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17th January 2021, 14:00 | #1 |
I really should get out more.......
Rover 75 connoisseur se v6 auto Join Date: May 2014
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Slight misfires but not triggering a Code
In late December i did a 125 mile trip - on a couple of occasions i felt a couple of slight misfires and a couple of mini surges. As i got home the flashing EML triggered and the fault code 0300 (multiple random misfire) and 0141 (Post cat O2 heater circuit malfunction. So swopped out the O2 sensor.
However am still getting misfires but no surges , more frequently, but still not throwing a code up . The idle appears normal and no hunting and the misfires seem to only happen under load. Using my OBD and my rudimentary knowledge of data stream readings - the Short and Long trim seems fine, the 02 sensors OK, and the MAP and IAT seem OK . So thoughts and suggestions welcome as to most likely cause.
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She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. |
17th January 2021, 14:23 | #2 |
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Do the simple things first Martin, plug gaps, leads and coil packs 👍
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Lest we forget..
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17th January 2021, 15:00 | #3 |
I really should get out more.......
Rover 75 connoisseur se v6 auto Join Date: May 2014
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Will do Andy - however just popped to the shop (2 minutes) and parked up and ran the OBD data stream again ( well twice as i have 2 code readers for comparison purposes) and the IAT was showing 39 C - then with 2nd reader a minute or 2 later 42 C - its a cold day and the ambient temp is 7 C - so that does not sound right does it ?
And looking at the symptoms of a failing IAT sensor misfiring features. Will investigate further tomorrow.
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She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. Last edited by Yorkshire GOC; 17th January 2021 at 15:05.. |
17th January 2021, 17:25 | #4 |
I really should get out more.......
Rover 75 connoisseur se v6 auto Join Date: May 2014
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I understand the IAT only features on the 1.8 non turbo engine - so where am i getting these temperature readings -the MAF sensor i assume ?
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She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. Last edited by Yorkshire GOC; 17th January 2021 at 17:37.. |
17th January 2021, 22:49 | #5 |
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Had the same thing, misfire under load. It was diagnosed as a the coil on number 4. Replaced and ok. I eventually replaced all six. Sweet as a bird now. They were 100,000 miles over..
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17th January 2021, 23:39 | #6 | |
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Quote:
The Manifold Pressure (MAP) and Temperature sensors are combined into one on the 75 (not sure why Rimmers show the earlier separate temp sensor) - it's the one on the left hand end of the manifold. The temps you've quoted sound perfectly plausible, especially if you have the VVC manifold fitted - it gets a lot of heatsoak from the engine. |
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18th January 2021, 00:38 | #7 | |
I really should get out more.......
Rover 75 connoisseur se v6 auto Join Date: May 2014
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Quote:
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She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. |
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