Rudi

One thing that is different - I don't think my car ever goes into limp mode. I've had previous cars do that, and I've not had anything like it with the Octy - it just dies on me. Also, wouldn't / shouldn't limp mode throw up a fault code? I'm clutching at straws here but the gradual return to startup that I had with the car in my drive this evening made me think of fuel starvation. Running the engine at 2k rpm for a minute or so made the engine die. The engine then tried to restart on the starter motor, and got better at it the longer I waited between attempts (and the gaps weren't long: initially maybe 5 seconds <cough, splutter ...dies>, wait maybe 15 seconds <cough, slow 'n low feeble turnover for a second, splutter ...dies>, wait maybe half a minute <cough, slow feeble turnover for a few seconds, splutter ...dies>, and a successful restart after waiting maybe 45 seconds). I'm minded to change the fuel filter and put some fuel additive / cleaner in (I bought some strong stuff that was highly recommended elsewhere...). If something, somewhere, is gummed up and impeding the flow of fuel, this might help...🤞

@Looby2411 So.... it took a week to get the coolant temp sensor, replaced it today and the car started and ran like a dream. I was v. cautious, took it round the block several times at first - engine warmed up but no sign of the slightly rough idle and no stalls, etc. So took it on a longer run around the houses and onto the nearby dual carriageway. Car felt that little bit more 'willing' to make progress than previously and I pulled over, stopped it, waited ten mins (simulating the 'quick visit to supermarket' scenario) and started it several times - no problems. I also tried to reproduce the randomly increasing revs when I tried to hold the accelerator at 2000 rpm while parked up, and the climbing revs didn't happen - all very comforting. After 18 miles of this (in three sessions, morning afternoon and evening) I thought the car deserved a top-up as the fuel was getting low. Took it to the local Sainsbury's as they have premium E5 fuel. Paid for fuel, went back to car ....and it wouldn't start. I won't tell you what language I used. Sat on the forecourt like a lemon for five minutes with the car steadfastly refusing to start, then went into the reception to explain why I wasn't moving. I said it could take 15-20 minutes before it started. Went out again and - it started first time, of course. Drove home (ca. 10 minutes) without a problem. Got home and thought I'd see if the 2k rpm revs issue had returned too. It hadn't, but after about 30 seconds of holding the revs at 2k, the engine simply died. Then it wouldn't start again, but this time it was different: the engine would turn over - maybe only for a fraction of a second, but the longer I waited between attempts the restart, the longer the engine turned over for, before dying again. Eventually, it restarted completely. Is there such a thing as demonic possession for cars? If so, does anyone know a good car exorcist..?

Ooooh @Looby2411 well done! I'll do likewise here with my reluctant Octy and report back. Cross everything....

So... not long after your post @Looby2411 I unlocked the car with my key fob and then opened the driver's door and listened. Perfectly audible zzzzzzz-ing came from somewhere near the rear wheel arch, lasted maybe 3 seconds then stopped. Is that the fuel pump priming? Car started fine. Ran it round the block a couple of times (= maybe 1.5 miles) parked up in the drive, stopped the engine, got out, locked the door via key fob, waited a minute or so, then unlocked, and opened drivers door again. No zzzzz-ing, but car started fine. Suspect the pump, having primed the fuel line once, didn't need to do it again so soon after a short run. Tried again after a couple of hours and still no zzzzzz noise, and still car started OK. The car then hasn't turned a wheel for almost two weeks, so I repeated the same experiment today: got the zzzzzz-ing noise first time around, ran the car round the block a few times (= 3 miles-ish) until it had warmed up, stopped, got out, locked door, waited a few mins then reopened. No zzzzzzz noise, but car started OK again. During the 3 mile run the car seemed, as usual, to lose it's initial willingess to accelerate 'briskly' and I am sure had I carried on it would eventually have cut out, again, as usual. Went back to the car 15 mins later: no zzzzzz noise but started fine. So I think all this rules out for me is any problem with the fuel line priming function, which only seems necessary after prolonged inactivity anyway...? 😐

I'm sadly old enough to remember when power steering was a mechanical/hydraulic process so the engine had to be running for it to work, but these days I think modern cars use an electronic system? If the power steering is faulty I think that would only become apparent (on the dashboard) after the engine had started and the steering wheel symbol stays illuminated, but I'm not sure if we can therefore conclude that the power steering is 'off' until the engine is started. But certainly, when my car stalls the steering becomes really heavy immediately, which implies there's no power getting to the power steering module when the engine isn't running, even if the ignition is on.

Thanks for the update @Looby2411 - listening for the pump priming isn't something I'd thought to do. Not sure if I'm putting 2 and 2 together and making 5, but I've just recalled that I there was a smell of petrol that I pointed out to Skoda about five years ago and they replaced the fuel filter, but I'm now wondering if if was symptomatic of something more fundamental with the fuel system, as the troubles started (very, very intermittently) around that time.... I also note @bigjohn's comment above. I'll have a go at 'listening' for the pump over the weekend and report back.

@Looby2411: this sounds similar, if not quite identical, to the problem for me about a year ago. It has since become more frequent to the point where the car is undriveable. Interestingly, I have only noticed the over-revving when I have warmed the engine up on the driveway and then tried to hold the revs at about 2,000 rpm. With the pedal perfectly still, the revs climb to between 4,000 and 5,000 rpm for no apparent reason. Inevitably, it doesn't do this consistently though. Unfortunately, if your MPI follows my one, your problem will only get worse 😞. What's the mileage on your Octavia?

