SilverBKY

I have just had a character building experience with my Polo 1.4 16V Auto with a petrol BKY engine, I know it is not a Skoda but is a close cousin and I’ve found this forum handy in the past. (So I write Seat / Skoda / VW in the text to enable a search to catch this). I am posting it as it may help someone else and to make it searchable so others may be helped. Situation is that it was being used and just would not start, not a specially cold day. It has done this twice before and mysteriously springs back into life. This time it took 2.5 weeks to get going this time. This is what happened. I know that to get an engine going you need : spark + fuel + cam timing + etc. 1. When I sprayed Easy Start down the throttle body it did not start. As Easy Start replaces the petrol this ruled out a fuel issue. 2. The cam timing was easily checked by pulling off the cam cover and observing the movement of the cams and their markings whilst a long screwdriver was being pushed up and down by poking it down a spark plug hole (which on this engine is vertically above and inline with the piston stroke). I used a spanner on the big cam wheel nut to turn the engine gently. 3. I pulled a coil out and put a spark plug in the end, then using a large crocodile clip grounded the thread of the spark plug. When I cranked the engine there was a yellow/orange spark. An internet evening told me that yellow/orange is a weak spark which can be quenched by fuel and a blue spark is required. So I’m loosing voltage somewhere. 4. I got 4 second hand coils. Put them in – no difference. 5. Cleaned all the earthing points that I could find, there are a few. – no difference. 6. I tested a coil on the engine as before – no spark at all. 7. I figured out the coil wiring on the car (which is not like I found on the internet) There are 4 wires. Starting at the square end of the connector a. Brown – Ground b. Brown / Yellow – Gound locally on the cam cover. c. Purple – Ignition permanent positive. d. Thin coloured wire – Pulse from the ECU to trigger the coil and hence the spark. 8. I tested a coil pack on the bench by connecting the first 3 wires to a battery, grounding the spark plug using the croc clip. When I dabbed the pulse wire onto the battery a nice blue spark. So at least one coil is good. 9. Then I changed all sorts thinking the ECU was not working or getting a signal from a sensor. 10. I had observed on VCDS that the crank speed was about 200 RPM using the crank sensor. 11. Finally the battery was charged for many hours and after cranking and then full throttle and cranking (which stops fuel injection and thus dries the engine a little) it spluttered into life and has not looked back. 12. CONCLUSION – THE BATTERY WAS LOW. It now cranks a lot quicker and starts easily. I hope that this helps someone as there are a lot of cranking and no start posts out there. RRegards, John

I thought that I would update you on this as I have fixed the car. As discussed above I bought an exhaust pipe front to back so 3 bits, the single catalyst front section and the 2 silencer sections for the rear end. All purchased and delivered for a remarkable £182. They were fitted and the car drives nicely now. The forensic examination of the exhaust showed that the centre catalyst was clean and solid whereas the front catalyst was partly blocked as can be seen on the photo. It is clean on the downstream side. The new exhaust pipe information sheet indicated that this is possibly due to incorrect fuel or poor running. Well it does burn a little oil, but only a little. Attached is a photo of the top of the front cat through the hole it bolts onto the manifold. I am pretty sure that this part blocked catalyst prevented full revs and confused the engine management unit as the inlet manifold pressure sensor and throttle body positions were way different to the map in the ECU. Thank you for your help and advice and if anyone else has such an issue they can shortcut to the solution.

Interesting, you are right I have had a look and I have not found a twin cat pipe. Can I fit a single cat pipe to the car? If I am off line for several days Christmas has got in the way.

Thanks for the link, I swapped the throttle body early on and it made no difference so I think cleaning the throttle body as that person seems to have done to fix their car I do not think will fix mine, but I can give it spray anyway, I have nothing to lose. As you may imagine I have been thinking about this, does anyone have the throttle body % opening figures for when the engine is idling and warm. My results last night are as below and the pressure is less vacuum than previous forum discussion at this address. www.briskoda.net/forums/topic/456368-intake-air-leak VCDS Block 003 680rpm, 373Mbar, 13.7% Throttle Drive, 3deg Ign VCDS Block 033 3% Lambda Control (Fuel Trim), 0.444V Oxygen Sensor (Lambda) I have suspected the exhaust catalyst is blocked hence drastically reducing the power and unable to rev it due to exhaust flow rate. This would explain 2 things. 1. why the fuel trim is all wrong at higher revs as the ECU is encountering an unmapped exhaust restriction so to keep the lambda at 0.45V has to back off the fuelling. 2. the pressure is high when idling as the throttle body has to be more open than it ideally should be to overcome the exhaust back pressure. With 90K and 17 years on what looks like the original exhaust system it may be on borrowed time. How is my logic or am I getting excited for a solution again ?????? John

