1998 Felicia Diesel problems

[kata999]

Hello! I have a problem with my Felicia. It first started this autumn when the temperatures dropped. It starts ok even when it is very cold outside but it fails to stay on, if i dont keep my foot on acceleration pedal it dyes. It makes a lot of white smoke too. When is not that cold outside it works fine.

Some other problem that i discovered recently is that it overheats. Checked the fuses and the relay, all ok.

Also, this winter in a very cold morning the rev counter failed to work, it start, got up to 3000 rpm then felt to 0 and since then it doesent move at all. Any ideeas are wellcome. Catalin.

[RicardoM]

If you are 100% sure the 'white smoke' is not normal condensation, that indicates the presence of coolant in combustion chamber. Usually that is associated with a bad head gasket, a bad seal under cylinder linings or any other crack between coolant passages and combustion chamber. Do you have coolant level dropping in time? Even a very small level drop counts. Overheating is a direct consequence.

 

The rpm meter stopped working because there is:

• a cold solder joint or a very fine crack on the PCB of instrument cluster.
• an open circuit between the rpm sensing wire on the alternator and instrument cluster

Any other info about car history of maintenance, repair, operation might help.

[TeflonTom]

Head gasket is a good call, but it wouldn't be where i would look first, these dont often go pop unless you cook them up good and hot. white smoke on a diesel engine is normally caused by raw unburnt diesel fuel coming through to thd exhaust system.

i would start with the basics, drain any water from the tap on the bottom of the fuel filter, or better still just put a new one in, very cold weather forms lots of condensation in the tank and sometimes gelling of the fuel which can choke the filter, you could try wrapping something round the filter to stop it getting so cold

overheating could just be a sticky thermostat

[kata999]

Thank you RicardoM, but that is not condensation becouse it have a heavy diesel smell, and it is present only on cold mornings for a few minutes, exacly in that time that i need to keep the gas pedal so the engine doesent stop. Coolant level is the same. Last summer when temperatures were higher then now it didint overheat and the blower was working, now i didint heard that ventilator run. I will check out if it works later.

Teflon Tom, i had some issuses with the thermostat, was stuck open (still is). I'm planning some repairs next week and i will replace the thermostat, but there is anything else that i need to check about that overheating problem?

[kata999]

Hey, i'm back! Just checked up that fan working issue, it figures up it comes from the thermoswich... not working. I took off the dashboard, checked for cracks, cold solder joints and the wire from alternator to instrument cluster. The wire is ok, no signs of craks on the pcb lines, no cold solders, measured the coil of the tachometer and is not intrerupted. Any ideeas?

Does anybody have some electrical schematics of the dashboard instruments? I'm not that good at reverse engeneering to draw a schematic backwards from a pcb.

Edited 26 April, 2015 by kata999

[RicardoM]

i had some issuses with the thermostat, was stuck open (still is). I'm planning some repairs next week and i will replace the thermostat, but there is anything else that i need to check about that overheating problem?

A Diesel engine that overheats with the thermostat stuck open will obviously still overheat with a brand new thermostat. From your information I don't see any other reason for overheating but a tiny passage (crack) between combustion chamber and cooling system. The crack may be too small for coolant level to drop, but enough to overheat. Unless you forgot to tell us other symptoms, this is my explanation.

 

I've repaired 7-8 dashboard PCBs with similar issues. The copper tracks are very thin and crack from age and vibration. What may look a continuous track or a good solder joint when measured with an ohmmeter, will change to open circuit if the board is slightly bend. Start from pin 7 of yellow connector all the way to the gauge. Use a good soldering station and tin to resolder the joints. Check also with a multimeter on AC voltage scale (or oscilloscope) if you get signal from alternator on pin y (yellow or green wire).

[kata999]

The overheating problem was becouse the fan doesent start. I will replace the thermoswich tomorow. I measured that circuit with an multimeter set on continuity, there is no intrerupted tracks.

[RicardoM]

The overheating problem was becouse the fan doesent start. I will replace the thermoswich tomorow.

