Hi everyone i recently bought a 320i e90 automatic 2009 bmw it started with exhaust fumes after 1month of owning it i took it to bmw autohaus in east london where they did checks and said that it has a damagsd exhaust system and i will need to replace it an i took it to other mechanic because i could not afford their whole exhaust system who later refferd me to poerflow saying that my cats were blocked and they took them off two of them infront and replaced them with straight pipes. They did that last week but i still see some fumes especialy when im accelerating and reversing..please advise as to what must i do.
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exhaust system damaged
- Thread starter nuty
- Start date
Ralf*
///Member
The exhaust is just a "means" to evacuate the burnt exhaust gases from the combustion process
So apart from
1)Blocked CATS
2)Damaged Lambda sensor probes/wiring
3)Incorrect aftermarket size exhaust pipe fitted which might not provide the correct (little) amount of back-pressure sometimes required....mainly an issue on Turbo motors as far as I have read.
most smoke is not the exhaust's fault, but it is coming from the engine.
It could be that the ECU is receiving incorrect signals because of a damaged O2/Lambda sensor.
The rings could be worn, or the cylinder head gasket is allowing oil into the combustion chamber, or the valve stem seals are worn.
there used to be a old "rule-of-thumb" diagnostic method
1) If it smokes when under positive acceleration (throttle applied) = then it is likely rings
2) If it smokes when under "suction" or freewheeling against engine compression ( ie downhill) = then it is likely valve stem seals
So apart from
1)Blocked CATS
2)Damaged Lambda sensor probes/wiring
3)Incorrect aftermarket size exhaust pipe fitted which might not provide the correct (little) amount of back-pressure sometimes required....mainly an issue on Turbo motors as far as I have read.
most smoke is not the exhaust's fault, but it is coming from the engine.
It could be that the ECU is receiving incorrect signals because of a damaged O2/Lambda sensor.
The rings could be worn, or the cylinder head gasket is allowing oil into the combustion chamber, or the valve stem seals are worn.
zippy320 said:
there used to be a old "rule-of-thumb" diagnostic method
1) If it smokes when under positive acceleration (throttle applied) = then it is likely rings
2) If it smokes when under "suction" or freewheeling against engine compression ( ie downhill) = then it is likely valve stem seals
ballisticz466
///Member
I had this issue with a previous car, turned out to be the rear boot seal letting the exaust gas into the cabin.
Iceman007
Active member
ballisticz466 said:
Jip I have also seen this on a previous car I owned. Some idot rear ended me and after a panel shop repaired it I had this problem. After investigation it was found that in some places there was a gap for they did not do a proper repair. Just note it was not due to the rubber but the frame was to low and this can be seen by removing the boot rubber completely and closing the boot gently and then inspecting the gap from the inside
ET was here
New member
is the originator referring to fumes inside the cabin of the car, or visible exhaust smoke exiting the rear end ?
Luis Malhou
///Member
NOT SURE IF THIS HELPS,
also not sure if on diesel the turbo has the same system. When I was contemplating doing the 335 DP's I had heard about cars smoking afterwards. After speaking to a turbo specialist he told me it was normal due to the fact that the turbos use a oil feed lubricated seal which needs some back pressure off the exhaust to the keep the seal full seated. If the cats are removed the back pressure is less with the DP's causing in some cases for the oil to seep past the seal and burnoff in the exhaust. Its normal, has no permanent damage other than a little smoke at some occasions, idling and pull offs.
Keep an eye on oil consumption and top up when necessary. It could be valve stem seals but you would have had the same problem before, also valve stem seals leak early on start ups and on gear changes. Hope the above helps. Do a wet head leak test and see if it picks up a problem.
also not sure if on diesel the turbo has the same system. When I was contemplating doing the 335 DP's I had heard about cars smoking afterwards. After speaking to a turbo specialist he told me it was normal due to the fact that the turbos use a oil feed lubricated seal which needs some back pressure off the exhaust to the keep the seal full seated. If the cats are removed the back pressure is less with the DP's causing in some cases for the oil to seep past the seal and burnoff in the exhaust. Its normal, has no permanent damage other than a little smoke at some occasions, idling and pull offs.
Keep an eye on oil consumption and top up when necessary. It could be valve stem seals but you would have had the same problem before, also valve stem seals leak early on start ups and on gear changes. Hope the above helps. Do a wet head leak test and see if it picks up a problem.
deanbenn
Member
e90 + 320I + SMOKING ON TAKE OFF OR IN TRAFFIC + OIL USAGE = VALVE STEM SEALS!!
On my 320i I had the same problem. After many checks and wasting money..I had the valve stem seals replaced and smoking stopped immediately. Just check if the car is using alot of oil...if it does..it is the valve stem seals.
Hope this helps.
On my 320i I had the same problem. After many checks and wasting money..I had the valve stem seals replaced and smoking stopped immediately. Just check if the car is using alot of oil...if it does..it is the valve stem seals.
Hope this helps.
Hi everyone thank you very much for tour advice about my exhaust fumes it turn out to be valve stem seals causing the smokes as you have sugested,your input much apreciated. Now i have fixed it at autohaus monti but the problem is the fuel consumption is too high now from 10 l/100km to 13.9 l/100km after they have done the valve stem seals. What could be the cause? I dontknow...
Lizzard
Active member
You need to do at least 200km before you start believing the dash instrument. When I reset mine after filling up, for the first 80km mine says 16L/100km and at that rate I will use half a tank in just 2 days but I wait until I have done 200km before I go ape about my consumption.
And remember that when working on it like this major change the car will take a few kilometres before it will settle down. Drive 200 - 400km and then check it out.
And remember that when working on it like this major change the car will take a few kilometres before it will settle down. Drive 200 - 400km and then check it out.
