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Newbie question(s) on engine maintenance

2K views 9 replies 4 participants last post by  Morgenster 
#1 ·
Hello :)

I recently purchased a 15 year-old black E30 316i. It's my first car and I'm a little unfamiliar with the lingo and the technics. I've had it for about a month and I'm getting the impression that this car has been neglected somewhat. As I want to hold on to it for as long as I can, I'm in need of some advice. These sorts of engine troubles have probably been discussed before, but I'd like to tell the story in full. So here goes:

When starting cold the engine runs fine for about 10 to 30 minutes. After that, when in idle, it gently bobs from 500 to 800 RPM and shudders somewhat. At this point, when I hold the throttle at +/- 2000 RPM I can hear some random poofs. When driving, again after some 20 minutes from starting, the ride gets a little bumpy, but it still works. This only happens when I accelarate.
Now, in reading some posts on similar problems I ran into all kinds of solutions for all kinds of problems, but I'm not sure if mine's the same.

-should I do something about the ICV, and if so: what?
-Could the fact that the cap on the gastank is missing have anything to do with this (I've ordered a new one)
-I'm inclined to replace the spark plugs. Should I? And what should they be like?
-I'm going to do an oil change, which is best, and should I use one of those flashy additives that "greatly reduce friction"?
-I'm going to use a product for cleaning the injectors. will that help in any way?
Does cleaning or changing the air filter help?
-Do you have any other suggestions?

I'm willing to put some tender loving care into this baby, but I'm strapped for cash at this time. I've ordered a service manual to get to know the car properly. I learn fast, faster with some help :D.
Greets & thanks,

Mark
 
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#2 ·
Here is a good resource for the tech answers for the bobbing idle...
http://www.pelicanparts.com/BMW/techarticles/JF-Tech/BMW_E30_3_Series_Idle_speed_troubleshooting.htm
No gas cap can cause some injection problems because the system can not pressure up properly, so replacing the cap might help some of the issues with acceleration.
As for fluid changing, I am a fan of full synthetic oils like Syntec or what not. I have not seen too many threads with people singing the praises of friction reducers, but then again, I haven't seen many that say they are worthless either! A lot of people on this board sing the praises of Redline Synthetic Lubes, and I have used them with other cars I have owned, and they DO work very well, but are somewhat pricier than Castrol/Kendall/Chevron etc... brands.
For injector cleaning, do a search on this forum for "Hot Soak" and you will see a VERY effective, and not terribly complicated method for effectively cleaning the injectors and build-up on the back side of the valves.
Air Cleaner... Yes, replacing it is a cost effective way to ensure your intake air charge is as smooth and clean as possible. Shouldn't be more than 20-25 euro's for an OEM quality filter.
Bumpy ride? Is this a physical shaking of the chassis? Like a wheel out of balance? Or is this more of a sputtering hesitation coming from the engine kind of thing?

Oh, and Welcome to the board Mark!

Hope these get you on the right track!

Josh W.
 
#3 ·
325eXTATIC said:
Bumpy ride? Is this a physical shaking of the chassis? Like a wheel out of balance? Or is this more of a sputtering hesitation coming from the engine kind of thing?
Thanks for the info!
The shaking only happens in accelarating and I'm guessing it is due to misfires.

I also forgot to mention the following:

I don't know the exact word for it so I'll describe it. The steel wire controlling throttle on the engine by pulling the lever on top of it (God this sounds like baby-talk) has a tube encasing it up to a point holding the encasing and leaving the wire bare to the lever. This tube is kind of gnawed at the end and adjusting the screws holding it doesn't seem to have any effect. I remember because my dad and I once tried to adjust the screws to increase the RPM in idle, but it doesn't work.
Can it be adjusted? And if so, is there a trick to it?

I'll keep you posted on my progress. If I get this sorted, the next step will be to take the car to the local touring agency for an inspection and assessment. If they tell me I can hold on to this car for about a year or three, I'll consider some restauration/paint work, etc.

And again, thanks!
 
#4 ·
first off welcome...

"sounds like bad ICV for idle", but first pull your O2 sensor and try driving her, if it gets better then their's your cluprit. O2's only come into play when your car comes up to temp and enters into what's called "closed loop".......if she starts up and runs fine when cold (idle the whole shebang) and then goes to crap when she warms up i would suspect the O2. try testing that first and let us know what happens. i am not however ruling out your ICV, but just something else to check.

replace the gas cap first off. that is a safety hazard of the highest degree.

nothing wrong with going with new spark plugs. here again if you don't know the history of the car, nothing wrong with doing items such as this....this way YOU create the history of the car going forward.

