AFM lean/rich adjustment

[HairyScreech]

Edit - ignore this i MAY have read the wiring backwards.

from what i can read on that thread (only a quick scan)

the 12v power supply is used to heat the hot wire/clean the wire on start up.

the brown split wire is the 5v feed that most sensors work on.

the other two are the signal to ecu wires.

so im not sure what the problem with the maf going over 5v would be unless there is a spike caused by the cleaning cook off.
but i would have thought the cleaning cook off wouldnt happen as thats an ecu controlled thing?

[e301988325i]

Where exactly does the lambda need to be on the exhaust (if any one place is prefered)? And where does the signal get routed? I would go the MAF route before M30 AFM.

Even got a load of shrink tubing from work today to make the adapter harness. A sealed plastic bag with around probably 60-70 or more 6" pieces of all sizes. They have a "shelf life" and the stock supervisor said the only way to get new stuff is if all the old is used up (leaves the drawer open and walks away).

I don't know about the stock lambda location. I had one lambda welded in about 8inches below the exh manifold, assumming everythings in good order, ie injectors cam rockers/ clearances, measuring one bank shouldn't be a problem. The stock E30 M20 lambda lead is only 8 inches long so with the socket under the battery tray there is a limited area it can/should be fitted within.

My lambda is by the gearbox in my single 2.5" pipe. The lambda plugs into motronic under the battery tray. I have part numbers of bosch lambdas with various length leads that have the correct plug fitted if required.

You also NEED the lambda heater relay, which is the same type in every pin/function as the fuel pump relay but is normally blue in colour, you may have a relay fitted already, it's located next to the fuel pump relay on the nearside suspension turret.

I agree MAF before M30 AFM, but there is no adjustment as far as I know on the MAF (Anyone know otherwise? I'm not clued up on them) you can (have to) tweak the wheel in the M30 AFM. I don't fully know if the MAF is a direct replacement for the M20 AFM, my car runs with the M30 AFM so I am working on the principal that the two outputs are similar and thus should be interchangable. I would make the adaptor loom as in the SA thread so that they can be swapped quickly and easily. HTH

[E30_Crazy]

I'll have to see about the lambda relay. It's fitted in the black plastic housing just forward of the nearside strut tower?

I think I've got the plug for the lambda. Kind of comes out of the main loom from the bulkhead, but then stops short and hangs there under the battery tray? I've got a regular two pipe exhaust system coming from a 6 branch. Can the sensor work from only 3 cylinders (one mid-pipe)? Never really messed with FL stuff before.

[e301988325i]

I'll have to see about the lambda relay. It's fitted in the black plastic housing just forward of the nearside strut tower?

I think I've got the plug for the lambda. Kind of comes out of the main loom from the bulkhead, but then stops short and hangs there under the battery tray? I've got a regular two pipe exhaust system coming from a 6 branch. Can the sensor work from only 3 cylinders (one mid-pipe)? Never really messed with FL stuff before.

Yeah, under that cover, round socket under the battery tray, should have a blanking plug screwed into it. As above, OEM can only use one exh pipe so this is all that can be done with the system.

[E30_Crazy]

You know, thinking about it, a lambda may just fix my immediate problem of burning through fuel... If I'm correct, the engine and loom (both facelift) both came out of a facelift shell. That would mean there was a lambda for it's exhaust, right? Mine, being a pre-FL, doesn't. The engine was supposedly tuned and chipped specifically for it's build specs, so wouldn't taking the lambda input out of the equation make it run poorly as it is?

[e301988325i]

Running a lamda on the later motronic will allow the motronic to actively adjust fueling to stoich, it is likely this will save you fuel, but if your engine was mapped rich to prevent detonation or allow advanced spark timing then it could cause running issues again.

In my personal opinion, the fitting of lambda's would cure a lot of the common E30 running problems such as worn AFM's, and kangarooing often caused by slightly blocked injectors making the engine run leaner than intended.

