Diesel combustion questions?
Discussion
Had my 306 Hdi90 remapped the other day.
Was clean as a whistle before but now off boost at say 1250>1500rpm at WOT (ie, 30 zone kinda work) it puffs a bit of smoke constantly, not huge amounts but enough to have left enough grime to write onto the rear bumper with my finger over 2 days of having the remap done.
Now I have removed the cat if that makes a difference, and the EGR isn't functioning either (disconnected) so it is pure A/F ratio business I assume (all before remap)
Once on boost it goes clean with a small common tuned derv puff of dark smoke. Just this off-boost high gear stuff.
Now the exhaust points out backwards like a petrol, not down, so this could make it seem worse than it really is vs other diesels.
I've put a 2x dose of Redex derv treatment into a full tank, so not sure what might happen. Will Redex make it smoke until it's used up, then if it's worked it'll go clean?
What else could be causing the smoke at low rpm apart from too rich A/F ratio?
Does injector atomisation and fitness really effect low end alot, considering it ran clean before low-end and now on boost it's clean too.
I have a feeling it's just over fuelling but this almost exact same map is applied to other cars perfectly fine (after a treatment of redex or two apparently)
Thanks for any hints or tips as to what else it could be causing it to smoke a bit.
Dave
Was clean as a whistle before but now off boost at say 1250>1500rpm at WOT (ie, 30 zone kinda work) it puffs a bit of smoke constantly, not huge amounts but enough to have left enough grime to write onto the rear bumper with my finger over 2 days of having the remap done.
Now I have removed the cat if that makes a difference, and the EGR isn't functioning either (disconnected) so it is pure A/F ratio business I assume (all before remap)
Once on boost it goes clean with a small common tuned derv puff of dark smoke. Just this off-boost high gear stuff.
Now the exhaust points out backwards like a petrol, not down, so this could make it seem worse than it really is vs other diesels.
I've put a 2x dose of Redex derv treatment into a full tank, so not sure what might happen. Will Redex make it smoke until it's used up, then if it's worked it'll go clean?
What else could be causing the smoke at low rpm apart from too rich A/F ratio?
Does injector atomisation and fitness really effect low end alot, considering it ran clean before low-end and now on boost it's clean too.
I have a feeling it's just over fuelling but this almost exact same map is applied to other cars perfectly fine (after a treatment of redex or two apparently)
Thanks for any hints or tips as to what else it could be causing it to smoke a bit.
Dave
combemarshal said:
I think you answered most of your own questions there!!
Tuned up diesels always tend to be smokey, you should have seen the black clouds at track level at Combe when the VW cup was there!
Tuned up diesels always tend to be smokey, you should have seen the black clouds at track level at Combe when the VW cup was there!
I'm good at that. I answer my questions, but still try to find answers to possible problems just in case
I guess I'm just going to have to wait and see if this Redex does the job. I've heard it can make the car more smokey while it's in there, then on a fresh tank it'll run clean(er).
Also have dyno tomorrow so I can view the A/F mixture post tune and see whats going on.
Just loose that stealthy derv appearance now. Quite clear it's a diesel when I put my foot down now!
Dave
Jacking up the fuelling on-boost is all very well but if you don't back it off off-boost you're going to get black smoke. I suspect the map is not adequately reducing fuelling off-boost, perhaps in order to make the transition to on-boost less of a jump.
With a proper diesel you'd just have a pressure capsule acting to move the fuel rack limit stop, and you'd have a screw to twiddle to adjust it...
With a proper diesel you'd just have a pressure capsule acting to move the fuel rack limit stop, and you'd have a screw to twiddle to adjust it...
Yep, this engine uses maps and AFM to control everything, no boost sensor apparently.
Considering my pre-tune dyno was spot on stock I'm guessing the engine is fit as a fiddle.
Might just be a blocked injector. In the SH from the last owner (from new) from Peugeot there are reports of "bit smokey under power, 1l of fuel conditioner added" or whatever...!?
