O2 sensor heater...what can affect it?

[lolcantturn]

[Beej '86 325es]

I inspected my harness, all that I could without completely tearing apart the engine bay. I couldn't find any signs of bad wires; all clean.

I realized I hadn't checked the air temp sensor yet, on account of how much of a pain in the ass it is to get to under the manifold. I checked resistance on the sensor and it looked ok.

[lolcantturn]

does the intake air temp sensor even affect anything? ..

[Beej '86 325es]

does the intake air temp sensor even affect anything? ..

It shares an ECU ground with the TPS and CTS, but I'm focusing my efforts on the CTS and O2 wiring for now.
It'll be Monday-Tuesday before I get back to it though.

[Fusion]

Maybe this'll help

http://www.r3vlimited.com/board/showthread.php?t=192533&highlight=idle

[nando]

does the intake air temp sensor even affect anything? ..

Is the pope from germany..

[boyd_dave]

where is your o2 sensor mounted in the exhaust/header? I had alot of trouble with 02 heater 1264 code for a long time. the ultimate fix was to move the o2 sensor alot closer to the engine. if its too far away, it will not work properly.

[trackjunkie21]

I seem to have solved my problem, it is infact exactly what Boyd_dave has said. Moving the 02 closer is a must, aswell as fixing any exhaust leak you have before the 02 sensor, they really mess with a lot of things.

[Beej '86 325es]

where is your o2 sensor mounted in the exhaust/header? I had alot of trouble with 02 heater 1264 code for a long time. the ultimate fix was to move the o2 sensor alot closer to the engine. if its too far away, it will not work properly.

Mine's mounted in the header.

Maybe this'll help
http://www.r3vlimited.com/board/show...highlight=idle

Already tried that.

[Beej '86 325es]

I checked my harness some more and read about the E34/E36 differences. Now I'm certain I have an E36 harness. So I'm not as concerned about bad wires now.

So I guess I'm back to asking myself what the fundamental issue is:
What would cause a lean condition at idle for 9 minutes, then suddenly it's fine? Not a bouncy idle, just lean and rough.

[trackjunkie21]

a lot of resistance in a circuit, but which one

[boyd_dave]

If the IAT is faulty and telling the ecu the air is hot, would it cause a lean fuel condition?

Otherwise, my first guesses are vacuum leak, fuel filter, fuel pump, injectors, o2 sensor...but it sounds like you covered most of those.

[Beej '86 325es]

So I think I've figured out the problem. I haven't tried to fix it yet, but hopefully I'll have time tonight.

I found some info on the VSS sensor, saying that if the road speed signal wire is not connected correctly, it can cause:
-the fuel to cut around 6800 RPM (yes)
-VANOS not kicking in (probably why I'm low on power and get a solonoid error code)
-idle won't hold when coming out of gear and slowing down (yes, mine dips when I blip the throttle)

So I think I've found the culprit.

The early Eta cars use both the C101 and the C104 in the glovebox. I've had a hell of a time trying to find out what the wires are for on the C104, but I know at least one of them is wrong.

Can someone verify these on the C104 for me?
BLK = tach signal
GRN/RED = OBC Fuel Cut (road speed signal)
YEL/WHT = Fuel Consumption (MPG gauge)

I've also got a separate BLU/YEL wire. I'm thinking that's a road speed signal that's supposed to go to the cruise control, not the ECU. I don't think this gets used though.

[328ijunkie]

Single Blu/Yel is AC switch to ECU IIRC
and grn/rd is not Road speed signal. You need to go into the back of the cluster to get it.

[Beej '86 325es]

Single Blu/Yel is AC switch to ECU IIRC
and grn/rd is not Road speed signal. You need to go into the back of the cluster to get it.

Crap.

Ok, thanks. I assume it's something obvious coming off the back of the speedo?