[E30_Crazy]

There's a local guy around here, John Gagen, who is known for his knowledge of BMW's in and out. Thinking of just taking it to him, getting the lambda done up, and see if he can find anything that would be making it run so poorly. He might even be able to do mapping and stuff, so I could just do the MAF conversion tuning through him.

[E30_Crazy]

I have part numbers of bosch lambdas with various length leads that have the correct plug fitted if required.

You also NEED the lambda heater relay, which is the same type in every pin/function as the fuel pump relay but is normally blue in colour, you may have a relay fitted already, it's located next to the fuel pump relay on the nearside suspension turret.

The bosch lambdas, I take it, are the OEM item and plug right into the motronic? I'll take the part numbers then if you don't mind

And you wouldn't happen to have the part number for the lambda heater relay would you? I had a look, and there isn't a blue relay under the cover by the fuel pump relay.

[Brianmoooore]

Relay is an ordinary one, the same as the fuel pump relay, or any of the orange relays in the fusebox, apart from the lugs on the case that retain it.

[E30_Crazy]

oh ok, so maybe I already have one, it's just not the blue one. It could be a "fuel pump" relay in its place.

[e301988325i]

I have part numbers of bosch lambdas with various length leads that have the correct plug fitted if required.

You also NEED the lambda heater relay, which is the same type in every pin/function as the fuel pump relay but is normally blue in colour, you may have a relay fitted already, it's located next to the fuel pump relay on the nearside suspension turret.

The bosch lambdas, I take it, are the OEM item and plug right into the motronic? I'll take the part numbers then if you don't mind

And you wouldn't happen to have the part number for the lambda heater relay would you? I had a look, and there isn't a blue relay under the cover by the fuel pump relay.

Bosch and generic lamdas plug straight in. I have to use bosch or NTK sensors due to running LPG (hence having bosch PN's), this isn't such an issue on petrol but if you race a lot then the cheaper one's won't last IMHO.

£25 generic sensor might be worth it for a test. Ebay is your friend for all. This links the image of the correct plug, check you've definitely got the socket before you start. I don't have the PN for the lambda relay, but they're the same on pretty much every beemer with a lambda and as Brian said are the same as the fuel pump relay just a different colour cover.

http://www.ebay.co.uk/itm/Front-Lambda- ... 2eb83af667

bosch lambda sensor part numbers
258005313 E34/E32 152cm cable
258005322 E34 M50 525i 145cm cable
258005324 e30 325i 57cm cable
258005325 e30 318i 94cm cable

[E30_Crazy]

Think I'll go with the 94cm one. Give me a little more room to play with location. I can always cut it short later anyways.

I must already have the relay, since there isn't any more room under the plastic cover. The loom and all did come from a facelift, so good chance that I'm just missing the actual lambda since I'm still using my pre-facelift exhaust. I'll look up some pictures or diagrams just to be sure.

By making the "quick switch" loom for the AFM/MAF, I could always get it "tuned" for MOT time with the AFM, and the switch it back to the MAF afterwards. Eh, well sod that, I shouldn't have to go through any more MOTs, since I'm moving out of the country in May.

[DmcL]

wow, surprised i never noticed this thread sooner.

the allen key bit the guy was adjusting is an idle bypass in the AFM so the AFM itself is still calibrated as standard. the adjustments people keep saying not to do are made under the black plastic lid by increasing or reducing spring tension.

heres a side by side picture i took of an M20 and M30 AFM with all internals removed. there is only one IAT sensor because the other one is wired up in a MAF conversion i built and used for experimenting with different MAF's and even tried my hand at a MAP sensor but had issues with that.



springs are different for different AFM's, the rest seems very similar. i have tuned my own M20 to run on a completely standard and un-modified M30 AFM as if it were from the factory, no piggy back stuff, no adding an O2 sensor or any other "crutch" to get it working. i re-tuned the AFM maps in the ECU. same goes for a MAF conversion, no piggy back stuff or O2 sensor, just pure tuning to get it working with the standard ECU.

