Hi, last winter my 1999 felicia 1300cc mpi with 75,000 miles developed an annoying fault, the fault can occur when stationary or moving, the fault has came back again recently

When stationary the engine rev's drop from 850 rpm to aproximatly 500 to 600 rpm after 1 to 2 seconds the engine then stalls, pushing the throttle pedal down does not help , the car can be restarted, usually without too much difficulty

When moving the car suddenly losses power and decelerates, if I do nothing it 'bump starts' and continues normal driving,

Anyone got any ideas or came across this before, all help and advice greatly appreciated

Sounds like a fuel starving issue. Clean the throttle body and clean all injectors/

Throttle body might be an issue, the fault doesn't occur all the time, it's an annoying intermittent fault, thanks for your reply it's give me an idea of something to look at

No problem. One other thing could be the fuel quality. Sometimes, gas pump owners raise their profit adding water or there is dirt on the bottom of their tank. Change the fuel filter if it's old.

Does the exhaust rattle? I've had this problem on a Felicia before. It turned out to be caused by a collapsed catalytic converter. The broken bit would get forced into the cats exit and therefore block the exhaust gases from escaping....then fall back inside and the engine then runs well again.

 

Also [as said] replace fuel filter...because of it's horrible location under the car near the tank it gets missed on services and becomes blocked and cause the fuel pump to get hot. Tight valve clearances and inlet manifold [gasket] leaks will also cause stalling.

Had a look today, inside the throttle body is very grubby, I've a new gasket ordered so when that arrives I'll give it a clean, also waiting on a new alternator, in the 6 years I've owned it very little problems but suddenly a rush of them

On the stalling issue there's one bit of information I left out, last year it always happened at the same place on my journey to work, from cold I'd drive to the traffic lights half a mile away, the car would stall at the lights nearly every time, only way to avoid this was to use the throttle pedal to hold the engine rev's between 1500 rpm and 2000 rpm

There's no rattle from the exhaust and I don't think it's fuel starvation, the fault seems to be related to colder weather, it didn't occur from last winter till 2 weeks ago

Edited 30 November, 201411 yr by Fergal71

There's no rattle from the exhaust and I don't think it's fuel starvation, the fault seems to be related to colder weather, it didn't occur from last winter till 2 weeks ago

Since you have already a very generic opinion (cold weather) yet you don't feel the need to check further in some areas (fuel pressure, injectors cleaning, fuel filter), what effect do you think has cold weather on fuel/air system? Moreover, what system of the car you feel is affected by cold weather in order to have the stalling symptom? Do you think the problem was there, but hidden or less evident, during warm season?

Edited 1 December, 201411 yr by RicardoM

I think the problem is more pronounced in the colder weather, on looking in the Haynes manual I noticed there's a device that directs warm air from over the exhaust manifold to the air cleaner while the engine warms up,

over the weekend I'm planning to clean the throttle body, check the warm air device, change the fuel and air filters and have a good look at the vacuum hoses, if nothing else it will rule out these areas

The replies on this post are helpful, I'm getting some very good suggestions where to look

Edited 1 December, 201411 yr by Fergal71

Don't forget to do a throttle body reset after cleaning it and before re-starting the engine.

 

Cold weather reveals any pre-existing imperfection that could go by during summer. Winter is the time of the year that reminds us how good or bad we maintained our cars. It is already hard for an IC engine to fight the low volatility of the gasoline, any overlooked maintenance operation worsens things. So far your maintenance plan is right.

Going to sound a bit daft here but how do you do a throttle body reset, and what happens if you don't do a reset, lucky I logged in today, was going to do the work tomorrow

Edited 5 December, 201411 yr by Fergal71

With ignition key OFF disconnect the battery (-) cable for about one minute

Reconnect the battery (-) cable

Turn ignition key ON and wait for 20 seconds

Start the engine without touching the accelerator pedal.

 

If that doesn't reset the throttle body, you will need the VAG-COM interface and software to clean any errors stored and perform the throttle body reset via software.

Edited 6 December, 201411 yr by RicardoM

Just taking off the negative does not always work, take off both negative, and positive, and then earth both of them.

As posted before this way of resetting throttle body only works if there are no fault codes stored.

Don't forget to take precautions if you have a coded radio, aswell.