From my understanding, Diesel engines run colder than petrol engines. I find hard to accept you need even 1st speed of the radiator fan working in cold weather as described by you, moreover with a thermostat stuck open. So before blaming the fan thermoswitch for overheating, ask yourself if it is normal for the engine to heat so much that radiator fan should kick in. My car is on petrol and the fan kicks in only if there are 20 C outside... Is that cold?

 

Take high resolution photos of the PCB (front and back) and I will show you where I found most often problems.

I suggest you take at least 3 photos of the back and 3 photos of the front (left side, middle part, right side). Lighting and focus are very important so that PCB tracks are clearly visible. You must understand that if you insist that you have rpm signal from alternator, you have tracks continuity, and you have good gauge, then tachometer should work. We're not talking about a mystery, it is basic electronics.

 

This is how a good photo should look like.

 

Edited 26 April, 2015 by RicardoM

[kata999]

Thank you RichardoM. You missunderstood me about the heating problem. I have that thermostat stuck open since last autumn, that is not what makes the engine overheat, now is warmer outside ( winter time i didnt had any overheating problems, it actualy never passed 80°C). I checked the fan and it works if i close the circuit like that thermoswich should do, put a wire between the red wire and blue/black wire at the thermoswich socket. Now water can get over 90°C and the fan doesent kick in. Anyways, i will fix this by replacing the thermoswich. Thank you for that photo, i will try to check again those lines for the tachometer.

Another problem: this winter when it was cold outside, engine stated normaly, but i had to keep the gas pedal on, if i took my foot of it, the engine stopped. What can i check there?

[RicardoM]

Another problem: this winter when it was cold outside, engine stated normaly, but i had to keep the gas pedal on, if i took my foot of it, the engine stopped. What can i check there?

TeflonTom gave you a very good answer. He has a Felicia Diesel too and he knows those engines inside out.

 

 Thank you for that photo, i will try to check again those lines for the tachometer.

The photo is just an example for reverse engineering the PCB. Skoda fitted 12 (twelve!) types of dashboards on Felicia depending on engine type (135, 135/6B, 135/6M, AEE, AEF), year of manufacture ('94-'96, '96-'98, '98-'01) and extra-options (LX, GLX). The photo happens to be from a '96 136B GLX Felicia. Your dashboard will be slightly different, but nevertheless the electronic diagnosis is the same. Basically rpm impulses from ECU (135/6B, 135/6M, and AEE engines), alternator (AEF engines) or ignition coil (135 engines) get at pin 7 of PCB yellow connector, then the impulses are reduced in amplitude to about 3 Volt pp and they feed the input (pin 13) of a custom IC made by ITT (KEFB-842) that drives the gauge as in the image below.

 

Edited 26 April, 2015 by RicardoM

[kata999]

Hey! Mine is AEF engine, 1998 moddel, LX if this is any help. Il check out again that part of the dashboard, also i'l re-check the wire that cames from the alternator. The schematic of the KEFB842 is very usefull, searched the internet all over for a datasheet, but none...

[KenONeill]

The white smoke on a cold start is almost certainly an indication of failed glow plugs and/or a failed preheat control box. The glow plugs can be checked with a multimeter, or by removing them and seeing if they heat up, in principle. However, I've mentioned the preheat controller, and I don't know how to check that on a Fellie.

[RicardoM]

The schematic of the KEFB842 is very usefull, searched the internet all over for a datasheet, but none...

The German manufacturer of Felicia instrument cluster (VDO) has no intention to make the schematics public (not that it can't be reverse engineered). But I happen to bump into one of VDO designers on an electronic engineering forum and he was kind enough to share the datasheet. By the way, worst case scenario in case all tracks are good (there is signal at pin 13), and V_DD is present at pin 1... you have a dead IC. I had one PCB on my workbench with a dead IC. But you can find a second hand instrument cluster locally.

 

Is the instrument cluster original from factory? Or did you retrofit it from a GLX car?

Edited 27 April, 2015 by RicardoM

[kata999]

I just finished checking all tracks again, all good. Replaced the oscilating crystal with another one, no change. Even worse, now evrything has gone crazy. All signals are messed up. When i start the engine it showes front fog lights running ( i dont have instaled fog lights), tachometer still doesent work, but now nothing works...

