RazMan
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| posted on 25/3/11 at 06:11 PM |
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Bang Pop Bang
Since fitting my homebrew ITBs I have been doing a lot of miles while tweaking the map. I have got things running quite nicely now except I get a fair
bit of popping and banging when slowing down. Now I don't mind a bit of 'character noise' but I freaked out a horse today and the
rider was lucky to stay on the beastie so I need to quieten things down a bit.
I have tried cutting all fuel above 2500rpm on 0% throttle but with no real improvement - is there a trick to this?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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jacko
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| posted on 25/3/11 at 06:22 PM |
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Do you have any air leeks in your exhaust ? that will make it back fire
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r1_pete
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| posted on 25/3/11 at 06:36 PM |
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If the ignition is over advanced it too can cause popping on overrun
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ashg
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| posted on 25/3/11 at 06:40 PM |
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its actually caused by being under fuelled at low throttle openings. There is not enough air velocity so the fuel puddles, doesn't ignite and
ends up burning in the exhaust. increase the fuelling as you come off the throttle a little before fuel cut comes in and it should cure it. theory
is that a little bit more fuel will cause it to ignite in the cylinder rather than the exhaust.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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David Jenkins
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| posted on 25/3/11 at 06:43 PM |
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My car pops a little bit on over-run when it's hot - I like it! 
If I have to pass a horse (there are a few riding schools near me) I usually floor the clutch and coast past nice and slowly. The engine's just
on tick-over instead of over-run, so barely audible.
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zetec
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| posted on 25/3/11 at 06:56 PM |
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My Emerald map has fueling till cut off, which is at RPM below 1500 with 0% opening, so agree perhaps a little fuel might help.
" I only registered to look at the pictures, now I'm stuck with this username for the rest of my life!"
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coozer
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| posted on 25/3/11 at 06:57 PM |
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I want pops and bangs, some flames would be nice as well. Singe the hairs off the horses legs
1972 V8 Jago
1980 Z750
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slingshot2000
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| posted on 25/3/11 at 07:09 PM |
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+1
quote:
Originally posted by coozer
I want pops and bangs, some flames would be nice as well. Singe the hairs off the horses legs
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bi22le
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| posted on 25/3/11 at 07:19 PM |
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I want more 'character noises' as well. Count yourself lucky!!!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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chrisxr2
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| posted on 25/3/11 at 07:22 PM |
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scared a horse
Was scaring the horse related to the noise of the car or are the car noise and scaring the horse two seperate episodes?? ooerr missus
Life moves pretty fast, if you don't stop and look around once in a while, you could miss it.
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mrwibble
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| posted on 25/3/11 at 08:11 PM |
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whilst i agree horses should be confined to fields and bridle paths, breaking somones neck for being foolish enough to ride one of the fly ridden
immense turd producing beasts seems a bit harsh.
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matt_gsxr
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| posted on 26/3/11 at 07:55 AM |
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Raz, great to hear that you are putting some miles on your new TBI's.
I have had a similar thing from time to time. Actually I have never really got to the bottom of how to manage fuel cut.
I can get pops and bangs if I lower the fueling on the over-run.
If I use a fuel cut, then it isn't very nice when I come back on the power.
The solution (in my case), is to run about 15-16 on the over-run and disable fuel cut. This isn't ideal from a fuel consumption perspective.
I have read that you can tune these problems out, but it wasn't easy when I tried.
Matt
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RazMan
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| posted on 26/3/11 at 02:59 PM |
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Thanks for all the ideas guys - I live in a fairly rural part of Essex so horses are a part of life round these parts. I have to agree that the roads
are not the place for the beasties but I guess they have to get from A to B like the rest of us.
I tried a little more fuel on the over run and presto! - all is quiet and well mannered now.
I knew you lot wouldn't let me down 
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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atomic
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| posted on 29/3/11 at 11:15 AM |
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You should be using a Wideband AFR meter to tune and one of the result of doing it this way would be it this should reduce this type of thing to an
expectable level. What ecu are you using? as most can take a wideband feed directly and have some sort of Auto-tune feature these days which produce
good safe starting points.
Using Wideband will help you maximise your engines capabilities while reducing the likelihood to damage due to running too lean etc.
[Edited on 29/3/11 by atomic]
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fatbaldbloke
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| posted on 29/3/11 at 12:48 PM |
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quote:
The solution (in my case), is to run about 15-16 on the over-run and disable fuel cut.
Spot on, this is the correct way to do it.
