2000 540i M62 The usual hesitation / no acceleration / is it a vacuum leak, problem..

[plexus]

Hi all. I am in Canada with a domestic 2000 540i manual. Three years ago I started getting poor cold starts, especially in winter. At the time we had a mandatory every-2-years "drive clean" program and I was told the intake manifold gaskets needed to be replaced validated via a smoke test. At the time (2017) they quoted $950 CAD. But we got one "conditional pass" and then next drive clean test in 2019 I would be required to pass. So I began collecting knowledge and parts. Primarilly using google which more often than not would lead me to this site. So thanks for all your help.

It was very helpful to read the plethora of posts on these symptoms and the resulting hunt to solve them. I am adding mine here for future reference. These problems can be very tricky to track down it seems. I am trying to follow a logical train of troubleshooting.

In 2018 the governement dropped the drive clean program and so I didn't need to fix this, allowing me to procrastinate up until now. This job looks very daunting at first glance. There seems so much that can go wrong. That's what held me back. Now that's done it, it's actually not that big of a deal and I could it again much faster. I've made some modification to help make this job easier in the future, if ever it needs to be done.

The shop smoke test identified that there was a leak "in the back" which led us all the believe the CCV cover. As per usual. So I bought all the parts to replace it. Sure enough the Torx 30's were too seized to removed and that led to more procrastination. I finally decided the job would have to be the venerable removal of the intake manifold. This led to more procrastination.

I did the job this week. I wont go into all the details because its pretty much the same as others. However I will highlight some of the techniques I decided to use. There are some differences in the way people do this job.

The originating issue:
The car would start rough especially in cold weather. when really cold, < 0C, it would die in the first few cranks and then start up really rough. It seemed to smooth out as it warmed up. If I attempted to drive off without it reaching operating temp, it would lurch and chug in 1st. I'd have to pull over and wait. Then I could go. In all cases it lacked guts only allowing a limited slower range of acceleration. If I opened the throttle too far it would stop accelerating and run rough. But I could drive the car. I was constantly throwing Lean Bank 1 and 2 errors.

UPDATE Summary: After replacing all the intake gaskets, plugs and new CCV cover, the car was still exhibit rough idle and lack of acceleration. However the symptoms were different than before the intake work in that it was over-all better. I could accelerate better and it wouldn't take so long idling to be drivable. I believe this is because the leaking gaskets (verified by a professional smoke test) are now replaced - pre-replacement the car would need to come up to operating temp before it could be driven, otherwise it would jerk so much it was not drivable. now it just needs to warm up through the idle sequence and then it can be driven. it also has more power. but it still stops accelerating at certain RMPs and performance is inconsistent. I am thinking there are multiple issues going on. Until I replace the MAF I am speculating here: the intake job fixed the leaking gaskets. Now I am tracking down the next problem. The shop says it needs a new MAF so lets see how that goes...

I did the job at the beginning of the week. Here is what I replaced:
- intake block gaskets
- CCV cover and gasket
- throttle body gasket
- throttle coupler intake gasket
- cleaned the MAF
- new plugs

This did not solve the problem. It is still having the same problem however it does drive quite a bit better. But it's touch and go - what I mean is that sometime I will have good acceleration and other times it will do that thing where it hits a ceiling and stops accelerating. i figure out that if i pull back a bit and let it smooth out i can then ease the throttle open and it will contine to accelerate. before the job i couldnt do that. also on my last test drive today, the MIL came on and the car seemed to drive much better (!?). It threw Lean bank 1 & 2.

I am thinking it could be a combination of using the old intake spacers and the oil soaked plug boots. I have those on order and they are next to replace. Along with new valve cover gaskets.

Do any of you have any input on what you think I should look at? It seems that these cars are very sensitive to sensors and air leaks and many things can deteriorate simultaneously making this a complex troublshooting challenge. So I'd love you input!



Below are more details about the job I just completed and the results:

What I didn't replace:
- intake spacers. I measued about 1.7mm of overhang between the bottom of the spacer and the bottom of the new gaskets. I was hoping this might be enough to create a seal. Now I am unsure. I will have a set ordered soon.
- spark plug boots - there was a fair amount of oil in the plug wells on the drivers side and some in the passenger side. I've ordered valve cover gaskets. It is said that the boots soaking in oil can cause the spark to arc and cause the issues I am experiencing. I have a set of those on order.
- fuel filter - lean could also mean lack of fuel. there is an aspect to the symtoms that is almost like fuel starvation. it's possible. I have a fuel filter on my shelf ready to go.

