idle issues

[E30Gheko]

Please help this is really starting to do my head in....

My H reg 318i auto has been spot on for the 18 months I've had it. However, it has some sort of idle issue that's getting worse...

The engine behaves as it should when driving, no problems there. It's only when idling it's really lumpy. If I have it in gear it bobs up and down. When reversing, it judders backwards when I don't use any throttle. Now it is starting to cut out occaisionally when reversing too. It stalled about 3 times when trying to do a reverse park tonight.

Can anyone point me in the right direction?

All help appreciated.

[Grrrmachine]

Idle and stalling problems?

http://www.e30zone.net/e30zonewiki/inde ... n_Problems

[E30Gheko]

Nice one.

Blue plug. Do you know where I can find it?

[Billwill]

Nice one.

Blue plug. Do you know where I can find it?

Blue sensor on the M40 318i is under the intake manifold...next to the brown temperature gauge sender.

With a bit of fiddling you can get the sensor out without dis-assembling the manifold.....best to first test it with an Ohm meter at the ECU plug. Test it while cold...should be about 3,000 Ohms then test it while hot should be about 300 Ohms.

The ECU plug connections are in the Wiki.

And if this is the M40 then clean out the ICV and check for vacuum leaks everywhere!

[Grrrmachine]

Remember, all Blue Words in the wiki are clickable links. Click the "blue plug" and it'll take you to the blue plug page which outlines the problems, the testing procedure and... the location

http://www.e30zone.net/e30zonewiki/inde ... g#Location

[E30Gheko]

Thanks for the help. I didn't manage to find a picture of the blue plug and it's location. I read through the links though and went in search of it. I found a blue plug under the intake, in the cylinder head as described but I rather think it may have been a temperature sensor? When I removed it coolant was dribbling out. It just had a solid brass end on it.

I removed the throttle assembly but this was all I could find? If anyone has a picture of the TPS in it's location and even better removed, that would be enormously helpful....

[Grrrmachine]

I found a blue plug under the intake, in the cylinder head as described but I rather think it may have been a temperature sensor?

Have another read of the Blue Plug Wiki page; specifically the first line.

The TPS or Throttle Position Switch is something else.

http://www.e30zone.net/e30zonewiki/inde ... ion_Switch

[E30Gheko]

Ok I accidentally removed the TPS whilst trying to remove the TPS but actually removing the temp sensor. lol. It looked pretty clean on the outside. So, if I remove it again and then remove it from the throttle body I should be able to give it a clean right?

I'm going along these lines as
1. I don't think I own a multimeter and would have little clue how to use one..
2. The problem has got gradually worse leading me to suspect a build up of gunk somewhere
3. All hoses seem tip top so I don't think it's a vacuum leak

The ICV could also be suspect. I'm not sure where to locate it in the bay though? I read that I should be able to hear it humming. I'd like to remove it and give it a clean also.

Sorry to be so vague and ignorant. I like these cars but I'm not really any sort of mechanic. (you probably guessed that by now.) I could cook you a cracking dinner though, but that's not really going to sort my idling problems out. haha.

Thanks for your help so far...

[Grrrmachine]

If you really have no idea what you're doing, then there's a chance you'll make things worse, not better. Idle problems are caused by niggly little details, so you can't go about it in a ham-fisted way.

First things first, get a multimeter and learn how to use it. There's NO other way of confirming whether the TPS and Blue Plug are working without one. A visual inspection means f-all.

Same with the hoses. They might LOOK nice, but can you see a hairline crack on tbe bottom when fitted? You really need to spray carb cleaner about.

Don't be too quick to blame the ICV. It's one factor in a dozen of causes. But if you want to clean it out, it's the metal cylinder that connects to the big rubber hose, and it should vibrate/buzz with the IGN turned on.

Ideally, put your engine all back together properly and then work through the Wiki Idling Problem part step by step, crossing each thing off as you go.

[E30Gheko]

It's all back together! My E30 is also my daily driver. What comes off must go back on so I can get to work.

This problem seems to be worse when the engine is warm. Does that make anything less or more likely to be at fault?

I've had a few split hoses before and been able to spot them. I'm fairly sure it's not a hose at fault, but I'll get some carb cleaner to make sure.

I'm not as familiar with the M40 as I am with M20's. I struggle to identify parts. I'll have another read through the wiki but I've tended to find that whoever writes them assumes a degree of basic knowledge that I don't have. If someone shows me a picture and says 'take that bit off' etc etc I do a lot better.

[E30Gheko]

Fixed it!!

Turned out to be a split hose after all. It was the hose going from the intake boot to the idle control valve. I removed the whole inlet to get a better look and found a huge split on the underside of the hose. Taped it up for now and the problem has gone. I just need to get a new hose. Anyone got one?

Very chuffed. I had visions of spending a wad on garage bills and parts, but a bit of insulation tape done the job for now. It's purring like a kitten and verrrry smooth.

[Tan91]

This is good to know i have some idle problems was pretty rough, but when i serviced it last did the timing belt and tensioners etc, rotor arm, dizzy cap, new battery (bosch s5), new HT leads and the idle is very slightly moving up and down.

I just need to attack the hoses and sort those split ones out.

Mine is a 316i LUX 1990 on 146,000 so its not to bad, oh yeah a new ICV was bought as well bosch one, this was done about 4 years ago when i bought the car and it was on 108,000.

And maybe try BMW for the hose, can't imagine it being expensive, post it in the "Genuine BMW Parts section on the main forum page, getting a price won't cost you