High Idle? Poor Fuel Economy

[cookci]

basically my car still has a high idle. the thermostat is new and reaches operating temperature quickly however the idle takes a long time to drop and only ever reaches around 700 if im stationary but when i start driving again returns to over 1000

im thinking this is the reason for my poor fuel economy??

[GT4 BOOSTER]

does the temp guage read the same at speed or does it fall down to about quarter

[cookci]

sorry it always reads the same i.e. a touch under half and gets there pretty quickly

[GT4 BOOSTER]

has the throttle sensor ever been turned ??? this may eaT THE FUEL sending incorrect fueling messages to ecu .

i thought maybe the stat was jamming open and causing the engine to cool , hence the higher tickover.

[mikeb]

Have you checked the coolant temp sensor (THW)? (I think we've been through this before though? ).

Try cleaning out your idle control valve, it may just be that it's gunked up.

[cookci]

Have you checked the coolant temp sensor (THW)? (I think we've been through this before though?  ).

Try cleaning out your idle control valve, it may just be that it's gunked up.

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cheers for replies

dont think we have? any info for me?

the stat is 100% ok :ffs:

[mikeb]

Have you checked the coolant temp sensor (THW)? (I think we've been through this before though?  ).

Try cleaning out your idle control valve, it may just be that it's gunked up.

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cheers for replies

dont think we have? any info for me?

the stat is 100% ok :ffs:

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Try page 16 of this document:

www.autoshop101.com/forms/h24.pdf.

There are (probably) three devices that look like temp sensors on your water outlet (just below the throttle body). One is the sensor for the temp guage, one is the cold start injector switch, and the third is the THW sensor that goes to the ECU (this is the one you need to identify).

The simplest way to test it is to unplug it when the engine is cold (and off), and measure the resistance across it. It should correlate to the graph in the above document. Then reconnect it and get the car fully warmed up. Repeat the measurement (again with the engine turned off, or you will probably generate a fault code).

[Black Knight]

Having high idle in itself shouldn't cause poor fuel economy. Cars use very little fuel when the engine isn't under load.

It may however be indicative of another problem causing it to overfuel. Can't recommend anything other than has been mentioned above though

[GT4 BOOSTER]

i think after alot of thought the only answer left is for cooki to tie a knot in his fuel pipes :P

i'd check the throttle control position too though , it can and does affect tickover speeds and possibly fueling issues.Usually its set to the middle position , but it too can be tested with a multi meter to make sure its in the correct place, a job for those in the know though.

[Kevstir]

why dont you bite the bullet and get the car checked over m8 , you have had this trouble for so long now...

and iv told you before get rid of that brick you have tied to the loud pedal it might make it easyier to push but it does nothing for ur mpg :P

[cookci]

ive had it checked mate and toyota said the car was fine!!! lol

ubikh*les

Anyway cheers for the advice. ill get that sensor checked and look at the idle valve...

[paseoGT4]

Have u had a diag on it and checked if its throwing up any codes?

[cookci]

how do i run a diagnostic dude?

[paseoGT4]

easiest way is to look in the back of autotrader and get some1 to do it for £15, can be done manually but gotta be careful as can fry ecu if not done correctly. What sort of mpg are you getting? I get 30mpg doing mainly motorway. Drops down to about 25mpg around town

[paseoGT4]

your drilled airbox and de-cat are not going to help fuel economy - as your going to be throwing all sorts of wrong signals to your ecu