MOT fail

[morrispaul]

Car runs at 95 in traffic and cools to 70 on open road, if I stop it takes a minute to get up to 95.replaced thermostat ang sender unit last year, parhaps I have a faulty one.....car was tested at 95 degrees.

[RicardoM]

A bad coolant sensor (or a wrong one) is reason enough to fail any emission test. Using a VAG-COM scanner and a multimeter would be best to verify it and also if / what errors are stored in ECU. Particularly interesting are lambda sensor (temporary or permanent) errors.

[morrispaul]

running temperature is playing on my mind,although 95 deg when on test,but does that mean that the cat is getting hot enough to work as it should ?.....re-test booked for saturday,will need to refuel by then so will work out MPG, after my  350 mile run on sunday iam expecting mid to high 40`s....car seams to be a bit more livley after the service but that could be just me......

[RicardoM]

Keep in mind that the coolant temperature sensor is dual. There are two completely separated thermistors inside. One thermistor is in series with the temperature gauge. The other thermistor is connected to ECU. The former you test with a multimeter. The latter (which is more important for the engine) you can test it with VAG-COM or with a multimeter. In case that the sensor is good on both circuits, the thermostat is not working or sealing properly.

 

The cat is good. My car has no cat and I pass easily the emissions test (CO < 0.5) just because I set the carburetor and ignition by thr book. Your car, havin a computer, should self-adjust it automatically. But having an ECU is not enough. An engine runs well as long as all sensors work well. If you can't address my concer till MOT day, it will be 50/50 chances to pass. Not because of "Liquid Science" :wonder: but because doing maintenance properly.

[SuperbTWM]

A bad coolant sensor (or a wrong one) is reason enough to fail any emission test. Using a VAG-COM scanner and a multimeter would be best to verify it and also if / what errors are stored in ECU. Particularly interesting are lambda sensor (temporary or permanent) errors.

I would put my money on the thermostat

 

At least with old technology you can see when a thermostat has got a bit lazy just by looking and the temp gauge. Modern Vag cars sit at 90 on the temp gauge aslong as the coolant temp is between about 70 and 100 which means you need to use some form of diagnostics to determine the actual coolant temperature.

[RicardoM]

I would put my money on the thermostat

 

At least with old technology you can see when a thermostat has got a bit lazy just by looking and the temp gauge. Modern Vag cars sit at 90 on the temp gauge aslong as the coolant temp is between about 70 and 100 which means you need to use some form of diagnostics to determine the actual coolant temperature.

Since you quoted my yesterday message about the coolant temp. sensor, let's quote what I suggested 3 days ago too hoping the owner will do the test and report.

 

It is not normal for coolant temperature to stay at 70 C when driving on highway, regardless outside temperature. Engines run most efficient at 85-90 C. Colder engine means higher fuel consumption, lower power, higher emissions. Most probably the thermostat is faulty. It is very easy to verify that. From cold start let the engine idle or revv it a little (< 2,000 rpm). Feel the thick upper radiator hose. Up to about 80 C, the hose should be cold, except maybe 1-2 inches near thermostat.

Edited 16 February, 2016 by RicardoM

[bigjohn]

That time of year again, just got back from MOT test and my trusty pick up ( 1.3 mpi petrol ) has failed on emissions. Always struggles every year but manages to pass, new cat last year and readings were more or less nothing, co readings today averaged 0.5 so way over the 0.2 pass level.passed the other tests...not been looking after it as well as I should as I do relay on on it to get me to work every day.....going shopping shortly for plugs, filters, oil and might take a look at "cat cleaners" ive used these before in my daughters saxo with no change in the readings, mot man suggested using in the pick up along with new plugs and filters so will give it another try....my garage is full with other hard to move projects so working outside on the drive in the cold and wet.....not looking forward to that ....

 

My old petrol Octavia 1.4 16v passed the MOT last year but only just re emissions. This year before the MOT I added a bottle of Cataclean to 1/4 tank fuel drove for 50 miles and then topped up with Vpower - this time well within the emissions figures  :clap:

 

Didn't fix a broken front spring though 

[RicardoM]

Didn't fix a broken front spring though 

Why not? It's liquid science, man... By the way, I find my car runs faster if I paint speed stripes on it and add a Sport GTi sticker below Felicia logo

[bigjohn]

Why not? It's liquid science, man... By the way, I find my car runs faster if I paint speed stripes on it and add a Sport GTi sticker below Felicia logo

 

Don't care - snake oil or no snake oil  (no snakes died in the production of this potion   ) something did the job:-

 

CO Limits =< 0.20% , actual .09% , last year 0.17%

Lamba Limits =.97-1.03 , actual 1.007, last year 1.027

CO Limits=< 0.30%, actual 0.06%, last year 0.30%

[morrispaul]

As you have probably already guessed iam not too good with modern day car electrics, mechanical items I like to think iam good with, a few engine rebuilds under my belt and just finished rebuilding my bwm 2 series M10 unit, I like to see how things work, with electrics theres no moving parts.....witchcraft....thats what it is.....:-)

Been thinking about VAG COM as I also own a mk4 golf same year as the pick up.bit old school me but think its time I dragged myself into the 21st century........

Busy at work now , so will leave as is untill the re-test on saturday....thanjs for all your helpful replies.

[RicardoM]

Don't care -

That is why the car 'magic' products scam industry is still a multi billion $ one...

The only things one has to do is to not think, to not care, and to be proud of that.

