car under fueling?

[e30bmlover]

hi all and a happy new year.....
right, i have just put a new afm on the b25, the car dosent seem to go as well as it did before, it seems reluctant to rev, before it was just @ucking mad. i have taken some pics of the vdo and obc, im getting good milage though!!!! before i got 220 miles to a tank but they were mad miles i tell ya!!!! mad!!!! now it looks like galactic milage is on the clocks!!!! but im not bothered about consumption!! i dont drive like a mug, i just stretch her legs now and then.. i know the tappets need doing, its a case of when i can afford to lose the car for a day(apparently they have to be done cold) if the car is running lean will it do any damage??? shall i go and give her a half of a turn clockwise on the afm for the time being? any advise would be appreciated.

[Heyho]

It's impossible to diagnose a lean mixture from a distance - although it is possible, it's unlikely that you'll do any damage from normal driving.

As for the tappets - the only time I've ever adjusted them cold is when it's been a rebuild, so cannot be run up to temp. Always adjust M20 valve clearances to 0.35mm engine fully hot.

[Simon13]

or 0.25 with the engine fully cold as per BMW spec

[dannyboy759]

Always adjust M20 valve clearances to 0.35mm engine fully hot.

Since when?
Better cold and although BMW say 0.25.
But i believe 0.30 is better!

[zaust]

Danny is spot on. "warm" me think's not. 0.25. And this should take a couple minuets per valve. so you won't lose the car for a day.

[zaust]

And as for the afm adjust. pop into your local mot station and ask if they can stick the probe up your exhaust and go from there. 130 is the minumim and 230 is the max I would run these motors at and your hc's in an ideal world on these motors is 199.

[pacerpete]

I always do tappets on these cars hot at a snug .35mm . This is especially important on cars with tubular manifolds as they run hotter on the exhaust side than with a log manifold and the clearances close up. If you don't believe me try it !
Tight tappets as well as causing a nasty idle will cause High ppms, power loss and heavy fuel consumption.

[Heyho]

Always adjust M20 valve clearances to 0.35mm engine fully hot.

Since when?
Better cold and although BMW say 0.25.
But i believe 0.30 is better!

In my experience, .35 hot is the best method, and as stated also accounts for uneven expansion. Back in the day, I would regularly have to sort out running/consumption problems which were often down to tight tappets. Could usually achieve HCs of less than 150ppms - not bad for a Motronic engine.

Not least, most people want their car back the same day! Only ever adjusted M-power cold.

[e30bmlover]

problem has been solved, took the car back to ralph, he done the tappets and sorted the idle, when i got the car back ralph had changed the ecu, it was idleing at 900rpm. today i took the car to clive atthowe http://www.enginetuning.net/ ( currently number 1 in the country for bosche engine tuning ) for a static tune and general poke around, he was very pleased with the compression test(always a good thing) he sorted the c.o and the idle is back down to 750, no dips in the revs when the clutch is engaged... even when im moving, starts like a new car( @ucking should do!!! ) and is a pleasure to drive. i even reset the M/G gauge and managed 39.3m/g!!(vdo was sitting on 50m/g you know the bit below the speedo) although this figure did drop when i slowed down to turn into my road. now she purrs like a kitten, the engine is so, so quiet.......so quiet.