No Idle. Please Help...

[Lorenfb]

1. Check the fuel pressure.
2. Make sure that no water got into the DME unit.
3. Hopefully no one had the head off and failed to set
the cam timing properly (causes bad idle).
4. Check again the throttle position sensor (a resistor and not a switch).

Check out this website (systemsc.com) it may be helpful.

Good luck
Lorenfb@aol.com

[Drews323i]

Well guys, I took out the DME looks like the compartment that its in has been wet at one time. Leaves and such inside. took out DME, that someone has been into before. One of the tabs broken off. DME itself looks good, no corrosion. Once again car ran great for a couple of days. No idle problem at all. Then yesterday no idle. Got out the dwell meter, Fluke 83, checked for negitive pulse from DME to ICV. Recieving no signal to ICV. Checked pot. sweep on throttle position sensor again.OK. so i think its off to buy a used($400) or rebuilt ($600)DME i go. I really dont feel like giving $tealer ($1200)for a new one.

1980 323i
1985 325e
1994 325i

[Lorenfb]

You really need a scope to check for the idle signal.
When an idle problem occurs, a check engine light
is usually on.

If your unit is a Bosch 413, an idle problem results
after water damage. But it's usually a high idle.

Good luck
Lorenfb@aol.com

[Drews323i]

My DME is a 413. But when its running fine. I can unplug the ICV, start the car and no check engine light. Im not sure if thats the way its suppost to be? Ive unplugged the o2 sensor to make sure the check engine light is functioning correctly. It is. When the car is running correctly i can see the pulse from the DME to the ICV on my dwell meter. When its not, no pulse signal. Oh the maddness....

Thanks
1980 323i
1985 325e
1994 325i

[Lorenfb]

A quick test for the idle control function is to turn on the A/C and
see if the idle drops. If it doesn't, the ICV is working.

Good luck
Lorenfb@aol.com

[Drews323i]

When i turn on the A/C it idles down and almost dies. When i turn the steering wheel all the way to one side, and put a load on the motor, it dies instantly. thanks

1980 323i
1985 325e
1994 325i

[Lorenfb]

It appears that your valve is not working. At this point
point you need a scope or an LED test light.

The center pin is always +12V. The other two pins s/b
a square wave with a 50% duty cycle. Use the LED
tester and you should see the LED light (some have
a green and red) flash. You can use a Fluke set on
duty cycle to take a reading.

The best bet is to borrow another 413 DME. BMW really
did great by placing the DME in a "bathtub". I generally
can only save about 50% of the water damaged units
I receive.

Hope you don't have a water damage problem.

Good luck
Lorenfb
Systemsc.com

[Drews323i]

Thanks Lorenfb, You have been a big help. I have 12v+ at center pin. Regardless if car is in its" not idling mood" or not. the out side pins, i could be using my meter wrong,fluke 83, i will try the led test light. or follow the instructions for duty cycle with the meter. Im trying to locate a DME i can borrow, but no one wants to give up there car for a week or two, while i test. it only does it once a week or so. Whats your cost for saving one? Thank you very much!

1980 323i
1985 325e
1994 325i

[LeRoux Strydom]

I thought all along that your problem was related to DME water damage. In my previous post, I said to look for corrosion damage. You should carefully inspect the circuit boards for "dry" corrosion of the solder joints, which may appear like a greyish, whitish deposit on the circuit board. Sometimes these solder joints look OK, but may not make proper contact or intermittent contact. Running the affected joints over with a soldering iron will restore proper contact.

I feel confident that this will solve your problem. My wife's 328i had the identical symptom after the DME got wet in a heavy rainstorm. The drains to the DME "hole" were blocked with leaves, and I had to seal the joints in the bulkhead with silicone. Drying out the DME and cleaning up the "dry" corrosion restored proper idle control.

Your description of the "once-a-week" bad idle sound like a dry solder joint on the circuit boards, which wil show up intermittently for instance with temperature or humidity changes.

I really think you could have a go at cleaning up the DME again before sending it out. The fact that is works most of the time suggests that the electronics and software still work OK, you just have an intermittent contact problem to the ICV control.

regards

LeRoux

[Drews323i]

I think that this is where its all heading. Im going to take out the DME again this weekend, if not sooner. My friend works for an electronic repair shop. I'll have him go over it. When i had it out before it looked ok. but the compartment has been wet at sometime, so anything is possible. Thanks To Everyone!!!

1980 323i
1985 325e
1994 325i

[Drews323i]

Took DME out again today. removed entire case this time. Definite water to the bottom of panel. Grey corrosion! I also found the source of water entering!!!!!!!! The rubber boot for the A/C lines, on the bulkhead was not installed correctly!!!! Big hole for water to come in. That A/C hole and DME box are connected at the bottom. My friend cleaned and looked over circuit board tonight. He clened off corrosion best he could, but also suggested getting a DME that has not been for a swim. Probably damaged beyond repair. I installed it tonight. Sooo we will see in a few days if not sooner.....

1980 323i
1985 325e
1994 325i

[LeRoux Strydom]

Glad you found the source of the problem! I'm holding thumbs that your DME is still OK, but like I said, if it works most of the time, it should be fine once cleaned up and re-sealed. Let us know!

LeRoux

[Lorenfb]

Everyone with a 3 series needs to remove the drain hose which always
plugs-up behind the head and leave it OFF. Also, drill a small hole in the
cover to allow water to drain out of the compartment for the DME.

Good luck
Loren
Systemsc.com

[94-325i]

Or you order new style drain hose with part#: 51-73-8-144-152. Cost about $3.00 at Stealer.

[Lorenfb]

Still not a good idea. Start saving for a new DME then.

Good Luck
Loren
Systemsc.com

[Bijan]

Is there a tech article on how to do this?

[Drews323i]

Thats a good Question. I have a used DME on the way. But after looking inside the DME compartment again. The only hole i could find was on the left hand side, size of nickel or so, about half way up the height of the compartment. by the time water got up there the DME would be submerged! Am i not looking in the right place? Ill check at stealer for that drain kit. I hate the thought of drilling a hole in good sheetmetal. but if it saves me a DME its worth it. Yes a Tech article would be Great!

1980 323i
1985 325e
1994 325i

[Lorenfb]

The hole I suggested is about 10mm placed in the bottom-front of
the plastic and rubber covers for the DME and ABS compartment.
There should be no sheet metal drilling required.

Good luck
Lorenfb
Systemsc.com

[Drews323i]

OK i see what your saying. drill a hole in the plastic cover , where the wires run, that makes sense. Should have DME by this weekend, I Hope.

1980 323i
1985 325e
1994 325i

[Lorenfb]

Make sure that the hole is at the lowest point for proper drainage.
I tell all my repair shop customers to do this. I thought of this when
I first saw the problem. I don't know why BMW didn't think of this
and still suggests another drain hose to get plugged. I really hate to fix
water damaged DME units.

I hope you've found a good used unit and not a fakely rebuilt one.
These units are very complex and not easy to rebuild.

Don't forget to drill thru the rubber cover also.

Good luck
Loren
Systemsc.com