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The mkiv Supra Owners Club

Poor MPG on N/A


Greystoke

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Obvious questions first, but worth asking just in case....

 

Has it been a gradual decline in MPG, or a sudden drop?

If a sudden drop, have any mods/ servicing been done to the car at that time?

What revs does the car tick over at?

 

A clogged air filter could cause low MPG values...

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I only have the car about 1 month.

 

It had a service before I collected it.

 

Spark plugs were changed.

 

They only mods that I can see that have been done to it are:

 

1. An ARC Induction kit was installed.

 

2. There is 1 straight pipe from the second cat to the backbox (RS*R Exhaust Magic).

 

Other than those I can’t see anything else that was changed.

 

The air filter is a possibility, but can’t seem to find anyone selling Arc filters.

 

The car ticks over around 800-900 revs.

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O2 sensor :lalala:

 

When it gets dirty/old, it'll start faking a lean signal and forcing the ECU to run over-rich. Not only does this bugger up any closed-loop economy (i.e. anything other than acceleration and coasting) but it fails you your MOT as well, due to the emissions.

 

-Ian

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Tickover doesn't sound excessively high. I'm not familiar with ARC filters, but there might be a visual way of telling if its clogged up.

 

Someone more knowledgable than me may be along shortly.... :)

 

Edit: ... like Ian C, for example!

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I, too, would look at the O2 sensor closely, if the obvious have been verified (airfilter, collapsed exh backbox etc)

A tired sensor will still give a reasonable voltage, only lower than it should. The ECU adjusts accordingly, running rich. It may take quite some time before the sensor dies completely and the ECU flags it up.

If it's got over 60K miles on the same sensor, I'd change it anyway.

(I've got one ordered from the States as we speak.)

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