Whoaful Economy TD42T

[jtraf]

My bus is a TD42 GQ with Safari turbo hanging off the side.....It is lwb with bar work, dual batteries winch etc etc 3in lift running 265/75/16in A/T. Turbo has been on since 145k and the injectors were reco'd at turbo time.

Now it is an auto and does have a low 195k's on the clock.....

My issue is that I am averaging around 20lt's per hundred around town and not much better on a trip......Now I would expect it to be a little higher than normal due to the auto but 20lt's per hundred is petrol terrotiry.

Where do I start or should I make my way down to Deisel Tech in Lilydale??

Have done all the filters and even pumped tyres up etc etc but still no difference....

Would like to put the boost up but am a little concerned in increasing fuel usage???

Have I missed something or is this normal?

James

[coxy321]

Have you given the transmission a service and flush?

[jtraf]

Have you given the transmission a service and flush?

Yeah Coxy get it serviced every 15k just to be on the safe side....

[coxy321]

The only thing that comes to mind is valve clearances and pump timing. Have you got a boost gauge and pyro fitted? Have you notices any increase or drop in performance for the extra fuel being used?

[jtraf]

The only thing that comes to mind is valve clearances and pump timing. Have you got a boost gauge and pyro fitted? Have you notices any increase or drop in performance for the extra fuel being used?

How often should you adjust the valves?

I have just fitted a vdo pyro but I made the mistake of shortening the special red so need to get this replaced during the week. Temps look good but may be skewed.

Preformance is relative as I used to remeber driving it without a turbo and then the turbo was a huge increased but now it is normal.....

It doesn't blow smoke of any color except when it should........just high fuel usage.....

[zagan]

does it take a while for the glow plug light to go off?


I've been sort of having the same problem as you, my glow plugs are on the way out and when I have them on the motor will use up more diesel (I don't know why that is)

I've also been using some chemtech injector cleaner and that has helped but my injectors could be on the way out for me, as getting slightly more smoke.

The glow plugs are supposed to help with reducing smoke etc as well, but I can't figure out if they cause extra fuel burn or not.


on avg I have 8L per 100klms which is good but for some 20-30klm trips I can chew up a quarter of a tank of fuel so something is up, I guess you are getting the same thing?

I'm currently thinking of getting the glow plugs and the injectors done at the same time to see what happens.

[coxy321]

The only thing that comes to mind is valve clearances and pump timing. Have you got a boost gauge and pyro fitted? Have you notices any increase or drop in performance for the extra fuel being used?

How often should you adjust the valves?

That'd be a question for Andy. I think for cars as ols as ours, with 150,000km and over, it'd pay to get them checked next time you take it to a workshop.

Excuse the stupidly obvious question, but have you guys checked for leaks in the fuel system (from tank to pump)?

[jtraf]

Yeah I have no leaks in the fuel system. Will give dsltech a call and c if they can shed some light.

[BadMav]

How much boost are you running mate?

Winding it up won't increase fuel usage rather it will add the extra air needed to burn the extra fuel, which would make more power. Then you back off the throttle more and use less fuel (make sense?). In a diesel engine, it's the amount of fuel that is added to the cylinder that accelerates the engine as they just suck air in un-metered. This is why diesels are more efficient and more so when turboed. My 75 series 2H turbo diesel never even ran a wastegate, the boost was all relative to how much the fuel was wound up.

If your performance has slowly decreased, I'd be looking at servicing the injectors. I trust you would have replaced all your air and fuel filters.

[jtraf]

boost ???? whatever ARB set the Safari unit at when they install it....

Have booked it into Dieseltec for a run on the dyno next week to double check it too see what the hell is going on......over speculating and need to get to the bottom of it....

Also be good to see what it is making now before I decide to intercool....

Will wait and see what the verdict is before we go further though......with 200k almost may be pump work in the future...hope not though not the right time for me...but then again when is the right time hey!!!

[coxy321]

Make sure you post up the results!

[jtraf]

Make sure you post up the results!

will do......

