Causes of poorer economy of ZB 4 cyl 2 litre petrol turbo

[Tezza's ZB]

I have noticed that the economy of my ZB is lesser. I'm not confident of the accuracy of the dash read outs. I'm feeling I'm just running out more quickly. I only use 98 octane
Causes or experience of others would be appreciated.
Car has done lowish klms of 41k. It had 5k on it when purchased in April 2019

 

[stooge]

strange, you would not think the best car ever built with nitrogen in the tyres would have that issue.

 

[Tezza's ZB]

Get over it .. it was a long time ago.. And it reflects on you. I just asked a question

 

[Skylarking]

(1) fill up
(2) reset your trip meter
(3) run the car till the low fuel lamp turns on
(4) note the milage on the trip meter
(5) add info to a spread sheet
(6) if you have gathered some meaningful numbers analyse them else go to (1)

In doing the above, I get a good indication when my daily needs an oil change, though I’ve slackened in such analysis post covid.

As to the cause of poor consumption, it can be anything from a bad batch of fuel that’s porked the o2 sensor sensitivity to new shoes that better match one’s changed (Fangio?) driving attitude

PS: I’ve always found the cluster fuel consumption numbers within modern cars to be reasonably close to actual. Id guess only if fuel pressures an/or o2 sensors are borked will they start to differ from reality.

PPS: better not react to (what I found to be humorous) comments as it will just send your thread in the wrong directions. After all, all commodores have issues regardless of how it’s owner can think their car is the best thing since sliced bread

 

[Tezza's ZB]

(1) fill up
(2) reset your trip meter
(3) run the car till the low fuel lamp turns on
(4) note the milage on the trip meter
(5) add info to a spread sheet
(6) if you have gathered some meaningful numbers analyse them else go to (1)

In doing the above, I get a good indication when my daily needs an oil change, though I’ve slackened in such analysis post covid.

As to the cause of poor consumption, it can be anything from a bad batch of fuel that’s porked the o2 sensor sensitivity to new shoes that better match one’s changed (Fangio?) driving attitude

PS: I’ve always found the cluster fuel consumption numbers within modern cars to be reasonably close to actual. Id guess only if fuel pressures an/or o2 sensors are borked will they start to differ from reality.

PPS: better not react to (what I found to be humorous) comments as it will just send your thread in the wrong directions. After all, all commodores have issues regardless of how it’s owner can think their car is the best thing since sliced bread

Thank you for that detailed advice. I have been told years ago that I was gentle on my Honda civic because he saw the carbon build up.
These days I have been doing short journeys as well.
Do I give it some off the mark acceleration and some 80 to 110 bursts to clean it out, or is that an old wives tale. The car has been regularly serviced by GM Oakleigh dealer ahead of due klms. Can you recommend a dealer or mechanic that has that extra expertise.

 

[Tezza's ZB]

Thank you for that detailed advice. I have been told years ago that I was gentle on my Honda civic because he saw the carbon build up.
These days I have been doing short journeys as well.
Do I give it some off the mark acceleration and some 80 to 110 bursts to clean it out, or is that an old wives tale. The car has been regularly serviced by GM Oakleigh dealer ahead of due klms. Can you recommend a dealer or mechanic that has that extra expertise.

 

[Skylarking]

Thank you for that detailed advice. I have been told years ago that I was gentle on my Honda civic because he saw the carbon build up.
These days I have been doing short journeys as well.
Do I give it some off the mark acceleration and some 80 to 110 bursts to clean it out, or is that an old wives tale. The car has been regularly serviced by GM Oakleigh dealer ahead of due klms. Can you recommend a dealer or mechanic that has that extra expertise.

The ZB 4 cylinder turbo is a direct injected engine if I’m not mistaken. As such you can get lots of carbon buildup on the back of the intake valves which can impact performance. Such occurs because there is no fuel to wash the back of the intake valves as occurs in port injected vehicles.

Some directed injected engines suffer from this form of carbon build up to such an extent that disassembly is required to properly clean the valves. I’ve also heard that some mechanics use walnut blasting (or such) to clean this type of carbon buildup without needing disassembly. Guess it all depends on the engine’s intake port shape, etc, as to which method may work on your engine.

Supposedly normal service is supposed to include some form of decarbon fluid being let into the intake plenum to remove such carbon buildup. Whether Holden does this as part of their service, NFI.

Will the old mechanics tune solve this… worked on lots of carbi engines but not so much on EFI port injected engines and doubt any amount of flogging will resolve such carbon problems on a direct injectEd engine

As to whether you’re actually having such a problem, I’ve got no idea nor do I know which dealer to take your car to

I do remember one forum member said that he’s had luck with some Subaru decarbon fluid cleaner so if he notices this thread maybe he can comment.

Plenty of YouTube video’s describing the issue and how to clean the back of the intake valves

PS: short drives aren’t good for cars but if that’s your normal usage you either need to have more frequent servicing and/or go on hour long drives every month.

 

[stooge]

If i remember correctly in some places the lgt engine did have an issue mainly pertaining to a loose unit behind the righthand front wheel.
It might impact economy readings and it was not addressable with a recall.