Changed Coolant temp. sensor, now it wont idle.

j.bavarian · Post by **j.bavarian** » Sep 04, 2009 1:47 PM

1983 533i. Finally I found why my car would not idle...so I thought! A prior owner of this e28, had spliced the harness to the coolant temperature sensor and soldered in a resistor, disconnected the Cold Start Value, hose to fuel rail and all. I have replaced the CSV and fuel rail hose to it, added a new coolant temp sensor, and of course removed the spliced in resistor. I can not get the car to idle. She will start and die immediately. All of the inputs to my Motronic are correct, testing the Idle Control Module the only thing that seems to pop out at me is that instead of getting resistance between #11 (coolant temp sensor) & #4 (ground) on the harness- it is giving me voltage.
Please help me guys, this has been ongoing for a while now and I am beside myself. I want to drive my Bimmer!!!

"In the mist of chaos, keep stillness inside you"

Post by **Brad D.** » Sep 04, 2009 1:53 PM

The addition of the resistor was added as a technical bulletin by BMW to remedy a poor idle situation, it was not just some hack job deal that the PO probably did (then again it might be). Try adding it back in and see if the problem goes away.

tn535i · Post by **tn535i** » Sep 04, 2009 1:54 PM

I think resistors were added to some cars(per BMW) to improve driveability. Maybe there was a problem with the resistance range and I think that resistor you removed might have very little resistance anyway, something like the resistance of a cold engine. Did you check it's ohms?

It could be that your CSI is leaking and by reconnecting you are flooding the car out as soon as you try to start. If it is leaking then just unplugging it or the like wont do any good.

You've changed two things at once, you might want to back up and see which is really the problem?

Mark 88/M5 Houston · Post by **Mark 88/M5 Houston** » Sep 04, 2009 2:06 PM

Since you had it all apart doing the work, make sure that the AFM connections (both the male and female sides) are clean and the connector is fully seated. When the motronics senses enough RPM it begins looking for the AFM signal; if that signal is not present it will shut down. You are aware that the ICV (Idle Control Valve) and ICM (Idle Control Module) for the 533i are not compatible with the later (535) motronics - it is generally good practice to replace the ICV and ICM at the same time. The ICM is a known source of problems.

j.bavarian · Post by **j.bavarian** » Sep 04, 2009 5:49 PM

Initially the car stopped on me when the resistor had finally gave way to age, and snapped. I was unable to replace since I nor Radio Shack knew what it's resistance was, despite reading the color codes. Is the bulletin something that might be floating online? I will definitely try this if I can find the proper one.

Karl Grau · Post by **Karl Grau** » Sep 04, 2009 7:44 PM

I had the same deal with my 533.

Luckily I saved this:
"Ignition Upgrade for Idle Improvements - "Gene M." <MClan@worldnet.att.net>

Your 1982-1984 U.S. model 633 (also applies to 533 and 733) may have had an upgrade performed by the dealer to address idle problems. Technical Service Bulletin TSB 13 07 86 (1162) discuss these changes.
The major components of the upgrade were to:

(1) Replace the ignition system (coil, cap, rotor, wires) with the 30 kv components (the type in the 635) and adding a rotor adaptor;

(2) Install a 35 degree C thermotime switch;

(3) Replace the idle control unit with the green unit (or may be a black unit with green tape);

(4) Install a purge control module;

(5) install an external resistor in the wire for the temperature sensor that feeds the Motronics (should be the one with the light grey connector) Resistor type is 270 ohm, 1/2 watt, "Gold Band" metal film resistor for Motronics Control Units with a Bosch code date of 342 or higher (production date after 9/83) and for Motronics 341 and lower (9/81-9/83 production dates), it is a 560 ohm, 1/2 watt "Gold Band" metal film resistor .

This upgrade was performed at no charge, but may not have been done on your vehicle. If you have the slip on rotor instead of the bolt on type, the full upgrade was not done, but you may still have the external resistor installed under TSB 11 11 84 (920), which was only added to address a complaint of "hesitation/poor throttle response" during several minutes of operation after starting a cold or warm engine at an ambient temp above 75 degrees F.
A few things on these model years because of these changes.

First, when replacing ignition components, make sure you are getting the correct coil, cap, rotor and wires, depending on whether your car has the upgraded components. If the upgrade was not done, a rotor adaptor (PN 11 31 1 718 761) is still available if you choose to upgrade to the 30 kv components.

Second, if your car is not running right and you have questions, make sure to specifiy whether your car has had the upgrades.

Third, the external resistor may be the source of a "no run" condition, if the solder connection breaks from handling the temperature sensor connector. This resistor is usually soldered just behind the connector and may be concealed under the rubber boot. A broken or bad solder connection will mean that your car will not start or run, and this could be an intermittent problem because of engine vibration. In an emergency, you can disconnect a wire to the short 2 prong temperature sensor that feeds the idle control module, and the car will run, but the idle will surge hard. It may be better to carry a short wire with small insulated alligator clips on both ends in your tool kit to do a roadside repair."

Post by **Brad D.** » Sep 04, 2009 8:39 PM

j.bavarian wrote:Initially the car stopped on me when the resistor had finally gave way to age, and snapped. I was unable to replace since I nor Radio Shack knew what it's resistance was, despite reading the color codes. Is the bulletin something that might be floating online? I will definitely try this if I can find the proper one.

