ProjectBroke
10+ Year Contributor
- 60
- 6
- Aug 20, 2011
-
Indianapolis,
Indiana
Hi all,
Currently messing with my brother's 98 GSX. We are running an EVO 8 ecu with 9653 Rom. We have an issue where hitting 5k+ will start to breakup/miss. On or off boost, doesn't matter. I can vary the fuel from 11.1-12.4 with no change.
I have noticed one thing that helps, going lean. Running a 13+ AFR (E85) causes the break up to disappear. Obviously this is too lean to run normally, Is this simply the fuel overpowering the spark?
We have tried:
93 or E85
No Boost leaks
New plug wires,
New plugs (BR8ES @ .023)
New PTU
More timing,
Less timing
Less boost
More boost
Tested the Coil pack
Added Grounds
Changed Cam Sensor
Any ideas are appreciated. I don't have logs on this PC, however they don't show anything abnormal. TPS at WOT is 93%, 10.8% at idle. AFR and Injector cycle stays steady.
1). Any boost, vac, or exhaust leaks?
Tested to 35 PSI no leaks.
2). Verified mechanical timing?
Everything is aligned
3). Verified base timing?
5*BTDC
4). Ignition system
COP or Stock Coil: Stock
Wire brand and Age: TAYLOR Race Wires 1 month old
Spark Plug brand, type and Gap: NGK BR8ES 0.023
5). Motor health (Compression Test)
Cylinder 1:150
Cylinder 2:150
Cylinder 3:145
Cylinder 4:150
6). Performed basic throttle body adjustments?
Idle Switch: Adjusted
Throttle Cable: Like it should be
TPS: 0.63 volts closed
7). Compression ratio
Assumed Stock
8). Any known bad sensors or brittle wiring?
Nothing that I know
9). Any DTC/CEL codes?
Nothing
10). Electrical system
Car off (not running): 12.2
Car running: 13.5-14
11). Base fuel pressure and injector values
Base Fuel Pressure: 43psi
Injector Size (cc/min):1120cc
12). Properly calibrated and configured wideband sensor
Sensor Brand: AEM
Calibration Date: 2018
13). Type of fuel
Type: Meijer E85
Percent of Ethanol: 85-88%
Currently messing with my brother's 98 GSX. We are running an EVO 8 ecu with 9653 Rom. We have an issue where hitting 5k+ will start to breakup/miss. On or off boost, doesn't matter. I can vary the fuel from 11.1-12.4 with no change.
I have noticed one thing that helps, going lean. Running a 13+ AFR (E85) causes the break up to disappear. Obviously this is too lean to run normally, Is this simply the fuel overpowering the spark?
We have tried:
93 or E85
No Boost leaks
New plug wires,
New plugs (BR8ES @ .023)
New PTU
More timing,
Less timing
Less boost
More boost
Tested the Coil pack
Added Grounds
Changed Cam Sensor
Any ideas are appreciated. I don't have logs on this PC, however they don't show anything abnormal. TPS at WOT is 93%, 10.8% at idle. AFR and Injector cycle stays steady.
1). Any boost, vac, or exhaust leaks?
Tested to 35 PSI no leaks.
2). Verified mechanical timing?
Everything is aligned
3). Verified base timing?
5*BTDC
4). Ignition system
COP or Stock Coil: Stock
Wire brand and Age: TAYLOR Race Wires 1 month old
Spark Plug brand, type and Gap: NGK BR8ES 0.023
5). Motor health (Compression Test)
Cylinder 1:150
Cylinder 2:150
Cylinder 3:145
Cylinder 4:150
6). Performed basic throttle body adjustments?
Idle Switch: Adjusted
Throttle Cable: Like it should be
TPS: 0.63 volts closed
7). Compression ratio
Assumed Stock
8). Any known bad sensors or brittle wiring?
Nothing that I know
9). Any DTC/CEL codes?
Nothing
10). Electrical system
Car off (not running): 12.2
Car running: 13.5-14
11). Base fuel pressure and injector values
Base Fuel Pressure: 43psi
Injector Size (cc/min):1120cc
12). Properly calibrated and configured wideband sensor
Sensor Brand: AEM
Calibration Date: 2018
13). Type of fuel
Type: Meijer E85
Percent of Ethanol: 85-88%
.
