Ok, I know this is a commom theme throughout the forum but could someone give me logical sequence for diagnosing poor idling performance from a felicia 1.3 MPi (1997).:confused:

just purchased a 1997 felicia with 37K on the clock, have serviced it with the following; air filter, spark plugs, oil & filter. Car was runing poorly at tickover but fine at any other speed. After reading through the forum it seems that the obvious part for replacement was the temp sender & thermostat (low reading from temp gauge). Sure enough after replacement the gauge works fine and the car warms up quickly but..........................tickover is still 'lumpy'. To be fair it feels like it is now running on three cylinders and not two as before!

Any clues as what to try next? clean the butterfly, intake etc? If so what needs attention? Air mass sensor? etc......

Cheers

Check for leaks in the pipe work running to the throttle housing and / or a poor or non connection of the pipes.

I hope that makes sense!

Thanks for that. You're right I should have checked the pipe work first, it's easy to forget the basics!

Having said that there are no obvious leaks & I have checked all the electrical connections while the air cleaner assembly was out of the way.

The car starts no problem and runs well on tickover from cold. When it has warmed up tickover becomes 'lumpy'. If this engine had a carb fitted I would think that the choke was stuck, any ideas on what would cause rich mixture?:confused:

Defective temperature sensors, or air leak in the exhaust effecting lambda readings could cause the engine to run rich.

To be fair it feels like it is now running on three cylinders and not two as before!

Any clues as what to try next? clean the butterfly, intake etc? If so what needs attention? Air mass sensor? etc......

Cheers

This sounds exactly like mine, seems to be common. I suspect mine's running a bit rich, not too impressed with the economy. I cleaned the plugs, butterfly etc but no better (in fact worse for a while, high revving) I wonder if the air intake temp/pressure sensor is ok. Some info on the symptoms of a faulty temp/pressure sensor would be useful, and if there's some sort of test the diy mechanic can do on it, if at least to rule it out.

Spot on! Fuel ecenomy is 'pants' plus there is always the worry it will stall at an inconvenient moment. Air mass sensor? I thought if this was at fault then performance would be poor throughout the rev range? Lambda sensor? Any ideas on how to check?

Spot on! Fuel ecenomy is 'pants' plus there is always the worry it will stall at an inconvenient moment. Air mass sensor? I thought if this was at fault then performance would be poor throughout the rev range? Lambda sensor? Any ideas on how to check?

Try a google search on lambda sensor symptoms. I got some useful info. Testing looks difficult without specialist gear. Certainly not sure but from reading the results of the search it could well be lambda at fault or something related upsetting it (eg air leaks, maf, poor earthing etc-try the search). Such a problem is likely to cause poor economy, rough or random idle, wrong mixture etc. Sounds like mine alright!!! fyi mine doesn't tend to stall, if stalling, butterfly dirty? I just filled up and got 30mpg with a mix of long/short journeys. Don't drive it hard, seems poor, compares or not?

Also did a search on cleaning lambda sensor, that was interesting, lemon juice:confused: But I'm not recommending anything!!! it's only what I read.

Yes, low 30ish MPG seems to be the norm! Don't like the sound of it being a faulty Lambda sensor....not at nearly

Oh, checking the earth connection on the exhaust is also recommended.

Much grumblage indeed, these systems can be a bit of blank cheque. Finding the problem without the right test gear is the rub (and I think even with it it's not always conclusive-could be this could be that) My sister paid several hundred to diagnose and replace a couple of sensors on a corsa. Might be worth cleaning if you're brave enough. Got some info on cleaning at the fiat coupe owners site. Like to know how you get on. I'll see what else I can find out, in the meantime got a pool of water in the footwell to mop, b****** windscreen!!!

There is a tester from halford I believe which covers this injection system and gives you fault codes etc, no idea how effective it is or how usefull the information is. I have very little faith in fault code readers - after being told that a non running car was perfectly ok by a stealer

This might be worth a cheap purchase -

eBay.co.uk: SKODA TECH WORKSHOP SERVICE & REPAIR MANUAL CD ROM 2004 (item 230052072333 end time 21-Nov-06 22:41:10 GMT)

I purchased this CD (think it's the same) which has a lot of useful sensor diagnostics for the 1.6. Unfortunately it doesn't seem to give the same information for the 1.3 or the 1.9D but if the sensors are the same may well be covered - not sure!

Hope this helps.

