Changing the MAF Meter
Discussion
I don't think there's an easy way. on the 5 litre you run out of headroom in the scaling of the meter so once you reach 5volts you're just mapped against rising revs I think. It would seem sensible to bore the meter out so the output reaches 5volts at full power not before, but to be honest i've never seen any of the supposed leaning out on std cars that's talked about anyway. If you're wanting to change for power then there's other ways of doing it possibly without going to full aftermarket, though that's the best way. torquev8 certainly offer a kit, and the latest version with electronics in the car looks nicely done. you could also trim the meter output with a piggyback box. there's loads to consider before making a decision though, depends what you want to achieve really.
Thanks for that. I've seen the TorqueFlow system, but it isn't far of the price of a P&P Mega Squirt system, where I could ditch the MAF altogether and then have mappable fuel and ignition. If it was around the £400 mark I may have been tempted, but there's only £100 between the TorqueFlow and the ExtraEFI ECU.
http://www.extraefi.co.uk/RV8_Kits.html
http://www.extraefi.co.uk/RV8_Kits.html
spitfire4v8 said:
I don't think there's an easy way. on the 5 litre you run out of headroom in the scaling of the meter so once you reach 5volts you're just mapped against rising revs I think. It would seem sensible to bore the meter out so the output reaches 5volts at full power not before, but to be honest i've never seen any of the supposed leaning out on std cars that's talked about anyway. If you're wanting to change for power then there's other ways of doing it possibly without going to full aftermarket, though that's the best way. torquev8 certainly offer a kit, and the latest version with electronics in the car looks nicely done. you could also trim the meter output with a piggyback box. there's loads to consider before making a decision though, depends what you want to achieve really.
Best I see on full bore on my 4.0L was just over 4 volts I agree the bigger engines max out the AFM before they have run out of revs 
Chris 1972 have a look at Blitz's page it will make things clearer for you and worth keeping the page for future Lucas related stuff & fault finding anyway. Sardonicus said:
Best I see on full bore on my 4.0L was just over 4 volts I agree the bigger engines max out the AFM before they have run out of revs Chris 1972 have a look at Blitz's page it will make things clearer for you and worth keeping the page for future Lucas related stuff & fault finding anyway. I made a batch of conversion PCB's that allow both the Bosch or Lucas 20AM to plug inplace of the stock 5AM. The gain should be a bigger AFM means less air restriction so more BHP. The airflow scaling was set to be the same as the stock AFM do no remapping was needed, although I had to replicate the 5 volt limit on the stock unit as the ECU input does not read above this. It was analogue circuitry and I ran one for 6 months on my car, but I was never 100% happy it would withstand the 130'C you get near the AFM, so really it needs mounting inside the car where its cooler. I tested it on a 3.9 on the rollers and say no power increase at all, so I shelved the project. Im quite happy to dig one out and calibrate a bigger AFM if you want to try it, but dont bother if you are running less than about 250 BHP, it wont make any difference.
Mark Adams / ACT do a chip to go with a bigger AFM- on the 5lt cars it supposed to be worth 10-15 BHP, but its expensive considering the cost of afermaket now. Not that aftermarket is a perfect solution- you will always want to fiddle with it!
Mark Adams / ACT do a chip to go with a bigger AFM- on the 5lt cars it supposed to be worth 10-15 BHP, but its expensive considering the cost of afermaket now. Not that aftermarket is a perfect solution- you will always want to fiddle with it!
Edited by blitzracing on Thursday 9th May 13:22
blitzracing said:
I made a batch of conversion PCB's that allow both the Bosch or Lucas 20AM to plug inplace of the stock 5AM. The gain should be a bigger AFM means less air restriction so more BHP. The airflow scaling was set to be the same as the stock AFM do no remapping was needed, although I had to replicate the 5 volt limit on the stock unit as the ECU input does not read above this. It was analogue circuitry and I ran one for 6 months on my car, but I was never 100% happy it would withstand the 130'C you get near the AFM, so really it needs mounting inside the car where its cooler. I tested it on a 3.9 on the rollers and say no power increase at all, so I shelved the project. Im quite happy to dig one out and calibrate a bigger AFM if you want to try it, but dont bother if you are running less than about 250 BHP, it wont make any difference.
