BMW E46 Fanatics Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter #1
I'm having a rough idle, stalling with my MAF connected (multi random misfire codes). I've replaced CCV and hoses, upper and lower boots, several vacuum lines at rear of manifold. However the vacuum listed as #9 in the diagram is off. I've searched for days but can not find out where it goes too. Any help on this is appreciated.
 

Attachments

·
Registered
Joined
·
200 Posts
I thought somebody had a writeup on this connecting to a vacuum port at the back of the engine L/H side. It is essentially a capped off connection.
 

·
Registered
Joined
·
2,104 Posts
If I remember correctly that vac line goes to the a port on the underside of the intake manifold. But it is not capped and it's very hard to get to. I had a problem with the vac lines rotting, I also replaced the vacuum control valve.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #5 (Edited)
I will try again tomorrow to find it. After fixing the things mentioned above I'm down to P1343, P1347, P0174. Previous to the other repairs all I had was misfire codes. P0174 is new. **Edit P0174 is no longer displaying
 

·
Registered
Joined
·
815 Posts
Yes, it could well be the DISA/Intake Resonance Value broken, the flap breaks and goes to different positions trying to work and it will cause rough idle, random misfires, decreased gas mileage and performance issues. Easy to pull it off and check it, most likely the flap is hanging.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #10
Yes, it could well be the DISA/Intake Resonance Value broken, the flap breaks and goes to different positions trying to work and it will cause rough idle, random misfires, decreased gas mileage and performance issues. Easy to pull it off and check it, most likely the flap is hanging.
Thanks... From what I had been seeing I thought that was a possibility but wanted to double check before proceeding. Ive seen people cleaning it with carb cleaner?
 

·
Registered
Joined
·
28 Posts
Still having problems, if so start from the very beginning... Did you replace the CCV and hoses, upper and lower boots, several vacuum lines at rear of manifold to attempt to rectify this issue or did the issues start after doing some of the work?

In the one group of screen shots your short term bank 2 is at 27.3% and all others are at 0%. 0% for short term or long term is unusual to see, there is usually some correction +/-. Seeing one of the numbers so out of range is odd... Upstream 02 sensors switching high/low as they should? Smoke test it instead of throwing parts, and money, away. Make sure the engine is completely cold prior to smoke testing it. I have driven cars from in the shop to my bay, smoke tested them and found no leaks, CEL still on. Push the same vehicle in the next day without running it at all and found all kinds of un-metered air leaks.
 

·
Registered
Joined
·
815 Posts
Easy enough to see if the DISA/Intake Resonance Valve is broken when you remove it, the "flap" will be hanging. If the flap isn't hanging, you can use your mouth to see if the valve opens and closes smoothly which will check the diaphragm in the valve. A broken DISA will give you random mis-fire codes, poor performance, lower vacuum and poorer gas mileage depending on where it is stuck.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #14 (Edited)
Still having problems, if so start from the very beginning... Did you replace the CCV and hoses, upper and lower boots, several vacuum lines at rear of manifold to attempt to rectify this issue or did the issues start after doing some of the work?

In the one group of screen shots your short term bank 2 is at 27.3% and all others are at 0%. 0% for short term or long term is unusual to see, there is usually some correction +/-. Seeing one of the numbers so out of range is odd... Upstream 02 sensors switching high/low as they should? Smoke test it instead of throwing parts, and money, away. Make sure the engine is completely cold prior to smoke testing it. I have driven cars from in the shop to my bay, smoke tested them and found no leaks, CEL still on. Push the same vehicle in the next day without running it at all and found all kinds of un-metered air leaks.
I did do all of the above except a smoke test. With maf off and codes cleared fuel sys 1 and 2 show closed unless I gas it then they fault momentarily. Fuel trim 1 is 10~ and 2 is 7~. I do see the o2 changing values. **Edit it's not the act of raising the rpm's that causes the fault. I was watching as I.drove down the hwy. It faults when I release the accelerator and the rpm's drop towards 1000 such as stopping for a light or going down a hill. soon as I touch the gas again the fuel sys's close again.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #15
Easy enough to see if the DISA/Intake Resonance Valve is broken when you remove it, the "flap" will be hanging. If the flap isn't hanging, you can use your mouth to see if the valve opens and closes smoothly which will check the diaphragm in the valve. A broken DISA will give you random mis-fire codes, poor performance, lower vacuum and poorer gas mileage depending on where it is stuck.
hopefully I will get it checked by Friday. I was going to today but didn't have a T40, bought one but it got dark on me.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #16
Also I was able to get it to run without a code w/maf connected to get to interstate. I noticed it would have a fuel trim on both systems -4 to 10 but if I let off gas it would jump on both to 27.3, soon as I exited interstate it coded again at first stop and stalled out.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #17
I removed and cleaned both the DISA/ICV. I could not tell any difference. However I did notice if I block off aprox 30% of the MAF car idles great but has a loss of power on take off. I'm starting to wonder if this MAF was faulty out of the box or shorting at the control unit it goes too?
 

·
Registered
Joined
·
1,791 Posts
I know this probably isnt the actual cuase, but could help a tad (going to lean conditions on my 01 xi as well). When the disa IS pulled, make sure you put a new o ring on there. Most shops wont replace the oring if its not the servicable oring model :|

Also, scope out that capped conneciton people are tlaking about. Mine was cracked. Got a new gromet, and in addition to replacing boots and disa oring (CCV was just dont) my LTFT seems to be dropping midly (form 8% to 5is?).

Good luck on this. Keep us updated, let me know if you end up going with a smoke test and what htey find!
 

·
Registered
Joined
·
18 Posts
Discussion Starter #20
I know this probably isnt the actual cuase, but could help a tad (going to lean conditions on my 01 xi as well). When the disa IS pulled, make sure you put a new o ring on there. Most shops wont replace the oring if its not the servicable oring model :|

Also, scope out that capped conneciton people are tlaking about. Mine was cracked. Got a new gromet, and in addition to replacing boots and disa oring (CCV was just dont) my LTFT seems to be dropping midly (form 8% to 5is?).

Good luck on this. Keep us updated, let me know if you end up going with a smoke test and what htey find!
Mine would not even track the LTFT until I canged the MAF. I didnt replace the DISA ORing but I did use some of the Hi temp/sensor safe gasket maker. A new note though... After the car was running I reset codes etc, After it had enough cycles/miles to get to the o2 heaters test I do have lean codes on both banks. Wonder if running it so much with the MAF issues, vac leaks if it messed those sensors up?
 
1 - 20 of 28 Posts
Top