1996 E39 rough running - need some help

[AZBuman]

BLUF - Rebuild or continue to chase the problems

Good morning/afternoon from Germany! I started a thread on a here about a 1996 E39 my son and I are wrenching on. We've had it for around a month now and done some basic stuff, just to teach him and get me familiar with the engine/car. When I bought her I knew she'd need work, but that was the point.

Anyway so far we have gone in an cleaned our the idle control valve and replaced the CCV valve (used CCV from a pick and pull $5 total). When I was removing the lower hose from the bottom of the CCV valve to the oil dipstick it was insanely clogged! So we cleaned that out, removed the oil dipstick and cleaned out that Y intersection area with pipe cleaners and break cleaner. I thought that may be why she was running so rough and unable to keep running without pushing the accelerator. So we re-assembled and started her up and still the same problems.

Symptoms wise, she starts, but will either die immediately or idle extremely rough. When I try and drive her there is no power even with the accelerator pressed to the floor. Also there is a loud popping sound that seems to come from the airbox. When on the road and the popping sound happens she will lurch forward. (Not sure if its a backfire or intake spit) She also sounds like a tractor when you try and give her some gas. Also at idle a very strong odor of gasoline and exhaust.

I found a thread here that someone had similar issues i was having and they said all they did was change out the MAF and good to go. That seems very easy, too easy. Unfortunately without spending the money on a new MAF I don't have a known good one to check. No friends own a 5 series this old. And the pick and pull didn't have one that looked in good shape.

Unfortunately I don't have diagnostic tools to really check things out. On the plus side this car is not a daily driver, just a project for me and boy. So I am at an impasse where I am deciding whether to just take on a full rebuild or simply figure out this issue. I know that seems extreme but I have 2 years here to figure it out so time is not a main concern. I have the workspace in the garage here which is rare in Germany, also picked up the Bentley Manuals for reference. Also if I can get her running I have access to the on base automotive self-help with full lifts and any tool I could use. Unfortunately I can't check them out to bring home and use.

Any help/advice you have would be helpful. Thanks again. I've learned a lot searching these forums. Tons of knowledge here for sure! Cheers!

[southsouth]

unplug maf and see if problem goes away. if not then check for air leaks. `then report back

[AZBuman]

I will try that this evening after work. Thanks for the advice.

[AZBuman]

Here is video of what happened when I removed the MAF.



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I did once test start with only disconnecting the sensor, I did not video that but essentially it was the exact same result. Also did a check with mirror and light and didn't see any obvious vacuum leaks. When I replaced the CCV the hose connecting to the oil dipstick tube had a large tear where connects to the CCV, I've replaced that hose. This time there was no popping in the airbox area and then the rough idle was much more rhythmic. A lot more exhaust too! I had the garage open and I had to get out after running it for a couple minutes. There was some coming from the engine bay and pretty think smoke coming from the tail pipe. Also looks like a pretty good size leak from the power steering reservoir.

[Ed CT]

Any P-xxxx codes?

[AZBuman]

Any P-xxxx codes?

So unfortunately I need to get the adapter to read any codes. My reader is a VAG COM so I can only use it as a generic OBD2 reader so I'll only get P0 codes. But without the adapter I can't read anything.

[pimp cauldron]

If you have a standard OBD2 reader you don't need an adapter to read OBD2 codes from the plug under the dash. Without reading the codes you're flying blind. Same with vacuum leaks, you can forget trying to locate them without a proper tool.

Regardless, I would replace all of the vacuum hoses (all the ones that don't cost a fortune, anyway) in the engine bay.

[southsouth]

restart the car after you unplug the maf. see if its still surging like that.
my suspicion is a faulty icv or an air leak
when you replaced the ccv hose, was the hose gunky, a clogged ccv can cause a lot of smoke

[pimp cauldron]

I stand corrected...the German market car wouldn't have the OBD2 port. My fault.

[AZBuman]

So the old CCV was very clogged where it connected to the oil dipstick. And it was ripped open where it connected to the lower part of the CCV, that has all been replaced.

[AZBuman]

No worries. There is an adapter I can get. May need to look into that. It’s a project car. Learning with the kiddo. May get in and remove the intake manifold tomorrow and see what we see.

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Yes it was very clogged up. That hose was cleaned and replaced but it still ran awful. Must be a leak somewhere else.

[AZBuman]

Well finally got around to pulling the intake manifold off today. Fairly easy process and I followed the guide here https://www.bimmerfest.com/threads/o...ct-e39.379225/ and that helped a lot. I did not see any obvious tears or other issues that would cause the problem I am having. I am still going to replace vacuum lines since I have the cover off. I am also going to replace the intake manifold gaskets. The previous owner stated a mechanic he took it too said they is why the vehicle is having issues, but the gasket, as I see it, looks fine. But I have the new part so may as well change it.

So far, the kiddo and I have done the following over the past week:
changed spark plugs (old ones had a lot of carbon)
pulled intake manifold

Next up is to change power steering reservoir and hoses. There is a significant leak there. After only a day there is a small puddle in the drip pan.

So far the only obvious faults I have found are the power steering and the CCV valve. The CCV valve was torn where it joins at the bottom of the CCV and was clogged where it joins to the oil dipstick. I've repaired that and replaced the CCV valve as previously stated but that did not stop the issue. Also I notice a lot of oily residue in the area behind the CCV valve and the oil dipstick, my guess it was from that tear and clog.

My plan going forward is to get a new CCV valve and hose to replace the old one from the junk yard, replace the ICV, and replace the MAF, replace vacuum hoses under the IM. I noticed that when I pulled the MAF that the tractor sound and spitting stopped but the idle kept surging. I think I am also going to pull the valve cover and replace that gasket as preventative maintenance. Any one else have any suggestions on how we're doing? So far we have found the work pretty easy, and having the Bentley manual handy has helped.