V70 Diesel - Black smoke

[V70Zig]

Originally Posted by Hollowave101

Interested....

What quantity per tank? What product name? Pour as your fill the tank?

Sorry 2 hijack this thread!

I use Comma 2 stroke, mineral, low ash in mine. 300ml per 60 litres so the same volume per litre as Mark S60D5 states above.
If you shop around you can get 5 litres for £15 ish (prices do change a lot) last time I got some it was less than £15...today £18.49, it must be getting popular ?
Never used the Shell V-Power or know the price difference........I'm happy using the 2 stroke

[martin_r_smith]

V-power for me too but if I can't get it then I add 2 stroke. These cars don't have to smoke at all. Mine is injecting way more fuel than a standard unit but with proper setting up of pump timing and injection quantity it doesn't smoke.

If someone has a particularly smokey tdi and has vol fcr, I would be interested to see what figure you have in live data for injection quantity. The engine must be at full operating temp (~87) and at normal idle speed, if the figure could be posted up I'd really appreciate it. Even if yours is clean and you have the software then post that too.

For example mine is currently 4.8mg.

[B00TS]

Just to add that a small split in an induction hose can also cause excessive smoke.

I daresay that the D5 has pre and post turbo pressure monitoring and so should there should be a code stored if there is a big leak. A small one may be enough to make smoke but not register though.

[V70Zig]

Originally Posted by martin_r_smith

V-power for me too but if I can't get it then I add 2 stroke. These cars don't have to smoke at all. Mine is injecting way more fuel than a standard unit but with proper setting up of pump timing and injection quantity it doesn't smoke.

If someone has a particularly smokey tdi and has vol fcr, I would be interested to see what figure you have in live data for injection quantity. The engine must be at full operating temp (~87) and at normal idle speed, if the figure could be posted up I'd really appreciate it. Even if yours is clean and you have the software then post that too.

For example mine is currently 4.8mg.

Mine only really smokes after "grandadding" for a while on first "boot" but after that it's fine.

Here you go Martin......4.0mg. according to Vida Dice.

[brickman]

6.0/6.1mg for me!
But drops to 5.2/4.8 as the revs climb through 1200/1500 rpm, so it advances just fine!

Tis always smokey at idle, just ran a litre of liqui moly diesel purge through it, made a notable difference to <2000 rpm pickup, same over that. Idle a little less vibration and now almost no smoke at idle (when warm). More injection noise though, very clear to hear the tick tick tick.

[martin_r_smith]

Originally Posted by brickman

6.0/6.1mg for me!
But drops to 5.2/4.8 as the revs climb through 1200/1500 rpm, so it advances just fine!

Tis always smokey at idle, just ran a litre of liqui moly diesel purge through it, made a notable difference to <2000 rpm pickup, same over that. Idle a little less vibration and now almost no smoke at idle (when warm). More injection noise though, very clear to hear the tick tick tick.

6.0 mg is on the high side. Now I don't mean your injecting to much fuel but actually less. The higher the IQ value the lower the amount of fuel, the lower the IQ value the more fuel is added, strange I know!

What the value refers to is the fuel quantity adjuster position sensor. This monitors the quantity adjuster and tells the ecu whats going on. Now if it sees 6mg at idle the signal is sent and the ecu thinks that's too much (factory set is 4.5mg) so reduces the fuel accordingly. On the flip side, if the sensor sees 3mg the ecu will up the fuel.

I experienced some very poor starting issues last year and after checking the usual suspects, timing etc, I noticed my IQ was 7.6mg! So the ecu was limiting the amount if fuel so much (because it thought loads was being injected) that the car took a lot of cranking.

Now I personally use this to my advantage to make small adjustments to the fuelling without having to remap every time. If I want ultimate power and don't mind the smoke, I may knock it down as low as 2.5mg (any lower and the car shakes at idle), so the ecu increases the actual injection quantity. If I wish to do a long journey and save on fuel I may up it to say 6.5mg so the injected quantity is reduced thus making it more economical.

I hope this info is useful to someone.

