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Discussion Starter #1 (Edited)
Hey guys. So yesterday I changed my VCG in my 330ci. Everything went good. Left the car in garage for a next day to make a test drive and check for leaks. I havent seen any leaks yet.
After test drive - BOOM! check engine light!:(
Car drove and still drives normal like always but this anoying SES light. I went to autozone to read the codes and that's what I got:

- P0171 System too Lean (Bank 1)
- P0313 Misfire Detected With Low Fuel Level
- P1083 Fuel Control Mixture Lean (Bank 1 Sensor 1)
- P1085 Fuel Control Mixture Lean (Bank 2 Sensor 1)

I thought I got the engine light because I didnt have much fuel ( had only 44 miles of driving left, I know I should refill earlier) so I went to gas station, the went to autozone to EREASE the codes and was everything ok. No engine light. I thought my problem is done. But After few hours I got the check engine light again. And I dont have a clue. Can someone help me? I am thinking that maybe I messed up those cables around the valve cover, but I am not sure.
 

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Discussion Starter #4 (Edited)
I got codes only once after getting the gas. This is my story :) - First got my engine light then I went to get some gas. Then went to autozone to check and erase the fault codes, and then I was driving and everything was ok for few hours. Then in the evening I went to pick up my sister and got the engine light again. After this I didn't do anything, I am waiting till tomorrow to go to autozone and get the codes again to make sure that they are the same like these today
 

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op i will save you a lot of time on this problem. your vcg did NOT seat correctly. i had the EXACT same problem and spent a lot of time diagnosing it only to find out it was in fact the vcg itself. i promise you this is not a cooincidence. you are lean on BOTH BANKS thus you almost 100% positively have a leak on your vcg. i asked a lot of people if a leaky vcg could cause a vacuum leak and a lot said no but it CAN.
as i researched this A LOT my steps would be in this order


check all vaccum hoses and intake boots
pull vcg again, tighten down in a "Z" pattern , hand tight !do not overtighten use sealant on all 10 recommended spots
02 sensors
ccv

again my bet is on the vcg itself. it simply isnt a cooincidence usually. you dont just randomly develop a vacuum leak on both banks every day. i ended up having to pull mine like 3 times lol. it is easy though so who cares. just be careful and go with the z pattern from back to front on the top line, then z down, then back to front on the bottom line. then let the sealant dry. it works.
 

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hand tight !do not overtighten
Bentley lists 10nm tightening torque on the 15 nuts, and Beisan Systems VANOS replacement instructions say 8nm, which is what I used.

Use a mirror to confirm that the rear half moon seals seated correctly.

If you used RTV sealant on the half moons and where the Vanos unit joins the heads, you did use a light coat? (I'm stretching on where there could be a leak around the cover).
 

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Bentley lists 10nm tightening torque on the 15 nuts, and Beisan Systems VANOS replacement instructions say 8nm, which is what I used.

Use a mirror to confirm that the rear half moon seals seated correctly.

If you used RTV sealant on the half moons and where the Vanos unit joins the heads, you did use a light coat? (I'm stretching on where there could be a leak around the cover).
yeah do this if you have access to a torque wrench accurate in that range. i have seen alot of guys use the heavier duty ones thinking it will work but it is so innacurate in the low range they strip the thread. when they are this light, i usually just go by feel.
 

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Discussion Starter #8
Thanks a lot!!! I am going to do it now. I will let you if the problem gone. And one more question. When I ll be done with this the check engine light will be gone itself or I need to clear it with the obd tool?
 

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after a drive cycle it will go off. (there is some set algorithm in the car that constitutes a "drive cycle" certain speeds etc.) you can look it up. but if you want to accelerate the process you can use the tool. also if you dont use the tool the codes will still be stored, just the light will turn off. the sealant locations are just medium-small dabs on the corners of the half moons, and then where the vanos meets the head so 10 total. just be as careful as you can . i had identical codes to you btw. lean on both banks with random misfires.
 

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yeah do this if you have access to a torque wrench accurate in that range.
Agree ... I've heard that roughly the first 20% of a torque wrench can be pretty inaccurate, so those with the 150 ft lb torque wrenches would be in trouble.
 

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Agree ... I've heard that roughly the first 20% of a torque wrench can be pretty inaccurate, so those with the 150 ft lb torque wrenches would be in trouble.
yeah it sounds like you have the luxury of a more precise one lol. i had to hand tighten on my transmission pan and this. basically i just tighten until it "stops" then give it a slight torque and it works well. i would have to say that is some of the most valuable advice in working on a car,, do not not not overtighten, ever. 10 nm is "hand tight".

for critical components suspension etc or anything where safety is involved exact torque should ALWAYS be used.
 

