Misfire and bouncing idle on E46

[bimmerben33]

The other day as I slowed down I noticed that my 99 328i (114k) started missing and did not idle very well. It got worse and started bogging down. Felt like the car was not getting air. I pulled over and realized that the intake hose was cracked at the elbow vacuum hose connector. I ordered a new one and since replaced it. The car was still missing and the idle kept dropping while the car was sitting. While driving it ran smoothly and no noticeable drop in power. I quadrupole checked the entire intake hose and did not see cracks on the other pieces.

I went to Autozone. The CEL codes that tripped were P0130 & P0150 (intake O2 sensor and exhaust manifold O2 sensor), P1188 and P1189 (which as I understand it means the car is running lean. I read a bunch of forums and it sounds like any of these codes can trip when your intake hose cracks. I cleared the codes using their diagnostic tool. After starting it back up it started missing and the idle dropped while the car was sitting again. I cleared the codes another couple times while the car was both on and off and the same codes kept popping up. I cleared the codes one last time and kept the revs up a little as I pulled out of the parking lot. The SES light did not come on though I could tell there was a small miss, barely noticeable while driving. Parked it and let it sit over night. Tried again this morning and seemed ok. On the way to work going about 60 mph the light came on again as the car warmed up. When I slowed down it did not idle very well and was missing. When I left work it was ok with a slight miss and as it warmed up again it ran rough while idling.

Because the idle drops and doesn't rev high it seems like there is still probably a vacuum leak somewhere. I think the next step is to get a smoke test done.

Has anyone had the same issue before or have any suggestions on next steps?

[dworthy]

Yes you still have a vacuum leak, the best way to find it is pay for a smoke test on the intake.

[bmwdirtracer]

+1. And there is no O2 sensor on the intake; O2 sensors all live in the exhaust; you have 4 of them.

Smoke test is the first step.

[bimmerben33]

Took the lower intake hose off...no cracks anywhere. Put it all back together and it ran worse. Put some Lucas fuel system cleaner in the tank and cleaned the MAF. Well see after a day or two if it runs any better. Also, have some throttle body cleaner for tomorrow. If still nothing then smoke test will be next.

[dworthy]

There is more than one place you can get a vacuum leak. My other favorite spot is the CCV hoses.

[bimmerben33]

Sprayed the throttle body down and still ran rough but better. When it is cold it seems to run ok. As soon as it warms up when I put it in neutral coming up to stops the idle drops really low and almost stalls consistently while I am stopped. When I take off sometimes it bogs down really bad but others it runs fine with no noticeable power loss.

Check the CCV hoses but will double check tomorrow. Thanks for the tip.

[dworthy]

Please do not spary flamables about the motor, they will only find large leaks, and it can cause rubber to harden/crack.

[miami328]

My e36 is doing the same thing buy only when I come to a dead stop at a traffic light and the AC is on
i cleaned the throttle body changed can shaft sensor and smoked tested. Can't
seam to figure it out.

[bimmerben33]

So went and got a smoke test. Smoke was pouring out from underneath the intake manifold (front right when looking back at the car). Took that off....not easy.

The rubber hose along the fuel rail that goes through the intake manifold and connects up under is cracked at the point were it connects to the intake manifold. This is about were I saw the smoke coming from. This hose connects into a metal rod that goes across to the back of the intake manifold and then connects to another rubber hose and goes down into the engine to the back of the car. Does anyone know if this is a vacuum line for sure and is my problem?







Also, what is the circular thing that comes to a point under the intake manifold? It is hard to see but it looks like it has some kind of copper in the bottom and in the hose that it connects to. Anyone know what the copper it and if it is normal?

[bimmerben33]

So the hose that was cracked was the vacuum hose for the fuel pressure regulator. Replaced that and put everything back together but it's still running rough, but a little better. When I turn it on the idle is more stable. If I let it idle for 30 seconds or so it starts missing again and running really rough. I am getting codes P1188, P1189, P1250, P0300 - 306. When I reset the codes it runs pretty good but slowly starts running worse and the codes come back. If I continue driving it takes longer for the codes to come back as compared to letting it sit and idle. After I reset the codes it always runs much better (almost normal).

P1250 is low fuel level. I am thinking the next step is to replace the fuel filter/fuel pressure regulator. Also, check the vacuum line connection there. Anyone have any thoughts or the same experience?

- - - Updated - - -

So my gas cap was loose...duuuhhh. That fixed the 1250, at least it hasn't come up since.

It threw P0173, another fuel code. I'm thinking I am still going to replace the fuel filter tomorrow. Crawled under there and looked at it and it looked old. Probably a good idea at 115k anyway even if it isn't the problem.

I've been clearing the codes pretty quick when driving because it runs almost normal when the check engine is off. Still running really rough after I let it sit and idle for 30 sec or so. Bogs down if I try to take off after that but runs fine after I clear the codes. Not sure if I am driving it long enough to let all the codes come up...

After looking at some DIY's there was one hose for the CCV that I didn't check when I had it all apart. Its the one that runs basically directly up from the circular CCV thingy under the intake manifold and up through the intake manifold. This was the area that the smoke was coming from when I got the smoke test done so its possible there is still a leak there, however I have seen a lot of milky old in DIY's when the old separator fails. I don't have any milky oil. The car does not smoke at all either. Is is possible I still have a vacuum leak in the oil separator line without having the milky oil or smoking symptoms?

