AFM adjustment

[KKson]

Right I'm fed up waiting for a rolling road session for the 390 so I'm going to have a play with the AFM myself. Currently with the modified ECU and Jag AFM the engine runs horrible rich. I've read two articles on adjustment and the info differs. Can someone confirm that it's anti clockwise to weaken the mixture. There's a conflicting you tube video that says anti clockwise riches? Thanks.

[KKson]

Glen, it's the main wheel I'm playing with not the idle screw. The AFM is off a 4.2 Jag so I need less fuel/ weaker mix. Two written articles say that by rotating wheel anticlockwise this weakens the mix. There is however an American video which states the opposite.

[KKson]

rev-erend said:

Just mark tipex on both sides .. then move to the right, if the revs have risen its leaner.. if not try to the left.

You can always go back to what you started with.

For any kind of accuracy you really need an AFT guage or 4 gas analyser.

Well re-fitted the Tornado ECU and jag AFM, marked the starting spot and then rotated the AFM wheel clockwise, which tightened the spring and actually richened the mixture - engine ran like a dog. Rotated anti-clockwise about half a turn past original start point, revs picked up, engine ran sweeter and now it ticks over beautifully, starts on the button and revs its nuts off without a hiccup. Exhaust was blowing very smoky when revved but now no noticeable smoke. I know I'll need to get it set properly on an analyser but feeling much happier now that it is behaving.

Before I started fiddling with it, at tick-over if I gently manually opened the flap a few mm on the AFM then revs rose, hence assuming mixture was too rich. Winding it leaner, when I opened the flap the revs died a little. Where it is now set the revs rise marginally for a few seconds and then settle. Very similar to setting the mixture on an old SU carb!

Happy days, apart from stinking of exhaust fumes - it was way too wet to park the car outside the garage.

[KKson]

pieeater said:

when i spoke to Mark Adams at tornado he said that fitting a jag afm should release about 12 brake at top end and 15lb/ft

That's also what he told me, hence the upgrade to the Jag AFM. Time and rolling road will tell.....

[KKson]

rev-erend said:

Keep us posted on that one.

Only been waiting 8 months for a RR date - don't hold your breath!

I did spend several hours on Sunday tinkering with the AFM settings. I had set it up so that by opening the flap a small amount the engine idle speed increased for a second or two and then settled. A quick blast around the block and pulled the plugs out and they were way too lean. I then subsequently backed the AFM wheel back clockwise, 4 teeth at a time. The idle revs dropped off a little but each time I went around the block the plugs were looking a better colour. I reckon two more runs and I should be there or thereabouts. Engine ticks over nicely now, pulls like a train and pops nicely on the over run which it didn't do when on the lean side. I'm also going to plug in an old Gunsons colour tune on Saturday to see how that looks. Old and very course I know but it should give an indication of the fuel/air mix in the engine. I'm getting there.

[KKson]

mrzigazaga said:

Forgive my ignorance but have you had the 4CU ECU modified?..I always thought the 4CU wasn't mappable?..I know of people with the Tornado chip but they have hotwire and the 14CUX....

Yep Mark Adams has already modified a spare Tornado ECU i had for the 390 to suit the John Eales engine, standard injectors, Jag AFM and V8 developments Stealth camshaft. I do have a standard 390 ECU and AFM I can swap back over in 5 minutes which also runs fine but doesn't seem as frisky as the modified units.

[KKson]

mrzigazaga said:

So you can use Rover-gauge or ECU-mate to map?.....

No not with the flapper ECU. My understanding is that much of the mapping is actually changing internal resistors. Mark can modify the ECU with external pots so that it is truly adjustable.