Mark Adams / ACT do a chip to go with a bigger AFM- on the 5lt cars it supposed to be worth 10-15 BHP, but its expensive considering the cost of afermaket now. Not that aftermarket is a perfect solution- you will always want to fiddle with it!
Hi MarkMark Adams / ACT do a chip to go with a bigger AFM- on the 5lt cars it supposed to be worth 10-15 BHP, but its expensive considering the cost of afermaket now. Not that aftermarket is a perfect solution- you will always want to fiddle with it!
Edited by blitzracing on Thursday 9th May 13:22
Thanks for this. I think we exchanged a few e-mails with regards to trumpet mods a couple of weeks back. I never put two and two together!
I'd really like to give it a go if you wouldn't mind digging one out? As totally standard, my car was running at 274bhp. Since then, i've done the smooth bore induction with K&N filter, should have done the trumpets by next week, decatted and its had red top injectors, plus virtually new ignition components, from plugs, Magnecor leads etc etc. I'm hoping this would have gained me a few more horses already!
What do you need from me?
The conversion unit physically changes the voltage between the AFM output and the ECU input, so the ECU thinks its a Lucas 5AM, but you still have the better flow capacity of the bigger AFM. - Its an interesting one on the 5 ltr engine, as presumably the ECU is mapped origionaly with the peak airflow of the 5AM (and its restrictions) and so when you remove this restriction to get more air in, you are going to need more fuel, but nothing is telling the fuel map to provide more fuel as all the electrical inputs are the same as they where on the 5AM.
So you are in the situation of needing to boost the fuel pressure a couple of PSI (or bigger injectors)to get more fuel with the standard fuel map and then effectively reduce the AFM output at lower RPM to rematch the new fueling requirements with the higher fuel pressure. It gets fairly nasty quite quickly if you are using analoge means to do this as twiddling variable resistors is not a very precise way of controlling the fueling.
Triggerwheels do a digital piggy back controller for remapping AFM's for around £100, that really would be my weapon of choice, combined with a variable fuel pressure regulator, so you have two methods of acurate control. The Lucas 20AM AFM is a really good unit, and its output is consistently about 10% lower per given airflow than the 5AM that would make remapping its output relatively easy. The Bosch has a different curve, that means you need to remove voltage at low RPM, and add more at higher RPM. The idle is the critical area to get right to start with, if its as much as 150mv out the engine wont run as the AFM voltage change is large at low airflows and flattens off as the flow increases.
As you can see its no where near as simple as simply bolting something on, unless you can remap for the new AFMs voltage curve as the Mark Adams chip does, or take the time on a rolling road with tweeking fuel pressure and AFM digital remapping to get the fueling correct across the whole range.
As for the connectors- You can just use tiny spades onto each connector, or you can still get the correct connectors at a price.
So you are in the situation of needing to boost the fuel pressure a couple of PSI (or bigger injectors)to get more fuel with the standard fuel map and then effectively reduce the AFM output at lower RPM to rematch the new fueling requirements with the higher fuel pressure. It gets fairly nasty quite quickly if you are using analoge means to do this as twiddling variable resistors is not a very precise way of controlling the fueling.
Triggerwheels do a digital piggy back controller for remapping AFM's for around £100, that really would be my weapon of choice, combined with a variable fuel pressure regulator, so you have two methods of acurate control. The Lucas 20AM AFM is a really good unit, and its output is consistently about 10% lower per given airflow than the 5AM that would make remapping its output relatively easy. The Bosch has a different curve, that means you need to remove voltage at low RPM, and add more at higher RPM. The idle is the critical area to get right to start with, if its as much as 150mv out the engine wont run as the AFM voltage change is large at low airflows and flattens off as the flow increases.
As you can see its no where near as simple as simply bolting something on, unless you can remap for the new AFMs voltage curve as the Mark Adams chip does, or take the time on a rolling road with tweeking fuel pressure and AFM digital remapping to get the fueling correct across the whole range.
As for the connectors- You can just use tiny spades onto each connector, or you can still get the correct connectors at a price.
Mark the connectors on the current Lukas ATM and the Bosch one are completely different shape and wouldn't fit.
I think this highlights the reason why I haven't put this on already as all what you said before has gone completely over my head.
I already have a mark Adams tornado chip, a larger plenum and the smooth bore elbow, but I was under the impression that the final piece would be the Bosch afm? I also have some ported induction heads with new injectors with the plenum sandwich, but realistically I don't know what I'm actually talking about even though I have read lots of threads on the forum on the upgrade themes.
