IW STi Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
656 Posts
Discussion Starter · #1 ·
Hello everyone, I was hoping someone could give me a suggestion on what is going on with my cars engine. A few days ago while I was driving at 2k rpm with my oil pressure at 75psi (normal for my engine) suddenly dropped to 55psi without a change in rpm and my check engine light came on flashing P0011 and P0021 both having to do with camshaft timing. As a precaution I changed my oil and drove the car again for the next few days, and today It did the same thing dropped down to 55psi at 2k. One weird part is the oil pressure at idle is unaffected at 21 psi.

There are 3 main things that has happened the check engine light / rough idle / drop in oil pressure. I am willing to bet they are all linked together however I am not sure what could be the cause. Their are some possible scenarios that I can think of that could of caused this....

1. I recently installed a IAG Oil pan on my car and prior to the install it never had these symptoms or did anything weird. Part of the install involves spacing the oil pickup further down into the pan, maybe I installed the spacers wrong or something came loose causing a poor seal where the pickup meets the block messing with my oil pressure? I do have a IAG oil pickup as well.

2. This is a new engine going through a break in at about 1,500 miles on it so far. It is also the first engine I built myself so maybe their could of been an issue with my assemble.

3. There is a possibility that my oil pressure gauge is failing but it has normal OP at idle and only drops while cruising so I am not sure how effective testing it with another gauge would be.

Does anyone have any idea on how I should diagnosis this?
 

·
Registered
Joined
·
5,622 Posts
I would start by verifying what you're seeing with a mechanical gauge. They are cheap, fairly accurate, and will immediately let you know if you have an oil pressure sender or gauge issue... or if you actually have a pressure issue to diagnose.
 

·
Registered
Joined
·
109 Posts
Definitely make sure the gauge is working properly as killerb stated. I ran into something of the same. No codes came up, but on my new build it was clogging the oil filter up (went into bypass). That made my oil pressure drop. Try swapping out the oil filter and cutting the old one apart (filter probably clogged). My oil pressure went back to normal just from the filter swap.
 

·
Premium Member
See about
Joined
·
6,071 Posts
1) betting on #1 but a mechanical gauge will confirm.

2) rough idle separate issue
 

·
Registered
Joined
·
656 Posts
Discussion Starter · #5 ·
Going to give an update...

I looked around the car and noticed that my fuel injectors were not in line with the fuel rail, they had been pulled out of alinement. (probably when I lifted the motor to install the oil pan I forgot to unplug the main harness and it pulled on them my mistake). I made sure they were straight and the car's idle issues were gone.


Now I hooked up a mechanical oil pressure gauge to the top port by the alternator and on cold start it read 90-95 psi and at idle with my oil temp at 140F the OP was about 33 psi. Which is not 100% in line with my defi OP gauge but the analog gauge seems to be about 5-10 psi higher then the defi so maybe I could use a sensor replacement or gauge replacement.


Also When I had the gauge set up my car threw two codes and the poor idle came back, the codes were P2089 / P2093, I did a quick search and turns out those could be related to electrical grounds. Hopefully the issues I am encountering are related to an electrical issue and not a more serious mechanical issue.
 

·
Registered
Joined
·
5,622 Posts
You might have pulled a ground when you moved the engine. Or maybe one, or more, are corroded.

The GDs were also notorious for having poor grounds right from the factory. I myself made a custom grounding kit using welding ground cable. You used to be able to buy grounding 'kits' also. Might be worth looking into. I know on my car it smoothed the idle and the RPMs didn't dip nearly as much when the headlights came on, blinker dip disappeared, etc. It wasn't night and day, but a very noticeable improvement. I'm certain there are old threads in here that cover the topic quite well. Might be worth a read.

If you have an air compressor, you can quickly verify how accurate your mechanical gauge is if you have the right combinations of fittings. Typically, even the cheapo mechanical gauges are far more accurate than modern stepper electronic gauges. Just as an extra level of precaution, I would drive around some with the mechanical gauge and make sure you get the oil well into the normal temp range, just in case you have an internal high temperature bleed. I used to run along line and just set the gauge in the center console where I could see it. It's super janky, but works very well for troubleshooting.
 

·
Registered
Joined
·
1,148 Posts
You're echoing what I found with both my Defi oil pressure gauge and my Tanabe oil pressure gauge.

My mechanical OP reading was 10-12 psi higher than the electrical one.
 

·
Registered
Joined
·
1,148 Posts
You might have pulled a ground when you moved the engine. Or maybe one, or more, are corroded.

The GDs were also notorious for having poor grounds right from the factory. I myself made a custom grounding kit using welding ground cable. You used to be able to buy grounding 'kits' also. Might be worth looking into. I know on my car it smoothed the idle and the RPMs didn't dip nearly as much when the headlights came on, blinker dip disappeared, etc. It wasn't night and day, but a very noticeable improvement. I'm certain there are old threads in here that cover the topic quite well. Might be worth a read.

