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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Lambda light - on my Sport that had a misfire for yearsViews : 3061 Replies : 47Users Viewing This Thread : |
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Jun 27th, 2022, 23:03 | #11 |
Rogerthechorister
Last Online: Dec 16th, 2023 03:15
Join Date: May 2006
Location: Rochester
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More grief!
Well today she was booked in with Safi to slap her on his emissions tester (the one he uses for the MoT but not doing a full MoT). The theory was that if the actual lambda and emissions were OK it would give us a clue - ie the lambda sensor was toast - and if they weren't we would know what we were looking for - ish. Drove her the 100 yards to the garage, amd turned her off. Safi said to drive her round to the MoT bay. She refused to start! Pumping the accelerator and winding furiously produced some firing but not enough to keep running once the starter was no longer operating. Some dark-ish smoke out of the exhaust.
To me that sounds like running VERY weak, cold start enrichment will maybe start her when STONE cold. Pumping accelerator also richens mixture but only for short times. Possible causes of weakness the AMM or fuel pump. She does however have turboplus and that is largely a mystery to me. I have got a flash reader (see above) so could look for stored codes. BEFORE pulling number 1 fuse! Obvious things to try anyway (1) compression test (2) spark test (if poor dizzy cap, rotor arm, HT leads, maybe coil) (3) test lambda sensor (but the garage says it does not know how!!!) (4) try some of my spare AMMs. (5) smoke test for air/vacuum leaks - but garage has not got smoke tester either. (6) fuel pressure regulator. Open to other suggestions.
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B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold. |
Jun 29th, 2022, 14:26 | #12 |
Master Member
Last Online: Today 15:00
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Location: Amersfoort (NL)
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Turboplus
The only thing that the Volvo turboplus does is increasing the turbocharging pressure at full throttle. At less than full throttle the system is not active, hence it can have no effect on starting.
A faulty lambda sonde will have no effect on starting either, as the ECM only starts to fine-tune the mixture after it receives a stable lambda signal. During starting and picking up the combustion air flow is too low and too cold for the sensor to work properly. I am fairly sure the mixture is set according a fixed strategy based on temperature only and it will start even with a disconnected sensor. Only in the old carburettor days pumping the accelerator would enrich the mixture, as injection systems do not have an acceleration pump function. The only information the ECM gets about the position of the throttle is from the throttle position switch (TPS). This is either open or closed, nothing proportionally, so there is no way the ECM knows that you are pumping the pedal. The ECM only gets indirect information from your foot on the accelerator via the AMM, not from the throttle pedal position. |
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Jul 1st, 2022, 04:33 | #13 |
Rogerthechorister
Last Online: Dec 16th, 2023 03:15
Join Date: May 2006
Location: Rochester
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But something knows!
Well, pumping the accelerator pedal produces some firing and some dark smoke, so something is happening. I am open to suggestions about what!
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B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold. |
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Jul 1st, 2022, 08:04 | #14 |
Go redblock or go home
Last Online: Today 13:55
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Location: UK
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Have you checked the resistance figures for the ect?
Have you done any of the checks you listed before? |
Jul 2nd, 2022, 14:42 | #15 |
Rogerthechorister
Last Online: Dec 16th, 2023 03:15
Join Date: May 2006
Location: Rochester
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Ect?
That is a TLA I have not come across before. What does it stand for please?
On a slightly different tack, garage says BOTH crank position sensor and camshaft position sensors are toast. I'll order some on Monday.
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B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold. |
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Jul 2nd, 2022, 15:06 | #16 | |
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Quote:
Never come across a cam position sensor on a 7/9xx before, closest would be an rpm sensor on the V6 from ~1986 on, possibly the white block engines have a Cam Position Sensor so i'd ask for clarification before ordering.
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Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ |
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Jul 2nd, 2022, 15:25 | #17 |
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Could they be referring to the knock sensor ??
I know it's not for the cam but it's the only other sensor I can think of
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V70 D5 SE Geartronic 215bhp Saville Grey 2012MY 940 LPT Manual 1996 740 SE 1990 Last edited by griston64; Jul 2nd, 2022 at 15:29. |
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Jul 2nd, 2022, 18:35 | #18 | |
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Quote:
If they insist it's the cam sensor, gently point out that no such animal exists on your car.................
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Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ |
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Jul 5th, 2022, 16:22 | #19 |
Rogerthechorister
Last Online: Dec 16th, 2023 03:15
Join Date: May 2006
Location: Rochester
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No cam sensor
I have re-double-checked and no, she does NOT have a cam position sensor so I have just delivered the crank position sensor (flywheel sensor) to the garage with my second-best compliments!
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B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold. |
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Jul 5th, 2022, 18:58 | #20 |
Rogerthechorister
Last Online: Dec 16th, 2023 03:15
Join Date: May 2006
Location: Rochester
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Progress and puzzles!
Well now hot start is fine after changing Crank Position Sensor. Safi the garagiste made a bit of a meal of it, though, at my expense!
Now the puzzles. Safi did an emission test, and it is good but it says it is for a non-cat car. How can that be? She is 1995/6, and must have and indeed does have a cat. Second how different are the cat and non-cat standards for that year? Third, I am SURE but have not yet checked that I have seen lambda values on tests of some of my volvos, but this test does not state a lambda valu. Am I imagining things?
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B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold. |
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960sport, flash reader, lambda, too many mpg! |
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