Oil pressure drops to zero after a cold start?
 

Last Saturday I installed the Innovate Motorsports 3852 MTX Digital Series Dual Function Oil Pressure and Temperature Gauge Kit on my modded FRS. Since then I have noticed that after a cold start that my oil pressure would appear to drop to zero at around 3,000 rpm and sometimes at around 2,500 rpm.

Here's a video that I took with my camera phone after work before driving home. The car is parked and not in gear for the vid but the same thing happens when driving.

[ame="https://www.youtube.com/watch?v=jwYgi7c9Pmw"]Oil pressure drops to zero on cold start - YouTube[/ame]


Any ideas as to what is going on here? :iono:

This only happens when the engine oil is still cold. Once it has warmed up the oil pressure values behave as one would normally expect. You can check my build thread in my sig for my list of mods, but any relevant mods would most likely be my fm oil cooler with a mocal thermostatic sandwich plate, a Mishimoto MMOP-TPS Oil Sandwich Plate Adapter and an Innovate super charger.

https://dl.dropboxusercontent.com/s/...2014.13.22.jpg
https://dl.dropboxusercontent.com/s/...2014.13.01.jpg


The setup my look a little goofy but until now I thought it was working fine. The car has behaved fine for the most part on both the streets and at the track. I've had the sandwich plate adapter and sensors installed now for a few weeks. In that time I have tracked the car at Streets of Willow at Willow Spring Raceway. If you're unfamiliar with that track you can check it out on Gran Turismo 6 :D

I'm not losing any oil that I am aware of and the car feels no different than before. When I first installed the gauge and saw the pressure drop to zero all the time when revving to 3,000 I thought that I had a defective unit, but after the oil warmed up everything appeared fine. I don't know, maybe I do have a bad unit, but it's weird that it always happens at around 3,000 rpm.

I normally drive my car under 4,000 rpm due to an annoying rasp that starts up at that range. On cold starts I usually keep the rpms under 3,000, but in the mornings the pressure drops to zero sometimes at around 2,500 rpm. I live in a hilly area so short shifting at 2,000 rpm feels terrible and my oil doesn't usually get up to temp until I'm about 3 blocks away from work. So for the most part I'm really babying the car.

Is anyone else seeing this weird pressure drop? I can't imagine that this is normal.

I'm willing to bet you're exceeding the pressure range of the gauge and it doesn't know what to do so it goes back to zero. I've heard these engines when cold exceed 125psi oil pressure but I don't have a gauge to verify

I have same gauge, have never seen that behavior. Anything above 100, pegs at 100. Will be interesting to see if it is something electronically wrong with gauge/sender or actually oil cooler.

wow, thanks for the quick reply :)

You might be right. I hoping that someone with an oil pressure gauge like mine or similar (i.e. a max psi value of 100) can perhaps verify by checking to see if they notice the same weird behavior. I'm actually not too pleased with this gauge anyway. After installing it and seeing it in use I immediately wished that I went with a dual gauge that includes a readable temp value instead of just some lights. I guess it's like they often say, you get what you pay for.

For the temp, learn what each color interval means (set them up to your liking) and then know what each led increment means (e. g. each light means +5 degrees).

I set mine to 200 last green so first yellow is over 200, good to trash the car. Each increment yellow is + 4 degrees.

Another quick reply. Man this forum is awesome.

Thanks for the info. This is what I was afraid of. Perhaps I do have a bad unit. I guess if anyone else noticed this they would've posted something already.

Oh, but then again I didn't really do an extensive search before my post :bonk:

I mainly just found stuff about normal oil temps and pressures.

EDIT:

Oh, good to know. Thanks :w00t:

I new what the temp ranges were for the colors but I didn't know you could set the actual increment values as well. That's not as bad as I thought then.

But I wonder why the pressure is dropping to zero?

Man, that gauge would drive my peripheral vision utterly insane within twenty seconds. If they're gonna use a really bright, large, digital readout, they should at least make the update frequency like once every 3/4's of a second or something. With the numbers changing at that pace it just looks like the thing is flickering.

