1994 530i rough idle, cylinder miss?

[Been-Jammin]

I just bought a cherry 1994 530i with 102k miles. It's running a bit rough, like a cylinder misfire at idle and low rpm acceleration. I replaced the spark plugs and added Sea Foam injector cleaner. The old plugs looked well seasoned with large white deposits and lots of dark carbon build up. The cylinders nearest the firewall had some standing oil around the spark plugs when I pulled them out.

I read that to check the engine codes, simply turn the key on (without starting) and depress the accelerator pedal 5 times within 5 seconds. I tried that several times to no avail. Can anyone tell me how to display the codes?

I was going to do a vacuum check and have been hard pressed to locate an exposed vacuum line. Does anyone know of any "easy to spot" vacuum leaks?

I read about the nikasil leakdown problems and hope the rough idle is unrelated. I haven't been able to get under the car to check the block serial number.

[dacoyote]

....up. The cylinders nearest the firewall had some standing oil around the spark plugs when I pulled them out. ...

That oil is from a leaky Valve Cover Gasket, it's easy to replace and doesn't cost that much if you DIY. The bad new is that you may ruined a coil or the DME. There isn't a really great way to test without swaping them out with good ones.

....I read that to check the engine codes, simply turn the key on (without starting) and depress the accelerator pedal 5 times within 5 seconds. I tried that several times to no avail. Can anyone tell me how to display the codes?
...

Thats how you do it... it's a PITA to get it to work (or at least for me)... you need to make sure the petal is hitting the kick down switch... some of the times it takes either slamming it really hard.. or just a nice set of five solid clicks

....I was going to do a vacuum check and have been hard pressed to locate an exposed vacuum line. Does anyone know of any "easy to spot" vacuum leaks?...

HAHAHAHAHAHA... sorry there mate, shouldn't laugh.. get out some carb cleaner... spray it arround and listen for the idle to change.

-Charles

[Been-Jammin]

1 725 970 - Nikasil block.

This explains the noticible roughness throughout the RPM range as well as the rough idle. Also explains why I could not find a vacuum leak. (there isn't one)

Does anyone know of any tricks to help keep this engine "alive" for a while? Should I try a heavier oil or additive to help "seal" the cylinder?

Also, has anyone done a block replacement on this model? If so, can this be done in a home garage by a DIY'r? Would I be better of taking it to a shop?

Thanks

[Tiger]

First thing first... get leakdown test done...

V8 engine roughness can be caused by bad ICV valve, leaky intake manifold gasket, and bad coil pack... all very common... especially the first two... which is usually done when it has about 100,000 miles.

I have nik engine too... still alive and very smooth.

[Kalevera]

Jammin my man.

Given that it has a rough idle, I'd say it isn't cherry then, is it...or is there something I'm missing?

Now...if you haven't done so already, read Brett's article on the nikasil subject: http://www.koalamotorsport.com/tech-4.asp. He's already written many of the things I'd have to say on the subject. Mainly, that if it's working, no need to get in a tither about it getting worse.

"Rough idle" is a bit unclear to me. The cams in the M60 are responsible for some normal "roughness". And there's a fitted vacuum hose between the PCV plate and the FPR that, if loose or cracked, would result in a rough(er) idle. Beyond that, a compression test on each cylinder's the only thing that will confirm a block issue.

I completed my first alusil replacement a few weeks ago. It was routine, but I also do this for a living. A proficient tech can get the warranty job (if it still existed or applied) done in less than 8 hours (engine out, block replaced, engine back in). There are a few items, especially the transmission cooler, that I wouldn't want to deal with sans a lift and good tools.

EDIT: The other thing to note is that I see plenty of nikasil cars here in the midwest that are running just fine, many with 100k+ miles on them.


best, whit

[632 Regal]

read through barely nothing here... look into the spark plub boots and replace your intake gaskets...then go on to coils and crap. the boots and gaskets need replacing anyways...cant get into it now.

EDIT: PS intake leaks are notorius.


heath my advice.

[Been-Jammin]

First of all, thanks for the replies! All good information and appreciated.

I ordered a "leakdown tester" and will start there. But still want to be prepared for the worst. I'll order the plug boots.

