[Mpower]

Black smoke means its running rich. It happens in diesels when you step on the throttle hard and due to turbo lag, the air is yet to catch up with the fuel. Should'nt happen at steady state cruising.

[nitrous]

Mpower, even Naturally Aspirating diesel engines have the problem.

[rzoster]

Originally Posted by Mpower

Black smoke means its running rich. It happens in diesels when you step on the throttle hard and due to turbo lag, the air is yet to catch up with the fuel. Should'nt happen at steady state cruising.

I can't figure out how turbo lag is connected with this?
I thought the ECU would be fast enough to respond to any quick changes in throttling and make sure that the right proportion of air-fuel mixture is maintained. Is the loop that slow, or is it because of improper placement of the sensors?

[ananthkamath]

Originally Posted by rzoster

I can't figure out how turbo lag is connected with this?
I thought the ECU would be fast enough to respond to any quick changes in throttling and make sure that the right proportion of air-fuel mixture is maintained. Is the loop that slow, or is it because of improper placement of the sensors?

diesels dont have anything such as a right proportion of air-fuel mixture....in fact the engine speed is varied by making the mixture richer or leaner....if you go to a diesel tuner forum they discuss things such as "overfueling" meaning that when black smoke is coming out the tailpipe, max power is being obtained .

[Steeroid]

Originally Posted by Mpower

Black smoke means its running rich. It happens in diesels when you step on the throttle hard and due to turbo lag, the air is yet to catch up with the fuel. Should'nt happen at steady state cruising.

You're right, Mpower - this happens only when I accelerate hard. Thereafter there's NO smoke even if I'm cruising at 120...it disappears once you lift off the throttle.

[Mpower]

Originally Posted by rzoster

I can't figure out how turbo lag is connected with this?
I thought the ECU would be fast enough to respond to any quick changes in throttling and make sure that the right proportion of air-fuel mixture is maintained. Is the loop that slow, or is it because of improper placement of the sensors?

Actually the problem is because the ECU is too fast.
These diesels dont have a mass airflow sensor. When you step on the gaspedal, the ECU thinks you need power and immediately dumps excess fuel. But you also need excess air to burn it and due to lag, it takes a while to get there, which is why you see the puff of smoke momentarily.

Nitrous, same concept in NA diesels too, but should be much less because of no turbo. Its mostly poor calibration of pump.

[nitrous]

Its mostly poor calibration of pump.

There. U got it right now.

[Rayden]

Originally Posted by Mpower

Black smoke means its running rich. It happens in diesels when you step on the throttle hard and due to turbo lag, the air is yet to catch up with the fuel. Should'nt happen at steady state cruising.

I have never ever seen the Qualis smoking, have you?
No wonder taxi wallas want a relaunch of the Qualis.

[adit1329]

correct me if i am wrong..but i read on the forum some place that if insisted, the tata guys do some mods to reduce the smoke..

one of the tbhpians has got it done...and has posted a thread on the same

[abhibh]

Its because of bad quality of diesel used. Had the same problem too changed the pump to COCO (Company Owned Company Operated) and problem got solved

[directinjection]

Originally Posted by Rayden

I have never ever seen the Qualis smoking, have you?
No wonder taxi wallas want a relaunch of the Qualis.

Whereas the Innova with supposedly more advanced technology gives visible black smoke.

[nitinbhag]

Originally Posted by adit1329

correct me if i am wrong..but i read on the forum some place that if insisted, the tata guys do some mods to reduce the smoke..

one of the tbhpians has got it done...and has posted a thread on the same

True.. 2-3 months ago, Tata called in all Dicors for an ECU update and EGR system revision.. Smoke emission has gone down drastically after this.. Now I only notice a hint of smoke while starting in the morning..

[Steeroid]

Originally Posted by nitinbhag

True.. 2-3 months ago, Tata called in all Dicors for an ECU update and EGR system revision.. Smoke emission has gone down drastically after this.. Now I only notice a hint of smoke while starting in the morning..

I agree. This was done proactively by Tata Motors and inot based on how often you pester them (or 'insist').

Smoke is now a good indicator of the quality of fuel - there is NO smoke when the fuel is good, while you will see a bit of (still acceptable) smoke when your fuel is adultrated. The trick is to look at your rear view at night when there is another vehicle behind you (their headlamp helps) when you accelerate hard - if there is a trace of smoke you've been drinking from the wrong pub.

[PRADEEP KUMAR]

Well i hvn't come across this problem in Scorpio crde yet!

[cooldude1988765]

Originally Posted by directinjection

Whereas the Innova with supposedly more advanced technology gives visible black smoke.

My grandfather's Innova too had the same problem. Changing the fuel station solved the problem.