Thanks stevenc, much appreciated.

Thanks, rojbe. I think the biggest difference is that my MPI 'usually' starts from cold OK (but, admittedly, not always...) and the problems of slightly rough idle, engine dying, and difficulty re-starting, generally appear when the engine is up to normal running temperature. But I did wonder about the pre-cat lambda sensor because that was the only error code apparent when this problem first started (the mechanics wiped the code and it hasn't reappeared, but then again there are no other codes appearing either...). Thanks for your input!

Thanks for the responses. Since I first posted, I have (on the advice of a friend) disconnected the battery for almost 48 h. Reconnected it, took it for a run and after ca. 3 miles the car died and wouldn't start, although on this occasion it only took about five minutes before it decided it would start again (whereupon I drove it home - about a half mile - parked it on the drive, stopped it, and restarted it again three times with no problem). Still no error lights or codes. So basically no further forward. There seems to be 101 different possible explanations, and without any error codes or 'terminal' breakdowns to work on it seems like it's all really guesswork, so I'm trying to nail the most likely (or easiest/cheapest to fix) causes first. So..... @stevenc : according to workshop-manuals.com, I've got four relays in the engine bay fuse and relay box but a search for the position of the "main relay in the ignition circuit" doesn't throw up any info. Don't suppose you recall where the one you replaced was..? Cheers.

Anyone.....? 🙏

So this is a problem that I have literally had for years, although for the last 12 months or so the problem has been more frequent to the point where I am reluctant to use the car. VEHICLE: Skoda Octavia MkII, 1.6 MPI (BSE engine) 2011 reg, just under 40K miles done. SYMPTOMS: - Intermittently, the car won't start. The starter motor turns over very merrily, but there is no suggestion that the car is ever going to 'catch' and fire up. If I turn over on the starter motor for long enough (10-15 seconds?) the starter cuts out anyway (that might be normal?). - The problem usually appears from time-to-time when the engine is warm, but I have also had the same symptoms with an attempted cold start (see below). If I wait - anything between say 5 to 20 minutes - it will decide to start again. - When driving along, the engine may cut out/die, usually at low revs. Then it will refuse to start, as above. - After starting from cold and warming up, I am aware of a slightly rough idle, but it is pretty mild and might just be how this MPI engine idles? Idle is just over 700 rpm when warm, a little faster (and not remotely rough) when cold. WHAT I HAVE ALREADY DONE: - Taken it on several long runs on motorways. Last one was around 120 miles doing 70 mph for long stretches. On return to my house, the car was running fine. Next morning I drove to a supermarket (10 min journey) and when I had finished shopping (about another 20 mins) it refused to start, as described above. Finally got it going 15 mins later. - Bought a VAG/Audi/OBDII code reader. There were some error codes relating to a lambda sensor. - Took it to my local garage for service/MOT. Told mechanic about the lambda sensor code. Passed MOT, no emissions problems (and, inevitably, it didn't break down all the time it was with the garage). The mechanic couldn't find any other error codes when he hooked the car up. Cleared codes and service light. (The car has now passed three MOTs with this fault not emerging at the time (Sod's law!) nor having an impact on emissions, etc). - Checked the air intakes, and the throttle body. All clear. Air filter was replaced at last service, but these problems were apparent well before that. - Removed and checked (visually) the air intake manifold pressure sensor / air temp sender - looked all very clean and clear. - I have put throttle/carb cleaner spray into the throttle inlet (engine running) on two occasions - used a full can each time; no effect on the fault. Throttle butterfly and chamber look very clean. - Replaced the crankshaft sensor (because it was relatively easy) - no effect. No error codes and no service light on the dash. But the car still intermittently dies / won't start. Today was typical: took it for a run this morning, did around 6-7 miles without any issues. Got home. Let the car idle for about ten minutes, until the cooling fan came on. Then turned off ignition and re-started it three times without any problem. This afternoon (ie, about 3 hours later, engine cold) went to drive the car again - it wouldn't start (usual symptoms, as described above). Took about 5 mins before it would start, drove it about a mile and a half and it died on me. Then took about ten minutes before I could get it started. Got home, parked up and turned ignition off. Restarted the car three times without issue... Checked for fault codes: absolutely none. No warning/service lights. The garage advised me to run the car until whatever is wrong 'properly breaks' but that just isn't happening, and it isn't practical to use such an unreliable car on a daily basis... Thoughts, anyone....? I'd be very appreciative of any insight, especially if anyone has had similar issues.

Thanks LEricG. To follow up: I took Westbury63's advice and took the car on a 60-odd mile run down the A1. Kept the revs between 3-4k as recommended. Also topped up with 'super' formula petrol. All was good, car ran faultlessly, as indeed it did for the next two weeks which involved just a few runs in town (5-8 miles each), total mileage probably less than 25. Today I drove to my daughter's flat (around 5 miles, in town) stayed there for around two hours, got back in the car - and it wouldn't start. Engine turns in the starter motor, just doesn't 'catch', same as before. Took the key out of the ignition, waited two minutes, tried again - it started first time. 😌 Was wondering if I should disconnect the battery for a day or two (I have the radio code) to let the EMS completely re-set, which was suggested to me by someone at my work...

Many thanks for that. It certainly does spend most of its time in 4-8 mile trips across town. But would a clogged sensor cause intermittent stalls/failures to start?