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Harry Carri

Disappointing Mpg On Mk1 Avensis 1.8 Gs Estate (1998, Lean Burn)

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Hi, having searched, read and put into action recommendations on this forum I find myself in need of suggestions. I feel my 1998 Avensis Estate 1.8gs is not returning enough MPG. Average 32MPG, best 43MPG over 1000miles East Midlands to Cornwall and back.

Previous to this Avensis I had a Carina e 1.8 Hatch (7AFE lean burn) which wasn't the best example had no service history and slight blow on the downpipe but averaged 40 to 42 MPG typically and 50 MPG on a motorway journey. Really liked the car but needed an estate so last year bought the Avensis with the same engine hoping for similar figures.

The Avensis had one previous owner and a full service history up to the year sold so when I bought it I had the full part2 or B service done plus cambelt and water pump. So that meant new Oil and filter ( changed by me twice a year) new air filter, new irridium tipped plugs, coolant change, new fuel filter and a brake fluid change. Two new Michelin energy on the front and a few months later two more for the back. Bought with 141,000 on and now with 150,800. Injector cleaner is put through twice a year. MOT test showed nothing seriously wrong and emmisions passed. There is a slight blow somewhere in the middle of the exhaust system but that has not worsened in a year. This morning (thanks to Konrad C's previous posts) I found the diagnostic socket joined pins 4 and 13 and no faults showing.

So any ideas please, the Avensis doesn't seem to rev as willingly as old Carina e and between Oil changes (6 months) uses approx 0.5 to 0.8L.

Thanks in advance for all the members here who take the time and trouble to provide help and advice.

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Does the car feel like its hesitating and bit sluggish?

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Thanks for the post.

I think the car is slightly sluggish in comparison to the Carina. The revs don't seem to build up as quickly but the car runs smoothly with out flat spots or any coughs and splutters.

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As your car has covered a lot of miles I think I would try this product first:

http://www.amazon.co.uk/Cataclean-Catalytic-Converter-Cleaning-Treatment/dp/B002BVXM92

Then maybe the oxygen sensor, as if this is not working well your car might be running a bit rich

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Thanks for that, I think I will give that treatment a go.

As for the oxygen sensor I was half expecting that to flash up this morning (fault code 21 if my memory serves me) when I put the wire into the diagnostic socket, It did pass MOT at end of July and I have been a bit disappointed with fuel consumption from the beginning so do oxygen sensors have levels of failure or do they simply work or fail ?

If the oxygen sensor had failed I should have a fault code and had it failed prior to MOT then could the car get through the emissions test ?

I have read a bit on here and in workshop manual about the oxygen sensor and that has made me a bit cautious as I am sure I have read that they are not to be removed and cleaned and removing them from the manifold can cause them to fail.

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Hi Matthew,

I have read through your post and you have covered everything, and I need to ask a few questions. What kind of load are you carrying, and what kind of speed and traffic conditions, not forgetting hilly routes?

The estate is heavier than the hatchback which in turn, is heavier than the previous Carina.

Your figures show you about 2-3 mpg down on me. Very few medium sized 1.8 outside Toyota/Honda/Mitsubishi go into the 30 mpg range in town, especially a 15 year old car with 150,800 miles.

You have changed the spark plugs, but what about the HT leads? May sure that the vacuum switch which controls the inlet ports. I have posted on this topic on the forum. These can affect the performance. Fuel quality is another issue.

In the lower gears, can you rev to 5500 rpm? The limiter cuts in just after 6000 rpm, but in most driving situations you only need 4000 rpm for the very steep hills, if that.

Check the HT leads are fully connected to the plugs by pushing the wire through the insulating sheath.

Another thing you could try is to pull the EFI fuse for a minute, so the car ECU relearns a new map. The fuse is in the engine bay fuse box. I could add crank sensor but the car is working.

You could try additives.

I think everything has been covered but any other suggestion would be welcome.

Konrad

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May sure that the vacuum switch which controls the inlet ports. I have posted on this topic on the forum.

Konrad

Konrad would you give me a link to this topic about vacuum switch.

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May sure that the vacuum switch which controls the inlet ports. I have posted on this topic on the forum.

Konrad

Konrad would you give me a link to this topic about vacuum switch.

Here is the link as requested.

http://www.toyotaownersclub.com/forums/topic/148954-old-mk1-avensis-16-lean-burn-engine/

Just make sure the rod is attached to the lever. Don't worry what position of the rod.

Konrad

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Just make sure the rod is attached to the lever. Don't worry what position of the rod.

Konrad

Thanks. I haven't problem (7A-FE), just wanted to know about this...

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Thanks for your input Konrad, I was hoping you might pop up as I have found your posts a wealth of information.

My typical load carrying is myself and one passanger plus permanent boot tidy with a small socket set and screw driver set a couple of litres of assorted fluids plus waterproof coats and perhaps a kilo at most more of general bits and bobs. Approx 1/3 of time tools of weight 20kg. Now the general stuff all lived in the Carina e as well, the tool carrying not so much ( hence buying estate as no lip to lift stuff over).

