S54 swap - cluster oil light randomly coming on

[diesekte]

Hey guys, as per title....
Swap worked for 2 years without issues, then I started stalling all the time and having some really weird trouble codes. I replaced my ECU and everything is fine now.

Anyway...throughout this entire time...old and new ECU, if the revs drop (like when slowing down) or the car stalls or is about to stall, the oil light comes on. By that I mean the one that looks like an oil lamp that is on the bottom right of the cluster.

I thought with an S54 swap this shouldn't even be functional. Why is it coming on randomly, two years in? Does anyone have a similar issue, any ideas, or can you provide me with the diagram for this circuit so I can troubleshoot? I can't seem to find it and when I try to google this problem, get results for E39, E46, etc, but not what I'm looking for.

[FredK]

The oil pressure light on the cluster should be functional, if X60004 pin 11 is hooked up to C101 pin 5.

Can you describe more about why your car stalls? How low are the revs dropping?

Do any other lights start to illuminate? When lights start to illuminate for no apparent functional reason, I would suspect the alternator.

[diesekte]

I'll troubleshoot that circuit in the coming week, thanks. Is there anything else involved in it? As in, any chance the sensor itself may be going bad? Any way to troubleshoot the oil pump? I really hope that is not an issue as I don't really have the time or desire to pull the subframe to replace it but if I have to I have to.

It was stalling bc of a bad ECU. Now I have only driven probably 15 miles with the new one and it stalled twice, only when slowing down to a stop. I have the uuc ltfw and JE Pistons, so a few lbs of rotating mass shaved off via ltfw and almost 840g due to the pistons. The revs drop below 1k but not considerably low - I'll check next time it happens. I only stall when slowing down to a stop, bc of the above hardware the revs drop pretty quick when not giving it any gas.

I'm using Andrews harness so I should think the wires from x6004 to c101 are fine. Is there any possibility of there being a short or something in the cluster to make the light come on? Trying to consider all possibilities here.

As soon as my revs come back up the light goes off, and it doesn't happen every time the revs drop either. I ran this car probably 4k miles over 2 years without this issue, and it just started appearing around the same time my ECU went bad.

[FredK]

The pressure sender is threaded into the oil filter housing. It's a cheap part to replace to see if you have a bad sensor. The PN should be 12617568480. If you want to check oil pressure, it'd be best to get an aftermarket oil pressure gauge and install it in the car and monitor it to see what the pressure is actually dipping down to.

I haven't see cluster issues causing only the oil pressure light to illuminate. Stranger things have happened, so I would say that this is more of a remote possibility.

I think when a car is about to stall and your dash is about to become a Christmas tree of lights, that the oil pressure lamp is one of the first to illuminate. I think that this may actually be an artifact of your car wanting to stall during deceleration.

[diesekte]

I think that this may actually be an artifact of your car wanting to stall during deceleration

I think so too. Nothing seems wrong otherwise, oil level is fine, motor runs strong without strange noises. I ordered a sensor and will try replacing it.

This mostly only happens under hard off-load conditions, as in accelerating, then quick shift to neutral and off the gas. I could always get an aftermarket pressure gauge and try to see what the actual pressure is. ECS has a kit for E46 M3 that's 100$ or something like that.
What should the pressure be? Mean and lowest that is safe if those numbers are available.

[TobyB]

Sounds like oil pressure on the low end of the range, to me.
If the engine's a few hundred rpm from stalling, yes, oil pressure can
drop to almost zero.
What oil are you using? Thin oil exacerbates this.
Hot oil does, too.

So put a gauge on it, and see. The sensors have been known
to get pessimistic. (close early)

Personally, I can't NOT put a gauge on an engine I'm attached to.
It's not quite as good as an ekg, but it's cheaper.
Less beeping, too.

t

[diesekte]

I'm using liquimoly race tech gt1 10w60. It was 20 degrees out and maybe a 10 minute drive when it was happening.
The other day I drove about 12 miles and it didn't come on at all, but I also didn't almost stall either.

Will see how it looks in the coming days as I haven't had much of a chance to drive it recently due to large amounts of snow.

[diesekte]

Update:

I replaced the pressure sensor in the back of the oil filter housing to no avail.
Sometimes I can drive around for extended periods without the light coming on a single time.
Sometimes it comes on every time the idle dips below 1k.
Sometimes it comes on every time the idle dips below 1.4k.

So this has happened now with 2 pressure sensors. Wiring appears to be good, as I just recently went over my entire harness with all diagrams etc and made sure all grounds and wiring are good.
Of note when I changed sensors, no oil leaked out of the hole - should it have?
I have the arc asylum pan and I'm using the E30 oil cooler. My oil level is right at the top mark on the dipstick.

I read somewhere (can't find it now) that the CPV controls oil pressure at idle. Is this true? Any chance I could just have a bad CPV? This is a fully rebuilt motor about 4k miles ago. I replaced everything except the CPV itself. Bearing clearances were within spec with plastigauge.