My old 405 Tdi had a mechanical pump, and that was tought to tune to get on-boost fuelling gradient right as the boost built up, but this is like plain and simple NA diesel fuelling totally out... my dyno tomorrow morning will show me the AFR anyway so that could be usefull.
Been doing a bit of reading and indeed Redex can generate particulates, not sure how or why but it can, and I put 2x tanks worth in oops. Tie that in with no cat converter and it's probably worse than it should be right now for smoking, but hopefully will clear up on the next tank... fingers crossed.
All I can do for now is wait and see what the next tank of clean diesel and dyno comes up with... will do the fuel filter too
Main worry is sooting up the engine more, or is that not a worry at ~ 14.7 AFR (just smoking), or will exhaust temps be maybe a bit wild?
Tempted to get the injectors ultrasonic cleaned maybe, then I can be 100% certain it's not them and remove them from the problem...
Dave
Considering my pre-tune dyno was spot on stock I'm guessing the engine is fit as a fiddle.
Might just be a blocked injector. In the SH from the last owner (from new) from Peugeot there are reports of "bit smokey under power, 1l of fuel conditioner added" or whatever...!?
My old 405 Tdi had a mechanical pump, and that was tought to tune to get on-boost fuelling gradient right as the boost built up, but this is like plain and simple NA diesel fuelling totally out... my dyno tomorrow morning will show me the AFR anyway so that could be usefull.
Been doing a bit of reading and indeed Redex can generate particulates, not sure how or why but it can, and I put 2x tanks worth in
oops. Tie that in with no cat converter and it's probably worse than it should be right now for smoking, but hopefully will clear up on the next tank... fingers crossed. All I can do for now is wait and see what the next tank of clean diesel and dyno comes up with... will do the fuel filter too
Main worry is sooting up the engine more, or is that not a worry at ~ 14.7 AFR (just smoking), or will exhaust temps be maybe a bit wild?
Tempted to get the injectors ultrasonic cleaned maybe, then I can be 100% certain it's not them and remove them from the problem...
Dave
Yeah, I used to use that trick on my old 405 Tdi, mechanical pump, and relatively epic lag meant that a haze of smoke got the EGT up and the turbo kicking in a good 250rpm sooner.
Thing is on my car, coming on to boost it's a clearly defined hit and a puff of smoke (not black and solid, but like what VAG's up slip roads do )... just off boost at say 1000rpm>1500rpm in 4th or 5th especially, it's like just totally over-fuelled. Onto boost it's very nice and strong... the delivery and everything is lovely... just when you look behind you when WOT trundling in traffic at 30mph in top gear say
Can happily drive around it like I did in my 405, but they were a bugger to get right and I did it DIY. This one cost me £300 and is ECU controlled, you'd hope it was at least right...
Starting to think it's low-speed poor atomisation caused by dirty injectors and further emphasised by the double dose of Redex I bunged in straight after the remap (looking back would have been better leaving it to see what it settled down to )
Other people have used the same tune map (a forum member friend) just the other week and they are finding it fine with only on-boost puffs and a haze at the very top end.
Anyway, will just have to wait now, I think I've located all possible problem areas to check, it's just a matter of time to see what happens
Will get back if I need any advice on the results of my testing
Thanks for the interest and advice so far. Much appreciated!
Dave
Thing is on my car, coming on to boost it's a clearly defined hit and a puff of smoke (not black and solid, but like what VAG's up slip roads do
)... just off boost at say 1000rpm>1500rpm in 4th or 5th especially, it's like just totally over-fuelled. Onto boost it's very nice and strong... the delivery and everything is lovely... just when you look behind you when WOT trundling in traffic at 30mph in top gear say Can happily drive around it like I did in my 405, but they were a bugger to get right and I did it DIY. This one cost me £300 and is ECU controlled, you'd hope it was at least right...
Starting to think it's low-speed poor atomisation caused by dirty injectors and further emphasised by the double dose of Redex I bunged in straight after the remap (looking back would have been better leaving it to see what it settled down to
) Other people have used the same tune map (a forum member friend) just the other week and they are finding it fine with only on-boost puffs and a haze at the very top end.
