Hondata

I have a mostly stock RSX with a k20z1 (RBC intake manifold, CAI, race header, HKS exhaust). I just took the car to get Dyno tuned and although it runs great up to 8K RPM, it has been fuel cutting sometimes before the 8600 RPM limiter we have set. Before the car used to run out to 8600 consistently. My tuner is pretty widely respected so I didn't think it was something with the tune. I was surprised though to see Lambda close to 1.0 at ~7500 - 8500 RPM in my datalogs. I think the car is hitting lean protection before my limiter but I'm no expert.

I noticed the injector parameter goes to zero when it "fuel cuts" and Lambda shoots way up. My understanding is my AFR should stay 12.5 ish through redline or at least not go above 14. What might this be? Could it just be to little fuel in the tune? I'll attach a datalog sheet and tune. I could only get 1 and 2 pulls in my area but if need be I can get some highway 3 and 4 pulls.

A couple other things to note:
- I did my best to wire the grounds as Hondata suggests and with adequately thick wires.
- I had an issue with my ELD before and that has been replaced (tuner said the voltage looked fine throughout all the pulls)

Any help or opinions would be much appreciated

What time stamp in the datalog are you seeing the issue?

Right sorry thats a long file. Heres a list of the pulls:

Pull #1:
- (12.407) Start Time
- (14.063) 1st Gear running lean
- (17.782) 2nd Gear running lean

Pull #2:
- (97.329) Start Time
- (99.625) 1st Gear fuel cut (8380)
- (102.875) 2nd Gear fuel cut (8150)

Pull #3:
- (152.829) Start Time
- (154.266) 1st Gear running lean
- (158.125) 2nd Gear fuel cut (8600)

Pull #4:
- (232.641) Start Time
- (234.625) 1st Gear fuel cut (8070)
- (238.516) 2nd Gear fuel cut (8550)

Pull #5:
- (289.172) Start Time
- (290.329) 1st Gear fuel cut (~8000)

There are more but thats enough to show the point. The car is hitting a sluggish kind of "OEM" feeling cut sometimes below 8600. This is not like the spark cut limiter I'm used to where it doesn't feel like I'm stomping on the break.

IT appears that you are letting off the throttle in these instances, as you can see the TPS drop then the fuel shuts off. This looks completely normal.

First, thanks so much for your input. I still shouldn't be at Lambda = 0.95 at 100% throttle, 8K RPM though. Right? I'm wondering if there is a TPS issue going on. I do have very hard engine mounts.

Also how about the pull attached. This was one of the last ones (starts to be more noticeable when fully warmed up). I know for sure my foot was buried in the floor and it completely lost power at the top end. Looks like around 8200 here you can see TPS is at 100% and it cuts out.

I'm looking at actual datalogs, not spreadsheets.

Minor improvement: set the acceleration smoothing retard to -100% everywhere

Major improvement: tuning looks off. Injector size does not match injector dead time. High cam fuel tables peak at 7000 rpm, whereas 8000 rpm would be more typical. Multiple spurious values in the fuel tables and overlapping lines.

Thank you I agree. I definitely need more fuel up top. I'll double check my injectors (came with the car so I had to look up size)