the way the flap in the AFM works in the maps in the ECU is that basically the flap angle dictates engine load so by reducing spring tension it will read higher load columns in maps than it would otherwise. its just the opposite affect for increasing spring tension.

i recently built up a sort of hybrid AFM using an M30 AFM housing but with M20 AFM internals and M20 AFM spring. the M20 spring is alot weaker and was running very bad and quite rich until i increased spring tension in the region of like 7-8 clicks on the toothed wheel. it was still rich after that but load areas in maps were reading more normal so i opted to adjust fuel maps to finish ironing out the richness. have been running that tune and AFM setup for a couple months now with no ill affects. AFM seems to crack open a bit quicker and marginally improve response compared to an unmodified M30 AFM but only slightly so probably not worth the hassle unless u have a bunch of AFM's laying around and know someone who can tune it or supply a chip tuned for it.

as for my MAF efforts, i did 2 conversions so far, one using a volvo 850 T5 bosch MAF but the housing was too small and it would cut out sometimes at high load/full throttle (probably pegging the 5v output causing the ECU to poo itself). the latest incarnation took the sensor from the volvo MAF and put it into an 80mm MAF housing from another bosch MAF i found in a scrapyard with a dud sensor. that ran way better and only a couple times did i encounter any cutting out like before with the smaller housing. another alternative to increasing housing size would be to fit a resistor or something that will reduce the voltage output of a 5v MAF just enough to stop it pegging above like 4.7v.

the MAF i used took a 12v supply but output a 5v signal. there are 2 ways to wire one like this up. the first (what i did and wouldnt do again) is to solder a jumper wire on the ECU making the AFM harness get a 12v feed instead of the original 5v. means swapping ECU's to swap back to standard AFM. the second method would substitute a 12v ignition switched supply for the 5v supply from the AFM harness which would mean retaining a single ECU and only having to swap back to the AFM and swap back to a standard/normal chip.

M20 AFM opened up and explained:

(NOTE: "idle adjustment screw" in above pic is not the bypass idle screw mentioned earlier, thats at the back of the AFM in the round hole)

my first MAF conversion using 850 T5 MAF:


cold air intake i made for fun and giggles a while back:




standard airbox modded for M30 AFM and then modded for 80mm MAF using M30 AFM adaptors and a plastic velocity stack:



80mm MAF (2nd MAF conversion) + above airbox installed:


80mm MAF with 80mm alloy intake elbow and new harness wired to take a 12v switched feed instead of modded ECU:


some comparison pics:



80mm MAF under a bridge from inside car, had the modded airbox in if memmory serves so not as much of an intake road as an open intake:


older MAF conversion vid, think it was the smaller T5 MAF in this vid with an open filter and standard intake elbow:


recent vids of the hybrid M30 AFM with M20 internals, open HKS mushroom filter + air feeds from full beam lamp holes, silicone reducer elbow from the M30 AFM to a 64mm bored out M20 TB (had this TB in like all the pics/vids already) and running on ford mondeo ST24 17lb injectors.


(silver car was a 150bhp CDTi astra)

[e301988325i]

Think I'll go with the 94cm one. Give me a little more room to play with location. I can always cut it short later anyways.

I must already have the relay, since there isn't any more room under the plastic cover. The loom and all did come from a facelift, so good chance that I'm just missing the actual lambda since I'm still using my pre-facelift exhaust. I'll look up some pictures or diagrams just to be sure.

By making the "quick switch" loom for the AFM/MAF, I could always get it "tuned" for MOT time with the AFM, and the switch it back to the MAF afterwards. Eh, well sod that, I shouldn't have to go through any more MOTs, since I'm moving out of the country in May.

Just coil it up, don't cut the wire down, the lambda only gives an output of 1v and a this signal is easiy disturbed.

The logical and close place to take a switched 12v for the MAF is from the fuel pump feed from the fuel pump relay close by.