As for my regular routes and driving styles are very similar if not identical between the two cars. I live in a village outside Nottingham so typically my regular commutes involve 30mph limit built up area followed by single carriageway 60mph limit followed by dual carriageway 70mph limit then buit up area again all in a 12mile each way approx 5 miles of national speed limit then 7 miles of urban. I drive gently typically cruise at 50 something on the single and dual carriageway once out of village. Urban I just pootle about. I rarely exceed 3000rpm tytpically though often on way home when fully warmed up hold 2nd and 3rd up 4000 or 4500rpm in the belief that it isn't good to never extend the engine. Hills or gradient wise there are inclines (nothing that warrants a downchange) on the single carriageway road out of village but there is the other side of the slope later on so it probably evens out.

Plug leads not changed, I had wondered but having spent on getting the car's servicing up to scratch I stoppped spending.

I am pleased you have posted a link for the vacuum switch to the inlet ports as I had read that and got me wondering.

Fuel is a variety of Jet (my village station), Shell, Murco, ocasional supermarket fills and very occasional BP. Regular unleaded from all.

Thanks for the tip to push plug leads tighter.

That I think covers everything asked.

Maybe I am looking for something that isn't there which is a blow, but if that is the case at least there is nothing seriously wrong with the car so that is pleasing. That leaves as always a fault with the operator, fancy not checking the kerb weights of both cars DOH...

Thanks to all again.

Matt

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Great reply Matt.

This is what the forum is for - sharing ideas, advice and experiences.

I forgot to mention that some manufactors sometimes lower the gearing slightly, to compensate the extra weight of the estate version with its greater load capacity. If your car shows 3000rpm at 70mph, then it geared the same as the hatchback/saloon.

Glad to have helped.

Konrad

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Yesterday on the dual carriageway 3000RPM was very close to 70MPH but not quite, probably 68MPH so maybe the estate has slightly shorter gearing.

A bottle of cat and oxygen/lambda probe cleaner went through this week and a bottle of injector cleaner is now in with 40L of fuel so I would like to think that is all the cleaning done.

I shall give the plug leads a push and look to change those as I have had the car 18 months and I am not sure how old they are, I will check the service history to see if a lead change is listed on any of the invoices. What sort of life should I expect from leads ?

The vacuum switch operating the inlet ports is a remaining possibilty. I haven't found any mention of this switch and linkage in my workshop manual so I am lacking details and would greatly appreciate a bit of help.

Are these parts located inside the inlet manifold ?

Is it a relatively straightforward DIY job ?

What is the process to complete the job ?

The most involved job I did on a car was an injector change on my Carina e (7AFE 1.8) which I found OK. I am completly happy doing basic servicing such as Oil and filter changes, air filter changes, coolant drain and refill and I changed a thermostat. I have socket sets and a torque wrench.

Thanks in advance

Matt

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Hi Matt,

The vacuum switch only works when the engine is running. It usually parks in a certain position. Unless it the rod has disconnected, leave alone. If it does disconnect, just reconnect. I used speaker fittings to secure the connection.

Do not dismantle the inlet manifold. You may cause unnecessary damage and it is not worth it. If there is something wrong with the manifold and internal parts, you will have to get another one.

I would do the other things you said, then measure the amount of fuel you use again.

I tend to see how far I have gone by the distance traveled with every fill up. Right now I my car is down to 33 miles to the gallon of mainly town driving.

Konrad

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Hi and seasons greetings,

Following a tank of fuel with the cat cleaner and then a tank with a decent injector cleaner then normal use ( 25 quids worth of fuel each week)I have averaged a worst of 32MPG and over the last two fills 37MPG for each.

Bearing in mind what has been said in this thread I think that is reasonable enough and an improvement. I gave the car an Oil change last week and ordered new plug leads which arrived yesterday so they will go on as the leads on look to be Toyota ones, could they really be the original ones still working 15 years on ? Well they will be changed very soon and I shall continue to try to refill at the same point on the gauge and noting the mileage on the receipt. Hoping to break 40MPG. Lets see.

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Hi and seasons greetings,

Following a tank of fuel with the cat cleaner and then a tank with a decent injector cleaner then normal use ( 25 quids worth of fuel each week)I have averaged a worst of 32MPG and over the last two fills 37MPG for each.

Bearing in mind what has been said in this thread I think that is reasonable enough and an improvement. I gave the car an oil change last week and ordered new plug leads which arrived yesterday so they will go on as the leads on look to be Toyota ones, could they really be the original ones still working 15 years on ? Well they will be changed very soon and I shall continue to try to refill at the same point on the gauge and noting the mileage on the receipt. Hoping to break 40MPG. Lets see.

That a good result Matthew,

I am in the same ballpark as you with fuel consumption. You are getting better economy than some more modern cars of similar size or smaller (engine and class).

Keep an eye on your tyre pressures as they change with temperature.

I also write my MPG on the back of the receipts at fill up.

Konrad

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Hi folks,

I put the new leads on and the a day or so later added my weeks fuel, 25quids worth as usual. 19.1 Litres.

I had a couple of days of commuting for work and then 70 miles of mainly 50Mph limit A road patrolled by average speed cameras. An essential economy sapping short journey from a cold start and then this morning the regular shopping trip. After shopping I bought next weeks fuel ( same point on the gauge again, just as fuel light comes on) and noted the mileage.

