Megane 2004 fuel economy poor

[moonman5]

Hi
Can anyone throw any ideas at me? I have recently bought my daughter a Renault Megane 2004 1.4 dynamique.
She is very happy with the car but is a bit disapointed with the fuel economy, The dashboard display showing about 27 M.p.g?
The car is also very tempermental on start up requiring you to rev the engine slightly untill the engine settles?
Also somtimes the revs drop slightly to about 300/400 rpm, and then pick up to normal tickover again?
There is NO misfire, the car drives fine.
Are the two linked? poor economy and unstable tick-over at start up?

My 1.6 Vvt coupe cab showes betwwen 36.5 to 38 mpg a lot better and on a bigger (if slight) engine.

[STEVIE]

Hi mate ive got a 1.4 and its the same mpg its poor
me and a friend was going up the motorway him behind me in a megane 225 and me in my 1.4
he was getting and 10 more mpg than me
if anyone has any ideas i would like to hear them please

stevie

[AlexB]

There can be many reasons, including the type and length of journeys (the cold engine consumes twice as much), tyre make/pressures, etc.

Make sure the filters are good (air, fuel, oil), the oil is clean (change it every 9k or annually, use MB229.3/MB229.5) and clean the throttle body (usual problem). Then get ELM327 from ebay, read the ECU faults and record the operating parameters of the engine when warming up / driving (free version of ScanMaster program). It can be the temperature or O2 sensor.

I hope there is nothing else unusual, such as smoke, noise, warning lights, increased oil consumption, etc...

[moonman5]

Hi Alex b,

Thanks for your very informative reply,
There are no other problems with the car, does not burn oil, no mechanical noises (sounds sweet and very quite)
The car has just had a 35,000 mile service, tyre pressures are correct,
I have been reading posts (and as you said) about cleaning the throttle housing, this sounds promising!
My only concern is the oil spec the garage used when they serviced it, Iknow that this can affect the ecconomy.
It is a lovely car and my daughter loves it, just wish I,d have got a D.c.i!!
Thanks again

[moonman5]

Alex b,

Hi Again, Just curious about your comment on getting a ELM327, I have an auto enginuity scantool and another type of scantool (bought on E-bay) that never seem to be able to connect to both me and my daughters Renaults?

I never seem to have any luck with these am I doing something wrong? are they eobd compliant? can only renault connect thro the eobd port?

Thanks for any help.

[AlexB]

The oil quality mainly affects reliability, cleanliness and the length of service intervals. Switching from a mineral 10w40 to a full synthetic 0w30 MB229.3/MB229.5 will give about 2-3mpg improvement and additional 2-4bhp at the maximum revs. Not much.

There is a Technical Note describing how to clean the throttle body. I mentioned the TN number in one of my posts. Basically, you remove it, spray with carb cleaner, wipe with a special cloth and put it back. It is important to not spray the electrics and someone mentioned a plastic gasket which may be damaged. Technical Notes are included in the Dialogys system sold for a fiver on ebay. Repair manuals in French (PDF files) form the same Dialogys are pointed to in my message in Links. There you'll find the diagrams and torque values.

[AlexB]

I use ELM327 on my BM0G (1.9dci). The protocol is K-line (not CAN bus) ISO-14230, fast init sequence. The pin map of the connector is in the manual I mentioned before. It is pretty standard: ground, +12V, K-line, ignore everything else. ELM323 is the same, but does not support additional interfaces (CAN and American cars).

Are you sure that your computer recognises your scantool? There should be a driver installed and, if connected to the serial port, the latter must be enabled.

Alex b,

Hi Again, Just curious about your comment on getting a ELM327, I have an auto enginuity scantool and another type of scantool (bought on E-bay) that never seem to be able to connect to both me and my daughters Renaults?

I never seem to have any luck with these am I doing something wrong? are they eobd compliant? can only renault connect thro the eobd port?

Thanks for any help.

[AlexB]

EOBD port is standard and not encrypted -- this is required by law. There are several standard low-level protocols. ELM327 checks all and selects the one which is supported. In the other tools one may need to configure everything by hand.

[moonman5]

I am doing a 10 mile trip on small country A-roads driving between 30 to 60 M.p.h
Claned the throttle housing today, now showing 29 M.p.g, slightly better,

[Jonault]

On a long run my 1.4 returns just over 40mpg. Town driving with an average speed of around 19mph gives around 33mpg.
Check to see if your brakes are binding.

[Nige]

Personally i think the computer readouts on renaults are as accurate as a poor joiners measurements.....

Some work and some dont but my car says im only getting 27-35 to the gallon and still it returns a good 420 on a good stretch from full to red....

Watching them stupid things only depresses you....watch the speedo instead, its more fun!!!

[busternlouie]

Watching them stupid things only depresses you....watch the speedo instead, its more fun!!!

Ha ha yeah I know what you mean.
Just brimmed my tank and reset the trip... Cycled to MPG... Stuck in traffic, could see it dropping and dropping.
They're a waste of time until you have used your first gallon after resetting. Never seen mine over 24mpg after a run, and thats with the missus driving... with me its usually 19 - 20!!! Ouch!!

[Grrr]

Hey buds!

This thread is quite amusing for me for two reasons...

1. I came down from a 2.5L X-Type auto Jag that did about 22mpg at its best!!!
2. I think I have the most unreliable Megane ever and I have managed 36.6mpg in the 150 miles I have actually managed to drive in it (mix of motorway, but mostly town).

I hope the reliability issue will be sorted, and don't get too hung up over mpg... it is usually your style of driving rather than a car fault I've found over the years, and people who quote the high mpg figures tend to do a lot more distance driving than town driving.

Not to draw too many comparisons, but it's a bit like the Superfat vs Superskinny program... the fat one thinks they don't eat a lot but the skinny one thinks they eat too much!

I will err away from making any comments about the sex of the driver LOL
SERIOUSLY I WAS ONLY JOKING GIRLS!!