Felicia 1.3 Cylinder Head Corrosion Around Coolant Ways

[areed]

Small update: 

 

Checked the car for fault codes this evening, and the following appeared:

 

 

Monday, 25 January 2016, 18:02:01

VAG-COM Version: Release 409.1-US

 

Control Module Part Number: 047 906 030 N

  Component and/or Version: SIMOS 2P           7014

           Software Coding: 00000

            Work Shop Code: WSC 00000

1 Fault Found:

00525 - Oxygen Sensor (G39)

        05-10 - Input Open - Intermittent

---------------------------------------------------------------------------

 

Either the sensor is faulty, or there is a broken wire somewhere.  I will have a closer inspection of the car later this week, to see if I can spot anything.

[RicardoM]

Here is the wiring you need to check.

 

[areed]

Thanks very much for the reply, sorry if I'm being a bit slow but could you check my understanding of the diagram?

 

I'm guessing that the numbers are pin numbers on the connectors, so I should find that:

• Pin 1 on the lambda sensor connector is connected to +12V 
• Pin 2 on the lambda sensor connector is connected to pin 27 on the ECU connector?
• Pin 3 on the lambda sensor connector is connected to pin 25 on the ECU connector?
• Pin 4 on the lambda sensor connector is connected to pin 26 on the ECU connector?
• Pins 3 and 4 have a shield connected to ground? Or perhaps pins 3 and 4 are connected to ground?

I've found the pin numbering for the lambda sensor in the service manual, and the control unit.  The control unit has two connectors, one with 52 pins and the other with less. I'm guessing that the connections on the diagram are for the 52 pin section, as they all start with "52/"?  Presumably, I should disconnect the battery before disconnecting the control unit to test these wires?

[RicardoM]

I'm guessing that the numbers are pin numbers on the connectors, so I should find that:

• Pin 1 on the lambda sensor connector is connected to +12V (key on)
• Pin 2 on the lambda sensor connector is connected to pin 27 on the ECU connector?
• Pin 3 on the lambda sensor connector is connected to pin 25 on the ECU connector?
• Pin 4 on the lambda sensor connector is connected to pin 26 on the ECU connector?

Yes to all above. Wiggle the wires while testing continuity. Spray WD40 on ECU connectors.

• Pins 3 and 4 have a shield connected to ground? Yes.

I've found the pin numbering for the lambda sensor in the service manual, and the control unit.  The control unit has two connectors, one with 52 pins and the other with less. I'm guessing that the connections on the diagram are for the 52 pin section, as they all start with "52/"? Yes. Presumably, I should disconnect the battery before disconnecting the control unit to test these wires? Yes.

[RicardoM]

This makes an interesting reading about error codes.

http://wiki.ross-tech.com/wiki/index.php/Category:Fault_Codes

[areed]

Thanks again for the replies! That link looks very handy indeed  I will get out the multimeter and test the wiring as soon as possible!

[RicardoM]

I don't want to anticipate anything, but look at this video too.

[areed]

Thanks for the video, very helpful for improving my understanding of what the sensor is/does.  Unfortunately I don't have a blowtorch, or a suitable area to test it like that really, so I hope very much it doesn't come to that!  

 

Anyway, here are the pictures of the spark plugs, from left to right when facing the engine:

One:

 

Two:

 

Three:

 

Four:

 

Written on the plugs is the following:  "NGK Iridium BKR6EIX", they were fitted new when I bought the car last August.  The car did a 140 mile journey on Sunday, and since then has only been started for a few seconds to move it within the car park the other day.  I will test the wiring later this week when I have some more time.  Do these pictures tell you anything useful?

 

I have an unrelated question too, if thats OK.  When I was driving on Sunday the car lost traction on a wet corner and hit the grass verge hard enough to crack one of the front alloy wheels.  When I replace the wheel, are there any components of the steering, suspension etc. that I should/can check for damage/adjustment?  I've given it a visual inspection and can't see anything obviously bent or broken, but don't really know what I'm looking for.

