Inconsistant Idle (jumps 500-1000)

[winstontj]

Hi,
Maybe someone could help me with my poor idle. Fuel pump & filter are new, cap & rotor are new, plugs & wires are good, correctly gapped, etc. Coil is fine, Timing belt is brand new and not off a tooth. Valves are out of adjustment and need adjusting but not bad. This is a 325i (IS faker)

Car has a Split Second MAF (heated wire) conversion kit installed, 8mm bavauto wires, bavauto chip, K&N air filter, looks like cruise control has been removed, bavauto adjustable fuel pressure regulator (no idea what it's set at), uprated injectors - (no idea which ones)

Car starts fine and runs really great but the idle jumps. It stalls every once in a while but the jumpy idle has me thrown for a loop because i'm used to carburetors not EFI. The TPS works fine, I can hear it click when the throttle plate comes off idle. IAV works fine i think...and vacuum lines are OK but not great. I'll replace them shortly but they aren't cracked, just starting to get a little hard and brittle.

If anyone can point me in the right direction it would be much appreciated.

Thanks,
TJW

[Garageaholic]

What is an IAV? If it's the same as the ICV (idle control valve), then your thoughts are confirmed, because I believe that your problem lies with such an apparatus.

[winstontj]

Sorry frank. New to this EFI stuff. Aux Idle Air Valve or IAV, ICV, AIV, etc.

This could cause poor running? I thought it was either open or closed (solenoid) but can't really do anything other than dump air into the intake after the throttle plate... Am I wrong? Is this a progressive unit or does it have the ability to open/close randomly?

[Garageaholic]

I am not familiar with the internals of the ICV. I believe that it does get dirty, so before buying another one for $110 some-odd, try removing it and cleaning it, making sure that the hoses connecting it to the intake bellow are not cracked, bc that could introduce unmeasured air and cause an erratic idle as well.

Use brake-kleen or equivalent to clean it and see what kind of result you get.

[winstontj]

Saturday I sprayed the snot out of everything with ether and couldn't get the idle to change no matter what I sprayed. This leads me to believe that my hoses are old & tired but not cracked or leaking. I'll pull apart that ICV thing and have a look. Is it the same as the m10 e30's or different? I've got 4 or 5 used m10e30 VDO brand ICV's laying around.

Thanks for the help. Beers on me if you are in the boston area!

[Garageaholic]

haah, I could be in the boston area if you like. lol But I'm not sure about application of the ICV. I think that they vary between models, but if it fits, use it. Do you know where it is? can you locate it? I could give you a picture if you like.

[winstontj]

Yeah it's right next to the TB. I'm a noob here but I'm pretty well versed in all things BMW and german. I've had a bunch of Audi's, VW's, MB's & BMW's and they all sortof do the same thing, use the same parts (bosch, vdo, etc.)

Also I'm building an EFI stroked M10 for my 2002 and it uses an m20 TB among other things so I've gotten pretty familliar with the e30m20 intake setup so I know what to plug up and what to use on the M10. The part sits right on top and it's a little two wire solenoid with a 90 degree inlet/outlet config with an adjuster screw. I'll poke around it tonight and see what I can come up with. I'll start with cleaning and read my manual to see how exactly you can adjust them.