Octavia Mk II MPI ....intermittent start / stall problem

[Looby2411]

Hi @Rudi I think we have found the problem. We spoke to a local specialist who suggested it could have been the temperature sensor, with the car only failing to start  or cutting out when at temperature. 
The new sensor arrived and has been fitted and since then the car has been running like a dream (not cut out or failed to start once).

Fingers crossed the temperature sensor has solved the problem. 
 

[Rudi]

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

[Looby2411]

@Rudi so far so good for me.

fingers crossed it works for you 

[Rudi]

On 28/11/2021 at 18:31, Looby2411 said:

@Rudi so far so good for me.

fingers crossed it works for you 

 

@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..?

[Looby2411]

@Rudi I really do think we have exactly the same problem, my temp  sensor has been fitted a week - Friday similar sort of day to usual dropped hubby at work, Daughter at school nipped to the shop came back out and the car  wouldn’t start. Called hubby from work he messed with new sensor and it started.

 

Yesterday was a new fresh experience,

popped out shopping, car had been at temp for a good 30-40 mins maybe a little longer  including driving and on the way back the car went into limp mode and died going round a roundabout - So there I was stuck. Luckily hubby was with me but temp sensor fiddling didn’t solve it straight away, so five minutes or more of sitting patiently on the roundabout and another fiddle with sensor it started. Been out a few times Today less then 5 miles each journey and it’s been fine.

 

I think I officially give up 🤦‍♀️

[Rudi]

1 hour ago, Looby2411 said:

@Rudi I really do think we have exactly the same problem, my temp  sensor has been fitted a week - Friday similar sort of day to usual dropped hubby at work, Daughter at school nipped to the shop came back out and the car  wouldn’t start. Called hubby from work he messed with new sensor and it started.

 

Yesterday was a new fresh experience,

popped out shopping, car had been at temp for a good 30-40 mins maybe a little longer  including driving and on the way back the car went into limp mode and died going round a roundabout - So there I was stuck. Luckily hubby was with me but temp sensor fiddling didn’t solve it straight away, so five minutes or more of sitting patiently on the roundabout and another fiddle with sensor it started. Been out a few times Today less then 5 miles each journey and it’s been fine.

 

I think I officially give up 🤦‍♀️

 

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...🤞