit before redline but shouldn't I be able to hit the limiter?
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Yes you should be able to hit the limiter which iirc is around 200 revs above red line?
sounds to me like somethings wrong because red line in 4th gear is proberbly just over 100mph max. (at a guess, i dont have a race track so never go over 70mph on public roads :grin: )
if your sat in 4th doing 30mph how many revs are you on? could be something like wrong abs rings have been fitted this can make the car think its going faster/slower than it is.
unsure why you cant get above certain revs. could be that it is in limp mode and stoping you revving high to stop any damage to the engine?
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Thread tidied up, lets try and keep it on topic :rolleyes:
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I just went for a little test run and at 5000rpm in 4th was indicating 120. Had a gps app I use on my iPhone on the go too and that gave indicated 114. I'd say my speedo is fine. I had to let off because I was on an old abandoned strip I know and it's scary doing them sorts of speeds at night so I couldnt see where it just stopped climbing. I guess I may as well buy a decat downpipe and catback exhaust and then see what's what. Can't do any harm I guess
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1200rpm in 4th was bang on 30mph just in case you cared. Remembered to look on the way home from work
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Was the bit that broke off the exhaust the lambda sensor? If it was it would explain the warning light and probably put the car into limp mode
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Yeah it could be. My mate said something has been welded and that could have been to bodge the broken sensor. Although I'd like to think it's running in limp mode, the 0-60 is pretty quick, probably around the 7 second mark like it should be, so I'm not sure it is. I've seen a downpipe with a sports cat I'm thinking about buying, do you think that would possibly sort the problem? It's not a milltek one that requires the milltek catback, just a replacement downpipe with sports cat.
Thanks
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Depends which lambda/O2 sensor has come off. If its the first one, it's a wide band sensor on your engine and used to correct fuelling, which would explain why your car isn't running right in 4th 5th and 6th. The second one is just a step sensor to check the cat function. Hopefully it's just the boss that's come off and the sensor is ok as they ain't cheap! If that's the case then a new cat and downpipe would fix it.
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Would that do the job then?
http://www.ebay.co.uk/itm/AUDI-A3-1-8T-20v-STAINLESS-STEEL-200-CPI-SPORTS-CAT-PIPE-EXHAUST-DOWNPIPE-/221140776269?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AGolf%7CPlat_Gen%3AMK+IV&hash=item337d04754d
Says it's a straight swap for the original so should sort it out??
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It's hard to say with 1.8t's but yeah, if it's the lambda sensor boss that's snapped off then fitting that cat & downpipe will fix it, as long as you refit the lambda sensor.
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You'll have to bare with me because I'm not really a car man, but I do have some idea what you're on about. So what you're saying is if the place where the lambda sensor attaches is broken on this exhaust which is why it's giving the error, I should be able to buy the new downpipe which will have the boss to fit the lambda sensor and it will hopefully be all good?
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best taking the car to some1 that knows what they are doing or you could just be spending money on stuff not needed :smiley:
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Well my friend did say I should buy a decat exhaust to sort it so I guess by that he meant i should replace the downpipe, but I'd rather go sports cat than decat so I don't have the mess about with iffy MOTs. He's a hard fella to get hold of but it might be worth harassing him until I get an answer out of him I reckon :)
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See if you can get hold of your mate and confirm what's gone wrong. Failing that get your head under the bonnet and get familiar with your engine. There's loads of info available on here! It can save you quite a bit of cash just being able to replace simple stuff yourself. I love 1.8t's so my car is more of a hobby than something just to get me from a to b. plus being a mechanic helps, even though I'm more used to working on 26 liter v12 Diesel engines!
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Oh I like to get stuck in. I've got a modded zx6r and done almost all the work on that myself. Cars aren't quite so easy to fiddle with though without a ramp. What I can do myself I will, that's for sure. I'm taking it to a garage today to get it up on the ramp so I can take a decent look myself and see exactly what's going on and then decide what I'm going to do whether it's sports cat or decat. Apparently decat is much better than sports cat but which way I decide to go will really come down to the cost of switching back for my MOT every year. The decat is 140 quid cheaper so I'll take everything into account.... Cheers for the help though, I'm looking forward to doing more and learning more :)
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Right, just got back from the garage. One of the 4 bolts for the downpipe has snapped, hopefully it is a bolt and not a stud, and the downpipe itself has been welded for some reason and definitely wants replacing. The lambda sensor is there still so I'm not sure why there's even a error but I don't know a lot yet so that isn't surprising lol I took a couple of pics, hopefully you guys can take a look and tell me everything's gonna be alright ;)
(http://i176.photobucket.com/albums/w162/d1andonlyantman/null_zps7e26e15e.jpg)
(http://i176.photobucket.com/albums/w162/d1andonlyantman/null_zps692f7492.jpg)
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Is the downpipe blowing a lot where the stud is snapped?
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Ah, so it is a stud.... Bollox. Wasn't running when I was down there so couldn't say. Snapped stud isn't good though obviously. Damn
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Right, update. Got a more reliable friend to check the code today. It's 17704. Error in mapped cooling system. Check temperature sensor and thermostat. Funnily enough I've already made a thread saying how my car doesnt get up to proper operating temperature and the heaters don't blow out hot air, so this is obviously all linked. Apparently these sensors being dud can make the car run like crap and maybe that's why my performance is a bit lame. Already have the thermostat on order because of the heaters not working so with any luck that will sort it all out. No harm in hoping, ay :-)