Smoking

[cdtisri]

All

I've got the CR1 Tuning Box fitted to my Cdti 150 and have done for over 14 months now - No problems at, great in fact. Anyway, decided yesterday to empty the tank and fill up to the rim with BP Ultimate go go juice. (Always had mixed fuel in the past). Anyway, I would agree with many on the site that the car certainly enjoys the ulimate fuel much much better the normal supermarket stuff. But to my point....booted the car this morning to see what the pick up was like with the new fuel and yes it went like stink, but seemed to be smoking like hell out the back, left the car behind in a plum of black smoke and kept pumping it out under load....is this right???

Cheers all

[Ste]

Yes.

The tune box is causing fuelling / timing changes from the normal calibration tables. What you see is the effect of this fuelling / timing change. More carbon make during the combustion process. But more power.

Unless it is smoking heavily all the time, it isn't really an issue. Only environmental / pollution.

Unfortunately, 'tune it' boxes usually compromise emissions in favour of power and sometimes fuel economy.

[VectraV6CDTi]

On my 3.0 V6 facelift I've fitted a CRD2 and it hasnt smoked once, I think this is mainly due to the fact it probably has a particulate filter (DPF). Although I dont think this is a good thing as is could be masking potential problems....

[Ste]

Yes, the DPF will trap all (well almost all) the smoke particulate material on the structure and oxidise it to CO2 when the conditions are right. Hence no smoke unless it has a hole in it.

[Ross DTi 2.2]

Yes.

The tune box is causing fuelling / timing changes from the normal calibration tables. What you see is the effect of this fuelling / timing change. More carbon make during the combustion process. But more power.

Unless it is smoking heavily all the time, it isn't really an issue. Only environmental / pollution.

Unfortunately, 'tune it' boxes usually compromise emissions in favour of power and sometimes fuel economy.

I don't understand how this can be. There is no "timing" on a diesel engine as there are no spark plugs to time. The turbo gives a full charge of air all the time due to the fuel/air mix igniting on compression rather than sparking.

There is no way to control valve-open duration because the engines don't have variators.

The only thing I can see these boxes doing, is to increase the fuel pressure, thereby increasing fuel volume in the cylinder. This is fine up to a point, but only so long as you have enough air to burn all the fuel. The reason you have black smoke is that the fuel to air ratio is too high. Possible fixes for this are a free flowing air filter or lowering the setting of your box slightly.

You won't lose any performance by lowering the setting on the box as the car is not burning all the fuel its chucking in on your present setting. Your mpg will improve though.

[Ste]

Ross.

Your understanding of how high pressure common rail diesels works isn't quite right. The injection timing CAN and IS changed by varying exactly when the fuel is injected into the already compressed air charge. Yes, rail pressure can be changed aswell. BUT changing injection timing and fuelling amount will make most difference. Higher rail pressure is one way of allowing these changes to be made.

Cheers

[Ross DTi 2.2]

Ross.

Your understanding of how high pressure common rail diesels works isn't quite right. The injection timing CAN and IS changed by varying exactly when the fuel is injected into the already compressed air charge. Yes, rail pressure can be changed aswell. BUT changing injection timing and fuelling amount will make most difference. Higher rail pressure is one way of allowing these changes to be made.

Cheers

Now I understand, it can be varied by changing the injector opening duration rather than the valve opening duration.

Do you agree though that black smoke equals not enough air in relation to fuel?

[Ste]

Timing is when the injector actually opens, fuelling amount is controlled by rail pressure and injection duration (longer duration and higher rail pressure = more fuel).
High smoke, or particulate matter (PM), does indeed indicate incomplete combustion. It may not as simple as too little air though. In normal road car engines I would agree that the air is not flowing well enough. But in tuned engines this may not be the case.

Diesel combustion process is VERY complicated. And injecting the same amount of fuel at different timings can have very different outcomes in terms of PM.

[Ian]

the CR1 is, put simply, a resistor that lowers the pressure signal sent to the ECU by a said amount right across the rev range. The ECU respnds by upping the pressure in the common rail to what it thinks is the correct amount. The CRD2 on the other hand varies the fuel pressure throughtout the rev range, depending on what map is loaded onto it. Injector timings are not affected by the boxes.

So cdtisri, I would do as Ross DTi 2.2 says and turn it down a notch.

[VauxVeteran]

You need NiCARette patches for it.