[RicardoM]

The spark plugs show a consistent very lean mixture. The oxygen sensor reports erroneously a rich condition and in turn the ECU cuts the fuel to injectors. The engine has not enough power in this situation. Did you try Motordiag Simos Manager v1.53 for resetting the TB?

Edited 27 January, 2016 by RicardoM

[RicardoM]

Hitting the grass verge should not crack the rim, unless a boulder was involved. The part designed to bend in such event is the inner tie rod. That usually will affect in turn the steering.

 

[RicardoM]

One other thing. The spark plugs you got are not for your engine.

 

The right spark plugs are these:

https://www.ngk.de/nc/en/product-finder/produktfinder/PKW/ZK_BENZINER/SKODA/FELICIA/BKUR5ET-10/13018/

Don't bother using Iridium blabla plugs.

[KenONeill]

One other thing. The spark plugs you got are not for your engine.

 

The right spark plugs are these:

https://www.ngk.de/nc/en/product-finder/produktfinder/PKW/ZK_BENZINER/SKODA/FELICIA/BKUR5ET-10/13018/

Don't bother using Iridium blabla plugs.

Agreed; Iridium plugs are for highly tuned turbocharged engines (think in terms of, say, 150bhp/litre).

[areed]

More progress today:

 

Went out this morning to test the cables, and this happened as I was moving the cable to attach my test probes:

 

 

 

From testing the Lambda sensor leads, I know that the brown and black wires connect to the heater inside the sensor.   The yellow and white wires have good connections to the ECU terminals, but I struggled to get a measurement for the resistance from the black wire to +12V (the battery terminal is quite dirty though, which probably didn't help.)  The broken wire has snapped off flush with the connector housing, which is a shame.  Do you know if it is possible to buy replacements of these connectors, with leads attached so that I can just replace the whole thing? 

 

A side note also, I think the lambda sensor pin numbering on the wiring diagram you provided is backwards.  Using the pin numbering in the service manual, it is wired as follows (or at least, it is wired like this in my car):

• pin 1 connects to ECU pin 26
• pin 2 connects to ECU pin 25
• pin 3 connects to ECU pin 27
• pin 4 connects to +12V

One other thing. The spark plugs you got are not for your engine.

 

The right spark plugs are these:

https://www.ngk.de/nc/en/product-finder/produktfinder/PKW/ZK_BENZINER/SKODA/FELICIA/BKUR5ET-10/13018/

Don't bother using Iridium blabla plugs.

 

Are you sure about this? Although those plugs have the right year for my car, they are listed as being for engine code "AMH".    These are my plugs, and although the year is wrong the engine code is "136M" which is what my car has.

 

 

Hitting the grass verge should not crack the rim, unless a boulder was involved. The part designed to bend in such event is the inner tie rod. That usually will affect in turn the steering.

 

I guess I was unlucky then, or there was a hidden rock or something:

 

 

From what I can see, the tie rod looks straight but I will have a better look when I replace the wheel.

[Breezy_Pete]

The 12V to the sensor heater is probably only there when ignition is switched on, I think. So you won't see continuity to battery positive, unless ignition is on.

It's usually possible, with some thin stiff wire(s) to extract the pins out of these connectors. If you can do that, you could solder the brown wire onto the back end of the pin.

 

Edit: The 'proper' pin extractor tools tend to look like this:

 

 

They go in from the mating side of the connector, down some holes, and defeat the retention latch(es) that hold the pins in. Then the pin can slide back out towards the wire-entry side.

Edited 30 January, 2016 by Wino

[areed]

The 12V to the sensor heater is probably only there when ignition is switched on, I think. So you won't see continuity to battery positive, unless ignition is on.

It's usually possible, with some thin stiff wire(s) to extract the pins out of these connectors. If you can do that, you could solder the brown wire onto the back end of the pin.

