Box This Lap - Lime Rock Park

The track bug hit me hard after the last event with S2K Takeover so when I found out we were going to have another event at Lime Rock Park on a weekend, I couldn't say no. I had my first track day ever in 2006 at Lime Rock Park and hadn't returned since due to my cars always being too loud for that track but the Mugen exhaust is well within the sound limits of LRP so it was great to be able to return. 

Lime Rock Park - 4-2-2022

It was a bit on the chilly side but sunny so we were all set up for a nice track day especially since we had our own run group that wasn't too large so we had plenty of room to enjoy the track. I was mostly excited about testing my new tires, a set of Continental Extreme Contact Force. The first session went really well. The tires have a bit less peak grip than the Yokohama Advan A052 but remained consistent and very predictable lap after lap. The car was also a bit more playful at the limit and I found the balance to be quite good with just a bit of manageable oversteer at the limit. I ran 30psi front and 29psi rear cold. I may try lower pressures next time. 

Limp Mode

The second session didn't go as well. I started noticing that my oil pressure warning light kept blinking several times throughout my laps but looking at my dash, my oil pressure was always well at expected values of 70-80psi depending on load. Unfortunately, a few laps in, as I was going into West Bend, the car suddenly dropped out of VTEC and I had no power. I got off the racing line and checked my mirrors for any debris but saw nothing. My oil temp gauge was still showing good pressure but I couldn't get into VTEC anymore. Thankfully the pit in was only two corners later and downhill so I was able to pit in easily and I noticed the car behaving normally again. I got the car to grid and checked everything. No leaks and the car started and ran normally. Oil level was still good and I was able to drive around the paddock without issue as if nothing happened. I didn't bring a laptop to be able to view my camera footage to see what had happened but seeing as the car was running I decided to pack it up and go home just in case I had a real issue. The drive home itself was uneventful. The car drove perfectly at any gear for the 100-mile drive home though I was careful not to engage VTEC in case the issue was with the VTEC solenoid. 

Back home safe

When I got home I checked the GoPro footage to the exact moment when I lost power. I noticed the oil pressure warning light blink a few times despite the dash showing normal pressures (> 70psi) but you can see the car go into limp mode. I checked my tune and I have engine protection on to go into limp mode anytime the oil pressure drops below 25psi when I have more than 25% throttle and the RPMs are greater than 2000 so this is what must've tripped. Since the car was running normally I don't think it was related to my recent cam intake replacement or valve adjustment. Either I was having random and very brief real drops in oil pressure, enough to trigger the light but not long enough to register on my dash, or something was going on with my AEM oil pressure sender. 

Oil drained, new filter in

Today, I dumped all the oil out to check for anything unusual. It was debris-free and nothing was on the magnetic drain plug. There were no leaks anywhere. I double-checked the Mocal oil sandwich plate and it was a tad loose so I tightened it up but that was just likely from unscrewing the filter. I put in a new filter and torqued everything back down. 

VTEC solenoid upper gasket

I inspected the VTEC solenoid. The upper gasket was sealed and free of debris, same for the lower gasket and screen. There were a few specs on it but nothing of concern. I'll probably replace both gaskets with new ones while I'm already in there since these are now over a decade old years old but they look to be in good shape. 

VTEC solenoid screen is clear and unclogged

I didn't really think I had a VTEC solenoid problem after reviewing the video but I wanted to physically check for peace of mind. It was clear to me I never lost oil pressure so my current suspect is the AEM oil pressure sender. I already had a failure of my previous sender two years ago where I thought I had zero pressure when it was just the sender dying on me. 

Connector looks ok

The oil pressure sender connector looked ok. Nothing was loose and the seal was intact so it wasn't debris or moisture getting into the connector. I also didn't see anything physically wrong with the oil sender itself. 

Oil pressure sender

Given the symptoms, I suspect something is going on internally with this oil pressure sender. Although it does work normally under typical driving conditions, it may be occasionally sending momentary low readings to the ECU that's causing the engine protection mode to engage. I don't see, hear, smell or feel anything else physically wrong with the vehicle. If I had my tuning laptop at the track I could've actually just disabled engine protection, had it ignore the oil pressure value, and continued driving but it's one thing I actually don't want to disable as a safety net in case I actually do suddenly experience sudden oil pressure loss. I've got a new sensor ordered so I'll swap that in to see if it fixes the problem. Unfortunately, I can't reproduce this problem on the street even when I get into VTEC so I won't know for sure if it fixes anything until the next track day.