Just taking off the negative does not always work, take off both negative, and positive, and then earth both of them.

You should prove with specific arguments and real measurements what part still holds enough voltage to count after 1 minute with the negative cable disconnected from the battery. I have the wiring diagrams ready for a scientific debate. Please come with specific data for Skoda Felicia, not just generic theories. Thanks.

Edited 6 December, 201411 yr by RicardoM

A small update, since I've fitted the new alternator on Monday 1st December the stalling fault has not occurred and there's been some of the coldest mornings this winter,

last winter the alternator gave bother, I got the alternator rebuilt by a local auto electrician, since it was rebuilt the battery light never went out while the engine was running, got brighter as rev's increased, the voltage was tested by the electrician and was charging ok, he claimed the fault was in the cars wiring and wanted nothing further to do with it, when I fitted a replacement alternator the light goes out, could the alternator have been sending bad voltages or signals to the ECU

I haven't done any further work yet because I don't has access to VAG-COM to reste the throttle, and the weather was bad last Saturday, but I am intending to do the jobs I've already planned as a belt and braces sort of approach

The alternator can fail electrically or mechanically in many ways such as:

• bad voltage regulator
• worn carbon brushes
• worn copper slip rings
• open/shorted windings
• open/shorted diodes
• worn bearings

It is theoretically possible that one or more diodes failed and a higher voltage ripple affected the ECU, but I have no proof for Skoda Felicia's specific case. I don't think the ECU input voltage supply value is an issue, ECUs have a solid 5V referrence voltage.

With my alternator the diode pack had failed at the time it was rebuilt, this was causing the battery light to stay on

the brush pack was replaced when it was rebuilt, by the look of the alternator the brushes were the only part replaced, they were the part that had initially failed,

the battery light stayed on, when the aa arrived he jump started the car and hit the alternator a couple of times with a hammer to free the bushes and put the light out and advised that the fault was in the alternator

Don't really understand modern ECU's, I work on diesels in construction machinery, last time I done serious work on petrol engines it was still points and carburettors, the felicia is the first car I've had that doesn't have a distributor

A little update to the problem, as I've said in an earlier post since I've replaced the alternator the fault has disappeared, since the 1st of December not one re occurrence,

So looks like the alternator was the problem all along,

A big thank you to all that replied and helped me with suggestions and advice, it was much appreciated,

I'm posting this little update incase anyone else gets a similar fault

So basically you're saying that changing the alternator cured the engine stalling?

Up until I changed the alternator there was a problem, the car stalled almost every time it was used, since the alternator was replaced not one incident of stalling, I thought initially the low air temperature of winter was the cause, I failed to consider the fact that I was using more electrical systems such as lights, heater blower and wipers, putting more of a load on the battery and alternator,

I don't know why with any certainty, but I have a theory that the alternator was causing low voltage at the ECU, when I replaced the alternator this ment the ECU got the correct voltage and therefore was able to function correctly

I'm not an auto electricion, in fact electrical systems are a weak area for me so I might be wrong in my theory

Ok, I was just checking.

From my knowledge the ECU works with 5 Volts from a voltage regulator (12V -> 5V) so I don't see a weak battery/alternator influencing its operation.

A more plausible scenario would be a weak spark. I stand to be corrected.

Interesting problem. I have it too.

 

Hasn't happened at all over summer, but a couple of weeks ago the car stalled after about a mile. It restarts no problem.

In my inexperience, I was guessing at some electrical fault when the automatic choke cuts out after the car is warmed up. But I don't know if there even is a choke.

Last winter it would do it as I coasted up to a T junction, but not every day.

 

I also have a dim glow from the battery indicator on the dash, which fluctuates slightly.

 

Uh oh.

Uh oh.

Exactly.

With regards weak spark I'll not argue that, it definitely could be a possibility,

Reg with regards your battery light's dim glow that fluctuates, does it get brighter as the engine rev's increase and dim down as you reduce the rev's, this is what mine was doing,

But please don't rush out and blame the alternator straight away, get it checked out, my problems inically suggested the throttle body may have been the problem and the alternator was a separate issue, the only reason that I dealt with the alternator 1st was that it totally packed in, if it hadn't packed in I would have concentrated my efforts on the stalling problem