ballymoss

Hi all.,
Have an intermittant prob with my R reg Felicia L Hatchback which is happening more & more often, Had it put on diagnostic at Skoda dealer but no fault showing up. Every so often, the engine starts to rev on it's own without the throttle being touched, sometimes up & down, sometimes at high revs continuously, usually in heavy traffic. Sometimes turning ignition off stops the prob, other times it eventually settles down on it's own. Starting to drive me nuts & also potentially dangerous! Anyone able to suggest a cure? By the way, this is my 4th Skoda & the 1st to give me any hassle. Cheers, Ballymoss

pinkskud

what engine is it?
i have this trouble with my 1.6 and cant find a cure.
starting to think its the TB itself.is this a common part between 1.3's and 1.6's???????/

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harryhill

Do the revs go down when you blip the throttle? Do the revs jam on? How does it idle is it lumpy?

If you have said yes to the above i would confidently say that provided everything is well serviced it will be your inlet manifold gasket. A couple of hours fix and two gaskets for less than a fiver will see you right.

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Skoda 1.3GLi 1998 now reading LXi on the back due to tailgate swop.

Bought for £30 and still going strong

pinkskud

what if its a 1.6? they don't have an inlet manifold gasket?

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harryhill

sorry Pinkscud i am not that familiar with the 1.6.

As far as i know the 1.6 has a series of rubber individual 0 rings for gaskets. These would be much better than the crappy card things on a 1.3 so i doubt this will be an issue on your car but you never know especially if the manifold has been taken off and rings not renewed.

Perhaps a leak at the throttle body perhaps? You could get a ginsters packet like in the other post to replace it he he.

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Skoda 1.3GLi 1998 now reading LXi on the back due to tailgate swop.

Bought for £30 and still going strong

harryhill

By the way your throttle body is the Magneti Marelli 1AV type which is the one where you can get a replacement on Ebay for £80 if things go pair shaped.

If i am right i think that the throttle positioner module can be detached and replaced which may also be the problem, but again if anyone else can confirm or dismiss this as don't have a 1.6

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Skoda 1.3GLi 1998 now reading LXi on the back due to tailgate swop.

Bought for £30 and still going strong

Felicia racer

mine does that too.
i just turn it off. That cures it.
But it is a pain in the a*s

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Laurin & Klement
1.6 mpi Felicia estate
Towbar parking sensors are brilliant
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KenONeill

Does the Felicia have a separate temperature sensor for the EMS from the gauge (or does the gauge do daft things if it doesn't)?

If so, I'd suspect the temperature sensor is applying cold-start enrichment! Reasoning being that my Dad had a Maestro with a similar issue; fixed by fitting a manual choke carb.

GeoffStone

Do the revs go down when you blip the throttle?
YES

Do the revs jam on?
THEY REV UP AND DOWN ALMOST STALLING, THEN UPTO ABOUT 1500RPM

How does it idle is it lumpy?
YES BUT ONLY WHEN WARM

So you reckon inlet manifold gasket, estimated price for repair at a dealer????

KenONeill

Geoff, that sounds like the manifold gasket. I think parts prices are covered, and a decent local garage will probably need an hour or 2 to replace it/them (presume it's manifold to head; it's more like 30 mins for throttle body to manifold if that uses gaskets and not just a mounting block).

Richard Black

How on earth can that be a gasket? Revs unpredictably and randomly, sometimes to high figures - got to be electronic.

rigsby

Ive had an intermitent problem with my fun fof the last 3 years where it cuts out when using the torque of the engine , but today i changed the temp sender, on the advice of a vw engine specialist , and hey presto and fingers crossed is seems ok
Better still the bloke at the scrappies gave me the sender(not that he knows)lol

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ballymoss

Thanks guys but the car is the 1.3 L model (Cheap & Cheerful) - have heard dark mutterings about the black box but hoping its not that as it costs more than the car is worth!

Ballymoss

richardsfavorit

I would consider the temperature sensor first - my sisters would idle at 2500rpm when hers was dodgy!

Richard Black

It's ALMOST NEVER the black box on any car, especially when it's an intermittent fault like that. Quite often changing the black box will fix it, but in fact the problem was due to some dodgy wiring or connector that got sorted pretty much by accident (maybe only temporarily!) when the black box was changed.

Connectors, wiring and sensors, in that order, are the most unreliable components in electronic engine management systems.

surprising_skod

nah it doesn't


my mums car had this same fault for a while. new leads, new dizzy cap, and it seems to have sort of stopped it.

Stu_GLX

What about the Idle Control Valve??

ALL of my old Vauxhalls with an injection engine had this problem...

Just an idea!

harryhill

Geoff i am almost certain that this is the inlet manifold gasket. The gasket originally fitted is made of a plasticy card and is not up to the job. The replacement from the dealer is much better and has clearly been upgraded.

The reason why a leaking inlet manifold gasket is likely to be the problem is because of the following:

When the car is under load there is a need for substantially more air than at idle. To have a car steady at idle the measurement of fuel to air needs to be managed and all the electronics in the world cannot deal with a car where the gaskets are stuffed. The car will idle erratically because the management system is trying to find the optimum level at which to idle. The reason why it is not so bad when cold is because the revs are naturally set higher and their is the need for a different balance of air to fuel when idling until the car is warm.

