SR20 post-dyno touch up

[pacotaco345]

Hello!

I've had a pnp s15 link on my car for a while now (s13 w/s13 SR). The engine is 10.5:1 comp, bottom mount gtx2560 with HKS step 1 cams.

When I initially got the car running before I could get it to a tuner I trusted, I street tuned the car and got the AFRs pretty dialed, timing was intentionally left conservative because of the CR, and even though the car is setup for flex fuel I only ever ran it on E85 - but I was running into injector duty cycle warnings. When I street tuned it the car had a walbro 385 and ID1050, which I thought should've been plenty for fuel. The stock 5/16" hard line under the car was replaced with 3/8". I drove the car like this with no issues (other than duty cycle warnings) for 6 months.

When I finally got the car on a dyno with a tuner, I replaced the fuel pump with a walbro 525, and injectors with ID1300s. Base fuel pressure was turned up to 4 bar. The car was tuned for flex fuel (93 pump and e85) and made 400 wheel and change at 19 psi. I never really bothered to look back at the tune after that or paid too close attention to the wideband.

Fast forward another few months and I finally got the car out to a drift event and if I ever clutch kicked the car into a corner high load, mid-high rpm in third gear the car would hesitate, break up, then eventually drive through it as if everything was fine, almost like I was clutchkicking the car into a part of the VE table that was never mapped. Drove around the problem for the rest of the day and started to look into it when I got home.

Pulled the plugs, they looked normal. Did a few pulls on the street and noticed the car was running relatively lean under WOT (.9 ish lambda instead of the .82 target). I took a peek at the VE table as a result and realized the VE table was only touched in the narrow window the car operated in on the dyno. I'm no professional tuner, but I understand what VE is, how an engine works, and what changes I am making to the tune make to how the engine operates. I spent an afternoon richening the lambda target (as I'd rather be safe than sorry), correcting the VE table, and smoothing it out overall. I still have some fine tuning to do but the car runs much smoother and consistent in AFRs now in general. It does still hesitate (though not as bad) if I clutch kick the car under conditions similar to what I mentioned above.

That's a lot of background to get to my questions:

1) What does a typical spread in %VE look like from light load (0-40 kpa MAP) to full load (250 kpa MAP). I currently have about a 35% spread depending on RPM, but with no access to a dyno I don't really have a responsible way to get into high rpm, low load parts of the VE table.

2) Any ideas on what else may be causing the car to breakup under these conditions? My immediate thought was unmapped parts of the VE table but I'm sure there's other possibilities I could check as well.

3) When I log with my laptop it disconnects under high rpm/high load, then reconnects at the end of the pull, rendering my logs useless. This forces me to keep one eye on my dash on one on the... yeah... while I'm doing WOT pulls. It works, but it's not ideal. Has anyone had this problem and are there any solutions?

If you made it this far thanks! I've attached lambda target tables and VE tables from before and after I made my edits.

Original Lambda.lte Original VE.lte Corrected Lambda.lte Corrected VE.lte

[Adamw]

It would be better to attach the log and tune, tables arent useful without some context to how they are being used.

For the connection issue, the first check would be that it has resistor spark plugs.  If it is an older G4X it maybe able to come back to Link for a modification to the USB circuit that helps in cases where the connection is flaky.  There is also an updated USB cable with ferrite beads.  Note you have lots of ECU logging capacity in G4X, set it up and use it, you dont need a laptop connected then and it is recording all the time.  

 

[pacotaco345]

I've never tried the ECU logging function before... I'll try and get some done this weekend.

I just googled what a resistor spark plug is lol.. I have the standard copper NGK BKR7E, I think those have a resistor in them, correct? What constitutes an "older" G4X? I got mine in September of '20

[Adamw]

Yes the R in the spark plug number usually means it is a resistor type.

 

51 minutes ago, pacotaco345 said:

What constitutes an "older" G4X? I got mine in September of '20

I dont know the change over point off the top of my head so best to contact tech support with your serial number to confirm.  Purchase date doesnt mean much as it could have been sitting in one of our warehouses or the dealers stock for some time.  

 

[RyanD06]

On 12/10/2021 at 10:16 AM, pacotaco345 said:

I've had a pnp s15 link on my car for a while now (s13 w/s13 SR). 

2) Any ideas on what else may be causing the car to breakup under these conditions? My immediate thought was unmapped parts of the VE table but I'm sure there's other possibilities I could check as well.

3) When I log with my laptop it disconnects under high rpm/high load, then reconnects at the end of the pull, rendering my logs useless. This forces me to keep one eye on my dash on one on the... yeah... while I'm doing WOT pulls. It works, but it's not ideal. Has anyone had this problem and are there any solutions?

Just doing a quick search and its Interesting you mentioned these funky issues. I have a pnp S15 on a s13 setup. Im running the same plugs.

My car too breaks up at about 4k and manages to push through it.. IT ALSO drops out/loses comms while logging under high rpm/load as well.

Did you have any resolve with this issue?