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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8723 ![]() ![]() ![]() |
If you just watch the o2 sensors readings they should cycle between around 0.3 to 1.2 or close, the engine ecu richens the mixture until the o2 sensor says it's rich, then it leans out the mixture until the o2 says it's lean, this happens many times per second, no need for faffing with filters or spraying extra fuel in... the o2 sensors are also checked by the post cat sensors and if they don't agree, i,e one is faulty, then you get a MIL light on...
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
Magic |
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
Ok I've managed to check the short term fuel trim..there's 2 sets.of readings .
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fisha Member Since: 25 Sep 2009 Location: Scotland Posts: 1511 ![]() ![]() |
Gut feeling - your MAF is on its way out. The 4.4 BMW seems very sensitive to its air flow reading being correct if the sensor is attached. Is yours showing an engine management light?
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Rewmer Member Since: 14 Jan 2013 Location: Essex Posts: 142 ![]() ![]() |
I've got some good maf readings here somewhere. Hold on I will have a look.
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Rewmer Member Since: 14 Jan 2013 Location: Essex Posts: 142 ![]() ![]() |
Here you go. These are known good readings. All loads off
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
@ fisha no warning lights or faults stored at all buddy..if I start car cold it idles at about 1500rpm for a minute or 2 then bounces between 500/600rpm. If I give it some gas in idle the revs drop,lights dim and it nearly stalls....it seems more stable with the air con switched on then after a while it does the bouncy rev trick again |
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
@rewmer ..i googled them somewhere |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8723 ![]() ![]() ![]() |
Sounds to me like an air leak into the inlet manifold somewhere, it's getting extra air in somewhere, hence the low tickover... ![]() __________________________________________________ 2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior 2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold 2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold 2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold -Click for Project Fatty off roader- |
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
That doesn't sound too bad then! Matter if finding said leak..one thing I have noticed is if I quickly rev car there's a huge sucking,vaccum noise from the external air inlets (gills)..probably normal as I've never had a rangey |
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Haylands Member Since: 04 Mar 2014 Location: East Yorkshire Posts: 8723 ![]() ![]() ![]() |
That's weird as they aren't anywhere near the air inlet, it's right at the front of the wing, this has my elbow on it for the snorle the original one points downwards...!!!
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
Great..weekends jobs are to solve this issue(hopefully) |
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UK Marine Member Since: 22 Jul 2016 Location: Durham, County Durham UK Posts: 833 ![]() ![]() ![]() |
Daft question but do you have an air filter in the housing? That can usually attribute to a sucking vacuum sound. ______________________________
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alistairh Member Since: 17 Sep 2016 Location: edinburgh Posts: 801 ![]() ![]() ![]() |
Yeah...just changed it...good point actually! I did have the air housing out to fit the drivers side headlight..i had a nightmare refitting the pipe at the bottom to the lower housing..maybe its not meeting right? Definitely never heard the sucking noise before it...only issue is I did have the problem idle before I fitted headlight |
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