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Hi all,

This is my first thread on these forums and hopefully somebody can assist me in this problem I have :)

I have a 2001 E46 316ti compact 1.8. The old girl has been round the clock at 131k but has a strong service history.

1. Just the other day I started her up and noticed a rough idle when cold. It was about 5 degrees outside. Idling at 500rpm after coming off 1000rpm 1 minute choke. A little pump on the throttle and idle was normal near the 650rpm mark. I thought nothing of this. Had full power.

2. A few days after that (about 75 miles) I noticed the same problem but felt her still being lumpy/rough when it was warm. A few pumps on the throttle and then it picked up and stopped shaking but later on that 12 mile journey I was struggling to pull away quickly from junctions. I was having to give it about 3000rpm to launch safely. Crawling traffic sounded like she was going to stall.

3. Later that day I was in a McDonald's drive thru which is about 5 miles away and the rough/lumpy idle took a turn for the worse! I was having to keep her going as the revs were dropping as low as 300rpm then suddenly spiking to 1000rpm for a few seconds. After I pulled out the car park I felt severe power loss through every gear and at whatever RPM. I could feel she had no pull whatsoever no mater what the revs. I'm talking a close 20-25 seconds to reach 60mph! It was late at night so I limped her back home. Only to stall while reversing on the drive as I had to give her loads of revs. Started her back up lone behold, she idled perfectly at 650rpm!

NO FAULT LIGHTS ON THE DASH!!!

I'M CONFUSED!!!!!

Can somebody shine some light on my problem please?

Thanks
 

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Hello mate,

I've been searching these boards as I have a very similar issue which has had me tearing my hair out recently. I also am struggling to find anyone who has got to the bottom of these issues.

Car is a 2002 N42B20 318CI with 119k miles and I've replaced the following to recently before these issues started;

- Crank Case Ventilation (CCV) valve and hoses
- Oil sump gasket
- Cam Solenoid O-rings x4
- Rocker cover gasket
- Vacuum pump O-rings
- Oil filler cap
- Oil filter assembly profile gaskets & O-rings


Over the last few days the weather has noticeably colder (i.e. +8 degrees down to -5 degrees). This was the start of my problems - described below.

1. When the weather first got cold I noticed that once the engine was up to temperature the idle would be rough and "miss-firey" sounding and would fluctuate between 650-800, then rev itself to about 1600 rpm before dropping back to 650 and repeating. Exactly as shown in this video (not my car) E46 318i N42 idle / revving fault - YouTube When driving there was hesitation up to ~2500rpm, after which the car drives smoothly.

2. Unplugged the MAF. This would cause the car to idle correctly, BUT when driving and accelerating there was miss-fires and massive hesitation throughout the whole rev-range. It felt like the car was being under-fueled and running massively lean. The car has been run without the MAF for months as it was unplugged when I bought it earlier in the year, (suggesting a pre-existing issue)

3. Changed MAF for 3rd party cheap copy. Idle would be stable with no revving up/down like with the MAF unplugged but misfiring 1000-2500rpm. I also got a check engine light warning flashing at full throttle ~ 4000rpm. When driving and putting into neutral, revs drop below 500rpm often, occasionally causing engine to stall.

4. Changed the MAF for an OEM Bosch part. The car ran great both cold and once warmed up. Most importantly no missfires 1k-2k revs - pulled smooth. Still unstable idle revving up to 1600rpm and down again but otherwise perfect.

Other observations: My emissions vacuum pump used to run for approx 1min when the car is first cold started but now does not. Not sure if this is related.

Putting a new genuine MAF in definately helped the car but I suspect the cause of the unstable idle to be vacuum leaks caused by worn out gaskets and o-rings around the intake manifold assembly as I didn’t replace most of them when I changed the CCV (d’oh)…

Sorry for the hijack. I'll let you know if I solve it. Have you had any luck?
 

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Discussion Starter #3
Alright mate!

Since this thread I've put a 3rd party MAF on which made no difference! I've been running mine with the MAF off and has been running okish in terms of emissions and performance but not the best! I've had it plugged into a diagnostics machine which through error 2783 unknown!!! Arghhhh! After searching the net I found error 2783 to relate to heated film mass. You might think this is the MAF which it is but it is not just the MAF it effects. It affects the pre-cat oxygen sensor which is a heated sensor! I'm yet to change this but im tempted the next time i get a spare £60.

Hope this helps!
 

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Might have a crack in a hose somewhere...check for any excess air gettin drawn in. May have a dirty Idle control valve and throttle body... Also check the cranckcase breather valve as they get loaded up with junk too.
 

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Hi,

I bought my car with starting/hesitation issues around 3 months ago.
Rather that aftermarket, I went for OEM CCV and associated pipes and bought a new Bosch MAF off the .de version of ebay for an excellent price!
Not had any problems at all and have covered some 10k miles.

Hope this helps.
Shane
 

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Check and renew your vanos seals, easy job, bmw sell them as a 4 o-ring set. They can break down, start leaking oil and not holding vacuum pressure causing rough idle. Ask me how i know.
 

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CCV and Cam solenoid o-rings were one of the first things I did several months before these issues.

I suspect that the cold weather is causing the old o-rings and seals around the intake system to go hard and cause vacuum leaks - this only happens < about 5 degrees so my plan is to replace every o-ring and gasket in sight around the intake manifold / injectors etc when I get a chance; I'm kicking myself for not doing this when I did the CCV.

I will also try the "ether spray to find vacuum leaks" trick in the next week or two. Will keep you all updated on progress!

edit: Breather from the top of the crankcase was also cleaned when I did the rocker cover gasket, there actually wasn't that much sludge in there and timing chain guides were perfect.
 

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Hi there, I am waiting from UK BMW E46 328i 2000 reg manual.
Senders couldn't answer me is there doable vanos or not.
Can You please tell me: there is single or doable vanos on it?
Thank You
 

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In case anyone is interested: This was solved with a new MAF.

Replacing all gaskets on the intake manifold assembly and air box and throttle body cured all flat spots. I would recommend that everyone do this when changing the oil separator as this has made the single biggest performance difference for me
 

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Mate I think u have the N42, check the Tensioner on the side is the new one if not u WANT TO CHANGE THIS ASAP!, Maybe look at doin guides as well
 
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