[GTiJohn]

My '97 MEMS1.9 equipped 200vi has started showing some annoying electrical gremlins.

It has a quiescent drain of about 0.5amps, meaning it'll not want to start after about 36hrs, so I've been disconnecting the earth for a while.

Multimeter probing and pulling fuses, points at the alternator but I haven't got round to replacing it yet...

Disconnecting the battery earth several times caused the cable to fatigue at the earth point at the slam panel, so I've replaced that with new one from Halfords. I have also fitted a disconnection 'knob' to the negative terminal to stop me fatiguing the new cable.




Recently, the car has started to exhibit short, intermittent 'cuts'. There are no specific circumstances that I can attribute to this yet but the symptoms are:

- The ABS glows briefly (ABS undervoltage ?)
- Sometimes the speedo and rev counter dip, sometimes to zero
- Even rarer, the engine revs may dip

Then it all disappears...

Is this likely to be caused by the alternator?

Or another bad earth? Looking at the Haynes diagram, there is another engine earth somewhere in the engine bay (E1 on pic below) but where is it?




Any other things I should check out?

[g259fsg]

0.5 amp is quite a significant current. The alternator may be the culprit. The rectifier assembly maybe has a faulty diode. I have had trouble with these over the years. Certainly worth dealing with that first. It might also be dragging the battery voltage down when the engine is running - many years ago with a fault like that, there was a smell of hot windings.

[itcaptainslow]

I had similar with the voltage regulator on the R8. It sits very close to the exhaust manifold so gets fried…

You can change just the regulator rather than the whole alternator - I think they’re still available from Rimmers, but it’s also not a bad thing to take the opportunity to recondition/replace the whole unit.

Check the voltage output with the engine running & various electrical loads applied if you haven’t done so already - a big fluctuation or under/over voltage will point to the above, too.

[GTiJohn]

Thanks for the info

I fitted a NOS alternator when the aircon went in 3 or 4 years ago and I still have the original one, so I could put that one back in and then get the removed one rebuilt.

There should be a heatshield between the rear of the alternator and the manifold but these are NLA. I'd better find an old one or make one...

[GTiJohn]

A few developments - some good, some not...

Remember this ?

- The ABS glows briefly (ABS undervoltage ?)
- Sometimes the speedo and rev counter dip, sometimes to zero
- Even rarer, the engine revs may dip

I can now add:-

Speedo and rev counter dip to zero and stay there

Driving down a bit of a bumpy road, this happened. Turning the ign off then on again got the dash lights on at position I but not at position II, nor crank. And of course it didn't crank.

Luckily, when I returned to the car a couple of hours later with a tow car, it started and ran well, except for a couple of momentary ABS light glows and rev counter dips, which seemed to happen if I hit a bump.

This got me thinking that, if these 2 faults were connected and something inside the alternator was causing both a leak and an air gap, then changing it might fix both...

Well, the original alternator is back on the car and now with a home-made heatshield to try and help the alternator survive, as A/C alternators are much closer to the exhaust manifold than on a non-A/C car



Unfortunately, on the first drive I'm sure I saw the ABS light glow and rev counter dip.

Earths have been checked and appear good, so I'm a bit stumped as to what might be causing the dip or how to find it.

Does anyone have any suggestions?

The upside? I think the alternator swap has fixed the battery drain problem

[g259fsg]

I'm not so familiar with these later cars, but is there a crankshaft position sensor on yours next to the flywheel? If this goes intermittent it has pretty significant effect on operations as the ECU gets no RPM or angle data. The one on my older 214 was temperature sensitive. OK when cold but cut out when at working temperature. On the older cars it's simply a coil, but later models may use Hall-effect detector.

Cheers,
Hugh

[rjessett]

have you checked the earth that bolts to the gearbox.

There are two body earth points in the engine bay apart from the bulkhead - on the inner wing, behind the headlights.

Power drain could be mems not powering off - maybe the main relay is sticking on - worth swapping the mems relay back (in front of the fuse box) (or opening up and see if any of the relays are sticky

[GTiJohn]

Thanks for the comments - the earths are good but I'm intrigued by the crank angle sensor suggestion.

It's been a few days now and I'm learning a bit more...

The good news: The drain problem is fixed

The bad news: The cutting out isn't

It's had a couple more glows and momentary cuts but it's not stopped...yet.

It seems to happen only above c.3000rpm. When I drive below this, it doesn't seem to happen but blimey, it's boring !

Does this give any more credence to the crank angle sensor hypothesis?

[961tat]

In my experience no they have failed on restart ie over night or after a hour and never when the car was running but they are easy to change.

[g259fsg]

On our 1990 214 it did just cut out suddenly while driving, engine just went completely dead. Fortunately I wasn't too far from home. I'd just picked up my son from the station so we were able to push it off the road and walked home and got another car to tow it home. When we got back to the 214, it had cooled down and restarted immediately, so my son followed me home, but we didn't get all the way and had to tow it for the last bit. I was able to reproduce the fault in the garage and found when it stalled the CPS had gone open circuit. I now keep a spare in the boot in case it happens far from home. Probably worth changing as part of the process of elimination. These faults are sometimes difficult to identify as several things can interact in the ECU, and it's possible the ECU has an intermittent fault. Did you try connecting a diagnostic to it?

Hugh