Speedo sensor. clutch and idle issues

[Dr Firefly]

Right,
I've got three problems,
1.Instruments playing up.
I think the cable from the speed sensor on the diff has died, as I'm getting the speed when I accelerate and brake hard, but at no other time - seems to be a loose connection to do with the position of the diff.

Does anyone know how much effort is involved in redoing the wire from the speedo sensor, and what type of wire I need?

2. Clutch
Juddering if I don't pile on the revs when the car's hot. I'm going to change the clutch, but I really need to know if a 325 clutch and pressure plate will fit onto a 320 transmission and flywheel with no problems (apart from the clutch being heavier of course)

3. Motronic problems:
Car's a post-facelift (reg'd 09/11/8, so I think it's motronic?) I can't set the idle speed anyway.

Basically when I rev the engine and then let the revs fall, the engine almost stalls every time, and when it's cold it can actually stall on me. It just doesn't feel right, and it feels like it's revving too low. Any ideas? I got it re-CO'd, and the garage said it was spot on anyway, so it isn't that. Thought it could either be the throttle swith, the idle control valve, or the AFM. Anyone got any ideas on how to tell between them?

Thanks in advance, Ian

[Simon]

1. Firstly check and clean the sensor and wiring connector on the back of the diff, this is very common.

2. Try canging your clutch fluid first, if it's old and contaminated, it won't be doing the job properly especially when hot, hence the juddering.

It was actually a BMW afterthought on some BMWs to fit a braided clutch hose due to the juddering caused by high temps.

3. Yes, car will be motronic. Maybe an airleak, spray carb cleaner all around the intake area, listen for a change in the revs, if so, this is the location of the air leak, also remove ICV and give it a good clean.

[Dr Firefly]

Thanks for the quick reply Simon.

1. speedo
I'm pretty sure that I'll need to redo that wiring properly, as the sensor wire had frayed and broken so the speedo wasn't working when I got the car, and I did a quick-fix with solder and plenty of duct tape. So I just want to do the job properly this time. But a good point anyway.

2. clutch
I've been slack and not changed the clutch fluid yet, which I should really do. Hell of a lot less work than changing the clutch. I'll do that next weekend, especially if the juddering is a known problem caused by heat on poor clutch fluid (thanks for telling me that). But my gut feeling was just that it was the clutch, as it's got a really high biting point on it now. Does anyone know if a 325i clutch and pressure plate will fit straight onto a 320i transmission and flywheel? Because I've got a 325i clutch sat here.

3. Motronic problems
I'll do what you said with the carb cleaner - should the revs go up or down? I'll clean out the ICV too. But if it comes to it, anyone got ideas where to get new AFMs, ICVs etc at decent prices without going to the dealers? I just know that second-hand stuff will only be being sold cos its knackered.

Thanks for the help so far,
Ian

[Simon]

1. Ok, didn't realise you'd already had a problem, best to change the wiring back to somewhere you can make a good weatherproof joint.

2. Pressure plate is unique to 325i, but the clutch can be used between 320i/325i.

3. If you spray carb cleaner onto an airleak, the revs will rise as it takes in the carb cleaner.

GSF and ECP sell ICV's and AFM's, still not cheap, but cheaper than what you would pay from BMW.

[Dr Firefly]

So you're sure that a 325 pressure plate will not fit? It won't just be a bit heavier to use? Just it'll mean selling the one I've already gotten hold of cheap.

Cheers, Ian