First problem to diagnose and fix...

[mft]

Hi all

I've just picked up my first E30 - a red 2 door 320i Call me strange, but I've deliberately bought one that's not perfect - part of the fun of owning a car, for me, is learning about it and working on it. I've just come from owning a 200sx which had lots of DIY done on it over the years!

Anyway... first up, I've noticed it's not too happy idling: if you come off the accelerator, as the revs drop, they drop a bit too far, and it struggles for a second, almost (but not quite) stalling. It then idles a bit higher, but hunts for a while.

Any suggestions?


PS Are the MPG gauges accurate at all?

[gareth]

i'd guess that the (imaginatively named!) idle control valve (ICV) is bunged up with oil/crap or stuffed. there are 2 types. 'L' or 't' shaped. easy enough to find and a doddle to swap over though. switch the ignition and look for a cylindrical lump that sits on the inlet hose, between the airflow meter / airbox and the throttle body. when he engine is off but the ignition is on, these usually humm which makes finding it easy if you're not sure what you're looking for.

bung a post up in the wanted section and you'll probable get one for about £10 - £15.

oh and welcome to the zone

[Brianmoooore]

Cleaning out the ICV (with carburetor cleaner - nothing harsher) is one of the jobs that should be on your list. It won't need replacing - just cleaning.
But, the first thing to check for your problem, is the throttle position switch on the bottom end of the throttle butterfly spindle.
Use the forum search function to find details of how.
To gain access to the switch, remove the large air hose between the air meter/filter and the throttle body, and check this hose carefully for cracks and splits.

[gareth]

another thing to check is that the crackcase breather hoses are all connected up and in good condition (the one from the rocker cover is often split) and the oil filler cap is sealing.

[mft]

Brilliant - thanks for the advice. I'll have a look at these when I get a minute

[mft]

One thing I noticed this evening is poor cold starting: it takes a couple of goes to get going, and sounds like it's running on about 3 cylinders until you clear its throat a couple of times.

From a few searches on here, it appears that the TPS is a good place to start for both problems

[Martinaston]

Sounds like the injectors are sticking.

[mft]

More problems. Can they be cleared, or cleaned, or would it be a replacement job?

[rj]

The simplest method is to add injector cleaner into the fuel tank. It depends how dirty they are or if the car has been standing for a while.

Bosch for example will ultra sonically clean them, replace the O rings and flow test them.

[Speedtouch]

What year is the car? Just that the early (pre-'88/F-reg) 320i was L-Jetronic while later is Motronic. It may be that the fuel filter needs replacing (it should be done every 4 years/40,000 miles). A new one made quite a noticeable difference to my car's starting time (the old one was 6 years old!)

[mft]

E-reg, so L_Jetronic, I believe

I'll add injector cleaner and a fuel filter to my growing list of jobs!

[Speedtouch]

Well, it may possibly be a Motronic on an E-plate; is the distributor on the block on the inlet side of the engine (L-Jet) or at the end of the cam (in whcih case, it's Motronic)?

[mft]

I'll check for the distributor later.

Is it possible to clean the TPS, or is it something to replace, if it proves to be faulty?


Lastly, are there decent pictures of the location of the ICV and TPS, as it's a question that seems to get asked a lot? I couldn't find any, but then the search function isn't working properly. If not, I'll take some when (if!) I find them.

[mft]

It's too dark to work on the car tonight, so I've been taking pictures instead

Well, it may possibly be a Motronic on an E-plate; is the distributor on the block on the inlet side of the engine (L-Jet) or at the end of the cam (in whcih case, it's Motronic)?

If I'm right, and this is the distributor, would this make it a Motronic?



Would someone be able to point out roughly where to find / how to get at the TPS and the ICV on this picture?

[gareth]

ICV - the black cylindrical bit with the connector that is to the right of the (red) dipstick

TPS - i 'think' it's under the throttle body, on the other side to the throttle linkage (the part that rotates when the throttle cable is pulled). it's been a while since i've played with a M20 engine and it's out of shot...

[Brianmoooore]

TPS - i 'think' it's under the throttle body, on the other side to the throttle linkage

that's where it lives. Take off the big convoluted air hose and you can get at it.

[mft]

Right, so I cleaned the ICV the other day, and then tried to get at the TPS.

Firstly, I couldn't get what I think is the TPS off - if I've got the right unit, it seems to be attached by a couple of screws? Unfortunately, I couldn't get a decent purchase on them, and was at risk of knackering them. Have I got the right thing?

Secondly, I found a spare plug. Three plugs come from the same cable bundle: one to the ICV, one to the TPS, and another one, which wasn't attached to anything. Is this normal?




Thanks

[Brianmoooore]

Spare plug is for emissions equipment (along with the plugged hose hanging off the inlet manifold) that you don't have.
Only attempt to remove the TPS if it tests faulty. Pull the connector off and test it in situ.

[Speedtouch]

Yes that is Motronic.

[Brianmoooore]

along with the plugged hose hanging off the inlet manifold

Sorry, was thinking this was a four pot engine when I wrote this. 6 pots, like yours, don't have the plugged hose - they have a short stub pipe on the manifold which must have a plastic cap blocking it.
Check this cap is intact while you have the car apart. It's immediately behind the TPS, and you'll need a mirror to check it.