Thread: My (more than usual) sluggish 300tdi

^ Agree completely with Chris, however I'll say that I reckon my "normal average" EGTs are 50-100 higher than yours. I can easily hit 500's up a hill on the freeway.

Interesting that you appear to have lower EGTs than me and you've tweaked your pump too. Have you increased boost at all?

What tyres are you running Chris?

Originally Posted by Judo

^ Agree completely with Chris, however I'll say that I reckon my "normal average" EGTs are 50-100 higher than yours. I can easily hit 500's up a hill on the freeway.

Interesting that you appear to have lower EGTs than me and you've tweaked your pump too. Have you increased boost at all?

What tyres are you running Chris?

Hey Justin,

No boost tweak at this stage (planned though). I'm running on 245/75R16's as I should have mentioned earlier. I have only tweaked the pump on the no to low boost with the so called "smoke screw." It gave me a little extra up and go off the line and a little better responsiveness.

I am generally fairly pedantic on keeping the temps low, so I try to make sure that if I can back off a little bit and still maintain speed I will. I found that my "sports\performance car" driving habits of previous cars caused me to just leave the go pedal at one spot up hill (maintaining a particular speed) without actually realising I could have let off a bit and still kept the same speed.

That is also one thing different between petrol and turbo diesels that I have noticed. Science and stuff shows that a throttle position closer to WOT (Wide-Open Throttle) in a higher gear in fact uses less fuel due to the greater intake of air. This is however not the case with our diesels as the throttle directly affects fuel flow rather than air flow. So a WOT condition in a diesel would see LOTS more fuel going in causing higher temps and higher fuel usage. So different driving styles needed for different cars. Something a lot of people don't always think about.

Sorry for the hijack, just an interesting tidbit. On the temps though, the temps I stated are generally for sticking with the "flat ground gear" and maintaining speed. A lot of the time I change gears\slow down these days, in my old age (25) I have mellowed a little and don't really worry about "being first" any more. One thing I always remind myself, if the temp is lower, so is the fuel usage!

Chris

Thanks for the reply Chris,
Re: smoke, I get a good puff on start up but at idle I can see it, which makes me think it's an injector pump tuning problem - as you said. I had a quick feel around the turbo / intercooler hoses and they certainly feel a bit long in the tooth. I want to get some time under the bonnet this week.
I was also thinking that perhaps the engine timing is a little "late" which could cause unburnt fuel/white smoke as far as I know.

Interesting to hear you EGTs, impressively low! And in that note, I'm not sure I'm too confident opening up my injector pump, do you, or anyone, recommend a quality diesel tuner in Melbourne?

Thanks again for all your responses!

Originally Posted by libertyts

Hey Justin,

No boost tweak at this stage (planned though). I'm running on 245/75R16's as I should have mentioned earlier. I have only tweaked the pump on the no to low boost with the so called "smoke screw." It gave me a little extra up and go off the line and a little better responsiveness.

I am generally fairly pedantic on keeping the temps low, so I try to make sure that if I can back off a little bit and still maintain speed I will. I found that my "sports\performance car" driving habits of previous cars caused me to just leave the go pedal at one spot up hill (maintaining a particular speed) without actually realising I could have let off a bit and still kept the same speed.

That is also one thing different between petrol and turbo diesels that I have noticed. Science and stuff shows that a throttle position closer to WOT (Wide-Open Throttle) in a higher gear in fact uses less fuel due to the greater intake of air. This is however not the case with our diesels as the throttle directly affects fuel flow rather than air flow. So a WOT condition in a diesel would see LOTS more fuel going in causing higher temps and higher fuel usage. So different driving styles needed for different cars. Something a lot of people don't always think about.

Sorry for the hijack, just an interesting tidbit. On the temps though, the temps I stated are generally for sticking with the "flat ground gear" and maintaining speed. A lot of the time I change gears\slow down these days, in my old age (25) I have mellowed a little and don't really worry about "being first" any more. One thing I always remind myself, if the temp is lower, so is the fuel usage!

Chris

Same tyres as me... I hadn't seriously considered tweaking the pump until now, but if I can do it for only down low revs, I'm pretty keen! It's down low where I really feel the TDI lacks. I shall have to look into this....

Flexual, sorry I don't know of a good diesel tuner. Try a search on the forums - I would guess that someone has asked that question before!

Hey mate,

On these engines I'm fairly certain timing is not going to be your issue, they are fairly simple beasts and much different to a petrol engine where timing would put the spark in the wrong part of the cycle.

Are you saying the smoke on idle is white? If this is the case then there is some bigger problems with your engine. You are likely burning oil and if it's smoking visibly at idle, quite a lot of oil. You could have a head issue amongst other things. Sorry to be the doom and gloom king, but it is something you probably need to get looked at soon.

I'd love to offer my help, but obviously being in WA that's a little hard. I'm hoping someone from Vic will jump on here soon and offer a hand, to at least have a look. That's what we're about here as a community as far as I'm concerned.

I don't know any diesel tuners that I could recommend in Vic. There is an awesome one in Tassie!

If this is not the case then, the fuel pump is quite easy to adjust. There is a number of guides on here on how to go about it. I have a fairly comprehensive guide at home. So if you can't find something suitable for your knowledge/skill level let me know and I can send you a copy after work. One thing to keep in mind while working on the pump is to mark your stating points properly and write down EVERY change you make. If you don't, you will end up in all sorts of pain. The EGT gauge you have is essential for tuning the pump properly without breaking things. Only make small adjustments at a time and take the disco for a decent test drive (flat, small hills, big short hills, big long hills at varying speeds) after each change you make so you know what change does what for you in the end.

Chris

Originally Posted by Flexual

Factory temp gauge, seems to behave itself. I've got a coolant level sensor alarm too, which hasn't tripped in yonks. There is smoke, it's light in colour and noticeable at idle, heavier under throttle. More throttle, more smoke.
The pump, as far as I know was set to factory, but it was done 3rd party so I've really no idea. Hence wanting to find someone who knows how to tune them properly.

I had similar issues to you and it turned out to be the head. Maybe get your local shop to do a compression then an exhaust gas test on the overflow tank. They are both a cheap way to rule it out.

Mine was over heating under load and setting everything else off. After the new head I was getting better performance.

Well the smoke isn't white per sè, but it's not very dark... And Yep I can see a bit at idle.
I'm hoping its not an oil burning problem, it's got a new head and gasket and I'm scared to think of pulling the bottom end apart!

I've got a guide on the injector pump, so I might start with basic torx adjustments first and see how I go. I've read countless horror stories of injector pumps being modified!

Re timing, surely fuel late delivery would cause issues?

In regards to a mechanic, I've had so many people look at it, and so many issues, I think I should just do it all myself! Or at least try

Thanks again

at the end of the day they are a 15yr+ old diesel. The fact it can go up Mt baw baw fully loaded is pretty spesh