M62 idle on cold

[bmwE38r]

Hi friends I have the problem with my idle on cold start.When I start cold engine,engine running perfect,but sometimes(about 1 time in 1 minute) my idle rises to the about 1000-1100 rpm,then engine is running on this rpm about 5 second,and then go back to the normal My Idle control valve is cleared like a new Of course inpa dont show any errors,but in the morning when engine is cold, I connect Inpa,and in the analog values i saw,that when engine is warming up,the MAF sensnor values is about 25,and needed air consumption(I think this is ICV valve readings) is about 23,and of course this values drops,when engine temperature rise.But when my idle rpm up to the 1100,i saw,that MAF readings up to the 35-40 and needed air value olso up to the about 30 and more Now the question: I think that my MAF is bad,but who owned what?If the MAF values rise up,needed air values rise up also,because icv values depending on MAF values? Or MAF values depending on ICV values(when ICV shows more air,MAF shows too) ? sry for my bad english Please help friends

[bmwE38r]

Please help

[xboss]

Could be a sensor but cold engines can have leaky seals that seal shut once warm. If that is the case the culprit should be the intake seals, the maf boot, the throttle body or the intake it'self.

The PCV valve can be a problem as well.

Good luck!

[Timm]

Turn your A/C OFF (Snowflake LED NOT lit) - and then report back what changes!

[bmwE38r]

Timm This values is when acc is off xboss,pcv is changed,and no leaks,fuel trims ltft(additive) and stft(multiplicat) is good And this problem I have rarely,in week 1-2 times when start cold if it be a leak,i think it be forever and realy it not big problem,becouse when I had it,only 1 time per 1-2minutes raises rpm lightly to the 1100,then some seconds engine runs,and again lightly goes back to the normal idle in my situation this 2 values change together(needed air icv,and maf sensnor) if maf values raises,together raises the icv or contraries?when icv raises,then together maf sensnor raise values? and forever my readings beetween maf and icv varies needed air show 17 on warmed engine,and maf shows more,about 20,forever maf values is bigger and maf values changing every 3-5seconds 16-18,then 17.5..a sligh changing every 2-3 seconds,its normal? bad english,i am from lithuania,sry friends;/

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And if acc is on and only then I have this problem,and when off,engine runs perfectly,what it means? acc problem?

[Timm]

The ECU will change the idle speed for a couple of reasons:

A/C compressor clutch engaged - increase idle to 700 RPM
Battery Voltage low - increase idle to 900 RPM
Both at the same time - 1000 RPM

Base idle is 600 RPM

Your readings convince me that you had your A/C ON and your battery needs charging....

[bmwE38r]

Thanks tim AC is realy off,because weather is about +5 cealcius,no need ac in that weather battery is so good,because var start with no problem,but not fully crarged,its about 12.4 v,but weather about +5 celcius,and realy we have a mistake in this values when we check it realy is about 12.5V.Battery checks with no mistake is at about +25 celcius(battery manuals and literature means that) and I think 12.4 v its realy not a problem But maf sensnor here have a good values,and maf sensnor not to what here in this problem? and I want to know,what means what,if maf values rises,then behind rises icv(needed air) values? or when needed air values rises,behind go maf values to up? thanks for answers Tim

[bmwE38r]

I think this a last my question ^^

[Oleh007]

Hmm, is it happening after engine has warmed up? I know in my car when I idle for long, the RPM will jump up to 1000 RPM for 1-2 secs then jump down to 600RPM but it happens once. Try to idle for a little (until the Temp needle in middle of blue temp gauge) and then drive without pressing on the gas too much. Maybe the engine is compensating for the cold and tries to warm up? After the car is warm and driven, when you idle, does RPM rise to 1000RPM again or no? Sorry if this is no help.

[bmwE38r]

Thanks for al suggestions but its happening only when engine is warming up,when warmed its runs perfectly But ita happening very rarely,about 2 times when i start a cold and wait until engine warms up(on idle,no drive)to the operating temperature but now 3 weeks I dont have this problem Engine runs perfectly maybe its maf sensnor sometimes goes bad..but anyone dont answer to me:what means what,if maf values rises,then behind rises icv(needed air) values? or when needed air values rises,behind go maf values to up? When maf rise her values,maf says also to the needed air values to rise?

[priidik]

Sorry for bumping old thread but my E38 M62 (3.5l) has the same issue. It has been like this for 3 years on every cold start (running like a minute or so), the rev rises up to ~1200 rpm (for ~15 sec) and then back to ~1000rpm. Battery is brand new, climate control is off. Also have bad idle if there's cold temperatures outside (have changed a lot of parts, no leaks etc).

[BillConn]

Likely a Vacuum leak at intake manifold or throttle body. Problem is usually worse ( or sometimes only happens) when the engine is cold and weather is particularly cold. As the engine warms up, gaskets and parts expand sealing against the vacuum leak.