[morrispaul]

Sorry for slow update, gone mad at work.........took the pick up back to the mot man on saturday, emissions were lower, most likely due to the plugs,but not staying consistently below the 0.2 pass mark...tried a few times and just about managed a pass...bit hit or miss though, would have much perfered a good stable , well below limits pass.but, mot'ed now which now gives me time to sort it out proper...will start by getting it to run at 90/95 degrees all the time, at the moment it hits 95 in traffic when the fan kicks in but as soon as iam moving its down to sub 70 degrees......40.6 mpg on my last tank full, including a long motorway run at 70 mph with the cataclean added, normaly I would expect 47 mpg at average speed of 55/60 mph on a run so probably about right.....

[RicardoM]

...but as soon as i am moving its down to sub 70 degrees.

1. How long is "as soon" ? Minutes? Seconds?
2. Please remind me if you replaced or at least tested the thermostat
3. Do you have any alternative means to check the temperature of the radiator hose?

[KenONeill]

morrispaul said "...but as soon as i am moving its down to sub 70 degrees."

1. How long is "as soon" ? Minutes? Seconds?
2. Please remind me if you replaced or at least tested the thermostat
3. Do you have any alternative means to check the temperature of the radiator hose?

Should this model have a radiator shroud as standard? If so, does this example?

 

I'm asking because I experienced the same issue when working on a different model, and removed the shroud whilst doing a cambelt change.

[RicardoM]

morrispaul said "...but as soon as i am moving its down to sub 70 degrees."

Should this model have a radiator shroud as standard? If so, does this example?

I'm asking because I experienced the same issue when working on a different model, and removed the shroud whilst doing a cambelt change.

First of all, I don't see why did you feel the need to quote my questions for Paul. Do you have any idea where I am pointong to?

 

Second, the radiator has a shroud, or better said a deflector. Removing it results in loss of cooling efficiency. In other words, in overheating. Paul describes a very unusual 'overcooling'. So what's your point? More theories not related to Felicia?

[KenONeill]

First of all, I don't see why did you feel the need to quote my questions for Paul. Do you have any idea where I am pointong to?

 

Second, the radiator has a shroud, or better said a deflector. Removing it results in loss of cooling efficiency. In other words, in overheating. Paul describes a very unusual 'overcooling'. So what's your point? More theories not related to Felicia?

OK, get off your high horse!

 

I asked if the radiator was supposed to have a shroud because, in my experience, removing a shroud can cause over-cooling!

[Breezy_Pete]

I would imagine (absence of) it could cause either. Loss of efficiency when the fan is running, increased efficiency when it isn't?

Edited 26 February, 2016 by Wino

[RicardoM]

The main role of a good radiator shroud is to ensure that all of the air entering the grille also passes through the radiator. If most of the air will flow around it instead of through it... the radiator will be less efficient. Hence overheating problems.

 

The 'overcooling' issue described by Paul is more likely to happen because:

• the thermostat is faulty (dangling around)
• the coolant temperature sensor is faulty

 

OK, get off your high horse!

That is wrong from somebody who knows very little about Skoda Felicia. You have no respect or consideration for those that might read your far fetched or just wrong answers. You should feel more responsible for every information you put online. Somebody might believe your theories and based on them could either lose time chasing red herrings or lose money buying unnecesary parts. In contrast with your Wikipedia-Haynes knowledge, I base my answers on countless hours spent repairing Felicias. I go to great lengths for accuracy & details of my answers and I don't mislead people.

Edited 26 February, 2016 by RicardoM

[morrispaul]

I changed the thermostat last year as it was running cold all the time, with the new one fitted it gets upto 95 degrees when on idle , after about 1/2 mile aprox 1 min its down to 70 degrees and stays there until I stop, where it takes about a minute to get back upto 95 degrees.cars not been touched in my ownership,110,000 miles with mostly origanal parts , well looked after by previous owner with full skoda service history upto 85,000 miles, not been bodged in any way, thsts why I bought it.....

I have a infa red tempture probe like the one in ricardos picture, parhaps next weekend I'll get out there and spend some time trying to see whats going on......thanks for your replies, most helpful

[RicardoM]

Yesterday I replaced the coolant temperature sender and thermostat as a whole to a 1.3 MPi Felicia having similar issues.

The part I used and the result are shown below.

 

 

[daverapid]

RicardoM, I see you used a genuine thermostat assembly. Are the genuine units the modified type with a circlip to secure the thermostat or is it the original design with the plastic tags that break?

[RicardoM]

Every genuine unit that I bought had a circlip. Only el cheapo ones have the plastic tags crappy design.

[mikefelicia]

Would you happen to know Is this a genuine VW Skoda part or el cheapo

 

 http://www.ebay.co.uk/itm/131738015074?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

 

I have asked the seller and waiting for reply.

[RicardoM]

The photos are generic. Some show blue collar temp. sensor (theoretically for cars with A/C), some show yellow collar temp. sensor. Asking the seller usually will not help either. He will promise you the moon. Unless he can provide an actual photo of the inside, you can't tell for sure. One other thing, make sure the unit comes with the o-ring for attaching to cylinder head.

[morrispaul]

Not had chance to look at this yet, had an advisory on the MOT , worn brake discs, replaced these at the weekend along with a set of new pads, old discs were well worn and possibly the origanals, brakes much better now, so how dose the car reward me.....by blowinganother coil pack............see coil pack thread............I'll get the coil problem sorted and then get back to the tempture problem......still look on the bright side, no chance of me getting bored......