Air Fuel

[larrytoyota]

Hi there i have an air fuel problem, The thing is its computer controled. does anyone know
if it,s easy and not to the moon and back to investagate...HELP:)......Iv got a 1999 avensis 1.8

[waqar_lionheart]

What is your problem please? Simply saying air to fuel ratio problem isnt attracting a lot of attention. Secondly, can only tell whether its easy to investigate if i know what the problem is?

regards,

waqar

[Konrad C]

Due to lack of details in your post, I will give you all possibilities, starting with the basic things. First, have you recently change the air filter?

Look at the following links on my recent experience with the same setup. The leanburn (O2) sensor may be lazy and not switching properly. You may not see an EML, but if it comes up then goes out after a while, using the jumper wire method, on the OBD socket (pinouts 4 and 13), you will find code 21 stored.

http://www.toyotaownersclub.com/forums/topic/162669-techstream-diagnostics-on-7a-fe/

I was lucky to find another leanburn sensor, and with the air filter replaced, the car is back to normal.

Also there could be other issues. The vacuum switch to the inlet butterfly valves can detach.

https://www.google.com/url?q=http://www.toyotaownersclub.com/forums/topic/138015-1998-avensis-7afe-sputteringhickups-at-highway-speeds/&sa=U&ei=n-8GVI2IKsSm0AWXwYGQDQ&ved=0CAYQFjAA&client=internal-uds-cse&usg=AFQjCNGLTYC4v1R0G6zIphHTl-lXGtD40Q

https://www.google.com/url?q=http://www.toyotaownersclub.com/forums/topic/148954-old-mk1-avensis-16-lean-burn-engine/&sa=U&ei=Se4GVJqlEcS_ygP-hoBo&ved=0CAYQFjAA&client=internal-uds-cse&usg=AFQjCNHVW9WIs3YRZZCViam8tLZ0dego_A

https://www.google.com/url?q=http://www.toyotaownersclub.com/forums/topic/158472-light-throttle-splutterjudder/&sa=U&ei=n-8GVI2IKsSm0AWXwYGQDQ&ved=0CAoQFjAC&client=internal-uds-cse&usg=AFQjCNGgc_Q9XoY71HSUaQT1GUVJAMcNKQ

Make sure that the HT leads are plugged firmly onto the spark plugs. What is the condition of the spark plugs and are they Denso Iridium?

If you look up my posts you may find something useful.

Konrad

[larrytoyota]

Hi conrad thanks for getting back to me, Iv unplugged the throttle body accrl senser and it seems better. Ill have a look at the links and get back to you thanks again

[larrytoyota]

Hi konrad thanks for getting back to me, Very useful post thankyou, Ill give them a try and you never know.

Im sure it,s not to much of a problem as iv been everywere in my avensis. Plus it,s just started happerning in the last few months.

[B3rtie]

Also the MAF in the throttle body and the air bypass system could be a bit mucky - worth a go at cleaning out alongwith all the pipes etc. and ensuring electrical connections are clean and put it back together.

[korat102]

Be careful around the MAF sensor, it's delicate... If you think it needs cleaning just use a spray, don't go poking at it with a brush or you'll have to replace it.

[Konrad C]

Hi conrad thanks for getting back to me, Iv unplugged the throttle body accrl senser and it seems better. Ill have a look at the links and get back to you thanks again

This is why I would like to invest in a OBD1 scanner which uses Toyota techstream, if it can communicate with older pre-OBD2 cars. It would take away some of the guess work. The on board diagnostics can only tell you so much.

By the way, has the orange EML warning light come whilst driving?

As already mentioned, check and clean electrical connections.

Konrad

[larrytoyota]

Hi just an update, Iv unplugged the throttlebody senser and all is well, Im leaving it out for a week or tow untill i can afod another one...Is this not a good idea

larry

[korat102]

It'll probably run without the MAF sensor but the ECU will have to revert to default settings so performance is likely to be somewhat poorer than it would be with a working MAF. Shouldn't do any damage though.

[larrytoyota]

Will do.....No EML light on the dash. Comes on with ignision mind

[Konrad C]

Will do.....No EML light on the dash. Comes on with ignision mind

Good that means all is well so far. You have followed my other tips?

When I had my MOT recently, my car struggled to meet the emissions and then at the last minute suddenly dropped to a low figure. After that I changed my lean burn sensor and the cars fuel consumption improved a great deal. I must be in the high 30s at the moment. Yet to get a measurement.

Hopefully you may not have an mixture issue. If you pull the EFI fuse for a minute, it should reset and relearn settings.

[Konrad C]

Quick update on my fuel economy.

I have been on a run to Whitstable and then Hernebay, Kent last Thursday (a week and a bit back), a lot of local driving and visit to friends in Sutton. So far have done nearly 300 miles and just under half a tank left.

Before the leanburn sensor and air filter change, 240 miles barely covered half a tank. Last fill up was 48 litres @ 395 miles. Before that with the old exhaust was 55 litres @ 430 miles. So the fault I had was more the sensor/ air filter combination and not the exhaust.

I need to do a few more refuels to see what return I am getting.

Hopefully Lawrence, the air filter may help improve the mixture, but in my case, the sensor was the culprit.

Konrad.

PS. Going to Brighton today to watch the speed run, so more miles.