I guess radio shack has no multimeter to just measure it. They have plenty of cell phones they'll sell you though. Sad.

RonW · Post by **RonW** » Sep 04, 2009 9:14 PM

j.bavarian wrote:Initially the car stopped on me when the resistor had finally gave way to age, and snapped. I was unable to replace since I nor Radio Shack knew what it's resistance was, despite reading the color codes. Is the bulletin something that might be floating online? I will definitely try this if I can find the proper one.

Big Bronze Rim wrote:I guess radio shack has no multimeter to just measure it. They have plenty of cell phones they'll sell you though. Sad.

They do, however, still carry resistors.

wkohler · Post by **wkohler** » Sep 04, 2009 10:32 PM

Unplug the white sensor. Start the car. Plug it in. If it dies, there's your problem. Right after I got my latest 533 running, that's exactly what it did. Kyle helped me.

What's the PN for the sensor you installed?

tn535i · Post by **tn535i** » Sep 04, 2009 10:47 PM

Big Bronze Rim wrote:I guess radio shack has no multimeter to just measure it. They have plenty of cell phones they'll sell you though. Sad.

How many times have I had that same thought...

Hope the OP sorts out his issue also, curious to hear results

Post by **Brad D.** » Sep 04, 2009 11:18 PM

RonW wrote:
Big Bronze Rim wrote:I guess radio shack has no multimeter to just measure it. They have plenty of cell phones they'll sell you though. Sad.
They do, however, still carry resistors.

Ya, I'm grateful that they carry some electronics components, I just don't expect to find many employees there who know their ass from a hole in the ground.

wkohler · Post by **wkohler** » Sep 04, 2009 11:21 PM

We were in a pinch and needed a male-male XLR to 1/4" cable adapter for a band that was going to plug their feed into our board. I ran to Radio Shack. The doofus working in the store had no idea what I was looking for and kept trying to get me to switch to Sprint to get some phone that some guy tried to screw them on for the rebate.

j.bavarian · Post by **j.bavarian** » Sep 04, 2009 11:34 PM

I will go to the store tomorrow. You guys have no idea how happy I am right now. As far as the Radio Shack employees go, I agree after all it was I who read the resistor to him! (but could not tell the wattage) I will post tomorrow and let you know if I am motoring again.
-James

"Some days you're a bug, some days you're a windshield. "

j.bavarian · Post by **j.bavarian** » Sep 09, 2009 8:51 PM

Luckily enough I saved the resistor that broke. I visited a electronics store (not radio shack) and received an exact replacement. The one that broke is 270 ohms @ 2%. I replaced it into the harness and nothing has changed. Subsequently I have tried a 560 ohm resistor. Still nothing, but a start then stall. I am going to re-read every thing on this thread again and make the attempts. Thanks

spinedocab · Post by **spinedocab** » Sep 09, 2009 10:26 PM

Did you make SURE that the AFM is plugged in properly and that the harness to it is intact. This is the exact S/S of an unplugged AFM.

just sayin'

j.bavarian · Post by **j.bavarian** » Sep 12, 2009 11:30 AM

I checked continuity of the four wires connected to the AFM-to the Motronic. All is well. If I unplug the AFM harness the engine acts the same way. Starts then stalls. AFM no good??

spinedocab · Post by **spinedocab** » Sep 12, 2009 1:20 PM

j.bavarian wrote:I checked continuity of the four wires connected to the AFM-to the Motronic. All is well. If I unplug the AFM harness the engine acts the same way. Starts then stalls. AFM no good??

That's where I'd look. If you pull off a component and nothing changes, maybe that's your culprit. Where are you located? There are guys with extras, like me frinstance. Maybe you can try a known good unit and see if it changes anything.

j.bavarian · Post by **j.bavarian** » Sep 12, 2009 2:42 PM

I live in Portland Maine. I actually do work in my homes garage for fellow Bimmerphiles. But I will tell you - this problem has really has gotten my confidence down. I will see if I can find someone with an AFM of this model. Thanks for your help.

"I couldn't fix your brakes so I made your horn louder"

spinedocab · Post by **spinedocab** » Sep 12, 2009 3:13 PM

I would offer you one, but I have no X33i parts. Only X35i parts. Maybe someone can chime in as to the functional interchangeability even though BMW calls out different part numbers.

spinedocab · Post by **spinedocab** » Sep 12, 2009 3:21 PM

One more thing...is it possible that you have the connectors reversed for the coolant temp sensor and the thermo-time switch? Just a thought.

AllenC · Post by **AllenC** » Sep 13, 2009 1:05 AM

Check to see if your ECU is seeing the resistor plus Coolant Temp Sensor (CTS) resistance. I assume your CTS is fine.

I had this happen on my 533i when there was a short in the brown red wire leading to ECU PIN 13. Zero resistance

Ncamillucci · Post by **Ncamillucci** » Apr 29, 2013 3:24 PM

hey man, you ever figure the problem out? mines doing the same thing after a replacement harness and motor rebuild on my M30B32 533.

thanks!

MyE28.com

MyE28.com

Changed Coolant temp. sensor, now it wont idle.

Changed Coolant temp. sensor, now it wont idle.

temperature sensor