Another E30 Idle Problem
 

I have seen a few posts in reference to E30 idle problems, and unfortunatley, I am adding one more. I will try to be specific......and hopefully I will get some insight. Thanks for your help.

I have a 1990 325is. I live in cold NJ...and the motor will idle very roughly when started cold in the morning or after sitting 3 or 4 hours. If allowed ample time to warm up, the car will accelerate properly. When completley warm, the engine will run strong, and accelerate well, but still maintains a very erratic and lopy idle when resting. If driven cold, the motor will bog out while trying to accelerate until it is warm.

In the past three weeks I have done the following: new disributor cap, rotor, ignition coil, bavarian autosport plug wires, plat+4 plugs, k&n panel air filter, fuel filter....I have tested the idle control valve with a multi meter, and it is in accordance with the Haynes manual.

WHAT IS MY NEXT STEP HERE? IS THIS A FUEL PROBLEM? DO I NEED NEW INJECTORS? I AM JUST LOOKING FOR A FINGER IN THE RIGHT DIRECTION. THANKS FOR YOUR ADVICE!!!!

JIM

Hi there:

No offense dude, but I live in Arizona and mine idles pretty lopey as well. I have heard from a couple of BMW specialists that
"they all do that" I have done the same stuff you have and am about to try injectors too. I don't seem to remember these cars
idling this way when they were new.

good luck

jeff

well, I can't give up!... actually I was just reading some old posts, and saw someone mention that Bosch platinum+4 plugs do not work well in the M20 so I will try changing them. I would appreciate any other advice though........

Jeff, Let me know if you change your injectors.....

James....I just read a blurb on a guy that has the same problem..(Illl give you the link below for a good e30 forum)...and he basicallly took the Idle control valve off, cleaned it with carb spray, blew it out with compressed air & it works great!

I know you tested it for electical complinace, but they do have a mechanical aspect as well.

Try it.

Dave.

http://bimmer.roadfly.org/bmw/forums/e30/forum.php

i just wanted to add that i live in VA and mine doesnt do it yet but if it does atleast i know im not the only one

The lopey idle is typically caused by either a mixture problem or a vacuum leak. I would suspect vacuum. Change all your vacuum hoses (pretty cheap to do, and they are probably old anyways), and double check the vacuum levels. A small leak will only show up at idle - disappearing when running full speed...

-Wayne

James,

A few things,

First, get rid of the Platinum 4's, they do not work all that good in the M20 motor. I put some in my 325is and it actually caused a lopey idle.

You also will want to check that you have a good seal between the oil cap and the valve cover, and also the valve cover gasket. Even loose valve cover nuts can cause this.

Check the intake boot for cracks. It's pretty common to see these boots drying up and start cracking. When the cracks develop, they cause all sorts of problems.

Check the metal fittings on the sides of the throttle body that operate the power brakes. These are press-fittings and can work themselves loose over time. Just a dab of RTV around the fitting and it should be ok.

Right-o, I think that the platinum plugs are the wrong temperature range for that car anyways...

-Wayne

jared:

I heard that just the garden variety NGK plugs work the best in a 325i, what do you run in your car?

jeff

Right now I am running the single electrode Bosch Platinums and they work great. I took them out the other day during a valve adjustment, and they had almost no buildup on them at all.

Jared, Wayne,
I have changed all of the hoses coming off of the throttle body, and the intake boot. I also took dave325's suggestion about cleaning out the icv with carb cleaner, but that did not help. I will try changing the spark plugs today and let you know if that helps. However, the problem seems to have gotten worse. The car smells very rich and now bogs out throughout the rev range until warm.
As far as vacuum hoses go, how many do I have? I have found and replaced 2 today....one from the fuel pressure regulator to the intake manifold, and one below the throttle body. Where are the others?......and how do I check the vacuum levels?
Jim

Vacuum hoses - you should be able to see all of them from the engine compartment. If they aren't fuel hoses, then they are vacuum hoses. Some are special BMW hoses that you need to order, but most are regular 8mm or 10mm vacuum hose.

You should check the mixture of the car, and also see if it's pulling any fuel injection codes. Use this technical article as a guide:

http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm

Hope this helps,

Wayne

There is a vacuum hose going from the valve cover to the throttle body. That is the other vacuum hose from which leaks are pretty common. You might also want to check the hoses that go from the throttle body to the brake booster. Sometimes the little metal grommets that hold them in the throttle housing become loose, causing leaks. Just pull them out, put a little RTV around them and push them back in.

From what you are describing now, it sounds like this could be a bad oxygen sensor. Check the connection for the O2 sensor, is it loose? If the connection is ok, the car smells rich, and bogs down till warm, this could be an indication that the O2 sensor is going bad. They have a element inside them that heats up by electrical current, normally, when the o2 sensor is operating perfectly, it warms up, and it sends the correct signal to the OBC. Now, if the O2 sensor is failing, it's possible that this heating element is broken, and it does not function correctly until the exahust has heated up to normal temperature.

This would also account for an erratic idle as well, due to the inability of the sensor to detect the fuel/air mixture, and send the correct signals to the OBC.

Another thing to check is the valve cover gasket and the oil filler cap. If it is old or cracked, it will allow air to leak, and your engine will not run correctly. The system needs to be in total vacuum.


To test the O2 sensor you will need to have a digital voltmeter. You can use a analog one, but I've found that in cases like this, analog units are not sensitve enough to read the types of voltage fluctuation put out by the sensor.

That said, here's what you do. Start the engine and let it idle for a bit. take the oil filler cap off to simulate a a lean running condition. Next, unplug the O2 sensor from it's connection on the passenger side, close to the firewall. Just look at the exhaust manifold, find the sensor, then follow the wire back to it's plug. Once unplugged, you will notice there are four wires in the loom. With the engine running, check the voltage between the terminals. It should be fluctuating, if it is not, this indicates that the sensor is bad.

thanks guys....I will try these things and let you know:)

Here are some pics to help.


In the throttle body pic, the arrows point to the small metal grommets that press-fit in, and can become loose.

http://forums.pelicanparts.com/uploads/Mvc-043s.jpg




In this pic, I am looking down over the exhaust manifold on the passenger side of the engine.

http://forums.pelicanparts.com/uploads/Mvc-044s.jpg

Mine also...and been told the same thing.

I agree with the oxygen sensor thing. Changing that on my car cured about 80% of the idle issue and some of the midrange flat spot I had.

Am going to go over the hoses with fine tooth comb, change plugs, etc
and upgrade the injectors when I have the $$

good luck

Gee, I could point you to an o2 sensor replacement article, but...

:)

-Wayne

Jared, Somewhere above about ten messages up you mentioned that you did a valve adjustment. This is on my next to do list. I already have the valve cover gasket. I have read the bentley manual several times, was this an easy adjustment? I have a slight tapping and it's driving me nuts.