megasquirt pops and bangs
Discussion
If you've got no pops and bangs it must be running very well indeed, I'd be inclined to be very happy about that,
Does it not pop on overrun if you add a little throttle?
My Mbe will pop at around 1700 and then at about 1250 revs but not much more than that unless I introduce some fuel.
I do get some proper gun shots that sound like they are about to blow holes in my exhaust,,
Oddly Ole I've been thinking of seeing Jason at Powers to see if he can reduce the pops and bangs,,
IAm I right in thinking a lean mixture will create more pops so I'm assuming that's what's altered on the fuel map, it's obviously unburnt fuel so in essence over fuelling but the leaner the mixture the more it will explode in the pipes,,
I think introducing more throttle actually adds more air than fuel to the mix thus creating the bangs.
Does it not pop on overrun if you add a little throttle?
My Mbe will pop at around 1700 and then at about 1250 revs but not much more than that unless I introduce some fuel.
I do get some proper gun shots that sound like they are about to blow holes in my exhaust,,
Oddly Ole I've been thinking of seeing Jason at Powers to see if he can reduce the pops and bangs,,
IAm I right in thinking a lean mixture will create more pops so I'm assuming that's what's altered on the fuel map, it's obviously unburnt fuel so in essence over fuelling but the leaner the mixture the more it will explode in the pipes,,
I think introducing more throttle actually adds more air than fuel to the mix thus creating the bangs.
carsy said:
Yes, weaken the mixture where you want them and also retarding the ignition will also help.
Although initially I thought they were great I soon found them quite tiresome. Personally I never have them switched on now.
This ^ and like mentioned you need to disable over-run fuel cut Although initially I thought they were great I soon found them quite tiresome. Personally I never have them switched on now.
personally I can see this point having the this kind of tech to have it going down the road sounding like a giant bowl Rice Krispies 
kids might think it sounds good but you are not fooling the proper engine/car guys 
especially the V8 nuts 
In saying all this we are not all the same and what ever floats your boat and all that 
Edited by Sardonicus on Tuesday 31st May 12:46
BoostedChim said:
I find minus 5 ignition works well.
I'll try that. On another note, dont you get alot of shunting on cruise with all that advance? This map isnt for the SC is it? whats up with the advance on boost...? And what about 6-10 idle advance? Is it for smoothness?And guys! Post your ign tables! Do state what engine you have and if its FI
Edited by OleVix on Wednesday 1st June 00:16
sgrimshaw said:
Shaun installed mine, and about two maybe three years ago did a remap for me, damn thing pops bangs farts rumbles burbles growls, bangs thunderously like a bomb going off changing from second to third at 6k rpm (that momentary lift off) and screams like a banshee between 4 and 6k rpm with WOT
I suspect part of the reason it's constantly popping off is because I have a lot of cam overlap, and maybe a bit of overfuelling going on....
Whatever the reason I bloody love it and I'd be gutted if I lost all that luverly mechanical music.. with a bit of practise I could probably play a tune with it
I remember being told quite some time ago that a bit of trailing throttle quite often results in pops and bangs
Edited to add I see Alun already mentioned adding a bit of throttle above....
Chilli
Edited by ChilliWhizz on Wednesday 1st June 10:50
Another edit - sorry Ole just seen your request (I really should read a thread properly before posting), lost all the MS stuff (and everything else) off my laptop when it crashed a while back... I actually have two hard drives that I back up onto and duplicate stuff on but for some reason I didn't back up anything from the MS folders...
Engine though is a naturally aspirated V8D 5litre lump with lots of added goodies including a bespoke (Rob Robertson) cam shaft....
Photo opportunity too good to miss
Edited by ChilliWhizz on Wednesday 1st June 11:05
ChilliWhizz said:
sgrimshaw said:
Shaun installed mine, and about two maybe three years ago did a remap for me, damn thing pops bangs farts rumbles burbles growls, bangs thunderously like a bomb going off changing from second to third at 6k rpm (that momentary lift off) and screams like a banshee between 4 and 6k rpm with WOT
I suspect part of the reason it's constantly popping off is because I have a lot of cam overlap, and maybe a bit of overfuelling going on....
Whatever the reason I bloody love it and I'd be gutted if I lost all that luverly mechanical music.. with a bit of practise I could probably play a tune with it
I remember being told quite some time ago that a bit of trailing throttle quite often results in pops and bangs
Edited to add I see Alun already mentioned adding a bit of throttle above....
Chilli
Edited by ChilliWhizz on Wednesday 1st June 10:50
Another edit - sorry Ole just seen your request (I really should read a thread properly before posting), lost all the MS stuff (and everything else) off my laptop when it crashed a while back... I actually have two hard drives that I back up onto and duplicate stuff on but for some reason I didn't back up anything from the MS folders...
Engine though is a naturally aspirated V8D 5litre lump with lots of added goodies including a bespoke (Rob Robertson) cam shaft....
Photo opportunity too good to miss
Edited by ChilliWhizz on Wednesday 1st June 11:05
Ive long had contact with Shaun, he helped me get the car running after the build. But his pops and bangs magic hasnt worked, thats why I asked for tips
Guess I'll have to try some more. They turbo might be dampening the pops some... do get a big BANG here and there... funOleVix said:
I'll try that. On another note, dont you get alot of shunting on cruise with all that advance? This map isnt for the SC is it? whats up with the advance on boost...? And what about 6-10 idle advance? Is it for smoothness?
And guys! Post your ign tables! Do state what engine you have and if its FI
Nope, no shunting on cruise, I'll get a bit around 1200rpm in 5th but its normally time to change down then anyway. I don't find it that fussy on cruise, I'm guessing we're talking about 2800rpm & ~15% TPS. I run it about 15.5AFR around there. What is yours set to?And guys! Post your ign tables! Do state what engine you have and if its FI
Edited by OleVix on Wednesday 1st June 00:16
I've recently lowered the idle timing from 14 to 6. At 14 I found it was prone to surging to 1250rpm when dropping to idle. Once settled though 14 gave a good vacuum and didn't flinch when the fans start up. I've gone to 6 to lower the idle to 700rpm. I've changed my breather setup so the plenum is always sucking across the crankcase, the idle valve is already shut and the crankcase air of course raised the rpm.
I use dual tables so above 100kpa it switches to the the table below for boost.
BoostedChim said:
Is that turbo or supercharged? It looks like it could do with some smoothing on boost as the 4000 & 5000 columns have less timing than the ones either side.
Supercharged.Mapped by Shaun first on a dyno, and then on a separate occasion on the road.
It was good after the Dyno session but was even better after he mapped it on the road, going from 1000 or so RPM to full beans in both third and fourth on the M5 was, shall we say, "interesting"
OleVix said:
macdeb said:
No pops 'n bangs here, but the occasional flames out back so I'm told coming off boost 
Mac what plugs, leads and coils do you have? Im having a misfire at 3500 on full boost...Gassing Station | Chimaera | Top of Page | What's New | My Stuff