Car isn't stalling anymore, just the first drive after the battery was disconnected for a long time. It drives normal now, pulls hard, etc.

What is everyone's preferred method for checking oil pressure on S54? Any of the big parts store have a mechanical pressure gauge that will fit in the back of the oil filter housing I can rent?

Also, my thought is that the oil pumps are mechanical...so either they work or they don't. I don't have any terrible grinding or knocking noises, and drivability seems unaffected, so it makes me think the pump is pretty fine.

I read about oil squirters being stuck open causing low pressure. I cleaned mine during the rebuild but for some reason seem to remember being able to blow air through at least some of them. Should this not be the case? Shouldn't they be closed (like at idle) to keep pressure up until higher RPMs? How would I test them? I can't seem to find anything on Google about how to tell if they're good or not, just that they can go bad on S52 and S54. Can I get to them without removing the crank? I feel like I could but if anyone has done it and can chime in that would be appreciated.

Thanks for any help

Edit: also tbh, when I check at the dipstick the oil seems a bit thin for what I would expect 10w60 to act like, especially when cold. I may try CPV replacement and oil change first. I've driven the car a bit hard at times so maybe the oil is exhibiting some shearing? It has no more than 5k miles on it, but it's cheap enough to be worth a shot unless anyone feels it would be fruitless. Otherwise my next step is replacing all the squirters and upgrading to the VAC pump which combined will set me back almost 1k

[TobyB]

Yeah, the random nature of it would make me think it's something in the sender circuit-
at 5k miles, sometimes doing it cold, that's not a usual low oil pressure mode. I guess the
pressure bypass could be sticking open... but they usually stick closed, cold...

But spend the money for an oil pressure gauge you like- $100 gets the VDO electric parts,
which is pretty easy to do.

Personally, as I said above, I stick a good- quality mechanical gauge on it. It takes
an afternoon, but then I never have to think about it again.

t

[diesekte]

Looks like i do have an issue. I tried with a crappy harbor freight mechanical gauge and though not super accurate, looks like I'm generating 0 psi at hot idle. As I raise revs, the oil light goes off around 1500 rpm, and the gauge shows 5-7 psi.

I opened up the oil filter housing just to take a peek at the filter. The filter was saturated but there was almost zero oil in there....like about 2mm worth. This doesn't seem normal to me, right? Is there any way the oil filter housing could be bad? Is there some sort of anti-drain back into the pan valve or mechanism in there that may have gone out? I seem to find a few very rare posts on e46fanatics etc that say that there is some sort of anti-drain valve that can go bad. Here is what the inside of the housing looks like after opening it up...this may explain my low pressure? I would LOVE if this was the problem as this is a relatively easy fix compared to dropping the subframe and oil pan:


Any ideas on what the next step should be? Honestly I have been wanting to sell this car for months, but refuse to be shady and pass it on with a known problem. However I really need the cash and can't be dumping multiple grand into it...again...

I've been aggressively googling this issue and resolution has ranged from oil change only, pump replacement, oil squirters replacement, dont worry about it as long as pressure rises when you start driving, and any combination of the above. I don't mind doing the work etc if I knew a certain thing would fix it, but again I can't really be spending months and thousands of dollars troubleshooting, nor do I feel like selling it for a rock bottom price if it's just a dozen hours of labor and the cost of some oil squirters. I've dropped the subframe and pan a few times so I don't think it would take me all that long tbh...bang out in a weekend.

The fact that it was coming on randomly, then frequently under 900 rpm the other day, then 1k, then 1.5k...almost making me think the pump is trying to go have lunch with Jesus. The seemingly progressive pattern that's developing is making me think some mechanical part failure, either pump or CPV if it truly controls pressure at/near idle. Thoughts? What I don't like is I have seen people with this issue that have replaced the pump and it didn't do anything.

[TobyB]

Yeah, I hate to be the bearer, but that sounds like your oil pump is no longer doing its job...

the filter housing has a drain on the bottom that opens when you pull the filter.
It also has a drainback valve that fails, but that only affects startup.

sorry,

t

[moatilliatta]

Take the pump out and see if the woodruff key is sheared in the one channel of the pump. Or if you still have the oil pump nut.

[moatilliatta]

If you're lucky, motor is ok.

Would check rod bearings while pan is off and make sure no scaring under cam caps.

[diesekte]

Tore into the bottom end. Oil pump bolts holding it to the block were slightly loose. I think oil was squirting out between the pump and block instead of circulating into the block. Since I was there and had about 25 miles of potential oil delivery issues, I replaced the rod and main bearings. There were signs of mild contamination on a main bearing half shell or two. Rod bearings look almost pristine. Oil pump replaced with the "high flow" VAC unit.

Runs and drives great now. Light has been gone and stays gone. I definitely fixed the problem.