Anyway, will just have to wait now, I think I've located all possible problem areas to check, it's just a matter of time to see what happens
Will get back if I need any advice on the results of my testing
Thanks for the interest and advice so far. Much appreciated!
Dave
kenmorton said:
If the Redex dosn't clean the injectors then what was the point of using it.
Well I'm sure it said it was meant to, but I keep reading all kinds of conflicting reports. Some say it can end up restricting injectors more, others say it cleans but encourages black smoking while present (so it's working but appears not to be)...
It's yet another one of those areas where the internet in general is of no use whatsoever, hence me asking here for some good general hints and tips from people in the know.
I have been advised Wynns is good stuff, "diesel injector cleaner", sounds like it one thing in mind
Or the trade seem to have access to some good products, it's just getting hold of them as a public consumer.
Just gonna have to do lots of pointless miles to burn the tank off and get it through the system asap to see what it does on fresh branded diesel (tempted to move away from Sainsburys now I'm on derv, their 97Ron super was good but not sure about their diesel)
Dave
Injector atomisation affects everything and I would strongly recommend that you look at other cleaners to clear the injector tips. There may come a time when you will be better off fitting reconditioned injectors with the carbon cleaned off them - because you are always going to be running fairly rich the likelihood of burning off deposits is very low, in fact you will add to them.
93bhp > 122bhp = 31%
165lbft > 205lbft = 24%
Rpm / AFRpre / AFRpost / %change
1200 N/A 15.4 na%
1600 17.6 14.6 20%
2000 17.2 14.3 20%
2400 17.6 14.3 23%
2800 18.4 14.7 25%
3200 18.8 15.0 25%
3600 19.6 15.4 27%
4000 20.0 15.6 28%
4400 20.1 16.0 26%
4800 20.8 16.3 28%
Note how AFR ratio change almost matches the torque curve change.
Also interesting was that on run 1, the power was ~118bhp, and the AFR dropped to ~13, the second run it ran 121bhp, then the third 121.8bhp, with the lowest AFR then being 14.3... clearly the rev to 5000rpm a few times blew some cobwebs out of the system.
Went for a razz this evening, giving it beans over 2000rpm for most of the time and it seemed nice and clean, only puffing when coming onto boost sub 2000rpm, but still leaving a hazy smoke when half>WOT at very low rpm in a high gear.
I think it's slowly opening up and bedding in, with the turbo working to 1.2bar vs 1.0bar stock, and the injectors flowing more, along with additive which is maybe cleaning and causing smoke as it goes along... poisioned chalice wrt to trying to assess possible faults
Too many variables right now but I'm tempted to say it's getting better, the dyno runs and AFR change kinda proved the "bedding in" theory!
Dave
SprintV8 said:
What was the cost of your remap and who done it.
Has it efected the emmision's at all.
I.E MOT smoke Test?.
Celtic tuning £300 (if the smoking stops, well worth it, if not, well then I'll be exercising my money back I think)
Smoking a bit off boost now, hoping it'll clear up.
Not sure on MOT... Don't know enough about injectors and cleaners to know whats going on. No one seems to know the answers to such questions so it's just a matter of wait and see... I hear Redex can cause smoke, so maybe thats it?
Only problem is waiting sucks, and 500+ miles to a tank and a double dose of Redex means I've got alot of driving to do to burn it all off to see
Dave
Edited by Mr Whippy on Sunday 23 July 16:26
Bah, smoking hasn't stopped.
Went for a razz at the weekend with lots of sustained WOT and the car just smoked more and more. Water temp was fine, but I guess after the AFM (cool air), the turbo was heating it up so much and the red hot manifold (no intercooler) it was just running rich right through the power band.
Let it cool off, changed fuel filter and tried brand new air filter, ran again, clean for 5 mins of hard use, then started to get fine hazeyness after another few mins of over-moor hilly bendy razzing.
Remap is fine day to day except it still smokes a bit off-boost (though that has got a touch better), but this heat soak issue is a problem now as the main reason for the remap was for a bit more grunt out on runs! Having to back off is silly on a series production car with a remap, and having to already drive around the smokey boosting zone to reduce smoke is silly too!
