Cleaning air flow meter?

[e30 323i]

Can someone please familiarize me with the preferred method?

Q-tips and alchohol?

Couldn't find it searching...

Thanks.

[regis101]

I would not use any type of cleaner/solvent on the carbon track/PC board. I destroyed an AFM on our 78 Westfalia with L-jet from using CRC. It was a junkyard AFM but nonetheless. The lids are sealed with silicone to prevent outside air from entering. If you feel it is necessary to clean the inside, I'd prefer to see you use nothing more than a dry q-tip. And try not to rub too hard. And do not disturb the wiper arm tension. I have never seen any type of dirt build up in an AFM. Doesn't mean it can't happen, it's just not normal. If you find oil build-up inside then I'd say that the shaft seal has worn. If the carbon board is showing excessive wear, you'll need a new AFM. It is possible to slot the four holes and slide the board around, but only enuff to get you outta the woods. Just some thoughts.

[asubimmer]

mines dirty on the inside :/

[regis101]

Uncommon, yes. But you'll need to provide more info. Does it appear as an oily film? Straight up road dirt? WWWhat? As a side note, It was told to me by a tech at the FI rebuiling shop down the road that for some reason, the sealing compound used to seal to bottom plate to the body deteriorates over time. This can cause false air to enter between the AFM track via the CO adjustment path. Which in turn can cause bad smog readings. One way to tell is when the CO adjustment screw is all the way in and it does nothing to change the CO content. Similar but not a true indication of internal AFM air leakage is when you play with the CO screw and the idle sound/speed changes. As a rule of thumb, three turns out is ballpark for the CO. I'm no guru but I know enuff to get by.

[e30 323i]

OK, I was just looking to rule it out...I have a power loss/hard starting/rich mixture issue and I've been slowly working on eliminating possibilities. My cover comes off because the silicone bead is broken. I suppose I should probably seal it up, huh? I thought it was a jerry-rig fix because the lid was broken or something. Upon visual inspection, it's not dirty in the sweeping arm area, but I didn't know if maybe the filament inside the intake hose might be dirty.

Please advise...thanks.

ben

[regis101]

I use ty-wraps to hold mine on. I've yet had a problem with air leaking from the business part of it and the shaft. But It can be a hidden source of unmetered air and should be properly sealed. Thin bead of any RTV will do. Just let it dry. There is not a filament exposed except for the air temp sensor and that is part of the AFM housing and hangs in the air plenum. If you look under the blacklid, you'll see the two wires that are attached to the sensor. Generally, if you ohm it, it should read 2.5k at 70* ambient air temp. IMO, vacuum leaks are the largest cause of a bad running engine. L-jet is an easy Bosch FI to understand. It is somewhat archaic as compared to the later Motronic. But it is this simplicity that makes it easy/fun to diagnose. To back up a bit, a quote from an old mechanic goes, 90% of carbuerator problems are in the distributor. Don't be afraid to use a vacuum gauge readings. Again, archaic, but still an invaluable source of info about your engine. Don't forget about the vacuum leak checking. Peace out

[e30 323i]

I have already replaced all vacuum hoses. I was hoping to find a thread on testing the rest of the vacuum system...the only test I'm familiar with is the propane test, which I've already tried and the system seemed clean, but I'm with you, regis, I feel like maybe more than 90% of poor running engine problems are at least vacuum related.

Can anyone shed light on testing the remaining components of the vacuum system?

[regis101]

You might want to try the search or start another thread. It may start to sway off topic?