Blue temp sensor

[Wid77]

Hi,

Just swapped the above on my 1988 325i touring. The idle is now worse. It will stay at 1200 or so in traffic when warm and not want to drop back down to 800rpm where it normally sits. It also seems to be running hotter. I have since tried to bleed any air out of the thermostat using the little nut there but just water came out. I will drive her tomorrow and see if any improvement.

The fact remains that my car is still not running as it should and i think using a bit too much fuel (23mpg) but i don't know what to do next. I will try to clean the idle control valve tomorrow and see if that does anything. I have already used a can of carburettor cleaner in the intake system and checked for any air leaks but couldn't find any, in addition to changing plugs, filters and setting valve clearances.

If i thought the local tune up place would be able to sort it out then i would book it in tomorrow but my mate took his car there and it cost him £80 without them finding out what the problem was.

Sounds like i'm grumbling a bit but i just want to get her running smoothly as befits a bmw straight six. The car is a bit jumpy when trying to drive in traffic, which is where i spend most of my time.

I would be grateful for any suggestions.
Cheers.

[Brianmoooore]

Signal from the blue (and brown) temp senders goes through a round multipin plug and socket fixed to the metalwork below the inlet manifold. Check the condition of this connector carefully.
Also, don't assume that a new part is a good part.

[Wid77]

Thanks for the advice. I will have a look at this in the morning.

[Wid77]

Hi,

Still having a few problems trying to get my engine running as i think it should do. It is not serious i think but just not quite right. It is a 1988 325i touring.

After changing the blue temp sensor i now have the following problem. After driving the car for a bit so it is warm and then stopping say at a red light, the engine is idling at about 1200 then down to about 1000 and not 800 as it was before. I have checked the multipin plug and socket as advised and it seems ok. I have also had another go at letting any air out of the thermostat bleed valve but just a bit of water came out and no air.

I have also taken the idle control valve off and cleaned some of the muck out of it with carb cleaner. I have then reinstalled it and used a tiny bit of silicone around the rubber air hoses to make sure there is a good seal.

I think either i have a faulty blue temp sensor or i have some air in the system. If it's the sensor i can easily change for another. If it's a bit of air then i don't know where to start.

This new problem is in addition to the idle being a bit lumpy which was the thing i was trying to sort out in the first place. I also think the engine is running a touch hotter than before.

Any suggestions will be welcomed. Help!!!!!!!!

[sibzilla]

When my heaters ran cold and I bled from the thermostat without success I tried loosening the top heater hose under the inlet plenum at the bulkhead and this sorted things out for me.

[Brianmoooore]

Lumpy idle, high idle speed, hot running = air leak into inlet manifold.
Take out all the plugs, and see if one looks different.
Air lock in the coolant is an all or nothing affair. Either it is airlocked and the heater will be stone cold, or it won't be airlocked and the heater will be normal.

[bigun]

i have had trouble with my temp gauge i put a new one and it worked a red wire is also connected to the brown sensor that goes to the air con ? however i have a blue fitting for a blue sensor but i have a light brown one there any ideas also what should be on the bottom of my header cap its a2.5is soz for jacking your thread

[e30-320i]

have you had ant luck sorting your idle yet i think i have the same problem ,if i'm coasting etc the revs sit about 1200 and only drop to 800 when i come to a complete stop,i have changed plugs,dizzy cap,rotor arm,thermostat,idle control valve,air flow meter and the rocket cover gasket still no result.I have also sprayed carb cleaner trying to find an airleak and nothing

[Brianmoooore]

have you had ant luck sorting your idle yet i think i have the same problem ,if i'm coasting etc the revs sit about 1200 and only drop to 800 when i come to a complete stop,i have changed plugs,dizzy cap,rotor arm,thermostat,idle control valve,air flow meter and the rocket cover gasket still no result.I have also sprayed carb cleaner trying to find an airleak and nothing

This could well just be a worn ICV, sticking open slightly.

[Brianmoooore]

a red wire is also connected to the brown sensor that goes to the air con ? what should be on the bottom of my header cap its a2.5is soz for jacking your thread

Interested in the red wire. Does it look like factory fit? Does it come from the same single pin on the brown sensor, or do you have a two pin sensor? It's not shown on my wiring diagrams, and red wires on BMWs should be 12V permanebt live.
Coolant cap, in my experience, should have a yellow disc on it's base, but others are saying there is an alternative around with 200 on it's black base. Important thing is that it is not the original.

