Chopshop85

iTrader: (4)

My oil pressure light has started flickering on idle when the temperature is at "N" or above?!

What can be causing this? I thought it was the oil needed changing as I hadn't done it for a while and its a relatively new engine. Seemed to cure it for a day or two and now its doing it again. The car even stalled pulling up to a set of traffic lights a few minutes ago ?!

COLEYST200

iTrader: (3)

Is the tick over a bit on the low side

wayne dowling

iTrader: (1)

could be oil pressure switch playing up

Chopshop85

iTrader: (4)

Regular its set at 950. When the light starts to flicker it drops to about 400-500 ish

s1cab

iTrader: (1)

was there a new oil pump fitted when the engine was rebuilt? also i would try a new oil pressure switch. but the oil light only comes on when there is low oil pressure, which points to the pump.

Chopshop85

iTrader: (4)

yup, its actually had a new oil pump after the engine rebuild, about 3000 miles ago.

surely it wont be the switch as the revs woiuldn't drop would they, it would just be the light flickering?

rsmark86

iTrader: (3)

does the light come on first before it drops off the revs

RSargie

if its only coming on when the revs drop to 500 thats because the pump isnt able to provide the corect presure at that rpm try just tweking the idle a bit. or checking to see if you have any air leaks causing the low rpm

Chopshop85

iTrader: (4)

the revs drop off first, just before the light flickers. It just seems really wierd as its only when the engine is hot.

martysmartie

iTrader: (1)

More than likely a faulty sender or short in the wire, the lights are useless anyway as with most oil lights they only close at low pressure by which time the damage has already been done!

The stalling problem is probably unrelated. It won't be low engine speed, you should have good pressure even on cranking hence the light will extinguish and if you stalled car it would take a few seconds for the oil light to come on.

Martin

Chopshop85

iTrader: (4)

Its got me really confused! Last time it did this it turned out to be the big ends, which was the catalyst for the rebuild. However, It surely can't be the big ends on an engine thats only done about 7000 miles.

RSargie

does it do this as the cooling fan kicks in?

RichieST

iTrader: (2)

I'd say the low RPM is causing the light to flicker as the pump isn't turning quickly enough to supply enough pressure. Get this issue fixed first, it may be idle control valve, an air leak etc. Although an air leak would normally cause high RPM so I would be looking at the idle control valve first!

coswurv

iTrader: (8)

Well you'll be surprised as you did state earlier that the pump was only changed 3000 miles ago, so the damage could of been done in the first 4000 out of your 7000 you did before hand, if you was using an old pump, i would also look at wether it does this when the fans kick it causing the low revs.

Chopshop85

iTrader: (4)

Well it had a new one with the rebuild, but then it gave up after the first few thousand miles. lol thats what has got me so confused, everything in the engine is not old and barely used.

Chopshop85

iTrader: (4)

I'm not 100% sure, I should think it would be around that temp? what you thinking?

martysmartie

iTrader: (1)

When the fans run this takes massive power and so the alternator puts an increased load on the engine and so it needs to run faster, if there is no idle compensation the revs will drop, guess that what he was going to say.

Martin

Chopshop85

iTrader: (4)

That makes sense, I think we might be onto something! what would be a way to compensate this? the idle control valve, but makes the adjustments when the engine is hot?

Karlos G

iTrader: (4)

That sounds exactly like thats what it is, as it happens when the temp gauge hits the N.
If after dropping your revs do not pick up again then I would say the ICV is not working.

It's 100% not the bottom end or pump etc. as it only happens when the idle is between 400-500rpm which is as already said way too low for the pump to maintain correct oil pressure

drsrst2zvh

Karlos
How can you be so sure its not related to the bottom end as said previously all healthy engines should extinguish the oil light when cranking to start. I know mine always have. I think you need to be considering all angles especially as you stated the last oil pump didnt last very long so whats not to say that its that again or the damage was caused when the last pump failed?

Chopshop85

iTrader: (4)

In all fairness when the last pump failed the tapets went noisy as hell just pulling onto my driveway, after leaving it for a bit and starting it again, and the noise remained, the pump was replaced. Car must have only moved about 10-15 feet without the oil pump working.
The oil light does go out when the car starts, its just once the temperature reaches the N and the car has been idling for a few minutes it starts to flicker.

Chopshop85

iTrader: (4)

Is there a way to test the ICV is working correctly, or does it just need adjusting?

martysmartie

iTrader: (1)

Doubt that is the problem but yes the easiest way to test is to unplug, on a cold start etc it should be harder to start and when up to temp if you remove connector and plug back in revs should raise slightly for a moment.

Another way is to remove valve totally and put +12V to it this will open the valve fully, it's very rare the idle will drop below the base idle anyway.

I still thing a dodgy sender myself.

Martin

Karlos G

iTrader: (4)

Because the oil light will flicker on if the RPM is that low and the engine is warm, it's normal, try it with your own motor, turn the idle screw until the rpm is at around 400-500rpm (TBH it might struggle to idle and stall, like it has in this case) with the engine up to temperature and see.
When cold cranking the oil is so thick it would take no time to get up to pressure and turn the oil light out mate, although why your cranking long enough for it to do it I dont know?! Should have started by then! lol

Karlos G

iTrader: (4)

They have no adjustment on them, but as said if you unplug it when the engine has just started up from cold the RPM will drop as it's no longer getting the extra air needed to keep the revs up.
If it does drop then it points to the ICV working, if it doesnt drop then it isnt working.

rsmark86

iTrader: (3)

i think the fans are draining the power i had a rs with a dodgy alternator and it wouldnt even boost untill i changed it..... someone explain that one to me...

my battery kept going flat and it had no power and i changed the alternator and it was perfect again lol

Ukchopper

oil switch same fault as mine. revs mine still up and down like a yo yo some days good some bad. air leak but cant find it!!!!

martysmartie

iTrader: (1)

Are you sure that isn't the ISCV doing this, rather being told to do so?

Martin

Chopshop85

iTrader: (4)

Well the ICV is working, so i'm going to try a new sender and see if that fixes said problem.

RSargie

chop shop what management are you running? are you still mfi or efi?
because if your mfi it carnt be the icv as this is not controlled by the ecu or sensor it is a bi-metalic strip that opens and closes dependant on temp. if its efi and you have set the idle with icv unplugged it can not go below this as it us fully closed when unpluged.
if its to do with the fan kicking in and your mfi i would sugest just tweaking the c.o up a bit and setting the idle at 1k. at least this way when the fan kicks in it wont drop so low that the light will come on. (hopefully) if it does tho i would sugest gettin it sean to by a pro asap just in case.
and just to put you ease if your worried, my revs drop when the fan kicks in but only by 100pm ish and it is pritty normal with mfi. also when i had mine set as factory spec, base c.o and idle speed it ust to drop alot more than this like you yours. now i run with a base c.o of about 3% and this has sorted it for me. i put this down to the lower comp i am running compared to standard. i am still mfi.

Chopshop85

iTrader: (4)

yeah it is still MFI.

I am going to be at Northampton Motorsport 2moro sorting a few things out for them, so i'm gonna get an oil pressure gauge on it and see what it says. I'm starting to think it must just be the switch itself. I cant be anything major as the engine would have died by now.