 

Edit: The 'proper' pin extractor tools tend to look like this:

 

 

They go in from the mating side of the connector, down some holes, and defeat the retention latch(es) that hold the pins in. Then the pin can slide back out towards the wire-entry side.

 

Thanks for the info!  I made myself some "extractor tools" from some old packing staples straightened out and filed down to fit:

 

 

I put one in the gaps on each side to release the barbs, then used the third to push the crimp back out of the connector. Worked like a charm

 

My plan is to solder a length of wire to this indoors, then join that to the brown wire using a terminal block as a temporary fix.  I don't have any way to use a soldering iron in the car park, so this will have to do until I next visit my parents where I can solder it up properly.

[Breezy_Pete]

You're welcome.

Free fixes make me smile.

[RicardoM]

Went out this morning to test the cables, and this happened as I was moving the cable to attach my test probes:

 

That has a bright side too. The source of error code has been found.

Note : an intermittent open circuit does not necessarily mean total loss of continuity. The ECU may interpret a higher resistance (above a certain threshold) as open circuit. A continuity test using a multimeter can be deceiving sometimes because a very low current is used. But when the nominal current passes a strand of wire... that's another story because Ohm's law bites us. That's why I do the 'wiggle test'. To check for mechanical strength of the wiring.

 

From testing the Lambda sensor leads, I know that the brown and black wires connect to the heater inside the sensor. 

 

Agree. The pair of white wires is usually for the heater circuit.

 

The yellow and white wires have good connections to the ECU terminals, but I struggled to get a measurement for the resistance from the black wire to +12V (the battery terminal is quite dirty though, which probably didn't help.)  The broken wire has snapped off flush with the connector housing, which is a shame.  Do you know if it is possible to buy replacements of these connectors, with leads attached so that I can just replace the whole thing? 

 

You are fortunate enough to have access to many shops like this where you can buy new connector pins. To build an excellent tool to release the pins you'll want to watch this video.

 

 

A side note also, I think the lambda sensor pin numbering on the wiring diagram you provided is backwards.  Using the pin numbering in the service manual, it is wired as follows (or at least, it is wired like this in my car):

• pin 1 connects to ECU pin 26
• pin 2 connects to ECU pin 25
• pin 3 connects to ECU pin 27
• pin 4 connects to +12V

I've checked all Skoda factory wirings for Felicia 1.3 MPI 136M and they show the same thing. Did you phisically check the connections from pins 1,2, and 3 to ECU connector? Could it be possible somebody swapped the pins inside connector at one time to match a third party oxygen sensor? What brand / code is the old one?

 

Are you sure about this? Although those plugs have the right year for my car, they are listed as being for engine code "AMH".    These are my plugs, and although the year is wrong the engine code is "136M" which is what my car has.

 

 Didn't you tell me your spark plugs (shown in previous 4 photos) are "NGK Iridium BKR6EIX" ?? By the way they look in those photos (thin central electrode) they are not BKR6ES...

[areed]

That's why I do the 'wiggle test'. To check for mechanical strength of the wiring.

 

When I previously tested the sensor, I did give the leads a wiggle but clearly I wasn't vigorous enough!  

 

 

You are fortunate enough to have access to many shops like this where you can buy new connector pins. To build an excellent tool to release the pins you'll want to watch this video.

 

This site looks very useful, do you happen to know what the crimps are for this sensor?  For now, I've soldered a length of wire to the old crimp:

 

 

I will refit this and test it this evening.

 

 

I've checked all Skoda factory wirings for Felicia 1.3 MPI 136M and they show the same thing. Did you phisically check the connections from pins 1,2, and 3 to ECU connector? Could it be possible somebody swapped the pins inside connector at one time to match a third party oxygen sensor? What brand / code is the old one?

 

Once I have refitted the repaired lead, I will re-test the wires and upload photos of the connections for you to double-check.  I am fairly confident that the old sensor was the original one, as it has the VW/Audi logo on it.  The part number is difficult to read, but I can clean it up and have a go if you like:

 

 

Didn't you tell me your spark plugs (shown in previous 4 photos) are "NGK Iridium BKR6EIX" ?? By the way they look in those photos (thin central electrode) they are not BKR6ES...

