Vehicle & Technical > Discovery
300tdi need more power
Budgie:
--- Quote from: "TheBlueySilverThing" ---if your turning the diaphram and leaving the smoke screw, your not getting enough fuel vs the increase amount of air thats entering the cylinders due to it being denser as its cooler becouse of the intercooler
--- End quote ---
Now I maybe wrong here but, I was always told that the smoke screw only increased the initial amount of fuel as it compresses the diaphragm slightly, allowing the pin at the base of the diaphragm shaft to come out a wee bit more than standard. This is for low/no boost conditions.
Once the turbo is up to speed then that takes over and compresses the diaphragm further, increasing the fuel flow as the pin moves out further due to the shape of the offset shaft at the base of the diaphragm.
Thus, once the top of the diaphragm is clear of the bottom of the smoke screw the smoke screw does nothing to increase the fueling of the engine. It's all down to how the diaphragm offset shaft has been positioned and how far out the pin is allowed to go.
Altering the diaphragm and smoke screw will make quite a difference to how the motor drives and it's free to do, but follow the correct instructions and take note of the warnings about the exhaust gas temperatures increasing!! Details are available HERE. I would also clean the inside of the intercooler as this will also help.
You will get even more power if you put a larger intercooler in and if you don't fancy doing the alterations to the injector pump yourself then get the intercooler fitted at the supplier and they will set the pump for you. :wink:
L90OOK:
--- Quote from: "Budgie" ---
Now I maybe wrong here but, I was always told that the smoke screw only increased the initial amount of fuel as it compresses the diaphragm slightly, allowing the pin at the base of the diaphragm shaft to come out a wee bit more than standard. This is for low/no boost conditions.
Once the turbo is up to speed then that takes over and compresses the diaphragm further, increasing the fuel flow as the pin moves out further due to the shape of the offset shaft at the base of the diaphragm.
Thus, once the top of the diaphragm is clear of the bottom of the smoke screw the smoke screw does nothing to increase the fueling of the engine. It's all down to how the diaphragm offset shaft has been positioned and how far out the pin is allowed to go.
Altering the diaphram and smoke screw will make quite a difference to how the motor drives and it's free to do, but follow the correct instructions and take note of the warnings about the exhaust gas temperatures increasing!! Details are available HERE. I would also clean the inside of the intercooler as this will also help
You will get even more power if you put a larger intercooler in and if you don't fancy doing the alterations to the injector pump yourself then get the intercooler fitted at the supplier and they will set the pump for you. :wink:
--- End quote ---
You are correct!
Biggest gain is to remove the diaphram & put it back in for MOT time (30 second job) This allows the diaphram to depress another 5mm or so letting more fuel in & reducing turbo lag.
Turning the diaphram will also let more fuel in as it's on a eccentric pin. I have turned mine 30degrees from standard.
When first taking off the fuel pump diaphram housing ensure you mark it's "normal position" so you can reset it if needed.
The main fuelling screw is where the most damage to the engine can occur & personally I would leave it well alone. By turning the main fuelling screw 'in' you are increasing the amount of fuel at all stages, tickover to fuel boost. With increased fuelling here you are also increasing the Exhaust Gas Temperature (EGT) which is the main reason you will have cooling issues. A larger intercooler will help to reduce this but a larger intercooler sits infront of the radiator :-s
If you wish to increase the main fuelling then do so by 1/8 turn each time...they need very little adjustment. Take it for a drive & you should have no more smoke than a mist...not a black trail. Black smoke is unburnt fuel the engine can't cope with. Turning up the Main Fuelling screw can seriously damage your engine if you get it wrong!
Larger intercooler will give you a noticable increase in power aslong as its not obstructed by large winch, spots etc...
You can also increase the turbo boost pressure by screwing in the actuator rod...make sure it's no more than 1 bar pressure though. I know some are boosting at 1.2bar but 1 bar is still safe...especially as allot of Tdi's are getting on now!!
My preference in order of tuning a Tdi is:
1. Renew air filter...use standard not K&N type
2. Check throttle is opening all the way when peddle is depressed.
3. Clean intercooler out with paraffin...ensure dry before replacing.
4. Check hoses aren't collapsing/delaminated, if so get some silicone ones
5. Adjust pump diaphram as described above.
6. Increase turbo boost pressure to 1bar.
...if you are still not satisfied...
7. Larger intercooler
8. Adjust Main fuelling screw...monitor EGT
A rebuilt injector pump & new injectors will also help to increase the power of a Tdi with 100,000 + miles on it!! :roll:
extreme90:
yep yo right
but,
ive done 3 intercoolers now and all three where like me arse until the smoke screw was altered, off booste was rubbish and so was on boost
that was with the diaphram already at 90 on all
i do the smoke screw at work on the lathe
dan
Sharpshooter:
Well. I can only say from experiance but.
I have just fitted a full width Allisport intercooler to my 200Tdi Disco.
I also have an ITG Foam air filter.
As per Allisports instructions i have, adjusted the diaphragm so that the largest part of the step is towards the front of the engine. Also shortened the wastegate actuator rod approx 5mm.
I havnt adjusted the fuel at all. Im getting loads more performance and using less fuel.
On monday i had a car transporter trailer with an RRC on it in tow. Now thats about 6 tonnes.
I was pulling up hills in 5th and 4th no probs. And the fuel economy was good too.
I can only tell you what i have experienced, but that is what has worked for me.
NIVAD:
I also sometimes struggle towing with my 300tdi auto.
But as said i cleaned my intercooler out and i always like to put wynes injector cleaner in the fuel and its inproved mine a bit.
Like the sound of the intercoolers but fitting winch soon.
Got to say though best tow vehicle ive ever had..
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