EGR and PCV VALVES

[maccasparks]

Howdy - my stock Exec is currently using 11.2l/100 which is okay but thats mainly country driving it like a total nana!
I have progressively in the last 6 months replaced O2 sensors (bosch) ,plugs (NGK) , leads (Eagle) ,fuel filter(genuine) ,recharged K&N air filter and changed engine oil and filter( 10/30 ). Also cleaned throttle body. This has made the V6 smoother at idle and acceleration but has not reduced fuel use as I would have expected. I just found a thread about Idler pulleys being a possible cause so will check those. Is it worth checking the PCV and EGR valves and if so how do you do that?
Cheers

[wortus]

Howdy - my stock Exec is currently using 11.2l/100 which is okay but thats mainly country driving it like a total nana!
I have progressively in the last 6 months replaced O2 sensors (bosch) ,plugs (NGK) , leads (Eagle) ,fuel filter(genuine) ,recharged K&N air filter and changed engine oil and filter( 10/30 ). Also cleaned throttle body. This has made the V6 smoother at idle and acceleration but has not reduced fuel use as I would have expected. I just found a thread about Idler pulleys being a possible cause so will check those. Is it worth checking the PCV and EGR valves and if so how do you do that?
Cheers

Sounds like you have replaced the usual items that cause this. I can't see how the EGR and PCV valves would could have an effect. Have you checked the engines compression and is the lockup torque converter working?

[maccasparks]

Cheers Wortus - I'll give it a comp test this weekend.

[maccasparks]

Okay - I checked idler and tensioner pulley bearings and they are all free and smooth but the top idler is a little noisey . Can I just replace that one and best to get genuine one? Also any hot tips on fitting new pulleys?

[wortus]

Yes you can buy them individually from Holden and I would probably stick with genuine parts. If your talking about the pulley on the belt tensioner remember the bolt is a left hand thread so don't try to undo it with a lot of force in the normal direction. If the pulley on the belt tensioner that is there is a genuine one for a VY it should be made from metal and in this case the other optins are to go and buy just the new bearing and fit that to the existing pulley or what I have done in the past and it worked just fine is to take out the old bearing and then pick out the dust seals carefully so as to not damage them with a scriber and re pack the bearing with grease and reassemble it. I've also used this trick on an alternator and after repacking the bearing had no play and made no noise. If you repack it and there is excessive play it shoudl be replaced as soon as possible. You will probably need some circlip pliers as the bearing is most likely held in by a circlip (I've only removed the bearing from a VN pulley so I am assuming there held in the same way).

[ephect]

the other part you can try to replace is the ecu temp sender. from memory, VT and up had a combined dash and ecu sensor, but please correct me, im just going off memory here!

if its sending the wrong temp to the ecu, it still operates in open loop affecting economy

[cander24]

VT and up had a combined dash and ecu sensor, but please correct me, im just going off memory here!

That is correct

[maccasparks]

Thanks for that Ephect
So where is this senor - how do I test it and what does it do??

the other part you can try to replace is the ecu temp sender. from memory, VT and up had a combined dash and ecu sensor, but please correct me, im just going off memory here!

if its sending the wrong temp to the ecu, it still operates in open loop affecting economy

[ephect]

the sensor is located on the bottom half of the thermostat housing, it is roughly 20mm wide and will have a plug on the end with 2-4 wires (not 100% on how many wires), which simply unscrews from the housing.

with a multimeter you can test the resistance and pooring hot water over it, it should change. i dont know what resistance at what temp it should be, but generally economy is effected if its not operating correctly, telling the ecu the temp isnt right and it runs in open loop mode, pumping in more fuel on its base maps due to it thinking its cold. Now because you've replaced most things that a major affect on economy to me its logical to replace this next.

[maccasparks]

Does the ECU temp sender also do the temp on digital dash display - when u press mode and set and turn key on and go to "coolant temp" ?
It was showing 67 degress and when I held a digital thermometer on to the outside of the thermostat housing it showed 52 degress . Close enough yeah?