KFC
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| posted on 17/7/16 at 10:24 PM |
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KLDE V6 too much crankcase vacuum?
Hi all,
I am struggling with my V6 RX8 and I'm desperate to fix it as I've spent a 2 years on it and now I've lost my patience with it feel
like selling it as there are a few teething issues. I've got it running and drove it for about 60 miles or so. It has TB's on it and they
charge up a resivoir for the brakes and crankcase. It ran on the dyno with it disconnected and then reconnected it to drive it home. It was ok until a
misfire, running on 3 cylinders and the other 3 seemed to have the injectors stuck open, such a rediculas amount of smoke that was unburnt fuel, no
hint of oil smell, I changed the oil and filter as it stank of petrol.
I changed all the injectors with a used set and only improved a bit. The next thing I found is there is a huge amount of vacuum in the crankcase,
after the engine is running, I take off the oil filler cap and there's a huge hiss of suction of air going into the cam cover? It is a lot! When
the engine is running and I have the filler cap off and put my hand over the hole, it almost feels like putting your hand on the top of a carb! Is
too much vacuum is the crankcase dangerous?
I'm now thinking of putting a restrictor in the main feed to drop the crankcase vacuum. What should the vacuum the crankcase be?
I really am starting to pull my hair out!!!! I've actually been a bit stressed about this project as it's my commuter car, I've
been with out it for 6 weeks now, one disappointment after another..
Oh, my electric steering doesn't work either. 
[Edited on 17/7/16 by KFC]
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adithorp
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| posted on 17/7/16 at 11:01 PM |
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There shouldn't be vac' in the crankcase, it should be pressure. Vac' there is usually a fault in the crankcase vent' system
(PCV valve in particular) giving you inlet vac' in the crankcase.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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britishtrident
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| posted on 18/7/16 at 06:46 AM |
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The one-way check valve for the brake servo is completely different from the the PCV valve, the PCV almost completely closes at the high engine
valcuum at idle or on the over-run.
With a positive crankcase ventilation it is normal to have an air inlet some where on the engine valve cover or crankcase to allow air to circculate
through the crank case back via the PCV back to the inlet.
Also connecting the PCV and the brake servo to the same connection is likely to eventually cause oil contamination of the brake servo.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 18/7/16 at 07:30 AM |
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Re. one bank running rich, with this my first line of investigation is an electrical wiring problem, on a V engine bank 1 and bank 2 each have their
own upstream oxygen sensor although they may often share a downstream sensor. If the PCM is controling the bank 1 injectors based on the bank 2
oxygen sensor signal and vice versa you will get the PCM driving one bank of injectors lean the other rich. This could be result of either the
injector or sensor wiring getting swapped to the wrong side.
Other possible causes are an upstream oxygen sensors fault of some kind ie faulty sensor, bad wiring, wrong type of sensor or PCM problem.
Some on Japanese engines the PCM has an additional fuel trim based on the post-Cat oxygensor.
It would be easier to diagnose if you can see the fuel trims and O2 sensor signals.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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KFC
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| posted on 18/7/16 at 08:08 AM |
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quote:
Originally posted by britishtrident
Re. one bank running rich, with this my first line of investigation is an electrical wiring problem, on a V engine bank 1 and bank 2 each have their
own upstream oxygen sensor although they may often share a downstream sensor. If the PCM is controling the bank 1 injectors based on the bank 2
oxygen sensor signal and vice versa you will get the PCM driving one bank of injectors lean the other rich. This could be result of either the
injector or sensor wiring getting swapped to the wrong side.
Other possible causes are an upstream oxygen sensors fault of some kind ie faulty sensor, bad wiring, wrong type of sensor or PCM problem.
Some on Japanese engines the PCM has an additional fuel trim based on the post-Cat oxygensor.
It would be easier to diagnose if you can see the fuel trims and O2 sensor signals.
Thanks for the reply.
It's non standard setup with one lambda on a after market ECU. I'll have a look at the values tonight but it has to go back to jamsport
anyway because they made it far to rich, the exhaust made your eyes sting. I thought the injectors were too slow for the over demanding map?
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r1_pete
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| posted on 18/7/16 at 11:55 AM |
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Do you have the crankcase breather on the engine or air filter side of the throttle butterflies?
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adithorp
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| posted on 18/7/16 at 12:33 PM |
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"...It has TB's on it and they charge up a resivoir for the brakes and crankcase..."
Didn't see this before (only saw it because of BT's post). As he says the brake servo master shouldn't be linked to the crank case
vent. Depending on where it's all piped, it could be feeding crankcase gasses freely into one bank and causing that side to run weak. Lambda
sees that and tries to compensate by overfueling. Sort the crank vents and it might well sort the misfire.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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KFC
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| posted on 18/7/16 at 03:55 PM |
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quote:
Originally posted by adithorp
"...It has TB's on it and they charge up a resivoir for the brakes and crankcase..."
Didn't see this before (only saw it because of BT's post). As he says the brake servo master shouldn't be linked to the crank case
vent. Depending on where it's all piped, it could be feeding crankcase gasses freely into one bank and causing that side to run weak. Lambda
sees that and tries to compensate by overfueling. Sort the crank vents and it might well sort the misfire.
Ok, the brakes are fed by the resivoir through a one way valve so no fluctuations there. I wanted to run one resivoir to try and balance all
tb's.
I'll vent the crankcase now and see how that goes.
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