ddcboyle Posted November 27, 2012 Share Posted November 27, 2012 My exhaust has split where the mid pipe meets the back box, and now it seems like my fuel lasts 5minutes, will the broken pipe effect my mpg? Quote Link to comment Share on other sites More sharing options...
Dblock Posted November 27, 2012 Share Posted November 27, 2012 Yes. Quote Link to comment Share on other sites More sharing options...
Neilp Posted November 27, 2012 Share Posted November 27, 2012 Yes. Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted November 27, 2012 Author Share Posted November 27, 2012 Thanks, anyone mechanically minded able to explain how? I am braindead when it comes to how engines work Quote Link to comment Share on other sites More sharing options...
Neilp Posted November 27, 2012 Share Posted November 27, 2012 http://forums.moneysavingexpert.com/showthread.php?t=836505 Quote Link to comment Share on other sites More sharing options...
Ekona Posted November 27, 2012 Share Posted November 27, 2012 I'd have said otherwise, I must admit. Yes, it will effect the gasflow, but we are talking fractions here and certainly no more than would change if you fitted a freer-flowing exhaust that was backbox-less (like the K1), and we all know the Zed ECU will adapt to stop any power increases. Any difference a broken midpipe to backbox would make to the MPG of the car is negligable, IMHO. Quote Link to comment Share on other sites More sharing options...
Neilp Posted November 27, 2012 Share Posted November 27, 2012 Its to do with the pull in the exhaust though. Same as a boiler. The pull has to be there to remove the combustion gases or the A/F ratios go to pot. The lamda sensors will pick this up and adjust fuelling. Its all down to where its leaking from which will affect the severity. I'd agree with you Dan that it would be minor. Quote Link to comment Share on other sites More sharing options...
StevoD Posted November 27, 2012 Share Posted November 27, 2012 (edited) Would agree with Ekona the only way according to all information received whilst training with VW is that the ECU regarding regular running will put the right fuel to air ratio as set so if no extra air is going in the Ecu wont order up any extra fuel, the most plausible reason would be it might have affect performance and thus making you accelerate harder or the noise is to Addictive and your subconsciously going flat out more often. And if the bore and exhuast valve are the same size the whole way threw it shouldnt effect it either Edited November 27, 2012 by StevoD Quote Link to comment Share on other sites More sharing options...
Neilp Posted November 27, 2012 Share Posted November 27, 2012 Would agree with Ekona the only way according to all information received whilst training with VW is that the ECU regarding regular running will put the right fuel to air ratio as set so if no extra air is going in the Ecu wont order up any extra fuel, the most plausible reason would be it might have affect performance and thus making you accelerate harder or the noise is to Addictive and your subconsciously going flat out more often. And if the bore and exhuast valve are the same size the whole way threw it shouldnt effect it either The AFR will alter depending on the lamda reading though. If the gases arent exhausting quick enough the ratio will change in the exhaust. Quote Link to comment Share on other sites More sharing options...
StevoD Posted November 27, 2012 Share Posted November 27, 2012 Agreed but any change after both lambda probes in theory wont effect it, agreed if there is a crack between block and bank 1 or bank 2 secondary probes it will add fuel as it will think its running lean but a snap between midbox and rear box wouldn't effect the air at the probes Because air traveling at X speed will still be traveling at X speed if the pipe is 4ft long or 5 ft long granted if it was 15ft long and went down to 5ft id expect a difference but not over the space of 1-2ft worth of pipe Quote Link to comment Share on other sites More sharing options...
Dblock Posted November 27, 2012 Share Posted November 27, 2012 Alot or a little if I had poor MPG this would be my first fix, then lambda and so on. Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted November 28, 2012 Author Share Posted November 28, 2012 My trip computer is still reading normal 31mpg on motorway, just fuel is lasting 140miles when it should work out as 260 Quote Link to comment Share on other sites More sharing options...
StevoD Posted November 28, 2012 Share Posted November 28, 2012 hmm change of petrol station/supplier? starting early in the morning now its colder? Not carrying any extra goods in the boot? still not sure any of them or an exhaust would lose nearly 50% mpg Quote Link to comment Share on other sites More sharing options...
Stew Posted November 28, 2012 Share Posted November 28, 2012 Yes. Mainly because it probably sounds better so you are revving more..... 1 Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted November 28, 2012 Author Share Posted November 28, 2012 Just had a thoughtafter you mentioned revving more... Due to exhaust having a crack, that means id be losing a bit of power? So i presumably would be revving more to drive it normally? Not sure. I couldnt see a change of petrol supplier changing it more, and presumably the trip computer would realise i had more weight in the car if i has bags in there? Quote Link to comment Share on other sites More sharing options...
Ekona Posted November 28, 2012 Share Posted November 28, 2012 You could be gaining power more than anything, but don't forget the ECU adapts so it will cancel itself out. That's an awfully big discrepency in your miles to a tank. How many litres are you getting into the tank when filling up? And is your MPG calculation based on what the car is telling you or what you've worked out yourself? Quote Link to comment Share on other sites More sharing options...
glrnet Posted November 28, 2012 Share Posted November 28, 2012 You could also have dirty fuel tank gauge sender/s. Mine is out by 100 miles or so to tank full so I fitted a scangauge II, that's bang on Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted November 28, 2012 Author Share Posted November 28, 2012 i just mpg on my trip computer, id have no idea if it was a sensor or not. ive not topped it up fully for a while, but 50 gets me near half way up fuel gauge Quote Link to comment Share on other sites More sharing options...
Dblock Posted November 28, 2012 Share Posted November 28, 2012 Sounds about right Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted November 28, 2012 Author Share Posted November 28, 2012 hmm, once i get exhaust fixed, ill drive it a week, see if theres any difference then post if it was exhaust Quote Link to comment Share on other sites More sharing options...
ddcboyle Posted December 6, 2012 Author Share Posted December 6, 2012 Answer is, broken exhaust does rffect mpg. Changed exhaust and getting better mpg. The trip computer was lying when it said 26mpg, as now it says 26 and actually lasts. New exhaust (2nd hand oem) sounds more of muscle car engine but getting my bhp back so im happy Quote Link to comment Share on other sites More sharing options...
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