What I learned / techniques
- If you remove the intake manifold regardless if you replace the gaskets, replace all the spacers with new
- I was not able to pull off the injector boxes. I had to use a pick to pull off the connector clips. The clip on the rear passenger side was the hardest to get off. it was just a matter of learning to work looking into a mirror and trying to get just the right angle and hope it doesnt slip off. I had the mirror on the firewall looking towards the front so i could see the clip from the back.
- I did not reinstall the injector box clips. make it easier for the next guy. I ascertained they are not needed especially if you make sure to fully seat the connectors, check them and ensure the box is being pushed in when you bolt it into place.
- I replaced all the T30's with M6 stainless hex and used copper anti-seize. make it easier for the next guy.
- I took the trouble to torque the front and rear cover bolts in a cross pattern. I figured why not. Im used to doing it anyway and it eliminates one variable. I used 8 f-lbs excpet for those I use anti-seize on where I used 6 f-lbs.
- I did not use anti-seize on the manifold spacer nuts. I used 15 f-lb, a little higher than the recommended 11 f-lbs. I also used a cross patter to torque them. better to be safe than sorry.
- I had a hell of time trying to re-install the semi-rigid vacuum line from the intake duct in the front to the back vacuum valve. I forgot to take a good plcture of it installed. Make sure you take pictures that show the way all the wires and hoses are installed. also the brackes and the components they hold.
- I accidentally bend the semi-rigid line mentioned above. i tested it by blowing into it plugged and there was no sign of a leak. I reinstalled it but its not installed in the exact way it should be. but its working. i will replace with new.
- Be careful of the nipples on the vacuum container, dont ask me how I know. epoxy is your friend. I will replace with new.

What I think the next steps are?
- replace the intake spacers with new, torque to 11 f-lbs
- replace the spark plug boots
- i plan to replace the vacuum hose from the intake duct to the vacuum valve because i accidentally bent it. i tested it and it didnt appear to leak but i will replace for good measure.
- replace the valve cover gaskets to prevent the plug well oil problem

[Chedley]

...;..
What I think the next steps are?
....

Check / load test the battery and alternator...

[JimLev]

How many miles (km) are on the car? Have the pre-CAT O2 sensors ever been replaced?
Intake manifold spacers...the metal sleeves that the nuts crank down on?
Did you replace the 2 profile gaskets, throttle body and the one between the adapter plate and the intake manifold?
Any cracks in the air intake tube that’s between the MAF and the throttle body?

[plexus]

Today I test drove from a cold start. it was still exhibiting the same issues, mostly lack of acceleration and some cold start roughness. It was better than it was before I changed all the intake gaskets. I didn't get any error codes until the last leg of the test drive when it thew a lean bank 1 & 2.

As you know with this kind of problem there are many things that can contribute to it. For me, with lack of testing tools and troubleshooting experience with this car, I decided to take it to the shop I deal with for a diagnostic, rather than chase the problem down by swapping parts and hoping. The diagonstic was $100 CAD.

The shop did the diagnostic in less than an hour. They said it need a new MAF. I cleaned the MAF as part of my work on it but it didn't help. They also found a problem with a front control arm. I told them go ahead with the control arm job and leave the MAF to me.

I ordered a MAF for about 1/2 the shop price from a local parts place, it should come after the weekend. The shop confirmed that as far as their testing it was indeed the MAF only. So, we'll see.

The good news is that, apparently, my gasket job was a success. I don't know if they did a smoke test or not. I guess I'll find out on Monday when I put the MAF in.

Now to answer your questions:

How many miles (km) are on the car? Have the pre-CAT O2 sensors ever been replaced?

143k miles, 229k kms. I bought it in 2010 and I never replaced the O2 sensors. I dont know when/if they were replaced before that.

Intake manifold spacers...the metal sleeves that the nuts crank down on?

