E34 530i Wont idle when hot

S

Ste00

Active Member
This is kinda a follow up to my emissions problems as i think the 2 are linked...

When my 530 is cold it will run fine, smooth and pull like a train... when the temp gets up however it will misfire like mad, hunt for idle and hold back when moving under 3k revs.. end result is that when it comes to the emissions test you cant hold it at the required RPM and it fails on HC (Unburnt fuel).

So far I have:
Changed the Lambada sensors,
New intake gaskets,
New rubber sealing bung on the intake
Cleaned the ICV and checked that it "buzzes"
Changed the White temp sensor behind the intake.
Had the injectors serviced and ultrasonic cleaned.
Changed the fuel filter.

Anyone any ideas what to try next? its booked in for bmw diagnostics on Monday afternoon to check the sensors ect out.

This all seemed to start after I changed the back box from the old one to a more free-flowing one, now I have read that you need to reset the ecu (disconnect the battery's and join the to leads together for 10 minutes) as after a while it wont self learn and will use settings that no longer apply... so I might try this after the diagnostics...

Anyone any other ideas?
 
This vid shows what i am talking about,

when i take it to 3k and try to hold it their on the throttle (no movement in my foot) it gradually gains more and more RPM

tried to get a vid of the idle issue but of course when you want it it doesnt happen so all i have is 7 minutes of it warming up and another 2 when it had a hicup but stopped instant i turned my phone on...

Vid1 (problem One):

[ame=http://www.youtube.com/watch?v=Pye8e9Rn9PU]YouTube - M60B30 Warm Idle[/ame]

Vid2 (Cold start and idle):

[ame=http://www.youtube.com/watch?v=t67z4nQhriM]YouTube - M60B30 Cold start and idle[/ame]

Vid3 (Hot idle, can hear a slight miss and rev change in the background)

[ame=http://www.youtube.com/watch?v=wFYF0TxqN_o]YouTube - M60B30 Warm Idle[/ame]
 
Well the diagnostics is done....

*drum roll*

Idle Controll valve fault,
AFM Fault,
Heated o2 Sensor fault (think this is a old stored fault tbh as both were changed in march and the car has done 60 miles since)

So i am now on the lookout for a icv and MAF meter...
 
my 328 does exactly the same... i must try cleaning the idle control valve, then its change the AFM over i reckon :)
 
ICV is knackered its shorting out and has melted the plug, AFM i had cleaned before the test :(

Just got a quote for the two bits new... i need to morgage the flat lol... going to phone round local scrappys asap,
 
"new" ICV is here... going to go test fit it now E-bay ftw... also accidentally bid on another ICV so might end up with 2 lol...

AFM has been paid for today so fingers crossed monday or tuesday it should be here...
 
New icv is on and the idle is sorted... still gaining and losing rpm when you try to do a emissions test though... hoping its the afm miss reading and leaning out / richening the mix...
 
Just done a compression test... first 7 cylinders are sitting at 160psi... 8th is at 145-150..

now I am not 100% sure if this is the issue as the plug came out clean from this cylinder that tested low (cant rember if I tested right either... could have swore I had to remove all plugs at once but I didn't this time)
 
Just got back form another emissions test...

1st fast idle
CO Limit .3 Actual .32
HC Limit 200 Actual 24
LAM Limit 0.97-1.03 Actual 1.02

2nd Fast idle
CO Limit .3 Actual .36
HC Limit 200 Actual 29
LAM Limit 0.97-1.03 Actual 1.01

Idle CO % Limit 0.5 Actual 0.42

So it failed by .06 :(

Issue now is that on the way back is was idling like crap and cut out when i stopped outside my house...
 
You normally will see the comp drop off a little towards the end as the battery gets tired of spinning the engine over, the slower it turns, the less compression you'd see.

You could try a drop of oil in nr.8 that help tell you if it's nikasil wear.

There's also a crank case ventilation valve at the back that can cause problems on the V8s.
I'll see if i can find a DIY
 
the feed / flow line, it seems to be low on pressure as its easy to squash, normally on the cars i deal with the fuel lines are rock hard when running,

I am starting to think its the pump as it started just after i changed the filter...
 
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