Please look at my data log and tell me wtf is wrong with my sexy car - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

EJSS · 10-04-2021, 11:44 PM

Rough starts, intermittent misfires on all cylinders (but mainly cylinder 4), knock retard when I stab the gas, rough shifting.

WOT seems fine EXCEPT for the shifts at ~5800 rpm... The shifts (mainly 2nd-3rd) feels like it's slipping... the rpms drop and won't continue to climb for a second or two. Feel like slipping or like the throttle isn't obeying the pedal... Idk how else to explain it.

Please take a look at my data log, particulaly the 2nd WOT run. The pedal and throttle position fall out of sync for a minute. Really weird.

No codes. I changed spark plugs, checked plug wires, checked coils, checked exhaust for leaks, checked for vacuum leak, changed throttle body, checked grounds.

Any help is MUCH appreciated!

EJSS · 10-04-2021, 11:52 PM

Only mods are catless midpipes and z/28 air intake. No tune.

Street Demon · 10-05-2021, 03:48 AM

Get a tune......

EJSS · 10-09-2021, 11:20 PM

I brought it back to compete stock and it's still doing the same thing. Intermittent misfires on all cylinders and WOT shift feel loose, when the car upshifts the rpms go 4500~ it hesitates for a second before continuing to climb. Still getting knock retard almost Everytime I stab the gas. Misfires happen a lot in neutral or park when I rev to about 2k rpms. Manifold vacuum seems normal, stft are +/- 10%, ltft seem slightly biased toward the + side but stay under 5%.

Also, I changed my fuel pump 2 years ago but I noticed that when the car is off and I prime the pump, it shoots to 60psi and quickly drops to less than 10psi within a out 5 seconds. It holds 58psi while running though, idk what that's all about. Any idea would be greatly appreciated.

I don't want to tune the car right now as it may hide a potential problem that I'm having right now. I don't want to hide the problem I want to fix it.

11-Camaro · 10-10-2021, 10:58 AM

Are you running a 2 step? If so disconnect and see what happens.

EJSS · 10-10-2021, 04:53 PM

I dont even know what that is lol.
My car burned up the passenger side high-flow cat earlier this year and I never thought much of it but I wonder if the problem I'm having now is related to why the car destroyed the catalytic converter. I ended up putting my stock cats back on it a few days ago and the problem is the more or less the same.

eLeSthree · 10-15-2021, 07:13 AM

I noticed your logs only show 1 out of 4 o2 sensors and you say you melted a cat?

I would put it all back to stock, replace all 4 oxygen sensors and check the plugs and wires. use good fuel. re log.

EJSS · 10-18-2021, 07:46 PM

Just going to give this some closure for anyone who looks at it in the future...first some context:
Several months ago is when my shifting started acting weird, about a month after the nasty shifting my throttle position sensor went out and threw a code so I figured that was the culprit, so I replaced the throttle body, but the shifting still wasn't quite right, and it seemed to have gotten worse and worse over the last few months. I tried everything, went back to completely stock, tested for intake leaks, exhaust leaks, clogs, tested spark, fuel pressure, etc... Then I happened to look at the throttle body replacement procedure in the repair manual and noticed there is a "throttle/idle relearn procedure" that I never did. It doesn't seem to make sense that simply letting the car idle for 3 min, then off for a min, then idle again for 3 min would solve my problem but after going through the relearn procedure the car feels back to normal. So what can I say... It's only been a couple of days so far so maybe I'm speaking too soon but we'll see..

If you ever disconnect your throttle body for any reason, always do the relearn procedure!