If you have an air compressor, you can quickly verify how accurate your mechanical gauge is if you have the right combinations of fittings. Typically, even the cheapo mechanical gauges are far more accurate than modern stepper electronic gauges. Just as an extra level of precaution, I would drive around some with the mechanical gauge and make sure you get the oil well into the normal temp range, just in case you have an internal high temperature bleed. I used to run along line and just set the gauge in the center console where I could see it. It's super janky, but works very well for troubleshooting.
I taped mine to the windshield haha. It was so ghetto, but it worked.
 

·
Registered
Joined
·
656 Posts
Discussion Starter · #9 ·
I poked around on the car some more today and made two observations,

1. My oil pressure gauges sending unit plug seemed to have a poor connection which I need to look into to rule out wether or not it is reading low or giving a false reading.

2. My check engine light and rough idle problems may be related to a wiring issue. For example my I took a wire and connected it to my batteries negative terminal then touched it to multiple ground contacts with the engine running. When I connect that wire to the drivers side ground point on the intake manifold my rough idle smooths out and when I remove the wire from the point the rough idle returns. What I am trying to think is wether or not that means I have a poor connection with the ground point or a issue deeper in the engine harness with a wire? I do not have corrosion and the point is sanded down on the IM the contact is metal on metal so on paper it should be a good ground. Or as mentioned while lifting my engine to install my oil pan and forgetting to unplug the wiring harness have I puled a wire loosing that grounding point.

I do not know a lot about wiring and multimeters but I suspect Ill have to invest in one to help me figure this out.
 

·
Registered
Joined
·
656 Posts
Discussion Starter · #10 ·
Bumping this up hoping some electronic gurus are in here. As mentioned before when I add a additional wire to the engine harness ground point on the driver side of the intake manifold the car runs noticeably better. With that being said I bought a multimeter to check the wires continuity. I believe those 4 wires ground out the coil packs; the passenger side coil pack wires check out to .001 on the multimeter, when I check the driver side coil pack wires they both read .027. I do not know a lot about multimeters or wiring all together so this may be a obvious question to some, but is the higher reading on the drives side indicate a issue with those wires or is it normal?
 

·
Registered
Joined
·
5,622 Posts
Not an EE by any means, but as I said before, GDs had poor grounding issues. Over time and multiple owners they don't tend to get better, but worse. Search on here and you'll find more detailed info, kits, and even DIYs on how to resolve it.
 

·
Registered
Joined
·
1,148 Posts
Here's a good reason to verify. This happened to me last week:

Driving around I noticed my OP wouldn't get above 55 psi when hot. Coming to a stop the oil pressure would dip really low and when i got home, it was sitting at ~2 psi according to my Defi gauge

62991



You can see my oil temp(behind the pressure gauge) was sitting at ~190ish(temp sensor in KB oil pan) At this point, the engine should be knocking. I shut the car off, wait about 30 minutes and magically gained 20 psi oil pressure

62992


I hooked up my mechanical oil pressure gauge, and went for a drive.

62993


Its kinda hard to see, but this was a video and recorded at 190 degree oil temps after a 10-12 mile spirited drive

Warm Idle: ~19 to 20 psi
62994


3000 RPMs
62995


So obviously the Defi gauge is not reliable at all.
 

·
Registered
Joined
·
656 Posts
Discussion Starter · #13 ·
Hey guys going to give an update with good news, it turned out to be a broken AVCS Cam gear. Since my last update I had done some more of the usual things to try and clear up the P0021 code and none of them worked. I even bought a new engine harness hoping it was something electrical and that did not do anything either. I Did what KillerBee suggested and made a grounding kit along with cleaning up the existing grounds on the car (definitely recommend everyone doing that). Which I did notice the car seems to be happier after doing that but still the P0021 code existed.

While doing all of the above I noticed on my accessport my "AVCS In. Left" was always at zero, my right had always functioned properly but the left was stuck. I was starting to think it was the gear I just was not sure how or why. But there were two possibilities that I was wondering caused internal damage to the gear.

1. A week prior to making the original post in this thread I had removed the left AVCS gear and while reinstalling it I used my electronic torque wrench set to the proper 45 degree angle. As I was tightening the gear down my wrench turned off and turned back on mid turn. At the time It had seemed to of remembered the angle so I continued with tightening it. Fast forward to now I was thinking that I had overtightened the gear causing it to bind or something.

2. Up to this point I had been using Company 23 tools to install and remove the cam gears. Turns out when you apply the torque to tighten or remove the gear the Company 23 tool will hold the outside of the gear while the 10mm bolt will apply the force on the center of the gear. There are pins or something inside the gear that ends up taking all of the force when doing this which can damage the internals. The Oem subaru tool to hold the gear holds it in the center section not the outside section like the Company 23 tool. This is may not be the best video to explain what I am talking about but it does give an explanation of how the tool can cause damage to the gear internally.


So after all of that I then bought a new AVCS gear, installed it and "AVCS In. Left" now functions just as it should. I noticed that my oil pressure with a functioning AVCS gear is now higher compared to the old gear being stuck at 0. It has gained about 20psi.
 

·
Premium Member
See about
Joined
·
6,071 Posts
Thanks for posting.

Live and learn :)
Good job figuring it out too!

Added: Not really understanding what damage allowed a high oil flow.
 
1 - 14 of 14 Posts
Top