I did not replace the spacers. I mentioned this in my long intro. I measured about 1.7mm of over-hand between the new block gaskets and the bottom of the old spacers so I hoped this would create enough of a seal.

If the MAF fixed the problem then I can assume the old spacers worked. Do you think I should bother then with the cost of replacing all the spacers anyway? A set would cost about $100-150 CAD.

Did you replace the 2 profile gaskets, throttle body and the one between the adapter plate and the intake manifold?

Yes all gaskets related to the intake manifold and air inlet were replaced.

Any cracks in the air intake tube that’s between the MAF and the throttle body?

I inspected all hoses and tubes and there were not visible cracks or breaks I could see.

[Deadwake]

I was going to suggest bad MAF as well. I bought my car with a bad MAF and had similar issues, I also tried to clean it to no avail, I've actually tried to clean a couple mafs for friends/family and never had it work so I'm starting to suspect MAF cleaner is a scam.

[plexus]

I didn't have MAF cleaner handy so I looked up the list of ingredients on the CRC brand. Looked like mostly iso alcohol and propellants to get it out of the can. I happened to have some 99% iso on hand. I removed the sensor from the housing and soaked it in 99% and soak the housing in about 10% iso/water. I then dried them in a heated forced air appliance I have so they were thoroughly dry.

Apparently the sensor itself is bad so we'll see... I'll report back next week when I have the new MAF in. Here's hoping...

The shop said they diagnosed the MAF by disconnecting it: they said, if the car drives better then that's a sign its a bad MAF. when I picked up the car they said the MAF will disconnected and not to drive it a lot that way (I wont drive it at all until I get the new MAF). It does perform way better with the MAF disconnected - its like normal at least is the short city drive home.

[amklein]

If you haven't ordered a MAF yet, I would recommend only using Bosch MAF sensors and not an off brand. They are really proud of the assembly for the m62tu, but you can buy a more common Bosch 63136 assembly from a VW and swap the sensor over. They are usually about 1/3rd less expensive. The screws are 5pt security torx, so you will either need to get ahold of some bits or grind a flat in them.

[JimLev]

You can drive with the MAF disconnected as long as you want, you just won’t have the full power that you would get with a good MAF.
The DME has a table it uses to calculate the fuel delivery based on RPM.

[plexus]

You can drive with the MAF disconnected as long as you want, you just won’t have the full power that you would get with a good MAF.
The DME has a table it uses to calculate the fuel delivery based on RPM.

Good to know. But I have no need to use the car so it will sit until a MAF goes in. I think the shop was just being extra cautious. probably because they did the diagnostic, gave the advice and now feel they are exposed to risk. I've been going to this shop for 20 years and I know over time, because of the way other customers have treated them, they are very risk adverse now.

If you haven't ordered a MAF yet, I would recommend only using Bosch MAF sensors and not an off brand. They are really proud of the assembly for the m62tu, but you can buy a more common Bosch 63136 assembly from a VW and swap the sensor over. They are usually about 1/3rd less expensive. The screws are 5pt security torx, so you will either need to get ahold of some bits or grind a flat in them.

Also good to know! I did order an aftermarket MAF from a parts shop. It's on it's way. I'll just go with it. the next time around I will heed your advice. I also have a comprehensive set of driver bits including the torx security - thats how i got the old sensor out to clean it on it's own. cool that you can retro-fit one from a cheaper MAF!

Would this work? I am not sure how to identify the correct VW MAF.... https://www.fcpeuro.com/products/vw-...reg-0281002461

[Deadwake]

I'd just get this one: https://www.amazon.com/Bosch-Origina.../dp/B001CO8PH8

It's the one for your car... buying the VW one might save you a few bucks, but I dunno, seems kind of a silly thing to skimp on personally.

[JimLev]

That VW one is for a 2.o liter engine. The calibration is going to be way off.
Get the one Deadwake suggested.

[plexus]

I'd just get this one: https://www.amazon.com/Bosch-Origina.../dp/B001CO8PH8
It's the one for your car... buying the VW one might save you a few bucks, but I dunno, seems kind of a silly thing to skimp on personally.

That VW one is for a 2.o liter engine. The calibration is going to be way off.
Get the one Deadwake suggested.

