D23 ys23ddtt lacking power, fuel heavy

[d.j.]

I'm hoping that I solve this problem before this is read but I doubt it.
My 2018 d23 st ys23ddtt has done just a few ks shy of 149000km and it's feeling like I'm towing with nothing behind me...

I have been driving in mixed conditions in the last few months between freeway (a few hills that are quite long) and city driving in Geelong. Since my wife stopped driving constant freeway to and from Melbourne I have noticed when I take off it takes more effort to get up to speed unless I floor it. Which also puts up the average l/100km.

It currently varies from 9.8(very frugal driving) to 10.5 almost 12 in harsh driving. I find it using more on a freeway drive for some reason. In the mornings while I am idle the average jumps .1 after a few minutes.

I had done a trans service at 145,000 as I've started to tow more, the gears still feel smooth and shift down fine.
The turbo does boost, has a sleight whistle from I believe when I had the catch can fitted but has since been removed after advice from a co-worker.

Did a scan this afternoon no codes, checked injector read out as I thought perhaps they may be failing all readouts were between .91 - 1.1

the only other things I haven't sussed are the maf sensor and from what I've been reading here and a few other places the solenoid valve filters which can clogg up.

It's been a real head banger as one of my co-workers has a 20' stx, tows constantly and it just felt so much better off the mark.

 

[d.j.]

I would also like to add the fuel has been regular since taken ownership but this didn't seem like it had been causing issue, I had filled up premium diesel last tank and little difference was noticed. I had even gone to change the fuel filter last weekend which was only 4000km old and was squeaky clean.

 

[d.j.]

I would also like to add the fuel has been regular since taken ownership but this didn't seem like it had been causing issue, I had filled up premium diesel last tank and little difference was noticed. I had even gone to change the fuel filter last weekend which was only 4000km old and was squeaky clean.

Last night I had also done an injector adaptive relearn which at first didn't seem like it's made any difference but this mornings drive certainly did. Might just keep driving and see how a full tank goes....

 

[Gavand]

Good luck, keen to hear how it goes

 

[d.j.]

Just over a month, city driving to and from work little to no freeway, current average is at 10/100km.

Can't seem to fault anything but still seems fuel heavy.
Workmate with a nav 2 years younger than this one is averaging 8-9 he reckons.

 

[Old.Tony]

There are numerous things that can affect performance.

Wheel alignment - if your wheels aren't aligned properly, you'll not only increase the rate of tyre wear, but you'll use more fuel to do it. Try this: with a similar load as your mate's car, on flat ground, is yours harder to push than his? If so, check the tyres for uneven wear. Bear in mind the next possibility too.

Dragging brakes - we've sometimes had reports of the rear brakes dragging a little. It causes the hubs to warm up more than they should, so you can tell. Get your mate and your car and take both for the same drive at the same speed together. After about 10 minutes, stop and check the temperature of the brakes (front and rear). If they're NOT close between the cars, you might need to pay attention to the front calipers or rear pistons/shoe springs.

Excessive EGR. Your car MUST have its EGR connected - there are sensors preventing you from the simple solution of just blocking it - but it shouldn't be getting TOO much and sometimes the EGR valves fail. If you can, whack a blanking plate (1.6mm mild steel is good for a short test) in the EGR (where the tube meets the EGR valve is best) and go for a quick drive - does it feel considerably better? If so, your EGR valve may not be functioning correctly (opening too much). Remove the blanking plate, but test everything else before throwing money at the EGR (they rarely fail but it's not unheard of).

Turbocharger issues. There's two main things to look at.

1) Boost leaking. This is really easy to spot since your catch can isn't there - look for black oily emissions somewhere in the air path between the turbo and the intake manifold (including the intercooler). Examine the intercooler carefully - we heard of a couple of STX550s that balooned the top tank of the intercooler. Check yours.

2) Exhaust leaking. This one's dangerous, but easy to spot. You're checking the exhaust manifold (the entire manifold) and every join down to the dump pipe on the output side of the turbocharger. Look for black soot. If there's an exhaust leak, the turbo might be spooling ok but it'll be slow and therefore you'll feel "a little sluggish".

Finally - drop a bottle of Liqui Moly Fuel System Treatment in the tank and drive it (100-200km). This stuff works wonders on not only the injectors, but the fuel pump, SCV (if your pump has one) and the lines.

Good luck!