Diagnostic help needed! Hot film MAF and low oxygen adaptation.

[Danimal]

Update. I smoked the intake through the AOS connection on the plenum. I only had a leak at one of the boots for plenum that I reattached after cleaning the throttle body and a tiny bit from the top of the resonance tube hinge once I cranked the PSI up a bit on the smoke machine. Fixed the boot and reattached the AOS.

Then I smoked through the oil filler tube, but had a hard time sealing it off with plastic bags, rubber bands, and tape. I didn't see smoke come out anywhere.

After making sure everything was connected, I disconnected the battery for 10 minutes and did the e-gas learning sequence. Then it started right back up no problem.

However, while the SAI was running there was an exhaust rattling type sound that went right away as soon as the SAI kicked off. At first I was pretty worried, but it ran/idled perfect as soon as the SAI kicked off...so I'm a little less worried.

The only other issue is that the oil smelled a bit like gas. I'm not sure if its a leaky injector or just from the car running rich based on the error code. but it you put your nose over the filler tube, you get some stink. You have to get pretty close to smell it.

I took it on two 20 minute test runs around the neighborhood and highway. No error codes yet but I know it's too soon to tell if I am in the clear. There is definitely something going on with the SAI/exhaust. There is no exhaust smoke on start up or during driving.

I'm out of diagnostic time for a bit while we work on our house, but here is my current plan.

1. Back the car on race ramps, start it cold, climb under to see if there is something obvious going on with the exhaust.
2. Remove the engine cover, start it cold, and see if there is something obvious going on with the SAI.
3. Test the fuel pressure to see if the fuel pressure regulator is going bad. This is what caused similar fuel trim codes in of the "arrowhead garage" videos on youtube. He's got some helpful videos.
4. Possibly remove and clean the fuel injectors....does not sound fun, but could be good to do anyway.


Sorry, no time for pics right now, but I took a bunch.

[Danimal]

Had an about an hour to some more diagnostic work. Jacked up both sides of the car and banged along the exhaust from heard to tail pipe on both sides. It’s definitely the drivers side of the muffler, probably the top mount.

I took it on a 30 minute highway ride to run cycle the battery/fluids since it’s been sitting for awhile. No noise on start up, but some exhaust rattle at idle. Still no check engine lights, but I didn’t really push it.

[Danimal]

Another update. I've taken the car on 5-6 runs and the check engine light hasn't come back. However, I'm experiencing a slightly rough idle and slight hesitation around 4k (almost feels like power surges). Looking around I found someone on the pelican forums with the same issues.

https://forums.pelicanparts.com/boxster-cayman-forum/600891-bought-durametric-but-i-need-help-understanding-numbers.html

I checked my fuel trims and they are almost identical to what this person had. The fix for them was a new MAF. I'm going to order one and give it a shot.

Note: I also did the oil cap test. I took it off with the car idling. I was able to remove it no problem and the car immediately began to run poorly....so I think the crankcase vacuum is okay.

[Danimal]

Update: new Bosch MAF sensor is in and I reset the fuel trims. I’ve taken it on 4-5 medium trips and the fuel trims are now FRA 1.05 and RKAT -0.42 for bank 1 and FRA 1.02 and RKAT -0.42 for bank 2. A lot better than the 1.28 and -3 I had before.

I need a few more spirited drives before I declare victory. But it feels pretty nice!