Agreed. It's not a good idea to skimp on the air flow sensor considering it's criticality in the system. I ordered one for my E39 through a local parts place, I forgot to ask the make and I'm hoping its a Bosch as it's in that price range. Should be here Monday and I'll see if it fixed all my performance problems... or not...

[plexus]

UPDATE: I believe the car is fixed. The new MAF seems to be the ticket. I cleared codes and started it up. it idled rough a bit then settled out. I am guessing the ECU is getting use the MAF. I drove tested city/highway. Five minutes into the city driving, stopping in traffic, I took it out of gear and foot off the throttle, it stalled. I started it up an carried on. Then I drove it on the highway. I did about 10km of city and 10km of highway. Worked great! I forgot how much pull and power this car has! I now have to re-learn to drive it.

When I got home I scanned it and there as a lean bank 1/2 as pending codes. I am going to guess perhaps that was when it stalled. maybe the ECU was still gettting used to the MAF and re-coding itself?? The stall was in the first 5 mins of driving. After that the rest of the test drive went well. I didn't notice any performance issues so I am hoping the pending codes clear.

The other "hitch" was that since I saw Bosch MAFs everywhere, I didn't think to ask the parts shop what the make of the MAF they ordered me was. Turns out its a taiwanese knock off by Spectra Premium. I will drive on that for now, its so far working. I will order the "proper" Bosch and use the Spectra one as a spare. Live and learn.

So the problem was at the very least the CCV cover gasket and the MAF.

[Deadwake]

Yup, its pretty common for the after market mafs to be a little "off". I'd be surprised if it was off enough to cause lean codes though. Getting OEM parts is pretty important, but especially with sensors/electronics.

[plexus]

Yup, its pretty common for the after market mafs to be a little "off". I'd be surprised if it was off enough to cause lean codes though. Getting OEM parts is pretty important, but especially with sensors/electronics.

Well, I doubt the lean codes were because of the MAF, although I suppose they could have been but I would have expected a MIL if that was case. I think it's related to the stall 5 minutes in and likely a spurious thing. We'll see after I drive it more. I will be putting a 600km trip on it this weekend. Here's hoping....

The Spectra MAF has a limited lifetime warranty, so that's something... at least...

Bosch MAF on order.

[plexus]

Took the car on a test drive for 90 mins. Let it idle into closed-loop and then got on the highway right away. I drove it about an hour on the highway and it was fine. no issues. I had the scanner connected and monitored the fuel trims - they were well behaved, oscillating around +/- 0%. Sometimes they would go up or down to higher values but then would stabilize - I didn't see anything unusual.

After some city driving I fueled up. Before I turned the car off I checked for codes and there were no pending or trouble codes. I then filled the car up with fuel, reconnected the scanner and started it up. After it scanned, but before I left the gas station I checked for codes and it had 2 pending codes, lean banks 1/2. ??? What the heck? What would cause that?

The long term trims were at 24.2% which has dropped from 25% pre-all this work. I don't know if my scanner can reset those and/or the adaptations, which I've never reset. Wondering if these old long term values might be causing the existing lean codes? I guess I just need to do more driving?

I drove home with the pending codes. I drove somewhat agressively to see if CEL would come on but it didn't. back home, idling it was still showing reasonable trims. Pending codes remain.

Oh, and, I am not going to order a Bosch MAF. It drives well enough that I will stick with the knockoff for now. I just don't want a $200 part sitting around. Part of the point of DIY for me is to save money. There is preventative work I have planned that can also postively affect vacuum leaks so I will do those first and then assess. also from what I understand about the ECU etc it perhaps is still learning the repaired state of the engine. Those high long term trims vs the normal looking short term trims are a clue.

Thoughts?

[Trasportador]

I'd put the Bosch Maf in, drive the car for a couple of days, see what (if anything) pops back up on the scanner. Off brand parts cause the weirdest of issues. I run Bremi and Bosch Maf's so that I don't have to second guess whilst diagnosing issues.

[plexus]

I'd put the Bosch Maf in, drive the car for a couple of days, see what (if anything) pops back up on the scanner. Off brand parts cause the weirdest of issues. I run Bremi and Bosch Maf's so that I don't have to second guess whilst diagnosing issues.

