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2005 JDM, HKS panel filter, HKS copy exhaust, sport cats.  I had a misfire and oil pressure low on idle, finally found a code reader that could communicate with the car that gave me a coil error.  I replaced 6 coils with Hitachi and while there checked plugs and done a compression test as advised which gave an average of 165psi within 4 of each other with my cheap tester (think regardless of number the consistency is a good thing) and also while in there done the plenum riser so regardless right or wrong the car has everything done to it I want.


Misfire is gone, car starts ok, fast idles ok, but when it starts to warm up and the idle drops so does the oil pressure.  Idle rests at circa 700 and by that time oil pressure is down to .4-.5Kpa x100 which is about 5-7psi and the oil light flickers.


Kind of trying not to fear the worst but running out of ideas.  Any help (even garage as opposed to self help) appreciated, cheers... 

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Assuming the oil is good and the level correct, I would say confirm the readings with a manual gauge: the senders do fail and should only be replaced with an oem standard one: ebay Chinese copies will be cheap but unreliable. 


With ac off that idle speed sounds right: put the ac on and the idle speed and oil pressure will increase. 

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Sorry, info not on post...  Oil and filter just changed, level top of high mark.


Yes with AC on revs go up so does pressure but it's marginal, don't think ahd trust that as a fix and ah know you didn't suggest that.


So yes, sender was a thought and is probably the next move.





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  • 2 months later...

Sitrep, yes, long time since last post but I seem to have like 5 minutes a week free time for some reason...  Anyway, bought a sensor back in September and it wasnt good...  As in it read just under half and didnt move, at all, it was crap.  And that highlights what lots of people say, OEM / Hitachi, etc only as it wasnt one of them so money back and more time wasted...  


New OEM sensor ordered from Tarmac Sportz and fitted last weekend, pressure reads as it should so not (touch wood) anything worse.  Only went a short run as said, time limited and was going to bring it to work this morning to give it a good run but came out this morning to black ice everywhere and ah thought the better of it so that will have to wait...


Few electrical issues to sort out and loads of cosmetics, loads but I'll get there..



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The oil pump is a gerator type and is fixed displacement. This means the volume of oil and it's pressure output is proportional to it's speed.

So at low rpm it had minimum pressure. 

Obviously as cars get older the bearings wear allowing more pressurised oil to get past.

It may be a sign the engine is coming to the end of its service life and needs a rebuild.

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