Good evening. I have taken the inlet manifold off, which was amazingly easy. The head o-rings seals were hard and old but I am desperate so I using Loctite gasket paste both in the groove in the plastic, with the old seal in there and on the surface against the head and carefully put it back on. I arranged blocks for all the pipes from the EVAP valve, the PCV and the servo, i.e. blocked the holes in the inlet manifold and started it up. after a process of elimination it appears that the fat pipe from the PCV valve (low on back of crankcase) sends the trim over 10%. having blocked both pipe coming from the PCV and the hole in the inlet manifold and warming up it gave. 697 rpm, 375mBar. with -2.0% trim and 0.44V on the lambda. So quite an improvement on yesterday. So my hopes were up and a test drive..... which was disappointing, when you are trying to accelerate the trimming leans the mixture giving 2268 rpm, 975 mBar with -17% trim and 0.44V on the lambda (the lambda does move about abit and during warm up gives a result of more than a volt which I presume is the heating phase). I am convinced that this leaning off is causing the performance issue. Any ideas of the next step ? Please. John

No EGR on this BKY, it appears that some do. I had a look having read some of this Forum.

Hello Pete and others. I have had the VCDS plugged in and run the engine after warming up and a quick blip on the throttle it settled into this state. My impression is -the Lambda is about right at 0.44V, I understand the desired Stoichiometric is 0.45V. -idle speed is good. -the inlet manifold pressure is 433mBar and is rather higher than the 300mBar I see on a different thread I caught on this forum. I swapped the MAP sensor for another and it is exactly the same and with the engine running reads high 900's which is atmospheric. So all sounds good with the sensor if not the result. -the Bank 1 Lambda Control of -10% means that the ECU is trimming the injection low to keep the lambda at close to 0.44V -the throttle drive at 13.7% no idea. With the engine running I tried wafting an unlit blow torch around to see it it would pick up any air leaks apart from finding that lambda control value drops to about -40% when playing on the throttle body it showed nothing. I tried pulling the brake servo pipe off the moulding below the throttle body and blocking the hole, no effect. Like the earlier message above from Pete it appears to be an air leak in the inlet tract but can I find it...... Any ideas ? Thanks John

But wouldn't they affect the low speed running rather than the full throttle ? I've had a good look at those pipes and they look OK. Pulling that servo pipe off looks potentially terminal with snapping of bits of plastic a danger. There is a crankcase breather pipe around the back there. Is the EVAP valve the little one with a wire going to it on the drivers side strut top ? the PCV the crank breather ? I realise that i have omitted the key info that it starts and idles perfectly.

It has to be something like that doesn't it. If I pull the servo pipe off under the throttle body and block it up then that whole system will be out of the equation.

Thank you Pete. I have just been out and looked at that pipe, it has a junction 1/2 way along which goes off to the air filter. It looks good and I wriggled it with the engine running which caused not even a fluctuation in the revs. The connection of that pipe to the air filter was not super secure but I tried to improve that which I think I have but sadly with no affect. Any other ideas, I'll try anything. (within reason).

I need some help. I know its not a Skoda but its the same family and this Forum seems helpful. I have a Polo 1.4 16V Auto with a BKY engine and 90K on the clock which was running fine until it started losing power and revving alot before changing gear (it has a old style torque converter gearbox). Now it will not rev above 3500 in or out of gear and on the last drive would not manage over 50mpg on the flat. It is running lean as the plugs were white and the pre cat lambda sensor was also white. The symptoms as now very consistent although its degrading to this state was gradual So far I have changed Auto Gearbox oil as I though this may be the reason for over revving. No change. Fuel Filter. No change. Throttle Body. No change. MAP sensor. No change. In tank fuel pump. No change. Spark Plugs. Observed to be white. No change. Pre Cat Lambda sensor. No change. I have a VCDS and it had codes (which I have left in) 16804 - Catalyst System: Bank 1 P0420 - 35-00 _ Efficiency Below Threshold 17550 - Load Calculation Cross Check P1142 -35-10 Lower Limit Exceeded - Intermittent 16517 - Oxygen (Lambda) Sensor B1 S1 P0133 - 35_00 Response too slow 18049 - Please check DTC Memory of AC controler P1641 - 35-00 - Any ideas ? I am really struggling with this , the clue HAS to be the white plugs which is lean fuelling but why ???? John