This is not hard to do believe you me it takes no more than a couple of hours and is completely swear free!! The gaskets are about a fiver or there abouts for 2 (you need 2) so a garage should only charge a couple of hours labour. It is advisable to also purchase a gasket for the throttle body which is around a quid

To do this yourself:

1. Remove fuel pump fuse from fusebox and start the car. This depressurises the system when you undo the fuelline.
2. remove battery negative lead
3. remove airbox and throttle body cover (take care as you will need to pop out some wires at the back)
4. remove MAP sensor plug (at the back of throttle body)
5. remove idle control plug (at the top of throttle body)
6. undo the fuel supply and return lines at the end of the fuel rail (place a big rage underneath to mop up any fuel)
7. undo all 4 injector plugs from fuel rail and number them 1-4 from timing chain end to avoid mix up when refitting
8. undo all hoses to the throttle body and inlet manifold including charcoal canister, servo hoses etc.
9. undo the support arm from the inlet manifold (timing chain end)
10. unclip the throttle cable from the throttle body and put out of way
11. get a socket or ring spanner on the 6 inlet manifold retaining nuts (4 visible from above and 2 from below - don't confuse these with exhaust manifold nuts)
12. remove manifold from cylinder head by wiggling it back and up

Once this is off you will need to get rid of traces of the old gasket which is the only tricky bit as if it is like mine there will be melted fragments on the cylinder head. I cafefully used a stanley knife but be careful as you don't want to hack chunks out of the gasket mating surface. One you are satisfied all traces are removed from inlet manifold and cylinder head then whack the new gaskets on and put it all back together.

If you want to change the throttle body gasket this can be done when the inlet manifold is back in position. It is only held on by 4 screws and is a good excuse to give it a good clean

__________________
Skoda 1.3GLi 1998 now reading LXi on the back due to tailgate swop.

Bought for £30 and still going strong

ballymoss

Many thanks for your help, pretty comprehensive & ties in with the bulk of suggestions which tended towards the inlet manifold & throttle body gaskets. Just 2 let you know the prob vanished for a week, including a days drive to birmingham & back via gloucester, but then surfaced twice the following day on one short journey to work!!!! Hate those intermittant gremlins but hopefully on road to curing the little so & so's. Ballymoss

rigsby

i WOULD PUT IT DOWN TO A SENSOR FAULT THEN RATHER THAN A MANIFOLD GASKET

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richardsfavorit

I would agree

harryhill

Hmmm Some days can be worse than others but this would be due to engine temprenture and driving conditions (ie lots of motorway or lots of stop start). if you do a lot of stop starting the problem is worse as the engine is required to idle more at various engine temprentures. The question is whether your idle is constantly dog rough when the engine is warm. If not you may need to look at something else and something electronic, but i would have thought this would have been picked up by diagnostics.

A few more checks you can make to rule out inlet manifold gasket.

1. have car warmed up and let idle. Then go to back of exhaust. What noise is it making and how are fumes being dispersed? It should be constant not a putt putt noise with bursts of fumes if you know what i mean.

2. get the spark plugs out and have a good look are any different to the norm light brown deposits?. A telltale sign if i remember rightly is a very clean plug compared to the others meaning an air leak.

3. Finally have the car warm and idling and spray WD40 around the inlet manifold joints. If things smooth out then this is your culprit.

let us know how you get on

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Skoda 1.3GLi 1998 now reading LXi on the back due to tailgate swop.

Bought for £30 and still going strong

Richard Black

OK, so from what you're describing it's pretty much got to be an intermittent electrical fault. Either a sensor somewhere is faulty or the wiring from one of them is. Unfortunately these faults can be the absolute devil to find - put it this way, a friend who I consider one of the best electronics repairers I know (he's been working in electronics for 45 years and knows just as much about cars) took over a month, on and off, to fix a similar fault on his wife's car. That's just the nature of intermittent faults - they tend to go away when you're looking for them!

rigsby

The worse ones are indicators with intermitent faunts
works-dont work-works-dont work-works-dont work

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bazz2004

I had this problem with my 1.6 GLX Felicia T reg. Pulling in, switching off and restarting was the only way to stop it. The problem was intermittent but a great embarrassment when the engine went vroom! vroom! in heavy traffic.

The garage thought it was an expensive electronic part and advised me to put up with it for as long as possible. A couple of months later the car drastically overheated. The AA removed the thermostat. The engineer said that it was a common problem because the thermostat is badly designed and tends to break up blocking the water flow. Removing the thermostat appeared to solve the revving problem.

I tried to replace the thermostat and temperature sensor but it went drastically wrong. I thought there was a major airlock but after failing to solve the problem the local garage suspected a cylinder head failure or worse. First they replaced the water pump, which fell apart, plus the cambelt which was due for replacement.

It looked bad at that stage because the manifold glowed red hot. Next day there was a welcome call. They started the car up and everything seemed OK. The engine wasn't wrecked. That's over a thousand miles ago and touch wood the Felicia is running beautifully