 

That's correct, mine are BKR6EIX.  The page I linked is for BKR6ES, which are listed as being correct for the 136M engine, and on this page my spark plugs are listed on the right as "an upgrade for even better driving performance" so they must surely also be for this engine type?

[RicardoM]

Why do you say the pin numbers of the lambda connector are reversed in my initial diagram? In fact they match perfectly your layout.

 
 

This site looks very useful, do you happen to know what the crimps are for this sensor?  For now, I've soldered a length of wire to the old crimp:
Sorry, no.
 
That's correct, mine are BKR6EIX.  The page I linked is for BKR6ES, which are listed as being correct for the 136M engine, and on this page my spark plugs are listed on the right as "an upgrade for even better driving performance" so they must surely also be for this engine type?
 
Do the following: go to NGK product Finder/.

Then under Vehicles click on Spark plugs for petrol engines.

Then enter Manufacturer:: SKODA and Model: FELICIA.

Now you'll see only one database entry that says AMH as engine code for cars up to 2001. Click on it and you'll land on my initial recommendation page that has 2 spark plug types: the well-known BKUR5ET-10 with 3 electrodes, and BKR5EIX-11 with Iridium blabla. I'll let you the pleasure of comparing BKR5EIX-11 with your BKR6EIX. I hope this clears the matter.

 

While you're messing with lambda sensor connector, I recommend this definitive test for sensor itself. Start the engine and after a while the voltage should vary between 0.1V - 0.9V. Do NOT switch the multimeter to 'Resistance' range!! while hooked to the sensor.

Edited 30 January, 2016 by RicardoM

[areed]

Why do you say the pin numbers of the lambda connector are reversed in my initial diagram? In fact they match perfectly your layout.

 

 

I meant that this numbering here is backwards compared to the diagram in the service manual, that's all:

 

 

 

Do the following: go to NGK product Finder/.

Then under Vehicles click on Spark plugs for petrol engines.

Then enter Manufacturer:: SKODA and Model: FELICIA.

 

Now you'll see only one database entry that says AMH as engine code for cars up to 2001. Click on it and you'll land on my initial recommendation page that has 2 spark plug types: the well-known BKUR5ET-10 with 3 electrodes, and BKR5EIX-11 with Iridium blabla. I'll let you the pleasure of comparing BKR5EIX-11 with your BKR6EIX. I hope this clears the matter.

 

Is AMH an alternative code for the 136M engine then?  Or is there a difference between the two? Though given that the 136M engine wasn't even made from '94-'96, I'm a bit mistrustful of their listings.

 

Anyway, if I do have the wrong spark plugs fitted what does this mean for the engine?  

[areed]

Good news! it looks like my patching of the wire has been successful.  I was logging the sensor output, and when the car had warmed up a bit it was varying within a range of ~0.06-0.6V.  The bad news is it looks like VAG-COM didn't save the file, so I can't show you guys what it looked like :(

 

I also tried to do the basic setting of the throttle body using VAG-COM, but it wouldn't play along.  Selecting that option would prompt a message stating that the program was unregistered, even though it said it was in the "About" section.  

[RicardoM]

I meant that this numbering here is backwards compared to the diagram in the service manual, that's all:

 

 

Yeah... I am well aware of that figure. The only problem is the edition of the manual (10.96) - see bottom left of that page. But that is all I've got in English from Skoda. I wish somebody else have the same generosity to share a newer edition in English... Until then, see how the figure has been corrected in newer editions written in German and Russian. Keep in mind that I try to do my best to not disinform anyone. I do mistakes too but unintentionally and if somebody corrects me I will be grateful for learning something new.

 

 

Is AMH an alternative code for the 136M engine then?  Or is there a difference between the two? Though given that the 136M engine wasn't even made from '94-'96, I'm a bit mistrustful of their listings.

