Air Flow Meter Question....Help!!

[bennyp]

hello boys and girls,

ive still got a really lumpy idle and terrible "off idle" throttle response on my 325i, its been to the local "specalist" and he's had it connected to the diagnostics machine and nothing is wrong with the systems at all.

there is no air leak anywhere ( has been checked a million times ), all the plugs are fine etc etc, but im really stuck now.

the only thing that i can think of is that the car had an induction kit on before i bought it ( and when i tested it ) and there was no problem, however he took this off before i collected it and it was easier for him to just swap the whole unit ( AFM too ) for a spare with an airbox on. I have since fitted an induction kit also and im now sure that the AFM is broken.

I would love to know if this causes the symptoms i have and if it could be broken and not show on the diagnostics check?

please help as im driving it to france in 3 weeks

[TOURINGDADDY]

Sounds like a dodgy afm mate i would try and sorce another 1 ave a look on the parts 4 sale forum

[bennyp]

if it was a dodgy AFM would it not show on the diagnostics?

[TOURINGDADDY]

Not all the time as this is an e30 were talkin bout

[bennyp]

i think ill get a spare off the previous owner and try it.

fingers crossed x ( thats not a kiss by the way )

[psychochild187]

do u get any missfires when you drive eg hard throttle

had a similar problem . only was rough at idel and i little above . (but it was only a gentle miss at idle)

reved fine drove fine . might be hard to try. but would missfire in high 4th and mid 5th gear .

is yours a really lumpy idle and all over the place . ?

[bennyp]

get a very slight miss at idle and weeny bit above but idle rises and falls slightly, then when you "blip" the throttle from idle it drops in revs before almost dieing, its a pain in the a*rse as you have to be real gentle at lights and junctions.

runs perfect over 1500rpm or accelerating hard

[hogweed]

I had a lot of this, years ago - coudl be a few things mate. AFM is a possibility, but the diags in my experience only show thigns up which are totally how-you-say - if they're just a bit off, it won't notice.

The AFMs aren't great on pick-up form idle at the best of times, there's a geet big flap to get moving before the ECU notices. One thing to check... screwed mine up totally... the connectors where the wiring loom clips to the TPS might be corroded. The ECU relies on this switch to tell it whether the throttle is open or not.

If the connectors (or even the TPS itself) are dodgy, the ECU may not know when you sink the boot, so for the first little bit of the AFM opening, the ECU will meter fuel as if on idle, ie hardly any, so the engine will give a big cough.

Once the AFM's opened a little more, I think all control is transferred to it, ignoring the TPS, so the engine woudl then behave normally.

That's what it was with mine anyway! Transformed the beast just by pulling the harness off and thoroughly cleaning and greasing the connectors, inside and out.

Failing that, you're only down the road... take it to Gloucester BMW Specialists (independents) - I never use anyone else. 01452-300150.

Rog

[Jhonno]

vacuum leak? sounds like Dave's symptoms he had, replaced the ICV pipes n solved it (before the head issues!! )

[dazleeds]

sorry anyone here knowq bout diffs????

[bennyp]

ill check all the TPS connectors tonight, cheers rog.

i dont think its a vacum leak as ive had all the tubes, pipes etc off and all is perfect.

i shall try TPS connecter, and then a spare AFM. if none of that works ill go really really

dont know much about diffs daz, only that they are under the car at the back?!

[hogweed]

...I found my problem by just reaching under the TPS with the engine idling (bit of a bastard if you have big hands like me) and grabbed hold of the harness and wiggled it assertively. The idle leapt up to 1100 or so then back to normal etc.

Covered the contacts with vaseline once I'd sanded them a bit... nearly 5 years ago, no bother since.

[bennyp]

ill try that first, thanks.

ill let you all know what happens!!