I had covered 174 miles off that 19.1 Litres which I make 4.2 gallons so an average of 41.4 mpg.

I am pleased with that and don't think there is any more I can do. I will wait and see if the new leads improve my tyical weekly commuting figures of 36/37MPG. If I had more A road driving I can break the magic 40 mpg as last week showed.

Matt

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That is great Matt.

Funnily enough after checking my tyre pressures, my economy has improved too.

Even driving in traffic, fast driving and short journeys, I have done over 275 miles on just over half a tank.

Every little bit helps.

Konrad

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If it still feels sluggish, then maybe a throttle position sensor?

My car is due to see Japex in Herts in a months time. I spoke to the guy on the phone and he was incredibly knowledgeable. He asked if the car felt like it had a "flat spot" and I said I did feel that I got "bogged down" pulling away. He said he would first start with the TPS.

Just throwing that in there.

I do a 100mile commute each day in a 3sfe 2.0 and am averaging 38.1 down from 41 in the summer. Some of that I put down to winter tyres being a bit more resistant, some of it the cold, and the rest that I have a problem still somewhere! I've tried just about everything including regular servicing, new leads and plugs and a !Removed! good "Italian tuneup" so it's this next!

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Bought £500 Mk1 Avensis hatchback 1.8 GLS 1998 200 000 miles. Did 31 mpg with bad spark plugs, with tyres 24 psi, dirty cloggy power steering fluid (was hard to turn) - drive just in city (rush driving delivery food job). Now plugs new - Iridium, pumped more air, power steering fluid changed I see if mpg improves. Waiting Oil changing then money come :disgust:.

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Hi Folks,

My last fuel of 19.1 L took me 161 miles giving 38.3MPG from my regular commuting routes. The roads were a bit quieter earlier as not everyone was back at work until this Monday. I fuelled yesterday (Tuesday evening) so I did have two days of slower journeys home with more traffic.

So that is the second lot of fuel with the new leads. Typically I was getting 36MPG before. I had to go through the last three months receipts to record expenses so I checked a sample as I went and 36MPG was typical. The lows like 32 MPG were the freak results. However thae Carina e typically gave me 40MPG and more.

I am happier as 38mpg is higher than 36mpg and the car runs smoothly so the new leads were worth it. I am impressed Daniel that your 2litre car is giving 38mpg and has averaged 41mpg. I should be interested to hear how the tests on the throttle position sensor go. Those figures do make me wonder about mine as I am convinced the 1.8 7AFE lean burn was meant to be the pick of the range for economy so much so that I took some time and trouble to get another one after the Carina e and avoid (on the advice from here) a VVTI 1.8 from 2000 to 2003 hence my 1998 Avensis 1.8.

I shall bear in mind Konrads' suggestion of disconnecting the EFI fuse so the ECU resets and the vacuum switch but now I at an average of 38mpg I am within 10% of where I thought I should be.

I did find some weights listed in my Haynes' manuals for Carina e and Avensis. According to Haynes both Carina e and Avensis range of cars start at 1185 KG and go to 1290 so I imagine a 1.6 saloon or hatch would be 1185KG and a 2 litre estate 1290KG.

In the early days of having my Avensis new plugs and a new air filter transfomed the car, so if you haven't checked or changed the air filter Longas I would, it could be the best 6 quid you spend if your car has been a bit neglected prior to you having it. Good to hear of 200,000 miles and still powering on. I should like to get mine to 200K.

As for me 10% of my weekly fuel means two and a half quid and an hour of mechanics workshop is 50 quid any diagnostics and improvements on the cars economy are going to take a long time to come back so I think I shall stick with where I am for now ,keep an eye on the figures, tyre pressures and keep the car serviced.

The quest for economy continues.

Matt.

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Air filter I fitted new then bought car. My mpg goes up just cant tell exactly now, soon i put full tank petrol got Tesco 5p off offer. Throttle body was cleaned, was oily inside, performance improved. Was lazy to clean idle valve, my revs going up 2000 when engine cold and then idling hot revs up and down 600-1000. Another problem then idling lights dimmed and fan slow. Alternator voltage ok 14.3V then everything on 13.3V. Someone got this problem? And one more thing then idling 700 feel vibration. My friend put his idling revs up to 1000 to cure vibration. Looks no vacuum leak in pipes, maybe lambda faulty or other sensors is 200 000 miles.

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I would like to ask owners of 7A-FE cars, what are revs initially when start cold engine both winter and summer time (example around 5 and 25 degrees).

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by Haynes manual idle speed 700+-50 rpm

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My car idle at 2000 rpm on startup on cold mornings.

Fully warmed up with no heavy loads like air-con heater, lights, etc, just over 600rpm.

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by Haynes manual idle speed 700+-50 rpm

My question is idling speed not when engine is warm.

I mean when start cold engine, before it gets warm on both cold and warm weather ...

Conrad C said 2000 on cold weather. What about warm summer weather?

What's the point to be so high (3 times idling), I've never seen other car with 2000rpm cold idling...

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