Hey all, I bought a GReddy kit for my 2005 S2000 and got it installed over the last few weeks. I finally got it back on the ground, and am having some odd boost issues. The main components are the OEM GReddy kit, EManage Ultimate w/ the GReddy AP2 tune, RC550 injectors, GReddy Type RS blow off valve, new NGK Iridium BKR8EIX plugs with a gap at .032". Boost is straight wastegate pressure only and i'm on the factory MAP sensor. I've got a 2.5" test pipe with an Innovate wideband tied into the EMU, as well as a Tanabe Medalion Touring cat-back exhaust.

The compressor assembly was disconnected from the hotside when i got it, so i clocked it and reconnected the wastegate actuator arm to the wastegate. I had some pre-load but I was concerned that if i overloaded it, i'd have overboost issues so i was conservative on the preload.

I had a quick test drive without the bumper or liners on and boost and AFRs seemed adequate, and i was building boost and the BOV was functioning, so I cut the test drive short to double check for oil leaks before putting everything back together again. I should have been more diligent before putting everything back on since i'm now having issues. While driving, boost is as expected, 3-4 psig, until around 5k rpms. Then boost begins to degrade until it drops to 0 psig. Further, I can't accelerate past about 7,000 rpms. The best way to equate the feeling is having a car at top gear on the highway but not having enough power to accelerate anymore. I didn't feel or hear any misfires, nor did I hear any knock.

Pictures from the logs are attached from the EMU. The first is the primary 2nd gear pull. 1 kg/cm2 = 14.2 psi, so 0.25 kg/cm2 is 3.5psi. You can see the increase in erratic readings after 5500 or so, but boost has already been dropping by that point. The second attachment is a highway mid-range rpm pull, 4th gear around 70mph. You can get a clearer picture of the boost degrading. The third log is another highway pull but in 5th gear so you can see at lower rpms the boost is steady.

I tested the BOV as well as the vacuum block and both are holding pressure. I blocked off the throttle body connection as well as the PCV and SAP ports on the intake tube and put 10 psig to it to check for boost leaks. I couldn't identify anything major besides what seems to be higher-than-expected bubbling through the oil: , but i'm not sure if this is bad enough to call the turbo seals bad since the kit isn't high mileage.

Before I pull a few pieces off to add more preload to the wastegate, I wanted to get the forums' input. Thank you all!


Front of Car

Driver Side

Passenger Side

2nd gear pull showing no boost at higher rpms

5th gear steady low to mid rpms

4th gear boost drops mid rpms

 

I put the car back up on stands today and adjusted the wastegate arm to nearly full-closed. It feels much better, and is mostly holding boost to fuel cut now.

The Airflow Input remains extremely violent, and trends with the sporadic boost readings from the MAP. The pressure reading shows an average of 0.5 kg/c2 (7.1psig), but the AEM 30-4406 Boost Gauge i have reads spikes at 6 psig in mid-range and falls to around 4-5 psig by fuel cut. The AFRs from the Innovate MTX-L fluctuate between 10.5 in the early and mid range up to 11.6 at the upper end of the rpms. Timing seems conservative, but i'm not looking to adjust it until i'm confident in the feedback.

The following is a log from a 2nd gear pull. Any feedback is welcomed/appreciated.