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ed1801
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| posted on 29/3/11 at 02:04 PM |
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On mine, I've found that if you go rich on overrun (13-13.5ish) you get a burble noise rather than the lean bangs and pops. May be worth a try
Obviously you will use a touch more fuel.
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mikemph
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| posted on 29/3/11 at 02:38 PM |
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quote:
Originally posted by fatbaldbloke
quote:
The solution (in my case), is to run about 15-16 on the over-run and disable fuel cut.
Spot on, this is the correct way to do it.
+1
Defo the correct way to do it where economy is not most important, but it's a half way house between reasonable economy and have good throttle
response after over run 0% tp.
Although personally I am running Decel 98% but it is on a supercharged mini 1380
[Edited on 29/3/2011 by mikemph]
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RazMan
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| posted on 29/3/11 at 03:17 PM |
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quote:
Originally posted by atomic
You should be using a Wideband AFR meter to tune and one of the result of doing it this way would be it this should reduce this type of thing to an
expectable level. What ecu are you using? as most can take a wideband feed directly and have some sort of Auto-tune feature these days which produce
good safe starting points.
Using Wideband will help you maximise your engines capabilities while reducing the likelihood to damage due to running too lean etc.
I have indeed been using my Innovate Wideband sensor and gauge to good effect - I have used 3 tankfuls to get the fine tuning done and its now running
beautifully. The popping stopped when I increased the fuel on the overrun slightly and I have noticed the AFR has gone up to around 13.5 so not lean
any more.
I would love to plumb the sensor into the ECU but have been told it is not very straight forward to do this on an MBE 970. I just keep an eye on the
AFR under various throttle positions and at the moment it is running on the safer side of the ideal 14.7. If anyone can offer advice on getting the
sensor to talk to the ECU I am all ears
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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mikemph
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| posted on 30/3/11 at 09:09 AM |
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quote:
Originally posted by RazMan
quote:
Originally posted by atomic
You should be using a Wideband AFR meter to tune and one of the result of doing it this way would be it this should reduce this type of thing to an
expectable level. What ecu are you using? as most can take a wideband feed directly and have some sort of Auto-tune feature these days which produce
good safe starting points.
Using Wideband will help you maximise your engines capabilities while reducing the likelihood to damage due to running too lean etc.
I have indeed been using my Innovate Wideband sensor and gauge to good effect - I have used 3 tankfuls to get the fine tuning done and its now running
beautifully. The popping stopped when I increased the fuel on the overrun slightly and I have noticed the AFR has gone up to around 13.5 so not lean
any more.
I would love to plumb the sensor into the ECU but have been told it is not very straight forward to do this on an MBE 970. I just keep an eye on the
AFR under various throttle positions and at the moment it is running on the safer side of the ideal 14.7. If anyone can offer advice on getting the
sensor to talk to the ECU I am all ears
Normally you use the 0-5v analogue output of the wb controller onto the ecu... And then you have to make sure the ecu is configured to accept 0-5v as
a wide band on which every input you are using. Im not familiar with mbe so can't tell you how exactly.
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Daddylonglegs
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| posted on 30/3/11 at 10:07 AM |
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quote:
Originally posted by coozer
I want pops and bangs, some flames would be nice as well. Singe the hairs off the horses legs
Not a horsey person then cooz?
It looks like the Midget is winning at the moment......
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ashg
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| posted on 30/3/11 at 10:31 AM |
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quote:
Originally posted by RazMan
quote:
Originally posted by atomic
You should be using a Wideband AFR meter to tune and one of the result of doing it this way would be it this should reduce this type of thing to an
expectable level. What ecu are you using? as most can take a wideband feed directly and have some sort of Auto-tune feature these days which produce
good safe starting points.
Using Wideband will help you maximise your engines capabilities while reducing the likelihood to damage due to running too lean etc.
I have indeed been using my Innovate Wideband sensor and gauge to good effect - I have used 3 tankfuls to get the fine tuning done and its now running
beautifully. The popping stopped when I increased the fuel on the overrun slightly and I have noticed the AFR has gone up to around 13.5 so not lean
any more.
I would love to plumb the sensor into the ECU but have been told it is not very straight forward to do this on an MBE 970. I just keep an eye on the
AFR under various throttle positions and at the moment it is running on the safer side of the ideal 14.7. If anyone can offer advice on getting the
sensor to talk to the ECU I am all ears
always use afr as a guide. never think yo have to make the engine work at an afr value, always give it what it wants to run well.the 13.5 afr isnt
that critical on overrun when you think in volumetric efficiency. with the throttle closed there is very little air going into the cylindermeaning it
would only take a very small amount of fuel to make it look rich. so in reality it wont make a lot of difference to your fuel economy. the place you
can make real fuel economy gains on cruse and idle which is where you should be concentrating on if its running well
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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RazMan
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| posted on 30/3/11 at 03:31 PM |
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quote:
Originally posted by mikemph
Normally you use the 0-5v analogue output of the wb controller onto the ecu... And then you have to make sure the ecu is configured to accept 0-5v as
a wide band on which every input you are using. Im not familiar with mbe so can't tell you how exactly.
