Moderator: martauto
Yes, my AFM has seen better days.Speedtouch wrote: ↑Sat Sep 28, 2019 2:02 pmIt's an interesting idea, but surely, if the AFM is in good condition then the ECU will automatically optimise the air-fuel ratio, as that's the whole point of the system.
What you're suggesting is something along the lines of the E-bay 'power resistors' that supposedly increase the amount of fuel being drawn in, probably to the point of cylinder bore wash and rapid engine wear!
This is controlled by the throttle position switch. Your whole idea leads down the route of high fuel consumption and bore wash for very little gain.blood69 wrote: ↑Sat Sep 28, 2019 2:21 pm
The main idea doing this is to fool the ecu, making to change to the full throttle ignition and fuel maps earlier than the standard 4500 rpm.
If i lighten the spring tension 4 clicks, i think i'm getting this effect, since i notice more go at 3800rpm. The idea is to make that happen with the flick of a switch, without fiddling with the spring tension.
Yes the throttle position switch discard the AFM changing from high AFM Ecu Map to Full Throttle ecu Map, but just when the barn door is open more than 70% to 80%, that's why i'm trying to do this.Brianmoooore wrote: ↑Sat Sep 28, 2019 4:26 pmThis is controlled by the throttle position switch. Your whole idea leads down the route of high fuel consumption and bore wash for very little gain.blood69 wrote: ↑Sat Sep 28, 2019 2:21 pm
The main idea doing this is to fool the ecu, making to change to the full throttle ignition and fuel maps earlier than the standard 4500 rpm.
If i lighten the spring tension 4 clicks, i think i'm getting this effect, since i notice more go at 3800rpm. The idea is to make that happen with the flick of a switch, without fiddling with the spring tension.
Better to sort the system to work as intended, making sure the injectors are all within spec., all air leaks are eliminated, and that you have a correctly calibrated AFM with no duff spots on the track.
Thanks for your advice, i clean the carbon track with a bit of paper and adjusted the middle contact and managed to smooth out some ohm flat spots. The ohms raises gradually while opening the barn door now.Brianmoooore wrote: ↑Sat Sep 28, 2019 6:23 pmThe carbon track in the AFM is laser trimmed to provide the correct air/fuel ratio at all engine revs and loads, with the actual ratios modified for power/emissions/economy by the throttle position switch. Without a full engine dyno. and air/fuel ratio measuring equipment you are not going to match or even come close to BMW's results.
The slackening of the spring trick is a facebook type bodge to crudely compensate for worn injectors and air leaks.
Concentrate your efforts on getting things back to how they were when the car left the factory, and you will get much more satisfactory results.
What makes you think your AFM is "past its best"?
100000 miles, its a 1990 316i btwBrianmoooore wrote: ↑Sat Sep 28, 2019 7:39 pmHow many miles has the car done on the current set of injectors?
Brianmoooore wrote: ↑Sat Sep 28, 2019 11:14 pmIn that case, getting them professionally rebuilt and balanced would be the first thing to do. Their flow rates will be way down on what they should be, some will be injecting more fuel than others, their spray patterns are likely to be far from ideal, and one or more may still be dribbling fuel when off.
By 100,000 miles each will have operated around 300,000,000 times.
Wow, the bosch injectors on e30 are really that bad?Brianmoooore wrote: ↑Sat Sep 28, 2019 11:14 pmIn that case, getting them professionally rebuilt and balanced would be the first thing to do. Their flow rates will be way down on what they should be, some will be injecting more fuel than others, their spray patterns are likely to be far from ideal, and one or more may still be dribbling fuel when off.
By 100,000 miles each will have operated around 300,000,000 times.
Ok, Understood. Also mine doesn't have O2 sensor, so i should check the injectors.Brianmoooore wrote: ↑Mon Sep 30, 2019 11:54 pmMost (UK) E30s do not have lambda sensors to determine if the average fuel mixture across all the cylinders is weak or rich. The ECU just assumes that the injectors are within spec., and applies pulses to them of the length that should give the correct mixture.
The later systems on the VW and Honda use lambda sensors to form a feedback loop to correct the average mixture strength, but a leaking injector on one cylinder will fool the electronics into running the other cylinders weak, possibly dangerously so.
I can have the injectors rebuild for 30€ a piece where i live. But for now i'm concentration on the AFM, with a little cleaning on the track the car smooth out a lot.Brianmoooore wrote: ↑Tue Oct 01, 2019 2:35 pmWithout an O2 sensor, the ECU doesn't know how much the injector flows will have reduced by now, and so will be making no attempt to compensate. The mixture will almost certainly be weaker than it should, which is consistent with what you were trying to achieve in your OP.
Full injector rebuilds, returning them to new spec. aren't particularly expensive. There's a trader on here offering the service for £10 per injector, although I realise that this might be of no use to you, living where you do.
, still want to test the other wires. Good point, also gonna review the Fuel Pressure Regulator, probably its still the same from factoryBrianmoooore wrote: ↑Tue Oct 01, 2019 6:36 pmWithout injectors working to spec., you are chasing unicorns by playing around with the AFM signal. At best you will end up with fuel mixture control no better than that offered by carburetors - correct at two points at the most.
The thing about having the injectors rebuilt is that it is an investment, not an expense. Injectors working properly will reduce fuel consumption for the same power, so they'll pay for themselves, then make a profit.
It probably is, and non the worse for it - one of the most reliable part on the car. They can be damaged by someone connecting the two fuel hoses the wrong way around, although this is rare, but apart from that, the only other thing that very rarely happens is that the diaphragm punctures, allowing fuel to flow along the reference vacuum pipe, into the inlet manifold. This can be checked by adding a temporary section of clear hose to the vacuum pipe, so that any fuel passing through it at idle can be seen.
I remember checking it once, the vaccum out of the FPR smelled a bit like fuel, but the hose has dry, so i guess it still has some more miles until it goes.Brianmoooore wrote: ↑Wed Oct 02, 2019 10:27 amIt probably is, and non the worse for it - one of the most reliable part on the car. They can be damaged by someone connecting the two fuel hoses the wrong way around, although this is rare, but apart from that, the only other thing that very rarely happens is that the diaphragm punctures, allowing fuel to flow along the reference vacuum pipe, into the inlet manifold. This can be checked by adding a temporary section of clear hose to the vacuum pipe, so that any fuel passing through it at idle can be seen.