Black smoke on boost?

[boxerbean]

Took my Boxer 1.9td camper out for a long run this weekend covering about 600miles and returning about 29mpg, pretty pleased to actually have the thing running again with hardly any leaks...

When I give it full throttle there's a large amount of black smoke from the exhaust - more so than from the previous engine I'd say (This engine was lifted from a '94 306 turbo).

The van runs the original van turbo, and I was wondering if possibly it's set up a bit rich - how would I figure this out?

Also, when in fifth and with the throttle open ( and producing smoke ), there's a light metalic rattle coming from the RHS of the engine - sounds a little like a vibrating heatshield, lift the throttle a touch noise and smoke subsides.

Any input appreciated.

[EDC5]

Are you using the Lucas or Bosch pump on this?

Is the boost sompensation hose as well as all other pressure side hoses fine and leak free?

[boxerbean]

Here's the pump, Bosch?

How to spot a leak?


This looks suspect?

[EDC5]

Yeah, that looks like the Bosch pump to me. It's difficult to tell from the second picture to be honest if anything is amiss.

Were you down on power at all or could you hear a hissing noise like air escaping? This engine has the top mounted intercooler, is it making a good seal with the inlet manifold?

[boxerbean]

Not sure if it's down on power since I've got nothing to compare it with but it seems to pull ok on boost bearing in mind it's over three tonnes. Front mounted intercooler on the van, I'll look for leaks. Did wonder if the fuelling was set up differently for a car and van since the van has a different turbo I think?

[MikeT]

Did wonder if the fuelling was set up differently for a car and van since the van has a different turbo I think?

That is a distinct possibility though what are your thoughts on the metallic sound?

[boxerbean]

I'm not sure, I've been out and wound the boost compensation out two turns (and subsequently back in one), made almost no difference to smoke or power so I wound the max fuel screw out one full turn. One full turn out meant the engine produced zero power and wouldn't move forward! Half a turn out and the smoke is significantly better, power is down a bit but I can cope.
The tuning stuff I've found has all been about power as the expense of smoke not a great deal of help when you want a clean running efficient vehicle...

[MikeT]

I would put the max fuel screw back to it's exact original position for now. It's quite sensitive as you've discovered so even a few degrees can make a noticeable difference and can mess up your idle(s) as well as other settings.
What do you regard as the "boost compensation"? I suspect you should reset that to how it was also.

The on-boost fuelling adjustments are only accessible inside the LDA itself, namely the LDA pin "profile" and a star-wheel to adjust the LDA return spring pretension.

If you have the time, you might be interested in my Bosch strip down blog viewtopic.php?t=28590 posts 6 & 7 particularly.

[boxerbean]

Hi Mike, the screw on the top of the LDA (smoke screw) with a torx 2.5 head and 13mm lock nut. I've found the pump cross section diagram and it makes more sense to me now with the screw adjusting the start point for enrichment as the profiled pin moves in the vertical plane during boost. I watched a YouTube video of a guy 'tuning' a 306 and worked backwards so forgive me if I get things wrong.

The fuelling must be way off because when revved the exhaust is depositing soot on the drive.

I'll have a read of your thread now.

[MikeT]

That's what's commonly (and confusingly imo) called the "smoke screw". Ignore that, it's largely irrelevant anyway.

You may get a result setting the LDA pin so it uses a less aggressive profile (no9). If that proves insufficient, you can increase the return spring's tension (no5).
And if that proves inadequate, then you can make micro adjustments to the max fuel screw but I doubt that will be necessary.

[MikeT]

Alternately, you could try increasing boost

[ekjdm14]

Alternately, you could try increasing boost

That's the only sensible way to dial out the smoke IMO

In all seriousness though, being from a 306 there's a good chance the pump settings have been tampered with before & as mentioned it'd be worth checking the orientation of the LDA pin in case it's been turned to the more aggressive side of the 'cone' (or even replaced/modified as a member found on their Xantia a while back, the pin was reputedly from a Land Rover and had been ground to such a steep slope there was barely any material left!).

The screw on the top of the LDA housing is just the base setting for the LDA pin & determines how much, if any, overfuelling is allowed if you floor it while off boost. (this only really balances out off boost smoke Vs. turbo spool-up time from how I understand it). The actual on-boost fuelling is determined by the ramp of the LDA pin, and the star wheel that adjusts the spring tension governs the pressure at which the pin is able to be pushed down (basically, the "curve" of how quickly the overfuelling kicks in relative to boost.)

That's my (basic) understanding of the LDA system, and I agree the max fuel screw doesn't need to be touched for the moment as most of the setting up can be achieved by the LDA adjustments. Not sure if there's a base setting available for the pump or if it's just done by "feel"?