I dont know if the car was equiped with this dashboard from factory, i brought it last year. It says it is LX moddel, all extras are tachometer, digital clock and power steering. Doesent even have central locking

I'm try to search for another dashboard and replace it tomorow afternoon.

Edited 27 April, 2015 by kata999

[kata999]

Back on the begening... fixed that fake signals on the dashboard. Tachometer still doesent work. I'l replace the dashboard. Thank you for all your answers and advices. Catalin

[RicardoM]

Don't give up just yet! Try one last thing before quitting. At this point you have nothing to lose. Look at photo below. FILL with fresh tin and flux around each of 3 vertical stubs (you know, nice concave flow soldering). They are notorious places for cracks. Don't assume they have continuity, when you fit in the gauge the cracks spread. You need to resolder too the tracks shown in cyan. I had to use small pieces of insulated wire. Yeah, I know, it may look overkill and ugly but it worked for me. Solder those wires at least temporary for a test. Solder directly from IC pins to each stub, tin to tin. The idea is to avoid 'copper' tracks. They are garbage, trust me. In fact you saw what happens when you just plug / unplug the connectors to PCB, weird things show up. In fact resolder each pin of yellow connector too.

 

NOTE: those who experience rpm meter needle jumping, this is why.

 

If you don't want to test it on the car you can use a signal generator at pin 7 of yellow connector, output voltage 10Vpp. Of course you need 12 V supply at pin 2 (+) and pin 10 (-) of the same 10-pin yellow connector. Remember the gauge will show only half of input frequency because of CD4040 counter (divider by 2). The alternator feeds 2 impulses / revolution. Good luck!

 

PS Very nice photos you did. If you have more photos please post them. We don't see PCBs from Felicia Diesel in here.

 

Edited 27 April, 2015 by RicardoM

[kata999]

Thank you Ricardo. I will take some more photos this week and i will place some wires there. Problem with fake signals was from an imperfect conection at a socket.

[RicardoM]

Thank you Ricardo. I will take some more photos this week

Don't forget to remove the digital clock case because it obscures part of PCB tracks.

[kata999]

Don't forget to remove the digital clock case because it obscures part of PCB tracks.

I will remuve it, i have'nt had any free time to deal with it, probably i'l have this weekend.

[RicardoM]

No problem, Catalin. Enjoy May 1^st holiday.

[RicardoM]

One more thing you might try is to resolder the terminal marked in the photo below. I usually do that when the needle jumps erratically.

 

 

I repaired in a similar manner non working temperature and fuel gauges.

 

Edited 5 May, 2015 by RicardoM

[kata999]

Hey! I'm back

I managed to fix that rev counter, It was a problem with the socket... Anyways, replaced the water temperature sensor, now the preheating system works only when water is cold, but now the temp gauge doesent move from 60°C. I will replace the thermostat this week when i get some time, maybe that way will work.

Another question, did anybody tryed to put a sport exhaust on Fely? I mean on diesel Felicia, and not all the exhaust, only the final part... I dont look for power and all that, just some sound and design.

I will stat some body work next month and i was wondring if thouse bumpers can be modified to make them a bit longer and clean look... i'l add some photos to let you know what i'm talking...

Another thing, what sport suspension will fit? I searched for a dedicated suspension for this car but i can not find any at here ( Roumania)... I thought to cut a few cm from the original springs? that will lower it, but not sure if is ok...

Edited 23 May, 2015 by kata999

[RicardoM]

Another question, did anybody tryed to put a sport exhaust on Fely?

A sport exhaust on a diesel? What, you want to cover the little tractor sound of the engine?

Sorry, it is too funny. Equally funny as painting racing stripes on a car hoping to get 10 extra HP.

[KenONeill]

Love the Eurostyle crossing with some JDM influence in the skirts.

[kata999]

Lol Ricardo, i want sound, no extra bhp... Lost my faith in Tooth Fairy ;-)

I was just curious about the sound, If somebody put a sport exhaustor on a diesel felicia.