Mr2 NA poor mpg?

[dabofoppo]

Hi guys. I recently got a mk2 mr2 (g plate) and since I got it last week iv been averaging 19mpg. What could be causing that? Iv found the brakes binding a bit and the exhaust is blowing but surely they won't make it that bad? It has the 3sge engine.

Cheers.

[Midshipracer]

O2 Sensor might be the problem, Its used (on mine anyway 3S GTE) when pootling around the O2 sensor gauges the air fuel mixture. If its not getting a good reading or none at all i.e. broken. It puts more fuel in as a safety thing

Only when you are on WOT aka foot down does the ECU take over measuring throttle positioning etc

N.B as with anything you read on the internet its important not to take it as gospel could be one of many things

[Mastodon2]

Is it a turbo? I know the MK2 turbos could be pretty bad on fuel, around the 22mpg mark according to some members, even when working normally, though I suppose it depends on how you drive it.

[TotalControl]

Check the O2 sensor, mine went on my ST202 Celica and gave me around 17mpg (9 at its worst). Definitely worth checking.

[danjama]

How does one check the o2 sensor is working?

[Midshipracer]

You can't really check if its working you, gotta do the error code thing. I think its code 22

[clarkson22]

brakes and the blowing exhaust will contribute, how are all ignition components? dizzy, rotor arm, plugs leads, id go about checking the ecu coolant temp, green sensor on the water elbow to the left of the dizzy cap, is it a rev 1? im sure the n/a rev1 did not have a lamba

[danjama]

Midshipracer said:

You can't really check if its working you, gotta do the error code thing. I think its code 22

Ah thanks.

Where is the port on these?

[clarkson22]

at the back behind inlet manifold, labled 'diagnostics'

[danjama]

clarkson22 said:

at the back behind inlet manifold, labled 'diagnostics'

Thanks again, shame there's no Haynes manual or similar for the mk2, love reading through those.

[Tib]

Even if no code comes up, it doesn't necessarily mean that the o2 sensor is working correctly. Mine didn't show up a fault code and I was getting similar MPG figures.

I found the car very 'lumpy' to drive when pootling around town; the throttle was either on or off and the whole ride felt quite jerky. You can get genuine o2 sensors for about £50 if you look in the right places. They are an absolute pain to fit mind as they are usually rusted in.

You can actually try disconnecting the sensor for a while and see if it improves/changes your running.

If it were me I'd sort out what I knew to be wrong first though - the brakes and blowing exhaust. If you need a new 'xorst it might be an idea to wing a new o2 sensor in as par for the course...

Edited by Tib on Monday 1st October 16:46

[dabofoppo]

Cheers for the help guys. I dont think the car has a lambda sensor but ill get it checked when i fit the new manifold and the brakes are hopefully getting done tommorow. However it does seem to be improving itself.

[hygt2]

If you have an air leak upstream of the lambda sensor, it will cause false reading and cause wrong fuelling.

[amnesia182]

Worth checking the timing with a strobe, too. Simple to check and adjust on the N/A mk2