Alllsooo, I noticed a ticking sort of knock when I start the engine up. Sometimes only a couple and then it goes away once its been running for a minute or I take off. It was doing it pretty consistently maybe 10-15 of them when I started it up once, then I rev'ed it and it stopped. I don't remember this ever happening before but noticed it a few times while its been running rough. Any idea if this could be related?

[bimmerben33]

I might just be talking to myself now but here goes...when I had everything apart I failed to check the CCV connecting hose because I didn't take it off the intake manifold. I read some other forums that a guy had the same ticking/knocking on start up due to failure of CCV system vacuum so I am heading back toward the CCV hoses. When I take of the connecting hose from on top of the intake manifold and blow into it I hear air escaping from below. Sounds like right around where the hose connects to the oil separator. I think this is probably where my leak is but I know there is the pressure regulation valve, crankcase ventalation valve, and PCV valves in the oil separator. I'm not 100% sure none of these are designed to let air out at the oil separator. Does anyone know?

There is a picture identifying the parts here:
http://www.e46zone.com/forum/topic/4...ve-m54-engine/

[dworthy]

If you haven't replace the CCV itself, you are way past due. I am willing to say that the diaphram is busted and that is also a reason for bouncy idle. I would recommend that you get the cold weather kit for the CCV, see the attached PDF for the parts. There is also a dip-stick tube too, while it is 75-80 bucks, but it is the improved version. Or you can try to clean out the old dip-stick as I am sure it is gunked up anyway.

[bimmerben33]

You are exactly right. The diaphram is non existent after tearing the damn thing out of there and opening it up. There are brittle pieces of plastic shaking around inside when I shook it. I'm worried some of the piece may have made it down to the oil. Will do an oil change this weekend (I'm due anyway).

Thank you very much for the article, it made me change my mind on the cold weather package.

[bimmerben33]

Fixed! The cold weather CCV is not easy to install with all the installation. Have patience if you decide to do that. Probably the best way I could have diagnosed the problem would have been from the hissing noise coming from the engine while running. Air was leaking out of the valve in the CCV which was only happening under vacuum pressure so probably would have been hard to tell from a smoke test without vacuum pressure though maybe that could have been part of it.

The CCV was the problem but also found a leak in the fuel regulator line and intake boot. Replaced the fuel filter for good measure and she runs awesome. Was a big learning exercise but was well worth it (and saved probably $1000+ going to a dealer).

[bmwdirtracer]

I hope that you replaced all 4 hoses involved with the CCV?

Did you remove the intake manifold, or sneak it in?

[bimmerben33]

Yep all the hoses. They didn't look bad and still flexed but replaced them. Was able to stick it in without removing the manifold

[dworthy]

Sneaking in the one from the valve cover to the CCV is fun. You have to know how to "clock" that hose before trying to put it in, as I did the cold weather CCV on the wagon about a month ago.

[krisN42e46]

Have the same problem with my 318i n42 engine

Timing chain done
Ccv done
Oil pump nut done

And now im having milky oil dip stick and rough idle but no white smoke or missing coolant no engine light codes
And im not doing short trips im driving 10 kms each way and still getting rough idle and vibrations.

Any ideas?thanks?

[bmwdirtracer]

10 kms = 6 miles = a short drive. My M5's oil reaches all the way up to the cold mark, at six miles.

Have the intake/CCV system smoke tested. Lack of a Service Engine Soon light does not mean that there are no codes. If you have no other signs of a blown headgasket, I would How many miles on this car? How much maintenance? Why a timing chain? Year of car and the Continent you're on would be helpful, for future posts.

[krisN42e46]

Its a 2001 318i 108000 mls on the clock n42 engine last year had a service mechanic said that my timing chain need to fixed because it was stretched and then having hesitation and miss fire bmw dealer said it was ccv so i replaced it it was clogged and all 4 pipes replaced and 3 months ago red oil light came on i driving in a motorway i pulled over and had it towed back to my house.did my research it was a oil pump nut issue so i took out sump and i was wright nut came off so i put high temp locktite and put it back together and now me problem is

Engine vibration
Hesitation to accelerate at stop
Milky oil cap and dip stick

[dworthy]

The milky oil cap and dipstick is from short trips, you cannot get the car warm enough in 6 miles to clean it all out. Also take the car for a good drive, 30 minutes of running min. After that have a look under the bonnet to see the cap and dipstick has cleared up.

[krisN42e46]

Thanks for your reply after few weeks still the same i was thinking maybe the oil type is wrong car is not losing coolant and not overheating im using 5w30 but on my car manual i only found out now i should be using 0w30 for n42 engines 1.9 petrol

[krisN42e46]

Any one know how to fix this problem i delete this before and it came back after 3 months p0491secondary injection system insufficient flow bank 1

Thanks for your help

[bmwdirtracer]

You're either going to have a broken secondary air pipe, or a bad secondary air pump. Pull the outlet pipe off of the secondary air pump, when the car is stone cold. Start the car, and see whether the pump is blowing tons of air out of that hole. If so, the pump is okay. If the pump is not blowing at all, either the pump is bad, or the electrical connections are bad (maybe the fuse or relay)

Be aware that the SAP relay works ENTIRELY differently from any other relay: Whatever you do, DO NOT put an incorrect relay in that slot, or you will melt your wiring harness!!!

[krisN42e46]

Thanks for the reply my problem is

What does it look like
Where is the location of this part

Because i checked google its only showing
6 cylinder engine my is 4 cylinder n42 engine

Thanks again