However I may have the answer. My son in law has his own tuning business and rolling road setup, he keeps saying ditch the arm and get emerald or similar which confuses me even more, so I'm sticking to scaffolding, anyone need an induction bits and pieces and Bosch ATM? My 500 is reading out at 290 bhp I think I will leave well alone :-)
I think this highlights the reason why I haven't put this on already as all what you said before has gone completely over my head.
I already have a mark Adams tornado chip, a larger plenum and the smooth bore elbow, but I was under the impression that the final piece would be the Bosch afm? I also have some ported induction heads with new injectors with the plenum sandwich, but realistically I don't know what I'm actually talking about even though I have read lots of threads on the forum on the upgrade themes.
However I may have the answer. My son in law has his own tuning business and rolling road setup, he keeps saying ditch the arm and get emerald or similar which confuses me even more, so I'm sticking to scaffolding, anyone need an induction bits and pieces and Bosch ATM? My 500 is reading out at 290 bhp I think I will leave well alone :-)
The Bosch AFM needs a 5 volt supply , not 12 volts like the 5AM and also does not have a CO trim resistor. The Mark Adams way of doing things is to take a 5 volt feed from the throttle pot, and fit a trim resistor into the loom, its do-able but a bit awkward. I had the same issues, but put both a trim resistor and the required voltage regulator onto my conversion PCB so you simply take the 5AM wires from the loom, into the PCB- and then from there straight into the Bosch AFM. In your case you dont need all the conversion electronics to match the voltages as you have the Adams chip. Its not something I considered, but I can simply leave only the voltage regulator and trim pot on the PCB and the wiring will be quite straight forward. To keep the cost down I was using small spades onto the Bosch connectors- you just need to make sure you connect the pins the right way round. Ill can put a unit together at the weekend if you are interested? I can fit the Bosch connector instead of spades if you have one?
blitzracing said:
Triggerwheels do a digital piggy back controller for remapping AFM's for around £100, that really would be my weapon of choice, combined with a variable fuel pressure regulator, so you have two methods of acurate control. The Lucas 20AM AFM is a really good unit, and its output is consistently about 10% lower per given airflow than the 5AM that would make remapping its output relatively easy. The Bosch has a different curve, that means you need to remove voltage at low RPM, and add more at higher RPM. The idle is the critical area to get right to start with, if its as much as 150mv out the engine wont run as the AFM voltage change is large at low airflows and flattens off as the flow increases.
As you can see its no where near as simple as simply bolting something on, unless you can remap for the new AFMs voltage curve as the Mark Adams chip does, or take the time on a rolling road with tweeking fuel pressure and AFM digital remapping to get the fueling correct across the whole range.
As for the connectors- You can just use tiny spades onto each connector, or you can still get the correct connectors at a price.
Cheers Mark. Do you have a link for the Triggerwheel controller to remap the AFM? I've looked at their site but it doesn't jump out at me! However, I was looking at their Megajolt/ Megasquirt ECU etc. Would it not be better to simply go down this route. Are they really difficult to wire in?As you can see its no where near as simple as simply bolting something on, unless you can remap for the new AFMs voltage curve as the Mark Adams chip does, or take the time on a rolling road with tweeking fuel pressure and AFM digital remapping to get the fueling correct across the whole range.
As for the connectors- You can just use tiny spades onto each connector, or you can still get the correct connectors at a price.
blitzracing said:
The Bosch AFM needs a 5 volt supply , not 12 volts like the 5AM and also does not have a CO trim resistor. The Mark Adams way of doing things is to take a 5 volt feed from the throttle pot, and fit a trim resistor into the loom, its do-able but a bit awkward. I had the same issues, but put both a trim resistor and the required voltage regulator onto my conversion PCB so you simply take the 5AM wires from the loom, into the PCB- and then from there straight into the Bosch AFM. In your case you dont need all the conversion electronics to match the voltages as you have the Adams chip. Its not something I considered, but I can simply leave only the voltage regulator and trim pot on the PCB and the wiring will be quite straight forward. To keep the cost down I was using small spades onto the Bosch connectors- you just need to make sure you connect the pins the right way round. Ill can put a unit together at the weekend if you are interested? I can fit the Bosch connector instead of spades if you have one?
Mark is there a number to call you on tomorrow ? Lester
Ta
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