oil change.......if you can find out what was used before that will help. if the owner didn't use synthetic i don't recommend swapping over to it. esp. if the hoopty has a good deal of miles. switching to synthetic produces bad results as it will tend to show up in the form of oil leaks you didn't know you had. now that being said, you can (and should) switch over to a 50/50 blend of synthetic without serious negitive side effects.......oil wise.... personally i am a fan of Mobile 1 and my bmw has had it from day one every 3k and she has 240k on the clock and is just as tight as the day she was bought. and also think about this....who uses Moblie 1 in their highest of the high vehicles? well factory Porsche, Mercedes, AND BMW to name a few. you know they tested oils before choosing Moblie and slapping the stickers under the hood on their highline cars.........now additives.....you can put some marvel mystery oil in your motor with your next oil change (not a lot, not substituting a quart or anything) and that will help to dislodge some of the sludge that may be up in there. just be sure not to wait too long before you change it (do it a bit sooner like 2,500 or 2,000). that will aid in cleaning up some of the crap at the bottom of the oil pan.

yes go read the injector cleaner thingy, that is the bomb....works excellent.

and most def. yes changing the air filter helps. go with the factory original. nothing beats it for filtering out crap in the air. don't even get me started on the K&N thing, that will open up a whole other can of worms.

as for other things........just look her over. i mean there isn't anything wrong with also changing out the fluid in the trans or the diff....never a thing as "too much service"....likewise you can also change out the p/s fluid (if you have p/s) if you are so inclined. you are timing belt free so enjoy that chain......basically take care of her and she will take care of you.

and if you find me a good cheap unimog i may have to come and visit and pick that sucker up........
 
#5 ·
Don't worry about "baby talk". Trust me, I am fairly new to Bimmers myself, but I am becoming more and more of an expert everyday thanks to the people on the BMW boards I frequent! As for where the Throttle Cable goes, that is the throttle body, which is where the air is metered into the intake manifold. Your car is a Euro spec and a 4 cylinder if I get my model designations right, so I don't have direct experience with your car, but if it is anything like my US spec 6 cylinder, then there is a "micro-adjust" screw on the throttle body linkage (that series of springs and arms where the throttle cable stops). It will probably be a VERY SMALL fine threaded slot head (flat head) screw. This can be used to very finely tune the idle speed, but only by a few dozen RPM. It won't affect the bobbing idle condition in any way, it is simply there to allow a bimmer nut like all of us to bring the idle speed from 775 to 750 RPM or some such thing. There may also be a plastic barrel on the end of the throttle cable with a tiny little metal nut at the bottom of that. The main reason for this piece is to take up slack on the throttle cable as it stretches over time. Not a good method to adjust idle speed as this is a fairly rough "by feel" type of adjustment. Again, this is based on my US '86 325e, so it may not be completely valid to your car, but should be CLOSE!

Hope this helps you out!

Josh W.
 
#7 ·
no, you won't do any harm if you unplug your 02 sensor and go drive it.....like i said your 02 sensor doesn't come into play until your car gets warm....if it's bad the car should run better. if it's not bad then the condition will not change.

and ask and you shall recieve.....back from page 27

http://www.bimmerwerkz.com/forum/showthread.php?t=25022
 
#8 ·
i think that u should change the spark plugs with any used car that u buy i dont know if your car is stock or not but if it is i tihnk that u should just use regular spark plugs instead of platinum as for the oil change i think that u should change out all of the fliuds in the car (oil,diff,radiator flush,bleed the brakes and w/e else im forgetting) the injector cleaner is a very good idea i just used some the other day for the very first time and i can already feel a big difference in my car i used this stuff called redline im not sure if the have it over in belgium but it works very well.


hope this helps

Vedo
 
#9 ·
Just finished changing the oil and filters and added an additive for injector cleaning. Also used an additive for the oil to improve lubrication and to prevent leakage. After 2 minutes I suddenly had a short series of surges and drops in idle from 800 to 1800 RPM (very quickly), turned the engine off and on again and it's running fine. The surges were weird, but they seem to be gone now.
Took a very short trip to the gasstation to fill her up and add the additive and already the noise level was way lower. (the oil that came out had some solids in it).
My dad was supervising and told me this:
The first two tanks I filled were with unleaded 95 octane (that's pretty much the lowest octane number you can get around here). It could be that I need to use 98 octane to get the bumpiness out. In Dutch the sound it made is referred to as "pingelen". It could have been just that. I'll know tomorrow.
What I found surprising was the ease with which this car can be serviced. This was fun. I'll post again to let you know what happens after a few rides.
Does anyone know how to reset the service counter in the dashboard?
Thanks a bunch!
 
#10 ·
Making progress

Hi,

so far I've managed to learn an incredible amount of stuff on cars, engines, and mine in particular.
The car runs better with just a few minor adjustments and fixes that were dirt-cheap.
I'm going to clean the ICV this weekend.
One small intermittent problem has me a little worried:
From time to time the engine will just cut and rev again. I'm not talking about the kind of stuff you see in false air intake or unstable idle. This is much more profound and I suspect it's the fuel pump suddenly stopping and going on again.
The mechanic I went to said it could be the pump cuts out because the tank is near empty, but it also happens on a full tank. With this in mind I started thinking of something else: the fuelpump relay.
Could this be the culprit? Since the cover is removed I pressed it in a little harder and so far it hasn't happened anymore, but then again it's an intermittent problem. I don't think it could be the pump or filter since it works fine most of the time (even at top speed, flooring it)
Or could there be another fuel system component involved?

I've learned a great deal from you guys and hope to learn more.
Thanks
 
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