 

Anyway, if I do have the wrong spark plugs fitted what does this mean for the engine?  

The short answer to the first question is 'yes'. While Skoda coded in-house all those engines made from 08.96 on as 136M , VW decided to standardize things according to their group coding. So now in their books there are two Skoda engine types coded AMH, both having the same power, but one made between 08.96 - 04.01, and the other between 01.98 - 08.01.

 

Regarding your second question, let's make things more interesting. Instead of spoonfeed you, why don't you give me your best guess?

[RicardoM]

I also tried to do the basic setting of the throttle body using VAG-COM, but it wouldn't play along.  Selecting that option would prompt a message stating that the program was unregistered, even though it said it was in the "About" section.  

Try reinstall VAG-COM.

Try using VCDS-Lite.

 

All Czechs use Motordiag Simos Manager v1.53. You didn't reply to my question about it.

[areed]

Yeah... I am well aware of that figure. The only problem is the edition of the manual (10.96) - see bottom left of that page. But that is all I've got in English from Skoda. I wish somebody else have the same generosity to share a newer edition in English... Until then, see how the figure has been corrected in newer editions written in German and Russian. Keep in mind that I try to do my best to not disinform anyone. I do mistakes too but unintentionally and if somebody corrects me I will be grateful for learning something new.

 

I stand corrected!  Wasn't pointing the numbering thing out as a criticism, just something I'd noticed and thought might help.

 

 

The short answer to the first question is 'yes'. While Skoda coded in-house all those engines made from 08.96 on as 136M , VW decided to standardize things according to their group coding. So now in their books there are two Skoda engine types coded AMH, both having the same power, but one made between 08.96 - 04.01, and the other between 01.98 - 08.01.

 

Regarding your second question, let's make things more interesting. Instead of spoonfeed you, why don't you give me your best guess?

 

Very confusing! I thought the M meant multi-point injection, guess it's not so clear-cut though.  

 

I would guess that having spark plugs with the wrong gaps/resistance would affect the ignition timing.  That said though, I would have expected something like that to show itself as something consistently wrong with the engine - though I'm not sure how such a thing would show.  Perhaps having the wrong plugs also puts undue stress on the ignition coil?

 

 

All Czechs use Motordiag Simos Manager v1.53. You didn't reply to my question about it.

 

Sorry, I did add it to the list of things to try, after testing the wiring and resetting the TB with VAG-COM.  I completely forgot about it while I was actually out in the car trying to get VAG-COM to work though. I will see about trying this tomorrow

[RicardoM]

I stand corrected!  Wasn't pointing the numbering thing out as a criticism, just something I'd noticed and thought might help.

No problem. I accept criticism as a form of progress in personal or professional life. I am counting on your observations. Curiosity and passion for your car could get you far.

 

Very confusing! I thought the M meant multi-point injection, guess it's not so clear-cut though.

M stands for Multipoint indeed in 135/136M engines, as B stands for Bosch in 135/136B engines. The latter are better known as 135/136BMM from Bosch Mono-Motronic.

 

I would guess that having spark plugs with the wrong gaps/resistance would affect the ignition timing.  That said though, I would have expected something like that to show itself as something consistently wrong with the engine - though I'm not sure how such a thing would show.  Perhaps having the wrong plugs also puts undue stress on the ignition coil?

You are partially correct. It is all about the quality of combustion in the end. A weak spark means unburnt air/fuel mixture. That in turn makes the oxygen sensor report a rich mixture. The ECU then cuts fuel to injectors resulting in a lean mixture which is again hard to ignite by a weak spark. The engine does not develop enough power and runs hotter putting more stress on valves. That is shown consistent enough on all your spark plugs.

 

If you want to know a little bit more on lost science of reading the spark plugs, see http://www.4secondsflat.com/Spark_plug_reading.html

Edited 31 January, 2016 by RicardoM