Ian C Posted October 26, 2006 Share Posted October 26, 2006 For the last two tankfuls, every time I've taken the car out it's been raining. When it rains, I switch the blower to feet & windscreen, fan position 1, and aircon on. Stops everything misting up. And for the last two tankfuls I've experienced a noticeable drop in fuel economy. For a while I thought something was up but could it really just be my constant use of aircon? With the driving style I've been using I should see about 180miles by half a tank and I'm getting 150... Thoughts please -Ian Link to comment Share on other sites More sharing options...
garetheves Posted October 26, 2006 Share Posted October 26, 2006 It will be the air con im fairly sure of it. Have you heard the difference it makes to the idle rev when you switch it on and off?? Link to comment Share on other sites More sharing options...
Ian W Posted October 26, 2006 Share Posted October 26, 2006 180 miles for half a tank? that's damn good, or is yours a UK spec Ian? it could well be the use of the air con i suppose although i have to admit i don't usually see a huge drop when i use mine (although admittedly it's in short bursts rather than constant usage). Link to comment Share on other sites More sharing options...
Gaz6002 Posted October 26, 2006 Share Posted October 26, 2006 switching my aircon on at idle raises the rpm by approx 200 - and i get a noticeable drop in performance. Doesn't seem the most efficient system TBH but it does do the job! I also drop around 40 miles per tank so maybe this is the norm? Link to comment Share on other sites More sharing options...
spaxy Posted October 26, 2006 Share Posted October 26, 2006 10% fuel efficiency drop they say mate,ive noticed it as well. Link to comment Share on other sites More sharing options...
Gaz6002 Posted October 26, 2006 Share Posted October 26, 2006 10% fuel efficiency drop they say mate,ive noticed it as well. (sorry,couldn't resist) Link to comment Share on other sites More sharing options...
DamanC Posted October 26, 2006 Share Posted October 26, 2006 Link to comment Share on other sites More sharing options...
Alex Posted October 26, 2006 Share Posted October 26, 2006 180 miles for half a tank? that's damn good, or is yours a UK spec Ian? J-spec T67 - big turbo's driven at normal speeds = better MPG because there is no turbo down low...+ the manifold and turbo have a better VE than the stock system. Link to comment Share on other sites More sharing options...
garetheves Posted October 26, 2006 Share Posted October 26, 2006 J-spec T67 - big turbo's driven at normal speeds = better MPG because there is no turbo down low...+ the manifold and turbo have a better VE than the stock system. Mine must be seriously overfueling then. I only get 200 miles to a full tank driving very economically...without air con on. Link to comment Share on other sites More sharing options...
Alex Posted October 26, 2006 Share Posted October 26, 2006 Junk the SAFC and get an EMU mapped Mine must be seriously overfueling then. I only get 200 miles to a full tank driving very economically...without air con on. Link to comment Share on other sites More sharing options...
Ian W Posted October 26, 2006 Share Posted October 26, 2006 J-spec T67 - big turbo's driven at normal speeds = better MPG because there is no turbo down low...+ the manifold and turbo have a better VE than the stock system. mine is an n/a and i'm lucky to see 150 to half a tank i think a new O2 sensor is in order Link to comment Share on other sites More sharing options...
garetheves Posted October 26, 2006 Share Posted October 26, 2006 Junk the SAFC and get an EMU mapped Its on the shopping list for prob next summer. Will it really make that much of a difference (Sorry for the thread hijack). Link to comment Share on other sites More sharing options...
Alex Posted October 26, 2006 Share Posted October 26, 2006 mine is an n/a and i'm lucky to see 150 to half a tank i think a new O2 sensor is in order NA = high compression... A big single set up will will do about 27mpg on cruise. Link to comment Share on other sites More sharing options...
Ian W Posted October 26, 2006 Share Posted October 26, 2006 NA = high compression... A big single set up will will do about 27mpg on cruise. god dammit Link to comment Share on other sites More sharing options...
imi Posted October 26, 2006 Share Posted October 26, 2006 Junk the SAFC and get an EMU mapped I easily get 260-270 miles to the tank, 70% London City driving The rest is either motorway or the occational blast. And I do have an Apexi SAFC. Link to comment Share on other sites More sharing options...
Alex Posted October 26, 2006 Share Posted October 26, 2006 I easily get 260-270 miles to the tank, 70% London City driving The rest is either motorway or the occational blast. And I do have an Apexi SAFC. But are you on larger injectors and a single turbo? Link to comment Share on other sites More sharing options...
Gazboy Posted October 26, 2006 Share Posted October 26, 2006 I've not really noticed- but most of my commute is on the motorway, I guess if you are doing a lot of stop-start or waiting at lights then it'll be worse as the idle rises by 200rpm. Link to comment Share on other sites More sharing options...
Ian C Posted October 26, 2006 Author Share Posted October 26, 2006 Er, right, wow, this got busy while I was away OK so it looks like my use of the aircon is what's doing it. That's cool as the only other option was a fuel leak as I know it's not running too rich under acceleration or cruise (AFR gauge for the win). Yep, turning the aircon on raises the idle. It also drops again when the compressor disengages - it doesn't actually constantly run it, I think it's off for about half the time it's on. I had the aircon on, the lights on, the rear demister, and it was running the cold start cycle, I didn't use the accelerator for half a mile the revs were that high Oh, and the aircon compressor is declutched if you go wide open throttle so it shouldn't affect performance under those conditions It's a J-spec tank, so 70 litres. I've squeaked 300 miles out of a tank, but the needle was on the last line (about 7 litres left) and my retina was burnt from the orange warning light. That was a good steady motorway cruise at 90mph as well, with some boostage. As Alex said, the VE of these engines goes up by about 3mpg when you junk the stock hotside bits and replace them with a big turbo and tubular manifold. You could use that to sell the conversion to your other half you know. -Ian Link to comment Share on other sites More sharing options...
RobSheffield Posted October 26, 2006 Share Posted October 26, 2006 You could use that to sell the conversion to your other half you know. You are a friendly and helpful person Can the same thinking be used to convince a bank manager Link to comment Share on other sites More sharing options...
Matt _Aero top_ Posted October 26, 2006 Share Posted October 26, 2006 So to cut a long story short what kind of mileage should i expect out of my N/A auto from a full tank ? Link to comment Share on other sites More sharing options...
Nic Posted October 26, 2006 Share Posted October 26, 2006 I can't survive without aircon most of the year Link to comment Share on other sites More sharing options...
Digsy Posted October 26, 2006 Share Posted October 26, 2006 I can knock 5mpg off my average by using aircon constantly. Ian, its about time you started getting shitty mileage like the rest of us Link to comment Share on other sites More sharing options...
lockys96 Posted October 26, 2006 Share Posted October 26, 2006 u should count yourself lucky to get 150 from half a tank. mind you, i prob use my turbo timer too much Link to comment Share on other sites More sharing options...
Animal Posted October 27, 2006 Share Posted October 27, 2006 My N/A will get anything between 260 - 300 miles on a full tank and the needle can get to the bottom line of the 'E' before there's nowt left in the tank... Link to comment Share on other sites More sharing options...
V Posted October 27, 2006 Share Posted October 27, 2006 I get 300 miles + 90% of the time Link to comment Share on other sites More sharing options...
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