DIS v57 - Setting idle RPM, always 100 RPM above what I set.

C

Cyph3r

Member
Hey all,

I've got a 2006 Z4 2.0i SE (N46 engine) and quite a while ago I was having some issues with the valvetronic which a local BMW indy couldn't figure out. One of the problems it was causing was a rough idle, so the indy set the idle RPM up to 950, which I guess helped abit? Not much.

Anyway the underlying issue was solved at another garage, but I forgot to ask them to lower the RPM. Using INPA I've found that setting the idle RPM to 750 gives the smoothest result. But I can't get INPA to save that value (as I'm sure many of you know).

Jumping into DIS v57, it allows me to set the RPM for when the AC is on and off. But the issue is, the DME is programmed at 850 RPM for both states, but the "idle target" is 950, and that's what it's idling at. So if I lower both the blocks down to 750 RPM, it actually idles at 850. And the lowest figure I can type in is 700 RPM, which results in an idle of 800 (which is nowhere near as smooth as 750).

So I'd need to type in 650 to end up with a real idle of 750, but as I said 700 is the min.

Does anyone know why my idle always ends up 100 RPM higher than what I set? And how I can solve this issue? I owe a beer to anyone who can figure it out!
 
Wow, that sounds like a total bodge! Don't know why a garage would play with the idle from what it's set as, surely that's just masking the actual problem rather than fixing it..............I really wouldn't be messing with the idle settings TBH.

I've seen those options in INPA and DIS, not adjusted mine so can't help with why it wouldn't be saving the idle state, seems strange tho. If it was me, I would probably be biting the bullet and taking it to a main dealer so they can program it back correctly rather than trying to *fudge* it. An hours labour at the most I imagine, probably worth it on this occasion for piece of mind. Plus they'll be using the latest ISTA software unlike INPA/DIS which is old tech now really. (Not that it doesn't have it's place of course, but I wouldn't use it for anything other than basic diagnostic.)

If your determined to fix it yourself, I would be ignoring the fact it's 'smoother' at 750rpm, it's set at 850rpm (or 840rpm, something liek that,as standard from factory I believe) for a reason, so I wouldn't be deviating from that. If INPA etc isn't letting you set it any lower maybe there's a reason.....
 
Yeah the garage's "solution" of increasing the rpm to smooth out the idle was definitely a bodge. No question about it.

Well INPA lets me set it down to like 650rpm, (didn't go any lower as it'd of stalled) and DIS allows a 700rpm min, but as I said, in the end it runs 100rpm higher than whatever I set, which I find odd.

If it's supposed to be 840/850 from the factory though I'll leave it at that. I may swing it by the main dealer when I get a chance though. In fact, I'll ring them shortly and ask about it.
 
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