I've read that there are common problems with the intake gaskets and PCV plate seal. That looks like a good weekend project. Is there a good way to check the condition of the ICV? (it's too expensive to just replace)

I took a closer listen today and will clarify that there is a noticible "miss" causing "roughness", like shaking. It can be heard from the tailpipe as well. Similar to pulling a plug wire, but quite as accentuated.

When the car warms up to a closed loop, the check engine light comes on and the engine practically dies (low rough idle, struggling to run) the ECU kicks in and RPM's go up briefly- kind of like a governor. After a few minutes the light goes out and it idles considerably better, but still feels as if it's dragging a cylinder. At higher RPM acceleration ( over 3500 RPM ) it is almost non-existent.

I'm having some serious issues doing the stomp test. Still haven't been able to get the codes to display. (irritating)

I've owned the same make and model before and remember that it wasn't exactly smooth at idle and "hard pull" low rpm acceleration. I just attributed it to a high compression, high cam engine and let it be. Put 70k of my own miles on that one with only a radiator, water inlet and brakes over 4 years. I used to pull a 5x8 enclosed motorcycle trailer without any problems.

As for my comment on the condition of this car being "cherry", it was referring to the physical appearance. ;O) The leather interior looks like new as well as the paint. It was owned by an old man, non-smoker. I have all the maintenance records, too. The O2 sensors were replaced at 90k 2 years ago, due to a "check engine light". There is no record of engine idle problems, nor a leakdown test. A year ago the air intake tube was replaced with the fan shroud during an oil change. The valve cover gaskets were replaced at 38k and 70k as well as the power steering hoses. There is still a reported leak, but nothing appearant under the car. I'll have to get a closer look.

All of this leads me to believe that there is hope that it is a coil, plug boot or PCV, ICV or even an Intake Seal problem, however I would still like to be prepared for the worst... In the mean time, it's still fun to drive the 5 speed. ;O)

[Been-Jammin]

read through barely nothing here... look into the spark plub boots and replace your intake gaskets...then go on to coils and crap. the boots and gaskets need replacing anyways...cant get into it now.

EDIT: PS intake leaks are notorius.


heath my advice.

Thanks! Here's the parts list: (for after the leakdown test) let me know if I'm missing anything!

8 Spark Plug Connector; Coil To Spark Plug; Updated Version 1.8kOhms
1 Intake Manifold Gasket; Front Intake Manifold to Throttle Housing
4 Intake Manifold Gasket; Intake Manifold to Cylinder Head
1 Intake Manifold Gasket; Rear Intake Manifold Cover O-Ring; 20x3.55mm
1 PCV Valve Grommet; Grommet for Ventilation Valve and Idle Control Valve

[Been-Jammin]

First thing first... get leakdown test done...

V8 engine roughness can be caused by bad ICV valve, leaky intake manifold gasket, and bad coil pack... all very common... especially the first two... which is usually done when it has about 100,000 miles.

I have nik engine too... still alive and very smooth.

Thanks! Is there an easy way to check the coil packs? I can get them for $48, but replacing 8 of them at once is a really bad day. Perhaps I should order one and just play swap 8 times. (or less)

[Bill R.]

intake manifold gaskets themselves, as far as vacum lines there really aren't that many, theres one cap on the backside as well as the line to the fuel pressure regulator that Whit mentioned. While the manifold is off, check these tubes for leaks at the back of the block

A new pcv plate with new intake manifold gasket stuck on the bottom of the manifold

And make sure you clean all the crap off of the intake manifold where it meets the head before you remove the manifold , otherwise dirt and stuff falls right into the intake ports and sometimes the cylinder... I scrub it out with a brush and a shop vacum.

Thanks! Here's the parts list: (for after the leakdown test) let me know if I'm missing anything!

8 Spark Plug Connector; Coil To Spark Plug; Updated Version 1.8kOhms
1 Intake Manifold Gasket; Front Intake Manifold to Throttle Housing
4 Intake Manifold Gasket; Intake Manifold to Cylinder Head
1 Intake Manifold Gasket; Rear Intake Manifold Cover O-Ring; 20x3.55mm
1 PCV Valve Grommet; Grommet for Ventilation Valve and Idle Control Valve