Low fuel mileage 1993 E10 1.3L 4EFE

[jayn5]

Hi all!

I get around 300 miles to a full 50L tank, I'm in the UK and I use Shell's E5 petrol. I've used RedEx and injector cleaners in this a few times but it hasn't helped. 

I do a mix of mainly motorway driving (constant 60mph) and a little bit of city driving. The owners manual says it should get about 36mpg in city driving and 53 mpg on motorway driving at 56mph.

What could be causing this? There's no fuel leaks I can smell (I had a Mazda 626 that just stank of fuel due to leaks) and I don't have a heavy right foot.

The only mods I have are a custom backbox and a cone filter on the stock tubing (so it has the pcv valve tubing)

Any ideas what's causing this?...

 

 

[APS]

It's not disastrous consumption, but sure is higher than you'd expect from that engine.

What have you checked so far?

• Tyre pressures
• Brakes (dragging)
• Wheel alignment
• clogged air filter (you can clean that cone filter)
• Check spark plugs (are they old? what do they look like?)
• Ignition timing?
• Remove injectors and clean them manually (or get someone to do it for you)
• Check engine compression (is it low and varies a lot between cylinders?)
• too much oil in the engine?
• too thick oil?

Also, how does it handle cold starts? Does it hold a fast idle that settles when it gets warm?

Very nice looking car by the way!

[jayn5]

6 minutes ago, APS said:

It's not disastrous consumption, but sure is higher than you'd expect from that engine.

What have you checked so far?

• Tyre pressures
• Brakes (dragging)
• Wheel alignment
• clogged air filter (you can clean that cone filter)
• Check spark plugs (are they old? what do they look like?)
• Ignition timing?
• Remove injectors and clean them manually (or get someone to do it for you)
• Check engine compression (is it low and varies a lot between cylinders?)
• too much oil in the engine?
• too thick oil?

Also, how does it handle cold starts? Does it hold a fast idle that settles when it gets warm?

Very nice looking car by the way!

Tyre pressures are at 36psi on each wheel, my front left leaks due to a crack in the alloy but it's a very slow leak which I top up regularly (and will get fixed soon!)

The spark plugs are new NGK plugs just done about 2000 miles ago, the old ones were a dusty grey color meaning it was more than likely running a bit lean.

I changed the oil (same time as spark plugs) about 2000 miles ago with magnatec 5w-30

It's due it's MOT this month so I'll get the garage to check its compression and timing while they're there. I have a hunch the N/S/F caliper is dragging slightly as I can hear it when I first drive it in the morning. It does have a high idle when cold, about 1.8k dropping to 1.3k then to about 1k when warm.

Thank you! It's my daily and I've been slowly doing it up over the past few months. Always been a hit at classic shows! 😁

[APS]

It certainly looks very clean.

 

Reg the spark plugs, these could easily foul up in a few hundred miles or less if it's running rich. I'd check them again.

You could have a problem with the O2 sensor or engine temperature sensor. Either of these could cause high fuel consumption. But, judging by your description of cold start behaviour, it sounds normal. You could still check for any error codes in the ECU which may give a hint. 

https://troubleshootmyvehicle.com/toyota/1.6L/how-to-retrieve-trouble-codes-1

(The above is for the 1.6 engine but I believe the procedure is the same for the 1.3

 

[oldcodger]

Might be worth waiting for the MOT emissions report  and see if thats showing a rich mixture / excess outputs.

Does the problem coincide with changing the air filters ?  have you tried replacing the stock ?

The  initial brake drag sounds more like the pads cleaning off the discs overnight light surface rust, better to check them after a run, though you will often hear a little pad drag noise, but the wheels should still turn easily by hand.