Hi fellas,

 

I've got a new issue with my 1.4 mpi 8v engine. In the morning or when leaving work, whenever the engine is cold, the starter motor cranks the engine, but it doesn't want to fire it up. Once started, I need to keep my foot on the accelerator to keep the revs over 1000 rpm, otherwise the engine will stall. Once the engine is warm, it starts flawlessly. There are no fault codes logged, other than the usual o2 probes failing. This morning I've noticed something not usual. After I've arrived at work, after less than 3 miles driven, both radiator fans were running at full speed, even if outside were 0C and the engine wasn't that hot. I've placed my hand on the expansion tank and it wasn't over 40-50 C. The instruments panel coolant temp gauge was in the middle, as it should've been, at 90C. I've left my engine idle for like 3 minutes and the fans kept spinning. I had to turn it off not to get late to work. The engine pulls fine, mpg is not out of the ordinary, it's still able to do 90 on the motorway, it can go up to 4000 and over rpm (I'm trying not to pass that figure though). 

The engine is not misfiring, runs all it's 4 cylinders and it's got plenty of go go juice once it's started.

Have you ever encountered this problem ?

Edited 7 December, 201510 yr by Alexandru

Coolant temp sensor?

G62? Working fine IMHO..is there another one ?

Evap valve?

On a VCDS scan, it shows fault codes 16514 - P0130 - 35-00 followed by 17511 P1103 - 35-10, which are related to O2 sensors only...nothing more, nothing less.

Cts may be on its way but not enough to flag an error. Look at the temp its reading on vcds when car is stone cold

Which block should I check ? It's brand new, you are talking about the G62 sensor, correct? 

Edited 7 December, 201510 yr by Alexandru

Urrrm, in engine, keep going until you find a block saying coolant temp, block 7? Iirc. Should read a reading that's consistent with the outside temperature at the time, providing engine is full cold

Urrrm, in engine, keep going until you find a block saying coolant temp, block 7? Iirc. Should read a reading that's consistent with the outside temperature at the time, providing engine is full cold

FWIW I have no idea what block to look at, but this was my thought too; either the CTS is failing to read a correct cold temperature, or the cold enrichment is not operating correctly.

Isn't P0130 the pre-cat one? Don't think that will help the running, surely that will make it harder for the ECU to get mixture right?

Probably way off the mark here, but have you checked battery voltage and also your coolant mixture (you mentioned 0C, water's freezing point). Bearing in mind that if its really cold when you check battery the reading will be off.

Edited 7 December, 201510 yr by wiredsoftware

I've checked the battery after driving a while. 12.8 with the engine off, drops to 8 to 10 when cranking with the headlights on and 13.8 with the engine running.

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Battery seems ok then.

Does it really need to be over 14V and under 14.8V when running ? I've parked the car, locked it and disconnected the battery terminals. I'll see how it starts in the morning. I don't think it's a bad battery though. First of all. it's cranking pretty good. Second of all, once started, why does it stall ? It's not an immo issue. When it's cranking, I can hear it how it wants to fire..but it doesn't.

I tried to plant my foot on the accelerator pedal as well, but nothing changed. Tried to pump it as well, keep it half way pressed ..

First time when turning the engine..nothing happens. I can keep it for a few seconds to turn .. nada. At a second try .. it tries to start...but no actual success. Only at third / fourth time ... it starts, but I need to keep it over 1500 for a few seconds (10 - 20 seconds, not more). After this, it idles at 800. Shouldn't it idle at >900rpm since there were 0C outside?

Edited 7 December, 201510 yr by Alexandru

Well it's not a bad reading, and it is winter where batteries work less efficiently.

Maybe replace that O2 sensor as you need to anyway, and as mentioned above the crank position sensor could be on the way out, which would also make it hard to start.

Edited 7 December, 201510 yr by wiredsoftware

G62? Working fine IMHO..is there another one ?

Are you sure?

 

Sounds like possible coolant sensor to me?

Thank you, wiredsoftware! Do you know how can I test that crank position sensor ? Is there a measuring data field in VCDS ? 

Sorry, not a VCDS expert :/ If it helps, I unearthed another thread with similar symptoms to you that seems to be CPS, http://www.briskoda.net/forums/topic/216024-fabia-mpi-wont-start/ 

 

Edit: Another one here too: http://www.briskoda.net/forums/topic/293692-fabia-mpi-14-power-loss/

 

Another edit: CPS (also known by Skoda as "engine speed sensor") is located in the transmission bell-housing.

Edited 8 December, 201510 yr by wiredsoftware

If it would be a faulty G28 sensor, shouldn't it spit an error related to it? Just saying..

Later edit: there are 2 engine speed related sensor:

1. G28 - Engine speed sender (gearbox housing)

2. G163 - Camshaft position sensor (cylinder block) 

 

I think you are talking about the last one or am I wrong ?
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Edited 8 December, 201510 yr by Alexandru

I'm talking G28 which would be at the bottom/crank end of the engine rather than the top/cam end, although you may well have similar problems if the other one was faulty...

 

As with all sensors, they *should* fail a certain way, but failure is unpredictable... I appreciate it's frustrating to not be able to identify a problem with certainty, changing parts until it works can get expensive.

Which sensor should detect the engine is cold and that it should raise the idle ?

Which sensor should detect the engine is cold and that it should raise the idle ?

I'll say it again. COOLANT TEMPERATURE SENSOR!

The g62 sensor has 4 pins. Two for the dashboard guage and two for the ecu. The dash may still look to be working fine but ecu getting incorrect temperature. When engine is cold check coolant temperature in vcds. Any inconsistencies and theres your problem

G62. Only 2-pin on a 2000 ATZ as far as I can see.

Edited 9 December, 201510 yr by Wino

There are 2 temp sensors as far as I know, one for the dashboard and one for the ECU...please correct me if I'm wrong...but I'm trying to find the second one.

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No, same one does both.

There are 2 temp sensors as far as I know, one for the dashboard and one for the ECU...please correct me if I'm wrong...but I'm trying to find the second one.

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No, same one does both.

Both sort of right; there are 2 sensors, but they're both physically in the same Line Replacement Unit.

 

So you can get a situation where one (usually for the gauge) works right and the other doesn't.