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fuel use issues http://www.gt4dc.co.uk/forum/viewtopic.php?f=2&t=7817 |
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Author: | ray405 [ Tue Mar 06, 2018 8:56 pm ] |
Post subject: | fuel use issues |
wondered if anyone could give some advise on a problem I've notice recently basically I think my car maybe using to much fuel, I usually get around 40 mile to £10 fuel/quarter of a tank (driven sensibly with no high speed boosting) but lately the car (seems) to be doing less I always use the mileage at ive found this to be more accurate than the needle (another issue) the car has run out of petrol twice! having filled the car up with set amounts of fuel, usually £80 and allowing for low level light, the car (seems) to be coming up around 20 mile short! which is a huge difference few points, the car does get serviced regular, but its due a fuel filter on the next service could this be enough to affect this? it has had a new fuel pump plus sender so there (shouldn't be an issue there) so id be grateful if anyone could shed some light on this on another note, we all know the fuel gauge isn't great on a gt4, but what actually controls it is it the sender in the tank, or is it to do with the actual dash needle too |
Author: | ray405 [ Fri Mar 09, 2018 3:38 pm ] |
Post subject: | Re: fuel use issues |
any thoughts at all?? |
Author: | бешаный 202 [ Fri Mar 09, 2018 7:05 pm ] |
Post subject: | Re: fuel use issues |
temperature sensor Oxygen Sensor |
Author: | Nibbles [ Fri Mar 09, 2018 8:53 pm ] |
Post subject: | Re: fuel use issues |
There are a number of things that affect ecconomy, one clue is whether the ecconomy dropped after having work done on the car. Ignition timing - sometimes timing gets set at 10 degrees without the diagnostics link in place leaving thetiming retarded by 5-10 degrees. Unlikely to change on it's own unless the distributer is loose. Some ECU error codes also result in 'safe mode' retarding timing. Fuel mixture - Poor ecconomy would usually mean too rich, unless it's so massively lean it's misfiring. Fuel filter would only make the mixture weaker so unlikely. Rich mixture would usually be a failing lambda (O2) sensor, but could also be a faulty engine temperature sensor (ECU one is separate to the gauge one) or a leak in the exhaust system between engine and sensor. If the new fuel pump is a high capacity aftermarket one, this will raise the fuel rail pressure slightly which will richen the mixture. A few other possibilities: Broken up cat or silencer baffles restricting the exhaust. Vac pipe from manifold to fuel pressure regulator blocked / cracked / come off. Vac pipe from manifold to turbo pressure senor (MAP sensor) blocked / cracked / come off. If it's a 185 or 165 then splits / leaks in any of the intake pipework will cause mixture errors. |
Author: | coldel [ Sat Mar 10, 2018 11:19 am ] |
Post subject: | Re: fuel use issues |
Pumped your tyres up after the cold spell?! |
Author: | ray405 [ Sat Mar 10, 2018 7:01 pm ] |
Post subject: | Re: fuel use issues |
thanks for al the reply's I will try and address a few of your questions O2 sensor is less than a year old, so it shouldn't be a issue now with regards to the temperature sensor, not 100% sure as to what one you mean exactly but im waiting to change the Rad temperature switch, having had a read about and (believe) this can cause issues?? but surely not enough make the fuelling bad?? ive had no recent work on the car, so I assume that nothing would have changer there except for the Rad switch the can is 100% having a look around the engine bay, there are no obvious loose pipework, also all of the original hoses have been replace, so shouldn't be a breaking/perishing issue no cat on car, has been like this for years with no issues at all ive yet to run a errorcode check, so should probably be first port of call |
Author: | Nibbles [ Sat Mar 10, 2018 7:28 pm ] |
Post subject: | Re: fuel use issues |
Error code check is quick & easy, though normally the light is on if there are current issues. The rad switch just controls the fans,so unless fans are running full time or not running at all I don't see any benefit to changing it. The water elbow on the side of the head is where the main temperature sensors are located. The one with a single connection drives the gauge and the the one with 2 wires is for the ECU. If the ECU thinks the engine is cold, it will inject more fuel (also a point - is the engine reaching full temperature in a reasonable time ? Could be thermostat sticking and not shutting fully) If you do a lot of short runs, then at this time of year the engine will spend much longer cold |
Author: | ray405 [ Sat Mar 10, 2018 7:38 pm ] |
Post subject: | Re: fuel use issues |
thanks, fan switch does need doing as the rads don't run at all no stored error codes newish thermostat, car does gets to temperature as normal thanks for the location of the water sensor, no way of checking I suppose don't have a multi meter but could borrow on, if instructed on what to check for yes currently the car is doing short runs, but as mentioned, it does get up to normal temps reasonably quickly |
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