Money back time methinks.
The Superchips and Speedbuster maps are offering 116PS kind of outputs (114bhp ish) which I think is low enough to just take the edge off the smoke off-boost and also limit that heat soak issue to the point where it probably never propogates to the situation I had at the weekend.
Dave
Went for a razz at the weekend with lots of sustained WOT and the car just smoked more and more. Water temp was fine, but I guess after the AFM (cool air), the turbo was heating it up so much and the red hot manifold (no intercooler) it was just running rich right through the power band.
Let it cool off, changed fuel filter and tried brand new air filter, ran again, clean for 5 mins of hard use, then started to get fine hazeyness after another few mins of over-moor hilly bendy razzing.
Remap is fine day to day except it still smokes a bit off-boost (though that has got a touch better), but this heat soak issue is a problem now as the main reason for the remap was for a bit more grunt out on runs! Having to back off is silly on a series production car with a remap, and having to already drive around the smokey boosting zone to reduce smoke is silly too!
Money back time methinks.
The Superchips and Speedbuster maps are offering 116PS kind of outputs (114bhp ish) which I think is low enough to just take the edge off the smoke off-boost and also limit that heat soak issue to the point where it probably never propogates to the situation I had at the weekend.
Dave
Edited by Mr Whippy on Monday 31st July 09:48
For anyone still following.
Got a refund on the remap. They tried a few other maps with lower fuelling but that 1250>2000rpm zone was still too smokey for my liking, and you could tell overall power had gone.
I had my car reverted to standard and on my way to work it seemed so much nicer to drive. I could use the zone where it normally smoked by simply being in 5th gear down to 35mph and then accelerating back upto 50mph at WOT with a nice smooth progressive torque surge.
Before it was quicker, but maybe a touch "spiky" and far too smokey for WOT use in a higher gear and sustained low rpm!
Then I just thought why? Why did they try two new maps with less fuelling *overall* when my main problem was just in that off>on boost phase?
Surely keeping it stock below 2000rpm and then just keeping on letting the torque rise would be fine, then just curbing the overall through the rev-range to just curb the onset of smoke when it gets hot?
This is my stock, remapped and my "vision" of what would work.
In my view yes torque is later on at it's peak, but it's gonna be more driveable, smoother, and revvy. If that removed almost all the smoke in that "driving around town/semi urban zone" but then opened up for overtaking and fast driving (where your willing to change gear anyway), then why not go for this solution?
Just seems simple to me, or am I missing something when tuners just go all out for the biggest gains all over the place?
Am I alone in wanting a thoughtful remap that considers various factors, and not just simply an all out power map that compromises alot in the name of a bit more torque earlier on!
Dave
Got a refund on the remap. They tried a few other maps with lower fuelling but that 1250>2000rpm zone was still too smokey for my liking, and you could tell overall power had gone.
I had my car reverted to standard and on my way to work it seemed so much nicer to drive. I could use the zone where it normally smoked by simply being in 5th gear down to 35mph and then accelerating back upto 50mph at WOT with a nice smooth progressive torque surge.
Before it was quicker, but maybe a touch "spiky" and far too smokey for WOT use in a higher gear and sustained low rpm!
Then I just thought why? Why did they try two new maps with less fuelling *overall* when my main problem was just in that off>on boost phase?
Surely keeping it stock below 2000rpm and then just keeping on letting the torque rise would be fine, then just curbing the overall through the rev-range to just curb the onset of smoke when it gets hot?
This is my stock, remapped and my "vision" of what would work.
In my view yes torque is later on at it's peak, but it's gonna be more driveable, smoother, and revvy. If that removed almost all the smoke in that "driving around town/semi urban zone" but then opened up for overtaking and fast driving (where your willing to change gear anyway), then why not go for this solution?
Just seems simple to me, or am I missing something when tuners just go all out for the biggest gains all over the place?
Am I alone in wanting a thoughtful remap that considers various factors, and not just simply an all out power map that compromises alot in the name of a bit more torque earlier on!
Dave
Edited by Mr Whippy on Wednesday 2nd August 10:35
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