Thread: Wind back the boost?

My 2 cents on this..

Regardless of your boost pressure, black smoke is caused mainly by unburnt fuel in the chamber. This comes about for 2 main reasons.

1. Too much fuel is injected and 2. the fuel is not correctly atomised during injection.

there is a relatively simple process of elimination for which it is and ideally you do the test before following Langy's ideas ( all good things to do on at least a 6 monthly basis IMHO) and again after.

You'll need a long flat bit of road, an easily attachable load (a 2 ton trailer works well) a friend to follow you in a vehicle that can match your speed and preferabley a pair of 2 ways.

Do the test with the vehicle warmed up and prefabley without winds or other outside influences. Depending on your gearing you may also not want the police present for this test... your vehicle may hit 110kph+ doing this test.

first up with the vehicle empty get up to about 50-60 kph in thrid and let it coast down to the speed you would normally downchange at(you should see very low boost on the gauge at this time). Stomp on the go pedal and hold it flat till you hit the rev limiter in the govenor.

Your friend should observe a dense cloud of black smoke untill your turbo winds up that will change to a moderate amount that peters off as vehicle speed increases and might come back again near top speed.

Repeat with the load on the results should be similar. (you can just do the test with the load on to save time but an unloaded test is your calibration run)

If your smoke trail doesent change after you hit full boost you are probabley over fueling and your fuel injection pump needs calibrating/servicing. (you may also notice some hunting at the govenor at full engine speed)

If your smoke trail does change after you hit full boost but the smoke returns higher in the RPM range you may have dirty injectors.

Depending on how dirty they are you might also have; hard starting on cold mornings, excess smoke at idle, poor pickup from idle or erratic idleing.

Of course you could just pull a couple of injectors and get them serviced or inspected, by eyeball immedieately after a good hard run there should be no hard to remove carbon on the injectors nozzles. Hard to remove carbon is typical of consistant overfueling.

When following Langy's advice Id suggest doing all but the injector cleaner to start with, if this solves your problem you were over fueling due to lack of air. It wont hurt to add the injector cleaner if this is the fault.


Dave

"In a Landrover the other vehicle is your crumple zone."

Originally Posted by Blknight.aus

My 2 cents on this..

Regardless of your boost pressure, black smoke is caused mainly by unburnt fuel in the chamber. This comes about for 2 main reasons.

1. Too much fuel is injected and 2. the fuel is not correctly atomised during injection.

there is a relatively simple process of elimination for which it is and ideally you do the test before following Langy's ideas ( all good things to do on at least a 6 monthly basis IMHO) and again after.

You'll need a long flat bit of road, an easily attachable load (a 2 ton trailer works well) a friend to follow you in a vehicle that can match your speed and preferabley a pair of 2 ways.

Do the test with the vehicle warmed up and prefabley without winds or other outside influences. Depending on your gearing you may also not want the police present for this test... your vehicle may hit 110kph+ doing this test.

first up with the vehicle empty get up to about 50-60 kph in thrid and let it coast down to the speed you would normally downchange at(you should see very low boost on the gauge at this time). Stomp on the go pedal and hold it flat till you hit the rev limiter in the govenor.

Your friend should observe a dense cloud of black smoke untill your turbo winds up that will change to a moderate amount that peters off as vehicle speed increases and might come back again near top speed.

Repeat with the load on the results should be similar. (you can just do the test with the load on to save time but an unloaded test is your calibration run)

If your smoke trail doesent change after you hit full boost you are probabley over fueling and your fuel injection pump needs calibrating/servicing. (you may also notice some hunting at the govenor at full engine speed)

If your smoke trail does change after you hit full boost but the smoke returns higher in the RPM range you may have dirty injectors.

Depending on how dirty they are you might also have; hard starting on cold mornings, excess smoke at idle, poor pickup from idle or erratic idleing.

Of course you could just pull a couple of injectors and get them serviced or inspected, by eyeball immedieately after a good hard run there should be no hard to remove carbon on the injectors nozzles. Hard to remove carbon is typical of consistant overfueling.

When following Langy's advice Id suggest doing all but the injector cleaner to start with, if this solves your problem you were over fueling due to lack of air. It wont hurt to add the injector cleaner if this is the fault.


Dave

"In a Landrover the other vehicle is your crumple zone."

That is a very impressive post, very informative. Are you a diesel mechanic if so where abouts are you located.

Thanks for the helpful posts indeed everyone! I'll give that test a go Blknight and see what happens. At the moment If I'm driving at night time and there are cars behind me I can see plumes of smoke under load in their headlights and they usually back off pretty quickly But your way will be a much better indicator. I'll grab my brother and get him to observe. I've been running injector cleaner for a little bit now but that hasn't seemed to change much.

dobbo; believe it or not that's the smallest gauge they had in the shop!

As for the "spot the difference" you all failed! The answer was the rear demister switch. From factory they're in the top left spot but I moved it to the lower right. Also had to pull the switch apart and turn the symbol upside down. Also had to trim it to fit the switch upside down.

thanks for all your replies, I'll keep you posted!

Hi Camel Landy,

Can you tell me more about the spring??. Is this in the diaphragm (boost compensator). I've had my 200 Tdi tweaked for about 5 years and it blows it fair share of smoke at lower speeds.

I have an egt gauge and know that the max temp is about 650 deg C.