Hitting a wall at 4500rpm [SOLVED]
Posted: Sat Sep 12, 2020 10:57 am
Gents,
Hello! Long time lurker, frequent searcher. Glad to be making a post. I'm in need of some help... haha
I recently got around to turboing my KA. I had to go through some standard troubleshooting issues, but I've got it running really well.... EXCEPT, I can't seem to push it past 4500rpm!
Car specs: KA24DE (S13, OBD1), Nismotronic ECU (running MAP GM3bar / IAT), LC-1 WB, OEM 550cc injectors (refurbed), ISR 255lph pump, Circuit Sports FPR, knock-off ssqv BOV, EMUSA Cast manifold, Precision WG w/ 10psi spring, NGK plug wires, NGK BRK7E plugs (.28 gap), Garrett T3 .48, running PCV to catch-can to preturbo intake, Valve cover vent just has filter, Mishimoto FMIC,
Things I've checked/additional info:
-Mapping all fuel/timing trims during a pull. Nothing I can see is trimming either one.
-Mapped knock voltage. Looks OK I think. 1.4ish under load.
-Battery voltage is consistent.
-I tried the coil hotwire mod
-AFRs are right around 12 when it starts stumbling, so it doesn't appear to be a fuel map issue.
-Put a camera on FPR gauge during a pull. Looks like its 1:1 like it should be. No loss of pressure at 4500rpm.
-Timing set to 20deg at idle. Timing matches FIGNV in Tunercode.
-Replaced fuel filter, pump sock, plug wires, plugs, cap/rotor, coil, O2 sensor (calibrated after install)
-Boost leak check looks OK. Shoots right up to 10PSI
-All injectors reading 11 to 12 ohms.
-I tried tightening the BOV all the way. I thought it might be chattering. No change.
Things I haven't done:
-I have not done a cyl leak down test. This engine has not been rebuilt. Would a bad piston ring cause this issue? Car runs great all the way up to this point.
-I've got some 370cc injectors. I thought I might try those. Maybe I've got an injector sticking at higher rpm (not even sure if that's a thing, but I'm to the point where I'm grasping).
-The only other thing I thought I might try was swapping ignition modules. The way I understand it, they either work or they don't, but again, grasping.
-I've got the timing map set up to retard about 1 deg per psi when in boost (5psi = 15deg). My set up is rather mild. I wasn't sure if that was overdoing it and maybe I need to add some timing back?
Other notes:
The turbo is only hitting about 5psi by 4500rpm. This seemed unusual to me. This is my first turbo project, but I wasn't expecting that much lag. Very minimal shaft play on the turbo (journal bearing). I was told by the seller that it's a rebuilt .48 / 50 trim. I didn't measure the wheels to confirm. I think this particular spec is pretty common for KA builds. So, I was surprised that the boost was hitting that late. Not sure if this has any bearing on my current issues, but thought it might be worth mentioning.
Apologies if the post format is hard to read.
Any help would be great.
Hello! Long time lurker, frequent searcher. Glad to be making a post. I'm in need of some help... haha
I recently got around to turboing my KA. I had to go through some standard troubleshooting issues, but I've got it running really well.... EXCEPT, I can't seem to push it past 4500rpm!
Car specs: KA24DE (S13, OBD1), Nismotronic ECU (running MAP GM3bar / IAT), LC-1 WB, OEM 550cc injectors (refurbed), ISR 255lph pump, Circuit Sports FPR, knock-off ssqv BOV, EMUSA Cast manifold, Precision WG w/ 10psi spring, NGK plug wires, NGK BRK7E plugs (.28 gap), Garrett T3 .48, running PCV to catch-can to preturbo intake, Valve cover vent just has filter, Mishimoto FMIC,
Things I've checked/additional info:
-Mapping all fuel/timing trims during a pull. Nothing I can see is trimming either one.
-Mapped knock voltage. Looks OK I think. 1.4ish under load.
-Battery voltage is consistent.
-I tried the coil hotwire mod
-AFRs are right around 12 when it starts stumbling, so it doesn't appear to be a fuel map issue.
-Put a camera on FPR gauge during a pull. Looks like its 1:1 like it should be. No loss of pressure at 4500rpm.
-Timing set to 20deg at idle. Timing matches FIGNV in Tunercode.
-Replaced fuel filter, pump sock, plug wires, plugs, cap/rotor, coil, O2 sensor (calibrated after install)
-Boost leak check looks OK. Shoots right up to 10PSI
-All injectors reading 11 to 12 ohms.
-I tried tightening the BOV all the way. I thought it might be chattering. No change.
Things I haven't done:
-I have not done a cyl leak down test. This engine has not been rebuilt. Would a bad piston ring cause this issue? Car runs great all the way up to this point.
-I've got some 370cc injectors. I thought I might try those. Maybe I've got an injector sticking at higher rpm (not even sure if that's a thing, but I'm to the point where I'm grasping).
-The only other thing I thought I might try was swapping ignition modules. The way I understand it, they either work or they don't, but again, grasping.
-I've got the timing map set up to retard about 1 deg per psi when in boost (5psi = 15deg). My set up is rather mild. I wasn't sure if that was overdoing it and maybe I need to add some timing back?
Other notes:
The turbo is only hitting about 5psi by 4500rpm. This seemed unusual to me. This is my first turbo project, but I wasn't expecting that much lag. Very minimal shaft play on the turbo (journal bearing). I was told by the seller that it's a rebuilt .48 / 50 trim. I didn't measure the wheels to confirm. I think this particular spec is pretty common for KA builds. So, I was surprised that the boost was hitting that late. Not sure if this has any bearing on my current issues, but thought it might be worth mentioning.
Apologies if the post format is hard to read.
Any help would be great.