Engine: B5244: - Will not start - Page 3

Backo · Feb 16th, 2016, 18:18

Quote:

Originally Posted by bournricha

+1on the coil packs.The do break down like this

...But will most certainly throw DTC...

Bernard46 · Feb 16th, 2016, 19:19

Thanks Guys, lots of advice here which I really do need to check out by blocking off the evap pipe - didn't get a chance today but hopefully will tomorrow.

One thing that really puzzles me about all this is that a number of things point to too much fuel (the smell of petrol after startup, the P0172 code), however others point to there being no problem with fuel (fuel consumption being fine, performance being OK, no misfiring or jerkiness when running at idle (when warm) or on the road at any speed), however the startup from cold, and only cold, problem has got progressively worse - but I have now found I can get round this problem by vigorous blipping of the accelerator when trying to start from cold, which should give me even more fuel, shouldn't it!!

This is not an easy problem to check out because I only really get one shot at it every 24 hours at most. The problem happens mainly (9 out of 10 times) with a stone cold engine, and then if I can get it above 750 rpm I can keep it going. As soon as it has just a bit of heat (30 seconds or less) it will keep going. Tomorrow morning after a cold night (around 3 degrees C) should be a good time for blanking off the evap port and seeing what happens.

Bernard46 · Feb 17th, 2016, 10:09

I clamped off the EVAP pipe to the manifold this morning and it started with the first turn of the key - so what does this prove? Well occasionally it will start first time from cold, so I guess I need to give it a try tomorrow morning and then possibly on Friday - two cold starts on the trot would start to look promising and three would be a very good sign. Watch this space.

Chris_Rogers · Feb 17th, 2016, 11:39

I'd suggest you take the car for a run with the evap valve clamped off.

Then have a look at the fuel trim figures, I expect you will find they are closer to zero.

Bernard46 · Feb 17th, 2016, 12:17

Yes, that thought went through my mind but its pouring with rain and I need to devise a safe permanent clamp before I go for a run - the weather should be more amenable to working on it in the open tomorrow so I'll give it a try then after a second cold start as well. Thanks for the suggestion.

Backo · Feb 17th, 2016, 15:05

My bet goes to flooding through the EVAP canister / valve.
When you floor the pedal you let more AIR rather than fuel in (with ECU's kind permission of course).
It's purely mechanical overfill and leaves no trace bar the slightly richer mixture on startup detected by the O2 sensor.
And I'd expect the source of all troubles to be in the tank/canister area.
Keep us posted.

Bernard46 · Feb 17th, 2016, 16:54

Thanks for that feedback - makes sense in terms of the P0172 as well. Interestingly enough I had to go out in the rain this afternoon and the car was a pig to start again despite having started first turn of the key this morning when the EVAP pipe was squeezed - I only let it run for a few seconds so it didn't warm up at all and it was three hours before I tried again. I'll definitely try getting a more permanent clamp on the EVAP tube tomorrow and then take it for a run to check the LTFT and STFT values. Do you guys think a new EVAP valve would fix the problem - they don't look too expensive?

KBB · Feb 17th, 2016, 17:48

The EVAP valve will often be fine electrically but fail mechanically (stick in the open position). You can often get them going temporarily by tapping on them. If this proves to be the issue then replacement is the best course of action.

Backo · Feb 17th, 2016, 18:04

Even if stuck open, EVAP valve on it's own shouldn't cause the engine to stall. It takes a canister full of petrol on top of that (mho only).
It shouldn't be difficult to check valve's condition anyway.

KBB · Feb 18th, 2016, 12:20

Quote:

Originally Posted by Backo

Even if stuck open, EVAP valve on it's own shouldn't cause the engine to stall. It takes a canister full of petrol on top of that (mho only).
It shouldn't be difficult to check valve's condition anyway.

