Why is my 300tdi not going so well?..

[Defendozer]

So my 300tdi is down on power, like a fair bit down on power!! Compared to when I bought it three years ago it is just sluggish and unresponsive and I'm not to happy! Anyway so here's the facts.... It is a standard tdi engine wise (as far as I know) apart from a tweaked injector pump by Bruce Davies, which I must say made a huge difference, it used to be able to accelerate up pretty much any big hill I could find in fifth gear and the best part was that it really blew minimal smoke, hardly more then a standard tdi.
Now looking back it was probably about a year and a half ago it just started slowing down a bit, blowing more smoke etc, a little bit harder to start, sort of just like it was getting old and tired (it's done 400k), so having the money and a bit of time I decided to rebuild it mid last year, the rebuild included all bottom end bearing shells, new piston rings, honed bores and a brand new AMC Turner performance head, and the other things like p gasket etc etc... Story short it is not going any better performance wise since that work, it's a dream to start now though, even on a cold morning I don't need to glow it at all and it fires up on the first or second turn over. So I'm thinking it's either blocked injectors or a worn injector pump??.... I'm really stumped by this one! Please share any ideas:)

[Bazzle218]

Just a quick check, Have you adjusted you accelerator cable, they will loosen off and cause a power loss. I have seen it a couple of times over the years. Start out diagnosis cheaply first, whens the last time you changed your air cleaner ? check turbo pipes and connections. Fuel filter and separator cleaned. Good luck.

[DeanoH]

Starts and runs well, no guts ? Assuming the work you've done already is OK I'd be looking at the turbo. Did you replace the turbo hoses with your rebuild ? could be one's de laminated internally or popped off. This would also give extra exhaust 'smoke' as unburned fuel is emitted. Hole in the intercooler, loose hose ?
I checked my turbo pressure by removing the hose from the turbo/manifold ? to the dump valve (pretty easy to see LHS of engine at rear below manifold near the turbo) and connected it via a length of clear PVC hose to a pressure gauge and went for a spin. :)


Deano :)

[Snail Bait]

My defender did the same thing a couple of years back, the pipe that goes from the turbo to the pump broke and did not supply air pressure to the injector pump for increased fuel supply. Fixed the pipe and right as rain.


95' 110 Defender
58' 109 Ex NSWFB SerII
50' 80"
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[Brett1066]

Had the same problem a couple of years ago, ended up replacing the turbo and all hoses and that seemed to do the job. Also cleaned out the intercooler. Good luck.

[Defendozer]

I haven't touched the accelerator cable but I'll have a look. Do you the mean the plastic screw thingy on the last bit of cable to the injector pump?
Turbo hoses have been replaced already with silicon ones.
Air filter was replaced with the rebuild.
Boost pressure is sitting at 16psi, that reading is the same from either the turbo or the inlet manifold. Bruce Davies might have turned that up originally, I'm not sure if that's part of their tune?....
There are no unusual turbo noises at all.
Fuel filter is getting near it's due replacement, I think I've got one at home so might try that when I get back.
I haven't checked the air supply hose to the injector pump, that is a possibility.
And the intercooler has been flushed out as well.

So no one thinks it is the expensive things like injectors or pump???

[Defendozer]

Or the turbo, they aren't cheap either!!
To be honest it most seems like it's not getting enough air into it.... But if it's boosting the standard 16psi of pressure then it should be fine shouldn't it?..

[Bazzle218]

yes the black round knob, just do it up to take slack out of cable, if you go to far the revs will start to rise.

[keith]

I had a similar problem with my td5, turned out to be a blocked particle remover (like a cat). I don't think your tdi will have one of these but could be somewhere else in exhaust with a blockage. To test remove exhaust from outlet of turbo and take it for a short drive, if there is an exhaust blockage you will feel the difference immediately.
Good luck
Keith

[Defendozer]

Haha sorry to be difficult but it's not the exhaust system either, I've had that off recently!

[camel_landy]

Could be a number of things but my money would be on the injectior pump not responding to the turbo boost.

Check the condition of the small pipe which runs from the turbo to the top of the pump. If that is leaking, it'll not increae the fuel:air mix.

If that's OK, it could be the internal workings of the pump. Undo the 4x screws and pop the top off the pump. Push on the diaphragm and check for free movement.

M

[Defendozer]

Ok that seems the best place to start I think.
I'm living away for work at the moment but I'll have a good look on the weekend and report back on what I find.

Thanks for the ideas everyone:)

[Jock The Rock]

Checked valve clearances?

When I first got my old 300 Tdi, it smashed one of the lash caps that sits on top of the valve. When I replaced that it made quite a noticeable difference to power

So the injectors and pump haven't been touched in 400,000km, apart from a tweak?

[justinc]

finally somebody has mentioned valve clearances:)

i have taught you well, grasshopper jock...:D


jc

[Defendozer]

Yes valve clearances have been checked twice since the rebuild and have been pretty spot on both times.

No they haven't been touched ever to my knowledge, I bought it with 365k and going from the very limited service history I got with it the only thing that has been done was the injector pump tune at 193k......

[Defendozer]

Hi all,

So here is bit of an update on my 300tdi.....

It still isn't going any better, if anything it's worse to be honest!
To give you an idea I have checked almost everything I can think of, I pulled the air system apart, replaced the boost line from the turbo to IP, checked valve clearances again, replaced the fuel filter and cleaned the water trap, checked all throttle linkage, checked for air leaks in the intercooling system and replaced the injectors.
New injectors made it run maybe a little bit smoother but didn't do anything power wise.

So short of something wrong with the IP I think the only possible and more likely thing is the turbo...?

I'm almost convinced it's the turbo now after I got to drive Dads Tdi again a few weeks ago, comparing the two my Def has heaps of turbo lag, you don't feel any "power" till about 12-13 psi where as you'll be able to notice the boost right down from about 4-5 psi in Dads.
Could this be a weak wastegate actuator spring problem? Even at full boost it feels flat.

What do you think?

[redrovertdi]

Do you have a egt guage? if the wastegate actuator spring has gone soft you will run very high egt and blow lots of smoke with no power, just befor xmas i had this happen to me, my turbo boosts to 22psi but it would only reach 14psi with egt of 750+ and lots of smoke and no power[the pump is tuned to the intercooler and turbo so when a link breaks in the chain.....], another wastegate actuator fixed the problem

[Defendozer]

I have actually just purchased an EGT gauge from Themoguard Instruments, should be able to get that fitted up next weekend.
Will be interesting to see what the results are, I'm pretty sure it will be somewhat similar to what you described.

And is it worth it to replace the whole turbo not just the actuator? The car has done 410k so I was thinking of just spending the extra and getting a new one... Maybe even a VGT would be really nice!!!
Any thoughts?..