If you have three relays under the plastic cover, then remove the lambda relay (until you fit a lambda, rearmost relay) and see how your car runs.

IIRC, the ECU uses the presence of the lambda heater relay to know whether a lambda is fitted or not and thus to look for a lambda signal or use a default value if no lambda is fitted, which was the case for 95% of UK E30's.

This in itself may explain why your car is running badly.

People do like to plug empty holes.

[E30_Crazy]

Thanks e301988325i, I'll try unplugging the rear relay under the cover.

DmcL, too bad you are so far away, sounds like you know your way around mapping. The one guy I can think of around here usually only messes with aftermarket/standalone jap ECU's, and not sure if he can tune our older style ECU.

So if I am understanding this right.... I can set up a MAF and harness as in the SA thread, switched power supplied by fuel relay, maybe a resistor in the 5v signal to ECU to keep it from going over 4.7v, and then a tune/chip set to accomodate fueling...? Keeping the old/current chip and/or ECU if I ever want or need to switch back to the AFM.

[DmcL]

basically yes..

the only issue i had with the T5 MAF was the cutting out at high or full load randomly. a resistor or something in line would sort that out. it ran great with the MAF, bit more of an improvement with a bigger MAF, smoother/bigger intake plumbing and a BBTB but not a huge difference.

as far as being far away.. ever fancy visiting ireland for a few days? haha

if the engine is a somewhat standard (ie no cam/internal fettling) late M20B25 i could tune something up on my B25 and then post a chip over. would need to be using the same MAF and injectors tho.. have done similar before with people sending me over their injectors so i can rustle up a tune for someone further away. bit of a spoil the buzz being over here in NI, have turned plenty of people away that are over in england due to their engine being essentially too modded to not be tuned in the flesh. too many variables once u go beyond the typical bolt on stuff. considered maybe moving across but would need to get in with someone owning a garage or something, couldnt swing a proper business yet, not enough workload to peel me away from my normal job so at the minute i tune in my spare time on the road or at a local-ish dyno i have an agreement with.

easiest way is feed the 12v to the MAF from somewhere in the engine bay so swapping back to normal setup only takes changing a chip and re-fitting the old AFM.

[E30_Crazy]

If I can get time off from work sometime before May, I would actually probably be up and around Ireland. I've always wanted to go, and here I've been living in England for three years and still haven't made it up.

As for the engine, yeah it's a bit far from standard late 2.5; Stroked to 2.7 and running a 288 cam.

I'll have to get in touch with you when/if I ever get a chance to come spend a week or so in Ireland.

[websky]

Hi everybody, I also have a problem with too rich fuel mixture.
At the first point, I check the fuel injectors. Have it already disassembly.

I added the result of my emission test and inside of the cylinder after 1000km (I cleaned it after replacing the head gasket).
Today I will check the blue sensors and also other sensors.
I will update this thread regularly.


I notice also that the 6,5,4 injector plug has power after removing the plug on the ECU and turning the key, but 3,2,1 has not (only if I plug the wire to the ECU then there is power).
Any idea why there is power on 6,5,4 injectors even if the wire is not plugged to the ECU?

[Brianmoooore]

I notice also that the 6,5,4 injector plug has power after removing the plug on the ECU and turning the key, but 3,2,1 has not (only if I plug the wire to the ECU then there is power).
Any idea why there is power on 6,5,4 injectors even if the wire is not plugged to the ECU?

Something not right here. (Assuming Motronic 1.3 - you haven't mentioned what engine and year).
Power to the injectors should come from the DME relay, which is switched by the ECU in response to power from the ignition switch. With the ECU unplugged, there's no route for power from the ignition switch to get anywhere near the injectors.
Also, all the injectors are connected together and are of low resistance, so with the ECU unplugged any voltage found on one wire should be the same as that on the other.

It would help if you started a tread of your own in E30 tech. help. When others add their problems to an existing thread, it can get VERY confusing.