Found this site useful;

Lambda Sensors diagnostic advice fault finding and symptoms

Makes a lot of sense, only test I can perform is the resistance of the heater element. This measured 3 ohms which is just outside of the recommended perameters of 6 - 14 ohms. Would it make that much difference? I know the heater is used at idle speed when the exhaust gas cannot fully heat up the lambda sensor. Cannot check the out put of unit but contamination is supect, cheap petrol, lack of oil change, short journeys etc.

Any experience with 'universal' sensors?

From the information I have (1.6), the resistance between terminals 1 and 2 of the lambda (heater) should be between 2.7 and 3.0 ohms - so sounds OK if this is the same part.

4 wire lambda sensors on ebay at

Just taken delivery of a universal 4 wire Zirconia lambda sensor from Gendan Automotive, ordered it on Sunday & delivered Tuesday.

Will fit it when weather & time permits. Will post results asap. Not sure this is the correct route to take but what the hell.........I contacted dealer to get price for a diagnostic check & they want approx

This might be worth checking. I think I might have found the cause of my lumpy tickover and high consumption. It was suggested here to look for intake air leaks and I asked a mechanic friend his opinion also. He thought a lambda sensor fault to be possible but reckoned an intake air leak to be more likely as even a slight one could upset the lambda readings and cause it to richen the mixture. He mentioned that he had a car that whistled due to a leak at an injector. The other day my car made a loud whistling (for a while until I revved the engine). So as advised by my friend, today I got a can of WD40 with the tube attached to precisiely direct the spray and, with the engine running, sprayed all the intake gaskets (ie base of throttle body, injector bases, manifold gasket). Sure enough when I got to the manifold gasket at the left cylinder (nearest the alternator) the engine note changed a lot, so it must be sucking in the WD40 through a leaky gasket. Continually spraying at this point smoothed the tickover quite a bit.

I didn't have time to investigate further but next I'll check the manifold bolts are tightened correctly. If that doesn't work it will be a new gasket, a fairly straightforward job I think and hopefully that will make a difference. If you haven't checked this it might be worthwhile, only takes a few minutes.

Our "Skoda" engined 1.3MPI had lumpy idle & refused to start when warm, eventually turned out to be a failing inlet manifold gasket. Once replaced everything fine, temperature sensor had also failed.

I know a mechanic who has had the same fault on VW Polo, I imagine these use the same Bosch designed inlet manifold.

The MPI Manifold can suffer a gasket failure its not uncommon, the earlier SPI combined inlet exhaust manifold gasket is actually less prone to failure and worth fitting that instead.

This might be worth checking. I think I might have found the cause of my lumpy tickover and high consumption. It was suggested here to look for intake air leaks and I asked a mechanic friend his opinion also. He thought a lambda sensor fault to be possible but reckoned an intake air leak to be more likely as even a slight one could upset the lambda readings and cause it to richen the mixture. He mentioned that he had a car that whistled due to a leak at an injector. The other day my car made a loud whistling (for a while until I revved the engine). So as advised by my friend, today I got a can of WD40 with the tube attached to precisiely direct the spray and, with the engine running, sprayed all the intake gaskets (ie base of throttle body, injector bases, manifold gasket). Sure enough when I got to the manifold gasket at the left cylinder (nearest the alternator) the engine note changed a lot, so it must be sucking in the WD40 through a leaky gasket. Continually spraying at this point smoothed the tickover quite a bit.

I didn't have time to investigate further but next I'll check the manifold bolts are tightened correctly. If that doesn't work it will be a new gasket, a fairly straightforward job I think and hopefully that will make a difference. If you haven't checked this it might be worthwhile, only takes a few minutes.

To report back on what I wrote above, tried tightening the manifold bolts, didn't feel very tight at all. Still leaking a bit but definitely an improvement in running. Will need a new gasket to fix completely but this is looking almost certain to be the problem in my case (and not too uncommon it would seem). Worth checking.

sounds very much like the inlet manifold gaskets are sucking in air very very common problem on 1.3 mpi's

Knock me down with a feather!!!

Tried the trcik with WD40 around the injectors & inlet manifold gasket. The pool around the gasket disappeared quickly as it was sucked through a porous gasket. The manifold bolts were tight as I had checked them previously. I never really expected there to be fault in the gasket even though this fault had been mentioned in other threads.

Quick trip to the dealer to purchase a couple of new gaskets & the problem is sorted.....purrs like a pussy cat.....sort of!

Quick observation about the gaskets, old ones appear to be made of thick waxed paper whereas the new ones are similar in construction to head gasket. i.e. have a metal reinforcement through the middle. Much tougher hopefully.

Any way, thanks for all the help folks.