[e30-320i]

i'll clean my spare with carb cleaner and switch them see it that makes a difference cheers

[Brianmoooore]

Cleaning is not always a cure for ICVs. Eventually they wear slightly and tend to stick in certain positions. It's a common problem with LPG cars, where the ICV is in a different position on LPG than on petrol.

[e30-320i]

i have noticed that one spins freely and the other will move only if you push it around how loose should the valve be

[bigun]

a red wire is also connected to the brown sensor that goes to the air con ? what should be on the bottom of my header cap its a2.5is soz for jacking your thread

Interested in the red wire. Does it look like factory fit? Does it come from the same single pin on the brown sensor, or do you have a two pin sensor? It's not shown on my wiring diagrams, and red wires on BMWs should be 12V permanebt live.
Coolant cap, in my experience, should have a yellow disc on it's base, but others are saying there is an alternative around with 200 on it's black base. Important thing is that it is not the original.

i think the aircon is a retro fit quote me if im wrong is it dalvia ? its connected to the brown single pin sensor any ideas why i would have a light brown sensor in place of the blue

[Wid77]

Thanks for the advice Brian. I will check again for any air leaks.

When i removed the idle control valve to clean it i had a look inside. All it seemed to do was make a buzzing noise when connected. There didn't seem to be much moving around in there. How can you check that it is working properly?

Thanks.

[Wid77]

Signal from the blue (and brown) temp senders goes through a round multipin plug and socket fixed to the metalwork below the inlet manifold. Check the condition of this connector carefully.
Also, don't assume that a new part is a good part.

Sorry, just thought.... when i take my plugs out and if one of them looks different then does this mean i need a new inlet manifold? If so, is this difficult/expensive to do?

Thanks.

[Brianmoooore]

[

Sorry, just thought.... when i take my plugs out and if one of them looks different then does this mean i need a new inlet manifold? If so, is this difficult/expensive to do?

Thanks.

Would mean that the problem probably lies with that cylinder. Very likely a blown inlet manifold gasket.

[Wid77]

Just thought i would update you on my car (1988 325i) which now seems to be fixed although i have only driven 2 miles so further testing will be needed.....

After numerous attempts myself at fixing the poor idle and intermittent fluctuating revs myself i took it to a Fuel Injection & Carburettor specialist in Leicester, tel. 2855010. They diagnosed that the blue temp sensor which i replaced recently was faulty. It was a non-Bosch one and they have replaced with a Bosch one. The other problem was that the wiring to the sensor was faulty and meant that the sensor would sometimes think the temperature was -55 degrees (i think this is what they said but i may have heard wrong). This connector and wiring was also replaced. Finally, the mixture was changed slightly to make a bit richer. They couldn't alter the timing as they said it was not possible on this engine and was altered by the ECU.

Anyway, i am a bit lighter of pocket but the engine seems to be running nice and smoothly. It wasn't the idle control valve after all, which i also changed.

I think the moral of this story is always buy the original parts because it is usually worth the extra money. I think it was Brian Moore in an earlier post who said this so top marks to that man!

[TouringMatt]

Also goes to show the value of professional testing equiptment, you can spend ages trying to chase a fault (as i have done) when the repair can be a relatively simple thing!

Matt

[Wid77]

Also goes to show the value of professional testing equiptment, you can spend ages trying to chase a fault (as i have done) when the repair can be a relatively simple thing!

Matt

I agree with that! The garage found out the fault code within a few minutes whereas i have spent quite a bit longer trying to sort it out. They said i was on the right track but i would never have known that the new temp sensor was faulty as i do not have a multimeter. Might put it on my Christmas list...

[ant2]

whats the name of the place you took it to ? my 335 runs like arse constantly and i need to get someone to look at it

[Brianmoooore]

Signal from the blue (and brown) temp senders goes through a round multipin plug and socket fixed to the metalwork below the inlet manifold. Check the condition of this connector carefully.
Also, don't assume that a new part is a good part.

My first post on this thread. The multipin plug and socket I refered to is where the" wiring would have been faulty"

[TheDutch]

Is there a recommended way of rejuvenating a tired connector?

[Brianmoooore]

If it's not corroded beyond redemption, scrape out any corrosion you can, small fine wire brush or fibreglass cleaning brush, switch cleaner, and a good helping of silicon grease when re assembling.
Be carefull not to "open up" the female half of plugs and sockets.
If all else fails, this particular plug and socket could be totaly removed and the wires soldered and heat shrink insulated.