Fuel Economy

[Odie]

What kinda Fuel economy do people you guys get out of your 5's?

My 1.6 mk2.5 is about 20-25mpg was just wondering if that was about right or if i needed to check into stuff further (lambda sensor etc)

[Dan_1981]

I've recently started using a fuel app on the iphone and my last few fills up have revealed the following:

12/4: 27.66 mpg
21/4: 32.67
23/4: 32.67
25/4: 30.93
03/5: 29.97
09/5: 32.57
17/5: 31.38

Its a 1.8 mk1.

Majority of journeys are the commute to work which is about 25 miles each way all motorway. Done at peak hours in the morning, so i'm usually limited to around 70 MPH, and the journey home is done outside peak hours - which means I can pick my own speed.

[Odie]

Dan whats the app called that you use? I think I shall do the same.

[JonnyFive]

Odie said:

Dan whats the app called that you use? I think I shall do the same.

Probably "RoadTrip Lite".. Pretty good, if you remember to put in the information

Mine is around 30mpg average I'd say.

[Dan_1981]

Yup road trip lite.

Its free and works well if you're only monitoring one car.

You just have to remember to put the info in!

[snotrag]

I've been using roadtrip lite for a few months now, also on a Mk1 1.8 and have got similar results to Dan.

Interesting point of note was a noted improvement in economy after an oil and filter change a few weeks ago. I'll screen shot it if I can and post up.

[durbster]

That does sound low - even when I had a fuel leak I could still get 30mpg (1991 1.6)!

I check every tank 'cos I love stats. I consistently get 37-38mpg on a long run.

On a typical commute (a 40 minute mixture of dual-carriageway and queuing) I usually get around 32, although the last tank I got 35mpg! That's probably because, due to the aforementioned fuel leak, I've got into the habit of changing 3k revs instead of the usual 4k+.

[Dan_1981]

Likewise - one week two of my stats above - I was driving carefully with a coolant leak.

Shifting at lower revs and keeping to lower speeds.

To be honest - the decrease in consumption was not comparable with the decrease in smiles.

[Rocketman105]

That app is perfect for car geeks who love geeky car facts I'm on 26.8mpg average at the moment...

Had it running on my previous car and it showed a marked difference in economy when I was driving compared to my wife!

[MX-5 Lazza]

I get around 25mpg from mine. I've very happy with that considering the mods (and I do like to use the power when I can )!

To the OP I'd suggest that maybe the ecu engine temp sensor needs replacing

[Odie]

MX-5 Lazza said:

I get around 25mpg from mine. I've very happy with that considering the mods (and I do like to use the power when I can )!

To the OP I'd suggest that maybe the ecu engine temp sensor needs replacing

is that also linked to the temp gauge on the dash? as the temp gauge on the dash sometimes shoots up for no reason (ie the engine isnt overheating)

Edited by Odie on Wednesday 18th May 12:10

[Riknos]

28.61 and 30.44 on my last two fill ups, using the Road Trip LE app.

It will be interesting putting my next fill up through it, as I had a track session on this tank

[Odie]

Is it worth getting a fault code reader? will the temp sensor show up as faulty on it?

ive got no warning lights showing on my dash (ie engine warning lights etc)

[MX-5 Lazza]

Odie said:

is that also linked to the temp gauge on the dash? as the temp gauge on the dash sometimes shoots up for no reason (ie the engine isnt overheating)

Edited by Odie on Wednesday 18th May 12:10

I don't think so though it might be. I know there are more than one of them.

Odie said:

Is it worth getting a fault code reader? will the temp sensor show up as faulty on it?

ive got no warning lights showing on my dash (ie engine warning lights etc)

I don't think the Mk1 ecu is clever enough to sense a faulty coolant temp sensor.

[Odie]

MX-5 Lazza said:

I don't think the Mk1 ecu is clever enough to sense a faulty coolant temp sensor.

Mines a mk2.5

[MX-5 Lazza]

Odie said:

MX-5 Lazza said:

I don't think the Mk1 ecu is clever enough to sense a faulty coolant temp sensor.

Mines a mk2.5

So it is! I saw 1.6 and just assumed Mk1

In that case yes, you have OBDII so you can get a lot of ecu information with a code reader. I used to have one, I think it was about £35 from eBay.

I have no idea if the coolant temp sensor issue is applicable to later cars but I see no reason why it wouldn't be. With the code reader you should be able to see the coolant temp so you should be able to use it to identify a fault. It would also say if there was another fault somewhere such as a vacuum leak or faulty MAF/O2 sensor (though I'd expect those to bring up a CEL).

[snotrag]

Does nobody use a multimeter anymore!?

A temp sensor should be pretty easy to diagnose, I'm pretty sure some resistance figures and in Rods manual to check against.

[Pints]

1.8 mk3

Miles Driven	Litres	Actual MPG
394.0	46.32	38.7
208.6	22.03	43.0
335.3	38.95	39.1
319.3	37.83	38.4
323.0	37.54	39.1
321.7	40.64	36.0
322.5	40.19	36.5
320.5	38.92	37.4
394.1	45.95	39.0
323.6	41.29	35.6
322.4	39.94	36.7
320.2	38.75	37.6
320.6	38.88	37.5
319.6	39.09	37.2
320.6	38.64	37.7
317.8	37.68	38.3
318.0	39.53	36.6
321.8	39.90	36.7
397.1	43.67	41.3
309.6	39.50	35.6
402.0	44.55	41.0
345.2	43.66	35.9
405.7	46.57	39.6
318.9	36.84	39.4
317.4	36.04	40.0
324.3	37.04	39.8

[Odie]

Pints said:

1.8 mk3

Miles Driven	Litres	Actual MPG
394.0	46.32	38.7
208.6	22.03	43.0
335.3	38.95	39.1
319.3	37.83	38.4
323.0	37.54	39.1
321.7	40.64	36.0
322.5	40.19	36.5
320.5	38.92	37.4
394.1	45.95	39.0
323.6	41.29	35.6
322.4	39.94	36.7
320.2	38.75	37.6
320.6	38.88	37.5
319.6	39.09	37.2
320.6	38.64	37.7
317.8	37.68	38.3
318.0	39.53	36.6
321.8	39.90	36.7
397.1	43.67	41.3
309.6	39.50	35.6
402.0	44.55	41.0
345.2	43.66	35.9
405.7	46.57	39.6
318.9	36.84	39.4
317.4	36.04	40.0
324.3	37.04	39.8

That is some seriously good MPG figures for a sports car

[Odie]

MX-5 Lazza said:

So it is! I saw 1.6 and just assumed Mk1

In that case yes, you have OBDII so you can get a lot of ecu information with a code reader. I used to have one, I think it was about £35 from eBay.

I have no idea if the coolant temp sensor issue is applicable to later cars but I see no reason why it wouldn't be. With the code reader you should be able to see the coolant temp so you should be able to use it to identify a fault. It would also say if there was another fault somewhere such as a vacuum leak or faulty MAF/O2 sensor (though I'd expect those to bring up a CEL).

yeah been looking at code readers (u480) they are about £15-£20 these days so I think I will order one, they work with alot of cars as well so would just be handy in the future.