[bj on roids]

How much boost are you running mate?

Winding it up won't increase fuel usage rather it will add the extra air needed to burn the extra fuel, which would make more power. Then you back off the throttle more and use less fuel (make sense?). In a diesel engine, it's the amount of fuel that is added to the cylinder that accelerates the engine as they just suck air in un-metered. This is why diesels are more efficient and more so when turboed. My 75 series 2H turbo diesel never even ran a wastegate, the boost was all relative to how much the fuel was wound up.

If your performance has slowly decreased, I'd be looking at servicing the injectors. I trust you would have replaced all your air and fuel filters.

x2

Thats basically a foating system. Many large trucks run this system!

[jtraf]

Ok spent the morning out at Diesel-tec and had my bus up on the dyno.....

First three runs saw the peak of 82Kw at the wheels........Everything was in check and Andrew mentioned that all was fine except..............When the auto went into forth overdrive and locked up at lower speeds I am over fueling............Also now know it runs between 10lb and 11lb on boost

I then asked about tappets and the answer is every 50k to have them adjusted.....and mine were due as the turbo was added 50k ago....

Anyway another 3 hours waiting and the tappets were adjusted and they were all out........He mentioned wear but I know that some is wear and the other is the fact that ARB do not adjust to spec and they have always been a little noisey......

Anyway tappets done and back on the dyno.......In second gear as per first run it achieved 90.6kw @ 76kays and 592nm @ 50kays....

So overall with just tappets a little under 10% gain which was pretty good. Now have to figure out what has to be done to stop the auto locking under 90kays and all will be fine........till the intercooler comes and we go back for a little more work....

[coxy321]

Excellent result! I'll put that on my list for the next visit i do down there.

Are the GQ auto's electronically controlled? If so, there's probably a pair of wires you can either isolate or bridge to lock/unlock the transmission. I know of a few people that did this in Commodores after they developed a vibration when the transmission locked up.

[jtraf]

Was a good result overall......Now have to get the auto fixed as this is probably why I have terrible fuel economy as the engine is always lugging at 1100RPM in 4th overdrive locked convertor.

I rang a certain auto specialist business today in Bayswater and explained my symtoms and was advised that I need to leave the car with them for a couple days so they can drive and fault find the problem. I told them about being told to drive with overdrive off so that the auto would not lock and he advised that the auto locks in all gears so that wouldn't work......Alarm bells at this stage.

Anyway I work in Footscray so a place in the west would be great........Either that or I replace the TPS and go from there....

And as a side note had my Pyro temps checked as I cut the special red wire when I installed it.....only out by 25deg so wont be replacing the special red wire at this time

[zookimal]

What's your rpm at 100kmh cruise in 4th?
During normal driving/throttle what road speed does it shift into 4th?
Tyre size?
Diff gearing?
1100rpm is pretty low to be lugging around in top gear.

[jtraf]

What's your rpm at 100kmh cruise in 4th?
During normal driving/throttle what road speed does it shift into 4th?
Tyre size?
Diff gearing?
1100rpm is pretty low to be lugging around in top gear.

100k's it is sitting just under 2000RPM......

this is 265/75/16 tyre with 4.1's.......

shifting in the auto is fine except for the fact that it will lock the convertor at any speed......So when cruising around town in a 60 zone it will cycle up through the gears normally but also lock the convertor dropping revs to around the 1100RPM mark and that is were I am struggling and overfueling all the time. Weeklly duties for the Patrol is wifes car so school drop off shopping etc etc so it just chews through the fuel.

I also had a Maverick for a while and it would cycle through the gears as well but only lock off the convertor if you went over 90k's which is what my current bus should do........

Can't see why two days is required to fault find it as the bus does it consistantly and has for as long as I have owned it. I think tappets out and low revs made fuel usage high but now that it has been highlighted as an issue I am going to try to fix it up.

Without lock up convertor in 4th at 60 it sits at a better 1600 RPM and doesn't struggle.....would be better on fuel, motor and tranny and hopefully my hip pocket if consumption fell to mid teens....