[V70Zig]

Originally Posted by martin_r_smith

6.0 mg is on the high side. Now I don't mean your injecting to much fuel but actually less. The higher the IQ value the lower the amount of fuel, the lower the IQ value the more fuel is added, strange I know!

What the value refers to is the fuel quantity adjuster position sensor. This monitors the quantity adjuster and tells the ecu whats going on. Now if it sees 6mg at idle the signal is sent and the ecu thinks that's too much (factory set is 4.5mg) so reduces the fuel accordingly. On the flip side, if the sensor sees 3mg the ecu will up the fuel.

I experienced some very poor starting issues last year and after checking the usual suspects, timing etc, I noticed my IQ was 7.6mg! So the ecu was limiting the amount if fuel so much (because it thought loads was being injected) that the car took a lot of cranking.

Now I personally use this to my advantage to make small adjustments to the fuelling without having to remap every time. If I want ultimate power and don't mind the smoke, I may knock it down as low as 2.5mg (any lower and the car shakes at idle), so the ecu increases the actual injection quantity. If I wish to do a long journey and save on fuel I may up it to say 6.5mg so the injected quantity is reduced thus making it more economical.

I hope this info is useful to someone.

Well....I've never used Vida to adjust any fuel settings......will have a gander soon and report back.

[martin_r_smith]

You can't use it to adjust. Changing the IQ is a mechanical adjustment made by moving the position sensor. This is achieved by loosening 3 bolts on the pump head and tapping the top in which ever way the adjustment is needed, to the left to decrease value and thus increase fuel, to the right to increase value and thus decrease fuel.

The amount of movement needed is miniscule! 1/2mm could benefit the difference between 4mg and 6mg. If there is enough interest I could do a how to I guess.

But search for tdi hammer mod on Google and it should give you an idea, although mostly for 4cyl VAG engines but the principles are the same.

[brickman]

Again cracking info Martin, you should write a big guide on the system as by now its likely you are more knowledgeable than any VAG tech was even back when there were loads of these engines around.

[B00TS]

Martin was kind enough to enlighten me about this setting too.

A bit more anecdotal info: Mine was fairly smoky and had idle stutter when the car was not stationary. The IQ at that time was 2.6.

I did some hammer modding to raise it to 3.0 and this cured the idle stutter and did improve the smoke a bit but it's still overfuelling under certain conditions. Interestingly this adjustment also knocked about 5 mpg off the trip computer's average.

I'm going to whack it again and set to 4.0. I expect this will cure the overfuelling and thus the smoke but if it curbs the power significantly I may decide to compromise on 3.5 because I like the power!

Some more on how it works: (my guessing only though - I'm perfectly happy to be corrected!)

The value we're talking about here is the readout from the ECU in Vol-FCR and it's a bit odd that they labelled it 'Injection Quantity' and gave it mg/stroke units as it's really not! It would have been much clearer to call it something like 'Requested Injection Volume' and dimension it in Volts or %.

When we're looking at the live readings, what's happening is that the ECU is maintaining the idle speed using closed-loop control. It uses the crank speed sensor (probably backed up by the frequency of the injector lift signal) and keeps trimming the fuel quantity signal to the pump until the idle speed is steady. For a particular engine with no load, the real-world injection rate this point is probably around 4.0 mg/stroke and never changes. What comes out in the live data as 'IQ' is a measure of what electrical input the ECU is having to give to the fuel adjuster to achieve the steady idle state.

So, if the engine is running at the correct no-load idle speed, it's consuming 4 mg/stroke of diesel - that's a fixed value determined by the characteristics of the engine. What varies from engine to engine (and is adjusted by the hammer mod) is the physical position of the fuel adjuster, in the top section of the pump body, in relation to the fuel metering collar, in the lower section of the pump body. That relationship is what determines the 'electrical' IQ that the ECU has to apply to the fuel adjuster to get the pump to deliver 4 mg/stroke in the real world.

What's interesting (and a bit odd!) is that the ECU selects different fuelling maps, for the whole engine operating range, based on what that initial requested IQ value at idle is.

Too low and it overfuels leading to smoke and idle stutter. Too high and it underfuels leading to starting problems and less power.

Boots.