moire76, I would remove the voltage regulator on the back of the alternator and check the length of the brushes. It's likely the brushes are worn down to short nubs, and the voltage regulator needs to be replaced. The worn brushes prevent the alternator from recharging the battery fully when the engine is running. Either that, or you may need a new battery if it doesn't hold a charge.

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Fred Hoelzle

Yesterday, I have found a thread about spark plug lubrication. Based on the conversation there, I'm thinking that I may caused the starting problem.
To prevent stuck, I applied a little copper paste on the plug threads that might cause inappropriate ground for the plugs.
Afaik copper paste is conductor, so this is just another theory.
I drive about 50km in city yesterday, with a few cold and hot start, and no problem at all with the startup.
I'm also curious about the consumption with the new plugs, 60km from last tank fill, and the gauge is still at full. I know it's not a linear scale, though. My Mondeo had full gas gauge after 120km with a low fuel warning at about 480km...

moire76, I always apply a light coating of Never Seize to spark plug threads before installing them and have never experienced any ignition problems ... same for Oxygen sensor threads.

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Fred Hoelzle

Thanks, Ferdman, that sound promising to me, as usually I also use a little lubricant for most threads and never had issues!

I'm now at 80km since full tank, the gauge arm started descending...

Thanks a lot, Ferdman, to be honest, I rushed to the car to check if my voltage regulator is ever replaced, I did not remove it, but it seems quite new, its much cleaner than my alternator, and it has a white plastic base plate that is still white and not dark grey from dust, so I assume that it has been replaced not very long ago.

Yesterday I drove home with high temp engine, and it did not ever dropped the idle rpm, so the only thing it does consequently is the rpm drop for 3-4 secs after hot start of the engine. The hectic low idle really comes on just occassionally. Might be a vacuum leak, or OVP relay contact failure???

I have just found a way to read diagnostic error codes with a multimeter (duty cycle function required)!!! It looks awesome, cannot wait the end of the day to check my error codes!

here's the link for your reference: Bosch Fault Code Table

UPDATE: Checked the error codes, bu I'm unsure about the results. First I measured with cold engine, and I got a near static duty cycle at around 50% which reads for an o2 sensor failure, but I guess it is because the o2 sensor is not working until is hot enough so i warmed up the engine and checked again. THen I got fluctuating value between 30 and 50. According to the guide, fluctuating value around 50 +/- 10 means no error codes. I don't know if my 30-50 fluctuation could mean the same, or I may have multiple error codes that I'll not be able to check by this method?

I will check out the VR tomorrow and see what I will find.

Ferdman, you must be right about the voltage regulator!!

Today I had the chance to monitor my idle while I've been in an hour traffic jam.
I was raining, and I noticed that whenever the wiper takes a round, my idle drops 1-2 hundreds, and also the oil pressure goes down from 2.2 to 1.8. The moment the wiper is steady again, it all goes back to normal. I could clearly see dashboard lights are faded away for that moment the wiper works, so I'was pretty sure that my charging at hot engine is low.
Stopped by and checked at the battery, and bingo, it was 13,6V with lights on, idling, and only 12,3V while the wiper's licking along the windscreen.

I'll check the voltage regulator brushes tomorrow, and hope for the bests. WIll post results here.

THanks again, Ferdman, you're awesome!

OK, I took out the VR, here it is.
It looks worn, but not deadly bad, I think.
I will replace it to a new, just to make sure its ok.
what do you think?

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moire76, the brushes are fine as-is. No need to replace the voltage regulator at this time. I would estimate they have at least another 3/4" of wear left.

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Fred Hoelzle

OK, thank you, I will leave it then for now.

I would check my ground cables' contacts to vehicle body, but other than that, I don't know what else I could check.
Other than the alternator itself...
Can an alternator be faulty this way? Charges OK at 1000 RPM and above, but just not charge enough at idle?

OK, I have cleaned my ground strap at the battery negative, and checked again. Turned on all consumers, headlights, fog lights, rear windshield heater, blower motor, etc, and it charges only 11.9v idle.
At about 1200 or above it charges fine.

My ground strap however looks ancient, and it's torn halfway by aging, so its definitely need to be replaced. I also need to check the ground strap at the bottom, between transmission and vehicle body, as I remember from last week, it was quite full of oil and dirt, so it might worth a check.

Are there any other ground straps on this car I need to look after, before visiting az automotive electrician with my possibly faulty alternator?

Hello there!
I've just filled full the tank and the results: 440km using 49 l of gas which stands for 11l/100km or 21mpg 100% city drive. That's not that bad from a 25 year old 2.0 car. My Mondeo mk2 ate the same with its 1.8i 16v. And I think it will improve after replacing my ignition wires and maybe rotor and cap.

The other good news: since I have cleaned the ground contact between battery negative and the chassis, my idle was never dropped during driving. The few seconds rpm-drop right after hot start remained, so I will need to still to take care of it.

I do not worry about my charging anymore, it looks perfect, even if its charge only 12v with everything is turned on. It's really not realistic having that much consumer turned on for any long while the engine's just idling, so I consider my charging system as perfectly working.

Thanks for all for your help!!! I'll get back with the news regarding the hot start rpm drop, once I get there.

Hello there!
I have cleaned up things a little in the engine bay, and hey I've found a completely broken ground link! Replaced the cable to a new one, as well as the one at battery negative. I have replaced the valve cover breather hose as it was old and hard and leaked oil. The thin vacuum hose there is quite loosy, so I may need a new one there too.

Does anyone know that to where this plugged (vac?) hole supposed to be connected? (red circle on the image)

Thanks!

moire76

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