I decided not to get the Bosch for now. I have a good drive coming up and we'll see how the knockoff does, and the car in general. I have the parts and a plan to replace the re-used intake spacers which will seal the block gaskets better, new vacuum hose to re-do the vac system, and the parts to do the valve cover gaskets and replace the plug boots because mine sit in oil. Some of these could help a lean 1/2 condition. So I'll do all that and see how the car is doing. If at some point the knockoff MAF dies, I will just order a Bosch at that time.

[JimLev]

Maybe you can find a Bosch MAF at the junkyard??

[dtw]

Agree with your approach on intake, etc. The intake must first be in good repair and sealed against air leaks (I recommend to smoke test the intake, even if you need to pay an indy to do it, after you complete your repairs). I suggest to replace all the soft vacuum hose joints - there are half a dozen or so, most probably dry rotted. Cheap to buy and easy to replace.

There is a good chance you will still be seeing lean codes, however, even after you have 100% ensured a leak-free intake. This can absolutely be due to your brand-new MAF. Think about it - in a closed loop system, the controls start with the MAF and end with the oxygen sensors. GIGO (garbage in, garbage out) applies here. If the MAF is sending an inaccurate air metering signal, then the oxygen sensors will struggle to do their job. This happens all the time with failed MAFs and aftermarket MAFs. There's a reason everyone is telling you not to mess with aftermarket MAFs - because we've BTDT. I once bought a Delphi MAF for an M54 engine, thinking "well, this should work, because it is GOOD aftermarket". Nope, throwing codes right out of the box. I hope that yours is the exception, and fixing up your intake solves all your problems - but in case it doesn't, be ready to look at the MAF (and possibly the oxygen sensors - do you have maintenance history on them?)

Sidebar on MAF cleaner. I have tried it countless times. It has worked for me exactly one time. I'll say this, though - that one time was a true emergency (long story) and we were all singing the praises. Oddly enough, that was on an E46/M54 that was shifting hard and throwing MAF codes. Getting the MAF in good working order not only got that nightmare of an engine to be worthy of an emissions inspection (this after a complete intake overhaul/coolant pipe replacement...this engine was a ticking time bomb), it cleared the hard shifting issue. A good friend that is a pro BMW indy told me that the MAF would fix the shifting, and I would not/could not believe it (even when he explained it to me) until I took the car for a test drive.

- - - Updated - - -

Maybe you can find a Bosch MAF at the junkyard??

100% agree. I would rather have a good used Bosch than a new aftermarket any day.

[plexus]

Yes, this is the plan: replace all the vacuum hoses, secure the intake down with new spacers (as opposed the old ones in there now). If I still get lean codes, i may take it to the shop for a smoke test, or just live with it. afterall, with these cars you have to learn to live with it not being perfect.

Regarding the MAF, as I mentioned I didn't choose to buy an aftermarket MAF - it's what the shop ordered for me and I assumed it would have been a Bosch.

So if the car is otherwise working ok and I still get lean codes, so be it. I've been driving with lean codes AND crappy engine performance for 3 years, so having to ignore lean codes and a MIL will be easy if the car actually works well otherwise. Maybe at some point I will get a Bosch MAF but there is no rush for me on this. And if I do, it will be new - no sense in adding more variables to the equation with a used MAF.

I have no history on the O2 sensors. I bought the car 10 years ago and haven't replaced it. the PO had the car dealer serviced and apparently brought it in whenever there was an issue. I talked to the stealer that the PO used and they gave me a general sense of the maintence of the car in its first 10 years.

[plexus]

I drove the car on a camping trip and did about 420km roung trip, mostly highway. Despite the engine light coming on and, yes, lean 1/2 codes, the car operated normally. Gone are the hesitations and rough idle. The temp dropped to about 9C and the car would have a problem starting at these temps with the hardened gaskets I replaced. This time it started up right away after sitting for a week with temps that dropped to 2C. Idled normally and drove like a champ.

The only issue I could sense was when coming to a stop, the idle would be the usual ~500 but after a few seconds it would drop then surge back. Might be related to this ongoing lean condition.

There are a few things I need to replace that could be related to the lean condition and so hopefully I can fix it. But if not, I'll just have to live with the lean.