10-04-2021, 11:44 PM	#1
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Please look at my data log and tell me wtf is wrong with my sexy car Rough starts, intermittent misfires on all cylinders (but mainly cylinder 4), knock retard when I stab the gas, rough shifting. WOT seems fine EXCEPT for the shifts at ~5800 rpm... The shifts (mainly 2nd-3rd) feels like it's slipping... the rpms drop and won't continue to climb for a second or two. Feel like slipping or like the throttle isn't obeying the pedal... Idk how else to explain it. Please take a look at my data log, particulaly the 2nd WOT run. The pedal and throttle position fall out of sync for a minute. Really weird. No codes. I changed spark plugs, checked plug wires, checked coils, checked exhaust for leaks, checked for vacuum leak, changed throttle body, checked grounds. Any help is MUCH appreciated! Attached Images

10-10-2021, 10:58 AM	#5
11-Camaro Drives: 11 Camaro SS, Ninja 1000, Santa Fe Join Date: Sep 2020 Location: Dallas Posts: 49	Question Are you running a 2 step? If so disconnect and see what happens. __________________ 11 Camaro TT SS. 14 1LE motor, full coilover, CNC ported LSA heads, stainless valves, dual springs, Comp 224 cam, Melling oil pump, AGP Garrett GTX30r's, 1400cc injectors, full 3" Magnaflow, dual Walbro 450lph fuel pump, ZL1 6L90 trans, trans cooler, Circle-D 3600, 3.91:1 Eaton Truetrac, line lock, Lingenfelter 2 step. Current boost - e85 814 RWHP.

10-15-2021, 07:13 AM	#7
eLeSthree Drives: 2011 Camaro SS 6sp Join Date: Nov 2016 Location: Drivers Seat Posts: 1,904	I noticed your logs only show 1 out of 4 o2 sensors and you say you melted a cat? I would put it all back to stock, replace all 4 oxygen sensors and check the plugs and wires. use good fuel. re log. __________________ 2011 Camaro SS---SOLD TMS Dart 427 FED M311s, ESS Tuning G4 Blower, DSX Triple FP Assembly, DSX FF, FIC1300, Mcleod RXT 1200HD, Edlebrock Pro Flo XT 1158whp 1017wtq. 2010 CTS-V A6 - "Stock" SOLD 630whp 658wtq 2024 F-150 RCSB 5.0 4x4 waiting for tunes...

10-04-2021, 11:52 PM	#2
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Only mods are catless midpipes and z/28 air intake. No tune.

10-05-2021, 03:48 AM	#3
Street Demon Drives: Camaro SS Join Date: Mar 2021 Location: Flo Posts: 17	Get a tune......

10-09-2021, 11:20 PM	#4
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	I brought it back to compete stock and it's still doing the same thing. Intermittent misfires on all cylinders and WOT shift feel loose, when the car upshifts the rpms go 4500~ it hesitates for a second before continuing to climb. Still getting knock retard almost Everytime I stab the gas. Misfires happen a lot in neutral or park when I rev to about 2k rpms. Manifold vacuum seems normal, stft are +/- 10%, ltft seem slightly biased toward the + side but stay under 5%. Also, I changed my fuel pump 2 years ago but I noticed that when the car is off and I prime the pump, it shoots to 60psi and quickly drops to less than 10psi within a out 5 seconds. It holds 58psi while running though, idk what that's all about. Any idea would be greatly appreciated. I don't want to tune the car right now as it may hide a potential problem that I'm having right now. I don't want to hide the problem I want to fix it.

10-10-2021, 04:53 PM	#6
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	I dont even know what that is lol. My car burned up the passenger side high-flow cat earlier this year and I never thought much of it but I wonder if the problem I'm having now is related to why the car destroyed the catalytic converter. I ended up putting my stock cats back on it a few days ago and the problem is the more or less the same.

10-18-2021, 07:46 PM	#8
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Just going to give this some closure for anyone who looks at it in the future...first some context: Several months ago is when my shifting started acting weird, about a month after the nasty shifting my throttle position sensor went out and threw a code so I figured that was the culprit, so I replaced the throttle body, but the shifting still wasn't quite right, and it seemed to have gotten worse and worse over the last few months. I tried everything, went back to completely stock, tested for intake leaks, exhaust leaks, clogs, tested spark, fuel pressure, etc... Then I happened to look at the throttle body replacement procedure in the repair manual and noticed there is a "throttle/idle relearn procedure" that I never did. It doesn't seem to make sense that simply letting the car idle for 3 min, then off for a min, then idle again for 3 min would solve my problem but after going through the relearn procedure the car feels back to normal. So what can I say... It's only been a couple of days so far so maybe I'm speaking too soon but we'll see.. If you ever disconnect your throttle body for any reason, always do the relearn procedure!