Removing the AFM
Discussion
After recently having an Emerald ECU fitted I decided to remove the AFM as it seemed to be restricting the air flow. So I replaced this:
with this:
But when I start the car the induction pipework seems to be resonating. The best way I can describe it is if you run a wet finger round the top of a crystal glass you get a clear high pitched note. The induction side seems to be producing a similar note. Has anyone any idea how I can get rid of this? I don't want to introduce a corrugated pipe as that produces turbulence in the air flow. Is it a simple matter of changing the length of the induction pipe? TIA
with this:
But when I start the car the induction pipework seems to be resonating. The best way I can describe it is if you run a wet finger round the top of a crystal glass you get a clear high pitched note. The induction side seems to be producing a similar note. Has anyone any idea how I can get rid of this? I don't want to introduce a corrugated pipe as that produces turbulence in the air flow. Is it a simple matter of changing the length of the induction pipe? TIA
I have to confess straight away that I don't recognise what you have fitted or how it works as a replacement for the AFM but, looking at the 'after' photo, the air filter doesn't seem to be sitting correctly on the back plate, could the noise be air whistling through here?
If it is the pipework resonating, does it go away if you hold it?
Do tell us what you have fitted, it certainly looks interesting!
If it is the pipework resonating, does it go away if you hold it?
Do tell us what you have fitted, it certainly looks interesting!
Can you do away with the elbow and fit the filter(#) directly to the plenum intake? Much less to flop about as the vicker said...
(#)is the black tube, where the AFM was, just a joint to fix the pipes together? IIRC Emerald doesn't meassure air flow and only uses the TPS. I guess there must be an air temp sensor somewhere? If you fancy starting another thread and telling us all about the Emarald install story I'm all
Leo
(#)is the black tube, where the AFM was, just a joint to fix the pipes together? IIRC Emerald doesn't meassure air flow and only uses the TPS. I guess there must be an air temp sensor somewhere? If you fancy starting another thread and telling us all about the Emarald install story I'm all
Leo
Leslie
I think to should give Dave Walker a call at Emerald ..
My guess is that it's just the inlet pulse travelling along the pipe and then hitting the plate on the end of the filter and then travelling back along the pipe and is a good thing but is the car running well aside from that.
I think to should give Dave Walker a call at Emerald ..
My guess is that it's just the inlet pulse travelling along the pipe and then hitting the plate on the end of the filter and then travelling back along the pipe and is a good thing but is the car running well aside from that.
So, I take it your emerald setup didn't use the air temperature sensor in the AFM then ?
The AFM contains a damping chamber, so it should reduce any intake resonance. I'm doing a similar thing on the 390 using megasquirt with a 250kPa map sensor but using the AFM air temperature sensor, that way I can swap back if the 'squirt blows up.
FYI if you change the intake at all you'll change the top end Volumetric Efficiency, and will need a remap or you may run dangerously lean, so I'd keep it where it is if I were in your shoes. (This is one drawback of not using an AFM - so I am told).
Incidentally, do you know what duty cycle your injectors are running at full throttle?
-Jim
The AFM contains a damping chamber, so it should reduce any intake resonance. I'm doing a similar thing on the 390 using megasquirt with a 250kPa map sensor but using the AFM air temperature sensor, that way I can swap back if the 'squirt blows up.
FYI if you change the intake at all you'll change the top end Volumetric Efficiency, and will need a remap or you may run dangerously lean, so I'd keep it where it is if I were in your shoes. (This is one drawback of not using an AFM - so I am told).
Incidentally, do you know what duty cycle your injectors are running at full throttle?
-Jim
OK. To answer your questions in order, I didn't want to shorten the length of the tube by mounting the filter directly in line with the plenum because I seem to remember reading on this forum something by Mark Adams that suggested that you lose torque if you remove the afm and shorten the pipe, although I may have got that wrong. The black tube is just a metal pipe (blue anodised aluminium actually) to link the silicon pipes together. The air temperature sensor is on the plenum, it's the thing with the orange sealant around it. I don't think it's an air leak. It's just like the sound a glass makes when it resonates, not a whistle like an air leak. I intend to have the re-map done later this week. The engine hasn't been fully mapped yet as it turned out the clutch was slipping when the last remap was tried. It goes in on Wednesday for the clutch to be done. I'd like to get this sorted before then so that I don't need another re-map once I find a solution.
The noise you're hearing is a resonance through the idle air bleed screw .. presumably they've/you've opened the screw and used less idle advance to help the idle stabilisation of the emerald ignition timing.
You might be able to sort it by closing the screw back down and either opening up the throttle on the threaded insert its lever rests on or by drilling a small air bleed hole throught the butterfly itself .. or running less total idle airflow and bring the idle ignition advance up a bit to get the tickover back.
You might be able to sort it by closing the screw back down and either opening up the throttle on the threaded insert its lever rests on or by drilling a small air bleed hole throught the butterfly itself .. or running less total idle airflow and bring the idle ignition advance up a bit to get the tickover back.
Well, trackcar has hit the nail on the head again. I was sceptical that such a loud noise (I could hear it above the exhaust at all revs.)could be produced from such a small by-pass channel. But, I turned the idle screw in one turn and the noise miraculously disappeared. It wouldn't tick over at that setting, but it shouldn't take much adjustment to get it right. It went in to get the new clutch fitted today and a re-map when that's done. So we shall see what it's like when it's finished. Thanks, trackcar you really know your stuff.
trackcar said:
The noise you're hearing is a resonance through the idle air bleed screw .. presumably they've/you've opened the screw and used less idle advance to help the idle stabilisation of the emerald ignition timing.
You might be able to sort it by closing the screw back down and either opening up the throttle on the threaded insert its lever rests on or by drilling a small air bleed hole throught the butterfly itself .. or running less total idle airflow and bring the idle ignition advance up a bit to get the tickover back.
You might be able to sort it by closing the screw back down and either opening up the throttle on the threaded insert its lever rests on or by drilling a small air bleed hole throught the butterfly itself .. or running less total idle airflow and bring the idle ignition advance up a bit to get the tickover back.
Hands up if you think Trackcar should be at BBWF
Would be great if you could show us your wares Track.
ACT does them in silicon.
And the more smooth the inside (like not corrugated) the better, as turbulence in the airstream in general is not good. For example the RV8 has a plenum to 'unturbulence' the incoming airflow as much as possible.
Rob
And the more smooth the inside (like not corrugated) the better, as turbulence in the airstream in general is not good. For example the RV8 has a plenum to 'unturbulence' the incoming airflow as much as possible.
Rob
Edited by 350zwelgje on Thursday 2nd November 20:58
Gassing Station | Wedges | Top of Page | What's New | My Stuff