Adjusting Mi16 Afm

[24seven 104]

How do I go about doing this? Just wind the screw in/out until it idles cleanly? Having had the cap off the afm itself, the screw doesn't really appear to do anything other that wind an S shape spring in, and that's it.

 

My car's idling on 3 cylinders and kangaroos & splutters like mad when cruising below 2500rpm. All the plugs are fresh today, but even the old ones were burning cleanly, so it's a fuelling issue. It was fine up until MOT time, after which the fuel pump earth died, but that's been replaced and definitely isn't an issue anymore. I'm thinking the AFM might have been fettled with for the MOT (it passed the emissions tests extremely cleanly), if not I'll send the injectors off for a proper cleaning (anyone on here got any recommendations where to get this done?) as no doubt they could use it.

[dcc 855]

Have you tried unplugging the injectors one at a time to find which is at fault? (you can hear a difference in the engine for ones which work healthily)

 

Check the ECU temp sensor, I think this could cause you the same issues, although it wouldn't cause the firing on 3 (at least I wouldn't have thought)

[24seven 104]

don't think its the injectors. I think they may be all underfuelling equally, hence none of the plugs looking particularly lean/rich. the temp sensor is ok too, it doesn't get any better/worse with temperature, other than the kangarooing becomes more violent as the gearbox temps rise.

[sussex_gti 0]

Hi mate, how you doing? Think i last spoke to you on 306gti-6.com? My mi used to do this, turned out to be a poor connection on the afm connector. Made it run lumpy on idle, and occasionally cut out on full power. Also found the jubilee clips for the intake hose between the afm and throttle body to be past their best, fitted decent new ones, nice and tight and was perfect after that.

[24seven 104]

hey, not too bad ta. another AOC refugee . It doesn't cut out at all, if anything it's so damm torquey (or maybe the car's just so damm light) it's impossible to stall it!. My AFM plug is dodgy and has been since I bought the engine - one of the pins has obviously gotten hot and melted its way out of the plug but has now been replaced with a regular spdeconnector straight onto the AFM - but it's run fine in like this in the past. I'll have a jiggery poke around the jubilee clips see if there's any leaks around there.

 

Does anyone know if it is as easy as fettling the AFM screw to see if it changes idle? I'm reluctant to do it without knowing first as I don't want to upset the balance of the thing, knowing how sensitive/temperamental they are.

[kyepan 291]

also look up the caps sticky somewhere near the top of the xu maintenance forum / mods forum.. it's a little program and it will tell you how to diagnose if it's sending back the correct resistance to the ecu.

 

It might be a connection issue at the plug, or perhaps the afm may need retracking.. both simple to fix.

 

think it also gives, instructions on how to set the afm, although this is also in the 405 haynes manual

Edited June 17, 2009 by kyepan

[24seven 104]

cheers kyepan. already got CAPS (I posted the sticky;))

 

turns out the screw on the AFM had been wound back for the MOT (I suspected it to be overfuelling when I took it down), but I think they'd wound it back too far as it was WELL within the emissions limits, and wasn't acting upon anything at all. wound it in until it made contact, then a little bit further until the idle smoothed out. Think it might want to come back a bit more though, as it tends to idle at around 1100-1200 for a while when first going into neutral.

 

Seems to have cured a number of issues. there's even more torque at low RPM and from cold, the engine power doesn't begin to tail off from 6500 onwards like it used to (just feels like it's got more and more and more power all the way to 7000), cruising through town is no longer the embarrassing jerky affair it used to be, and the whole lot seems to have quietened down a bit, so is less intrusive when I get home from my mates late at night... All because of 1 screw!