Could you maybe use one of those smartphone apps and OBD wifi adapters to get another pressure readout and see if that matches the gauge?

It's really not as bad as the video makes it out to be. In fact I don't even notice the flickering. Actually the flickering looks worse when captured using my gopro, but then again the gopro also make my stereo head unit look like it's flickering badly.

EDIT:
I actually do have a blutooth OBDII scanner and the torque app, but I am unable to get an oil pressure reading from it. I also do not trust the oem oil pressure sensor due to an incident that I had with one of my oil cooler lines popping off once and my car losing about 6 qts of oil without a single peep from the ecu. No check engine warning light or anything. Hence why I purchased the gauge and sandwich adapter.

That sounds reasonable. One way to check is to put a volt meter on the pressure Out terminal on that pressure sensor and watch it while watching the gauge in the car.
If you are correct the voltage will climb until it drops off adruptly.
This would just mean that you do not have a defective gauge.

Also the other terminal on that unit might be a low pressure switch (depends on the model).
If so, you could monitor that with a meter and see if you get continuity when the gauge reads zero.
That would mean a real pressure drop.

COuld you have your pressure gauge hooked in somewhere that gets no pressure as the thermostat switches??

On my racecar, I have a mechanical pressure gauge and a VDO electric one.
The mech was just in case I had an electrical probelm and couldnt trust the VDO during breakin.

More useful information and advice. Thanks!

I don't currently have a volt meter, but now I know that I should. So I'll give these two methods a shot.

As for if the gauge is hooked up near a no pressure area as the the thermostat switches, well... I dunno. I have the sensor installed on a sandwich plate that is in series with the thermostatic oil cooler plate, so it's possible. If I were to take a 50/50 guess just by looking at my pics above I would say, no?

But if the answer was Yes then wouldn't that mean that the switch is activating every time I hit 3000 rpms. That doesn't sound right to me. Honestly though I really have no idea.

I honestly felt like I could get by with a cheaper gauge like this one because I only track my car about 6 times a year. Right now it's primarily a street car and I didn't think that I would be pushing the car too hard on the streets to warrant race-level gauges and equipment. However, I'm starting to realize that one doesn't necessarily have anything to with the other. Only that when racing at the track (or whenever you are at speed) you really want to be able to trust your car and equipment, because there is definitely less room for error.

Ok, so I finally got a multi-meter to check my pressure sensor along with my gauge. However, the volt meter readings are as confusing to me as the gauge readings.

Here's a vid of my volt meter readings. Watch with volume to see the voltage change as I rev up the engine.
[ame]http://youtu.be/obc4J8yojFA[/ame]

I was only able to get a few revs in before the gauge stopped reading zero.

When revving to 3,000 rpms the multi-meter would display OL (over limit). The weird thing is though that as I would rev up the engine the meter would show the voltage drop before getting the OL symbol. From what I can see, the behavior from the meter and the gauge are both the same. The only difference is that when holding 3,000 RPMs, the gauge would read zero while the meter read 3.69 volts. At idle and when building revs to 3,000 the meter measurements were in mili-volts (mV). Only after hitting 3,000 revs and getting an OL on the meter would the measurements change to volts.

I'm still confused by what I saw, but my best guess is that since the meter displayed 3.69 volts when holding the engine at 3,000 then the pressure really isn't dropping. However, I'm still unsure about this because the meter did clearly show the volts drop when building up to 3K.

On my final rev to 3K the gauge did not show the pressure drop to zero, nor did the meter display OL or 3.69 volts. Instead the meter read 0.001 volts and the gauge read 100. I do not know what to make of that. According to the software by Innovate that came with my gauge, the sensor reads 0 to 5 volts- where 0 volts is 0 psi and 5 volts is 100 psi. The only time I saw a reading over 1 volt was when the gauge read zero and the meter read 3.69 volts. The rest of the time the measurements were in mV.

Ol on my fluke meter means an open circuit.

I can't see from the angle. Where did you hook the leads?

I connected the leads to the output terminals on the pressure sensor.