Long crank time after stalling help needed

[johndaily693]

The car takes along time to start up after stalling it cranks for 3 secs before starting, it struggles to start but only after stalling. It starts instantly from cold start and also starts instantly from hot start. Only when it stalls does it take a long time to start. It is 1.6 petrol and LPG engine rover 25 2003 model.

Here are my obd readings below once engine is idle and warm:

Feul sys1 - CL
Calcload - 2.74 %
Coolant - 66, this increases and stays between 90-102 eventually as car warms.
Stft b1 - hops around between -5%and 5%
Ltft b1 stays more or less constant at -3.91%
Map - 34 kpa approx
Engine rpm- 870
Spark adv - jumps around between 8-12 btdc
Iat- 23 celcius
Tps- 3.92%
O2sl - 1112
O2s11- varies between 0.1v to 0.8v for upstream 02 sensor
Shrtft11 - varies between -5%and 5%, I am guessing this is reading is from upstream 02 sensor
O2s12- voltage stays constant at approx 0.85v for downstream 02 sensor
Shrtft12- 99.2% does not change stays constant. This for downstream 02 sensor

Here are my obd readings below once engine is rev to 2000 rpm approx

Feul sys1 - CL changes between ol drive and CL
Calcload - 5.09%
Coolant -this increases and stays between 90-102 eventually as car warms further, does not go past 102
Stft b1 - fixed at 0%
Ltft b1 stays more or less constant at -2.35%
Map - 27 kpa approx
Engine rpm- 2000rpm
Spark adv- 28
Iat- 29 celcius
Tps- 3.92% does not seem to change
O2sl - 1112
O2s11- varies between 0.1v to 0.8v for upstream 02 sensor
Shrtft11 - varies between -5%and 5%, I am guessing this is reading is from upstream 02 sensor
O2s12- voltage stays constant at approx 0.85v for downstream 02 sensor, moves around a bit
Shrtft12- 99.2% does not change stays constant. This for downstream 02 sensor

Are readings ok?
Tps does not change, is this normal? What is normal?
Also shrtft12 is at 99.2%, is this normal reading from post cat 02 sensor. Voltage for this sensor does not move much is this expected? While pre cat sensor vol moves between 0.1 and 0.8 v constantly.

Is the 02 sensor causing the long crank after stalling or is it the Tps sensor or something else?
It took me a while to get all this information hence a response would be very much appreciated.


Thanks

[trickywoo]

Don't stall it - problem solved.

[TheEnd]

That just sounds like flooding, there's unburnt fuel hanging about and it needs a while to clear out.

[TooLateForAName]

I guess that when you stall it youre running lpg and a start requires petrol? So you have a switchover to happen. see the flooding comment above

[shalmaneser]

It's such a corner case it's barely worth worrying about.

[johndaily693]

Thanks for the replies, do my obd readings look fine? Reason for asking is I also get engine management light saying oxygen sensor bank 1 , but every mechanic I go says the sensor is fine.

[johndaily693]

Is this long crank time after stalling common on lpg vehicles in general just to put my mind at rest. Is it worth changing spark plugs ? I know it is a small case but one day, I may be in heavy traffic and the car may not start after stalling. I need to know if there is anything that can be done to resolve this issue if a solution exists. Thanks

[MotorsportTom]

Surely your car has a manual override to switch it over to running on just petrol. Pretty sure they have to!

Do that, stall it deliberately and then see the outcome.

Great having stloads of readings about sensors. Terrible if you have zero common sense.

[Baryonyx]

I'm guessing a flooding issue could be at play, especially if the LPG tank keeps fuelling after the stall. Naturally, the engine will need to be turned over a few times to clear the unburnt fuel. Had much the same issue after flooding my CG125, it needed about a minute cranking it via the kick starter before it fired into life. Usually it starts on one kick!

[ch427]

Pre cat looks ok to me,should switch back and forth from those readings every second or so. After cat looks a bit rich but cant see any other issues.

[Toaster Pilot]

I have pretty much exactly the same problem with my 1.8T Audi A6 (not LPG or anything)

[andrewrob]

I've had a couple of LPG cars and never had it take that long to start after a stall.
Its not an imobiliser issue is it?
I used to have a problem with an old 2 litre 406 where it could take up to 20 seconds to let me start

[Zerotonine]

No one has mentioned HGF yet..

OP, kudos on the intricate data. Much better than the usual:

I have a car. It won't start. Help! threads.

[johndaily693]

Thanks for the comments, immobiliser is ok. Is it common for lpg cars to take a while to start after stalling only? I assume the flooding comment is valid as it is only after the car switches to lpg does it take a while approx 3-4 secs cranking to start.

On a separate note

Should the os12 downstream post cat sensors voltage reading stay constant as it does for my vehicle from above readings?
Also if it stays constant is the voltage of around 0.85 correct Or should it be lower?

Does shrtft of around 99.2 sound right it never seems to change. Even before you switch engine on it stays at 99.2 I took a reading. while the voltage is 0.475 ,once you start engine and it is warmed up the voltage gets to 0.85 and stays constant.

Does the above sound right for the post cast sensor?

I also noticed from the obd reader when pressing read , I get following message:

P0340 pending camshaft position sensor A circuit bank 1 or single sensor, surprising no engine management light for this one like the O2 sensor. Any need for concern here?

O2 sensor management light which comes up randomly says po130 O2 sensor bank 1 sensor 1, but as you saw the readings above are fine. Some cars turn the management light on if an event happens for 20 seconds , wondering if this is what causes the management light to come one for the 02 sensor. Also mil-dist for the po130 error says 11000km , I only bought car two months ago.

In general car runs fine no problems apart from the long crank time after stalling and engine management light 02 sensor which pops up . Also the po340 pending code but this is what the obd reader picks up no management light for this one. Once I cleared the 02 sensor management light , if I press read on the obd reader I get the po340 code.

[andrewrob]

johndaily693 said:

P0340 pending camshaft position sensor A circuit bank 1 or single sensor, surprising no engine management light for this one like the O2 sensor. Any need for concern here?

Not sure about your car but on mine (e39 540) one of the camshaft sensors went (code like yours and no engine management light) and it did take longer to crank. Had a big impact on performance and fuel consumption too, setting off in 1st felt like setting off in second.

[johndaily693]

Longer to crank , was this after stalling only or every time cold or warm start? What happened to car in the end? Thanks

[andrewrob]

johndaily693 said:

Longer to crank , was this after stalling only or every time cold or warm start? What happened to car in the end? Thanks

Hi, its an auto so it doesn't really stall much!
Cold and warm starts but not every time. I replaced the sensor and everything was fine again, much faster start and performance back to normal.
That was a few months ago, the sensor on the other bank has just gone this week so replacing that next!

Mine are just held in buy one allen key bolt, very easy to get to.

[eltax91]

I have an LPG car. It's my second one. It's an auto so I can't speak for stalling, but.........

If I stop the car when it's running on gas, drop my son into nursery or drop into the shop or something, but leaving it for <5 mins, when I start it up again, it takes a little more cranking than normal and struggles a touch. Not serious but like a 2/3 second delay.

My LPG guy puts this down to the fact the car is starting on unleaded before it switches to gas, so there's a small delay whilst the unleaded injectors prime properly. Within 3 seconds of the car starting, it switches back over to gas.

For some reason it does not do this on cold starts, or even warm ones. Just on these hot ones where it's been stood under 5 mins.