lean mis fire on 3 then mulitpul cylinder z4 2.0

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Dave900

Member
Hello everyone
this is an odd one i have a z with the n4620b engine and yes i know how i am missing two pots, but I'm not missing 100kg on my front wheels. thank you..

well it is mis firing on 3 and multiple cylinders. please help...
It has had new plugs coils
compression test , head gasket test , smoke test and new pcv or crank vent thingy.
all seams good could it be a silly sensor or is it going to be a vanos repair.
thanks and look forward to the missing pot jokes ta
 
Dave900 said:
Hello everyone
this is an odd one i have a z with the n4620b engine and yes i know how i am missing two pots, but I'm not missing 100kg on my front wheels. thank you..

well it is mis firing on 3 and multiple cylinders. please help...
It has had new plugs coils
compression test , head gasket test , smoke test and new pcv or crank vent thingy.
all seams good could it be a silly sensor or is it going to be a vanos repair.
thanks and look forward to the missing pot jokes ta
Click to expand...

You need to hook it up to a code reader really to shed some more light, have you tried running it with the maf disconnected to see if the running improves?
Rob
 
thanks
codes are 29cc and 29cf it also tells me 02 sensor behind not ready don't know if that has owt to do with it
 
Some o2 sensors are electrically heated (they have an additional 2 wires) if it's saying "sensor not ready" it sounds suspect.
There will be a more experienced man along shortly to tell me I'm completely wrong :oops:
Rob
 
and yes maf clean with maf cleaner and tried with it disconnect . the guy at garage pulled vanos connector and it ran smooth and said it needed a new motor and i thought ,wrong it was cos it went into limp mode. it is missing cos of lean mix , the plugs tell me that
 
Dave900 said:
and yes maf clean with maf cleaner and tried with it disconnect . the guy at garage pulled vanos connector and it ran smooth and said it needed a new motor and i thought ,wrong it was cos it went into limp mode. it is missing cos of lean mix , the plugs tell me that
Click to expand...

He could of meant the vanos solonoid as they don't have a motor, that usually results in an unstable idle & flat spots whilst driving though.
Rob
 
could leaky o rings on the vanos corse lean burn..... just a thought
no i dont think he was that clued up to be honest
 
Dave900 said:
could leaky o rings on the vanos corse lean burn..... just a thought
no i dont think he was that clued up to be honest
Click to expand...

They work on oil pressure so leaks won't help, there's a bleed procedure for them.
Our Mini Cooper had a vanos issue which made the ignition timing dance around like mad & the engine was hunting & lurching-it felt like a weak mixture because of the flat spot on reapplication of throttle after a gearshift or pulling away from the lights, feels like it's bogging down then shoots off as the engine comes on cam ( the vanos normally smooths this lower rpm range)
 
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