Help with a bit of Black smoke issue please.

[titch]

Hi I am after a bit of help with a bit of a strange black smoking issue please.

Not that long ago the car (2001 hdi 172K) just wouldn’t start, after great help on here it was the ecu, so I got one from Pro Steve with one of his stage 1 + maps on.
Fitted it and car started and ran great.
 
While I had the car on PP2000 working out the above fault it also had a MAF fault logged on there.
So not that long after fitting the new ecu I replaced the MAF with one I got from a mate, it was a genuine item and was only about 2 months old, it made the car go so much better but I did notice that at full throttle under hard acceleration it smoked quite a bit of Black smoke.  Which it didn’t do with the old MAF fitted, but if you back off the throttle ever so slightly then it stops smoking.
 
I have unplugged the new MAF and taken it for a drive and as to be expected there is a slight drop in power nothing major but  there is next to no smoke at any time.
I have checked for boost leaks there is a tiny one at the inlet elbow but nothing major but thats been there a while and it never has smoked before only since fitting the new MAF, the boost leak will be sorted out soon. The EGR is blanked unplugged and has been mapped out of the ecu. Has a DE cat and straight through exhaust fitted too.
 
So could there be something wrong with the new MAF that causes the black smoke, I don’t really want to go and buy another genuine one and it be no different?
 
Cheers Titch 

[pro_steve]

I would focus more on the mileage and boost leaks etc. The new MAF is giving a higher air flow reading which allows the ECU to inject more fuel.

Either there isn't enough air to burn the fuel cleanly (boost leak, or too much fuel in the remap), or the EGR is faulty (unplug it and blank it to be sure), or it's just the high mileage and your engine isn't up to the full stage 1 + remap.

[titch]

I would focus more on the mileage and boost leaks etc. The new MAF is giving a higher air flow reading which allows the ECU to inject more fuel.

Either there isn't enough air to burn the fuel cleanly (boost leak, or too much fuel in the remap), or the EGR is faulty (unplug it and blank it to be sure), or it's just the high mileage and your engine isn't up to the full stage 1 + remap.

Cheers Steve the egr is blanked and un plugged and you mapped it out when i got the ecu.

Will sort out the little boost leak on the inlet and see what happens, i have got a new gasket for it. it is just a bit weird as it only does it on full throttle all other times there is no smoke at all.

[Poodle]

Could be worn injectors, knackered turbo, excess blowby... Any number of things common on a high-mileage engine that could cause excess smoke under high load tbh. Do you have a boost gauge fitted by any chance? Just to see if the turbo's boosting properly.

[titch]

Could be worn injectors, knackered turbo, excess blowby... Any number of things common on a high-mileage engine that could cause excess smoke under high load tbh. Do you have a boost gauge fitted by any chance? Just to see if the turbo's boosting properly.

No i don't have a boost gauge fitted, think i might have to get one fitted just to see 

[Poodle]

Fairy snuff, injector leak off and cylinder leak-down tests are other easy and cheap things to check. In all honesty i'd be inclined to just continue driving it with a mind to the issue, otherwise you could be chasing your tail for months and spending a lot on needless parts.

The only experience i can offer is that i had a similar problem before i fitted refurbished injectors.

[titch]

Yeah i have got a set of low mileage 076 injectors with new plastic guides and copper washers in the garage waiting to go in, i just need to pull my finger out and get them fitted, as mine are the originals and do tick quite a bit.

But i only noticed it when i put the new MAF on, so thought i would check that first.

[titch]

Right think this might be sorted, it was bugging me all afternoon, i remember when i  blanked up the egr i unplugged it, but i didn't unplug ( i forgot ) the air dozer solenoid, so just been out to the car popped the bonnet and it was still plugged in. I am not 100% sure really what the air dozer even does, it is now un plugged took the car for a quick spin now at full throttle there is a very tiny bit of smoke next to nothing.

So i guess the air dozer may of been preventing enough air to burn the fuel cleanly as Steve said ?

What do you think?

Cheers Titch

[Toms306]

The air doser partially closes the intake when the EGR is open... So yeah sounds like you're right!

[Poodle]

Ah that'll do it lol. If it's fixed the issue it's fixed the issue.

[titch]

Yeah done 300 + miles now and it is better, and now on full throttle it is just a little mist/haze compared to a thick black cloud. So must of been that.