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Discussion Starter #13 (Edited)
op i will save you a lot of time on this problem. your vcg did NOT seat correctly. i had the EXACT same problem and spent a lot of time diagnosing it only to find out it was in fact the vcg itself. i promise you this is not a cooincidence. you are lean on BOTH BANKS thus you almost 100% positively have a leak on your vcg. i asked a lot of people if a leaky vcg could cause a vacuum leak and a lot said no but it CAN.
as i researched this A LOT my steps would be in this order


check all vaccum hoses and intake boots
pull vcg again, tighten down in a "Z" pattern , hand tight !do not overtighten use sealant on all 10 recommended spots
02 sensors
ccv

again my bet is on the vcg itself. it simply isnt a cooincidence usually. you dont just randomly develop a vacuum leak on both banks every day. i ended up having to pull mine like 3 times lol. it is easy though so who cares. just be careful and go with the z pattern from back to front on the top line, then z down, then back to front on the bottom line. then let the sealant dry. it works.
I dont think so that valve cover gasket could casue the vaccum leak(but i can be wrong). There is no possibilty to make the computer read that there is a leak where VCG is. Probably the top engine cover tapped some cables and the vaccum hose while installing it. I did it wrong before. Finally fixed it. Waiting till tomorrow to let the rtv dry then going to autozone to get the codes cleared. I will let you know if I fixed this
 

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A faulty/unsealed valve cover gasket CAN cause a vacuum leak. Have seen it on three different occasions. Just think about crankcase pressures and that they're on the negative side creating a vacuum. Just open your oil cap with the car running and it will set lean mixture faults. Double check it and get back to us. Also make sure the hose on the drivers side front of the valve cover didn't crack when you removed it. Also make sure it is sealed good. That hose goes to the crank case vent valve down under the intake. Good Luck!

Erick
 

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I dont think so that valve cover gasket could casue the vaccum leak(but i can be wrong). There is no possibilty to make the computer read that there is a leak where VCG is. Probably the top engine cover tapped some cables and the vaccum hose while installing it. I did it wrong before. Finally fixed it. Waiting till tomorrow to let the rtv dry then going to autozone to get the codes cleared. I will let you know if I fixed this
trust me. been there , done that. it can. it isnt a cooincidence. reseating mine solved the problem. same exact story as op
 

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A faulty/unsealed valve cover gasket CAN cause a vacuum leak. Have seen it on three different occasions. Just think about crankcase pressures and that they're on the negative side creating a vacuum. Just open your oil cap with the car running and it will set lean mixture faults. Double check it and get back to us. Also make sure the hose on the drivers side front of the valve cover didn't crack when you removed it. Also make sure it is sealed good. That hose goes to the crank case vent valve down under the intake. Good Luck!

Erick
yep.


it is one of those things that is easy, but at the same time hard lol. to get it to seat properly
 

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vc gasket

Hello I am a BMW tech and yes a vcg can cause a leak and set the light. The crankcase is a sealed unit with an oil seperator which operates through intake vac thus causing a vac leak then the o2 sensors read a lean condition because the air going into the intake manifold is not seen by the mass air flow sensor and therfore there is not enough fuel being delivered. If you have the ability to watch the o2 sensor voltage while running open oil cap or pull the dipstick and watch how lean it gets good luck.....you will prob find gasket rolled under on you. AJ
 

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ps... in school they taught us to put a light film of grease on the gasket...not sealant these are two different types of metal/plastic which expand and contract differently and are designed to move independently through engine temps just a suggestion
 

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ps... in school they taught us to put a light film of grease on the gasket...not sealant these are two different types of metal/plastic which expand and contract differently and are designed to move independently through engine temps just a suggestion
i would agree with that but the bmw spec does call for sealant. just small dabs. it worked for me.
 

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Discussion Starter #20 (Edited)
So today rtv should be dried and I went to my garage to test it out. Started the car and... BIG DISAPPOITMENT! My car was shaking like crazy, I was so f**ing pissed off. Went to autozone to pick up the OBD tool. I checked the codes. I got only three(dont remeber them I was so pissed!) what i remember was

- P0171 System too Lean (Bank 1) (the same one I got before, probably this one turned on my check engine light again)
- Misfire bla bla bla manfucatrer igniton (something like that)
- Misfire bla bla bla manfucatrer igniton (something like that looked the same as the above one)

I didn't really look at the codes because I was so mad that my car was shaking like ass, so as fast as I could I wanted to erase them.

Cleared the codes car stopped shaking and everything is fine, I drove about 6 miles and still is everything fine ( no check engine light yet)
I hope it will be like that always. I didnt notice any leaks on the VCG but I need to drive more miles to make sure.
When I get the SD card reader I will post some pictures of my engine and vanos inside. I want to share it becasue my car just hit 190K miles and the engine looks not perfect but very good
I want to thank to all user that help me alot. "G6" your my angel. If not you I wouldn't take the valve cover off again andf I wouldn't notice my mistakes done before. Thanks man!
This forum is ****ing best ever!!!

I will be updating if something will be still wrong
 
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