MikeAK Posted February 6, 2008 Share Posted February 6, 2008 Hi, Bit of a long shot this one, but does anyone have the specs for the airflow meters used on the RRC. I am loking for data on both the the flapper (2AM) fitted to the 3.5 and the later hotwire (3AM I think) fitted to the 3.9. What I need is the voltage output vs airflow. The idea is to make a conversion box to allow the later hotwire to be used in place of a flapper (I am an electronics engineer). I've found the flapper system is fairly reliable on the whole apart from the flapper itself, hence the idea. Regards Mike Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted February 6, 2008 Share Posted February 6, 2008 While you could do this - with a bit of fiddling,I cant really see the benefit.What would be worth doing is to swap the efi over to 14CUX,then you have a reliable ECU,AFM,proper control of idle speed,(inc A/C comp load) and the ability to run open or closed loop.The engine will run like it never has before. Quote Link to comment Share on other sites More sharing options...
TomG Posted February 6, 2008 Share Posted February 6, 2008 Or alternatively.. remove AFM* then launch it in the direction of the nearest bin and fit Megasquirt n EDIS / Spark *Promptly followed by inner gubbins of distributor. Regarding voltage/airflow of the AFMs, you may get better exposure in the International forum as the question is common to Rover V8s - maybe a helpful mod could move it? Welcome to the forum by the way Quote Link to comment Share on other sites More sharing options...
MikeAK Posted February 6, 2008 Author Share Posted February 6, 2008 Hi, I know about megasquirt and 14CUX. The reason for not going down either of those roads is down cost, money scarce at the moment. I could build a conveter unit using bits I can pickup at work. It wouldn't need to be much more than an A/D converter a lookup table and a D/A converter (probably using a PIC) and a relay to take the place of the fuel pump switch, I just need the specs of the airflow meters. Also I like to do this sort of thing for fun!! Just like the tin bashers like to spend a weekend patching somthing like a lace curtain crossmember back together rather than just glue a new one on! I am already in the process of fitting EDIS ingnition but not using megajolt, again I am in the process of making my own controller. I would upset me to pay £100+ for megajolt whenI know it amounts to about £30ish of parts from Farnell or Radio Spares. Mike Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted February 6, 2008 Share Posted February 6, 2008 Hi,I know about megasquirt and 14CUX. The reason for not going down either of those roads is down cost, money scarce at the moment. I could build a conveter unit using bits I can pickup at work. It wouldn't need to be much more than an A/D converter a lookup table and a D/A converter (probably using a PIC) and a relay to take the place of the fuel pump switch, I just need the specs of the airflow meters. Also I like to do this sort of thing for fun!! Just like the tin bashers like to spend a weekend patching somthing like a lace curtain crossmember back together rather than just glue a new one on! I am already in the process of fitting EDIS ingnition but not using megajolt, again I am in the process of making my own controller. I would upset me to pay £100+ for megajolt whenI know it amounts to about £30ish of parts from Farnell or Radio Spares. Mike Very interesting and way beyond me, but I would be interested in your progress! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 6, 2008 Share Posted February 6, 2008 A megajolt in kit form is only about £50 and you save all the hard&software development work (believe me, lots has gone in). An MS kit is under £200, and both cost less if you just buy the PCB and programmed CPU and use parts you source yourself for those that can. Seems a hell of a lot of effort to save a couple of quid. Quote Link to comment Share on other sites More sharing options...
MikeAK Posted February 7, 2008 Author Share Posted February 7, 2008 Hi Thanks for the info FridgeFreezer. Saving the effort on the hard/software development isn't the point, thats the interesting bit for me (sad, I know). However that said I've now had a look proper look at the GlensGarage website in the states and a "partial kit" (pcb, proc and map) is $93 (approx £47) which seems pretty good value so I'll probably go down that route. I've already got the trigger wheel mounted and am in the process of mounting the sensor. Anyone know the optimum sensor to wheel gap? I know as close as possible for best signal but what clearance have others used to allow for vibration, thermal expansion etc. I'm still interested in arflow meter data if anyone has it because although I'll use MAP initally I may want to change back to AFM with megasquirt later. The reason being that MAF systems are self adapting (within limits) as they measure true air mass into the engine wheres MAP is a "tuned" estimate based on manifold depression. Not a problem on race/offroaders but mine is road car as well and has to pass MOT. With MAP engine wear, changes to manifolds or just about anything means having to redo the fuel map. Mike Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 7, 2008 Share Posted February 7, 2008 Ideal gap is less than 1mm although in reality I reckon mine may be more than that. Rog set his gap by butting the sensor up against the trigger wheel and letting the two fight it out until clearance appeared the VR sensors are pretty robust it seems Many car manufacturers use MAP not MAF, I have never heard anyone have any problem with having to re-tune (or indeed ever needed to) and never had a problem come MOT time with emissions. In theory you have a point but in practice it isn't an issue. A lambda sensor will correct most minor changes due to small changes, the weather, etc. If something major changes in your engine I'd imagine it'd be preferable to re-tune it anyway, surely? Plus there's an auto-tune function in the software for the terminally lazy If you want to tinker with software I'd say it'd be better to add your efforts to the already thriving MS community rather than go it alone on hardware no-one else has. Also saves you working all the boring stuff out from scratch. All the source code is available openly, that's kinda the point Quote Link to comment Share on other sites More sharing options...
MikeAK Posted February 7, 2008 Author Share Posted February 7, 2008 Hi again, OK Fridge, you've convinced me. I've placed an order with GlensGarage. I've got a few questions but I'll wait until I've had a good think about how I'm going to do it then post a BIG list of questions for you to answer in a new thread, serves you right for talking me into it The reason I was banging on about MAF vs MAP was that back in my (now distant) boy racer days I had some trouble with MAP cars not passing MOT emmisions just by changing airfilters and exhaust systems. Also had a couple of old rovers that had MAP an they failed MOT emmisions just due to general wear, but of corse I had no means of changing the fuel map those. Never had any problem with MAF cars. Doesn't realy matter as you say because with megesquirt as I'll have full control of everything. Mike Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted February 7, 2008 Share Posted February 7, 2008 Ideal gap is less than 1mm although in reality I reckon mine may be more than that. Rog set his gap by butting the sensor up against the trigger wheel and letting the two fight it out until clearance appeared the VR sensors are pretty robust it seems welcome to MS Mike, the tinkers dream! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 8, 2008 Share Posted February 8, 2008 Mike - I was going to add another point: Why would you fit a much better system and then attach it to one of the most unreliable bits of the old system? You could tune out "un-tuneable" cars by putting a resistance inline to the air temp or coolant temp sensors to make it think it was hotter than it was, I believe a chap tuned the MS in his Caterham this way as he had no room for a laptop, stuck a potentiometer on the dashboard and noted down the point at which it ran best, then looked up the enrichment % in the settings when he got home and tweaked it by that % Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted February 8, 2008 Share Posted February 8, 2008 Quote Link to comment Share on other sites More sharing options...
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