It will if the canister is flooded with fuel as the intake will draw the heavy fuel air mixture which would also be unmetered air fuel mix having by passed the MAF

Feb 17th, 2016, 15:05	#26
Backo Junior Member Last Online: Nov 23rd, 2021 11:46 Join Date: Oct 2007 Location: Newport IoW	My bet goes to flooding through the EVAP canister / valve. When you floor the pedal you let more AIR rather than fuel in (with ECU's kind permission of course). It's purely mechanical overfill and leaves no trace bar the slightly richer mixture on startup detected by the O2 sensor. And I'd expect the source of all troubles to be in the tank/canister area. Keep us posted. __________________ 2007 XC90 B8444S SE Sport 2002 V70 B5244S2 Manual 1996 V40 ex 1990 440 ex Yamaha MT01 1670 V2 / Aprilia Touno 998 V2

Feb 17th, 2016, 18:04	#29
Backo Junior Member Last Online: Nov 23rd, 2021 11:46 Join Date: Oct 2007 Location: Newport IoW	Even if stuck open, EVAP valve on it's own shouldn't cause the engine to stall. It takes a canister full of petrol on top of that (mho only). It shouldn't be difficult to check valve's condition anyway. __________________ 2007 XC90 B8444S SE Sport 2002 V70 B5244S2 Manual 1996 V40 ex 1990 440 ex Yamaha MT01 1670 V2 / Aprilia Touno 998 V2

Feb 16th, 2016, 19:19	#22
Bernard46 Member Last Online: Apr 21st, 2016 19:49 Join Date: Dec 2008 Location: Leamington Spa	Thanks Guys, lots of advice here which I really do need to check out by blocking off the evap pipe - didn't get a chance today but hopefully will tomorrow. One thing that really puzzles me about all this is that a number of things point to too much fuel (the smell of petrol after startup, the P0172 code), however others point to there being no problem with fuel (fuel consumption being fine, performance being OK, no misfiring or jerkiness when running at idle (when warm) or on the road at any speed), however the startup from cold, and only cold, problem has got progressively worse - but I have now found I can get round this problem by vigorous blipping of the accelerator when trying to start from cold, which should give me even more fuel, shouldn't it!! This is not an easy problem to check out because I only really get one shot at it every 24 hours at most. The problem happens mainly (9 out of 10 times) with a stone cold engine, and then if I can get it above 750 rpm I can keep it going. As soon as it has just a bit of heat (30 seconds or less) it will keep going. Tomorrow morning after a cold night (around 3 degrees C) should be a good time for blanking off the evap port and seeing what happens.

Feb 17th, 2016, 10:09	#23
Bernard46 Member Last Online: Apr 21st, 2016 19:49 Join Date: Dec 2008 Location: Leamington Spa	I clamped off the EVAP pipe to the manifold this morning and it started with the first turn of the key - so what does this prove? Well occasionally it will start first time from cold, so I guess I need to give it a try tomorrow morning and then possibly on Friday - two cold starts on the trot would start to look promising and three would be a very good sign. Watch this space.

Feb 17th, 2016, 11:39	#24
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	I'd suggest you take the car for a run with the evap valve clamped off. Then have a look at the fuel trim figures, I expect you will find they are closer to zero.

Feb 17th, 2016, 12:17	#25
Bernard46 Member Last Online: Apr 21st, 2016 19:49 Join Date: Dec 2008 Location: Leamington Spa	Yes, that thought went through my mind but its pouring with rain and I need to devise a safe permanent clamp before I go for a run - the weather should be more amenable to working on it in the open tomorrow so I'll give it a try then after a second cold start as well. Thanks for the suggestion.

Feb 17th, 2016, 16:54	#27
Bernard46 Member Last Online: Apr 21st, 2016 19:49 Join Date: Dec 2008 Location: Leamington Spa	Thanks for that feedback - makes sense in terms of the P0172 as well. Interestingly enough I had to go out in the rain this afternoon and the car was a pig to start again despite having started first turn of the key this morning when the EVAP pipe was squeezed - I only let it run for a few seconds so it didn't warm up at all and it was three hours before I tried again. I'll definitely try getting a more permanent clamp on the EVAP tube tomorrow and then take it for a run to check the LTFT and STFT values. Do you guys think a new EVAP valve would fix the problem - they don't look too expensive?

Feb 17th, 2016, 17:48	#28
KBB Master Tech Last Online: May 18th, 2020 10:57 Join Date: Dec 2006 Location: On Contract Dubai Automotve Technical Academy	The EVAP valve will often be fine electrically but fail mechanically (stick in the open position). You can often get them going temporarily by tapping on them. If this proves to be the issue then replacement is the best course of action.

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