The Innovate unit can output both wide and narrow band signals IIRC. The wideband is mainly used for mapping and gauge display, while the narrow band
is used for real time correction in the map. Apparently the wiring is the simple bit - the setup is something else! Easimap is not exactly ... erm
.... easy to master and switching on the lambda input is apparently quite complicated and best left to someone who knows what they are doing
Methinks a visit to Atspeed is required at this point - I am fairly confident that the map is as close as it needs to be for the time being but it
needs some expert input to get the lambda control switched on. I'll bung Colin an email.
quote:
Originally posted by ashg
always use afr as a guide. never think yo have to make the engine work at an afr value, always give it what it wants to run well.the 13.5 afr isnt
that critical on overrun when you think in volumetric efficiency. with the throttle closed there is very little air going into the cylindermeaning it
would only take a very small amount of fuel to make it look rich. so in reality it wont make a lot of difference to your fuel economy. the place you
can make real fuel economy gains on cruse and idle which is where you should be concentrating on if its running well
I find that running on the rich side of the 'magic 14.7' seems to be about the best in terms of power and driveability and anything
between 13.5 & 14.2 seems fine. Tickover needs a little more fuel to get it nice and steady but that might be down to my rather extreme timing I
am forced to use due to the leaky butterflies (about 2 degrees presently)
[Edited on 30-3-11 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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ashg
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| posted on 30/3/11 at 06:31 PM |
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i dont know the ins and outs of your ecu but if you connect to the innovate via serial and open up the software you can tell it what voltage it should
be pumping out at a particular afr. all you need to do then i find out what input your ecu is expecting. if i remember correctly you could set both
analogue outputs to wideband using the innovate software meaning you have one for the ecu and another for the gauge both outputting different voltage
ranges but still in wideband mode.
once its setup properly the map wont really change so technically you dont even need a lambda. the only real benefit of having one after its been
properly mapped is for safety should you get an unexpected lean situation e.g something on the inlet side fails allowing it run out of spec.
2 degrees isnt really a good thing to be doing i hope you are keeping an eye on your exhaust temps as you could kill your exhaust valves if your not
careful
[Edited on 30/3/2011 by ashg]
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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RazMan
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| posted on 30/3/11 at 09:42 PM |
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After speaking Colin @ atspeed, I am now convince that lambda control should not be neccessary if the map is set up well to start with - besides the
ar$e of a job it is to set up.
First you need to first tell the ecu the type of Lambda system you're using, along with a number of settings, (temperature to allow adaptive
mapping, how much fueling can be changed by in one go, that sort of thing.)
You then need to set up a table relating to the voltage that the ecu translates to the actual Lambda value
You then need to set up the target map. Typically, you would put a figure of Lambda 1 in the low rpm/low tps load sites and a value between 0.85 - 0.9
or so in the higher rpm/higher tps sites. (The theory is that you're running at Lambda 1 on low throttle openings, and richer when you give it
some beans).
My brain melted at this point and I just marvelled at how good my present map is 
Regarding the 2 degrees thing, I am very concious of the heat build up at tickover so I basically don't allow it to idle for very long and
switch off when waiting in traffic to keep the heat down to a minimum - its fine on a run though.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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ashg
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| posted on 31/3/11 at 12:31 AM |
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im just going off my own experience, don't claim to be an expert, far from it. i have done a fair bit of reading on the subject and put it in
to practice on my own car, mostly it has worked out ok for me.
sounds like your getting on well with it. im sure colin will be able to get a bit more out of it on the rollers as he can keep a constant load unlike
road conditions it also makes it more repeatable which helps. I would think there is a good bit of play to be found in your ignition map as i would
expect it to be reasonably conservative at the moment. you will have to post up the before and after results along with screen shots of the map
tables. he managed to find 18hp and a bit more torque on my old engine without too much bother. the good thing is that you have a working map so
hopefully the boys can just hone it in. the only thing that worries me is your itb issue on tick over as they will have to map around it, in an ideal
world it would be better to get that sorted and redo your map before going down to them and parting with money, but if you cant find a way round it
then that's how it will have to be.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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