nvr2muchboost
15+ Year Contributor
- 35
- 0
- Oct 8, 2004
-
San Diego,
California
Basics:
'97 GS-T
Denso 720
Walbro 255 (rewired)
NGK Platinum plugs
Stock wires
DSM Link
264/272 cams
Issue:
During cold startup or when the car has been sitting for more than 6 hours - the car will miss and stumble as if its not running on all cylinders.
If I wait about 30 seconds while its 'coughing' everything will begin to smooth out and the engine will begin to run normally.
If the car has been sitting for less than six hours (engine still warm to the touch) - startup and idle is very clean.
Once out of the driveway its drivable - unless accelerating up an on-ramp - where the car will buck and surge until I let off the gas.
I have noticed at night that during the cold start sequence the interior lights will flicker and the Walbro's hum will oscillate up until that 30 second point where everything begins to stabilize.
Work Performed:
Thus far I have changed out the plugs - checking for any contamination in each cylinder bore - very clean.
Swapped around plug wires.
The Walbro is rewired and has a clean source of power coming directly from the battery.
I had the electrical system checked by a garage (battery/alt/starter) and all readings show normal charging/use of the system.
Where help needed:
I'm stuck at this point on what would cause the car to act so poorly when cold - better when warm - and the bucking/surging when accelerating up an incline.
I plan to get some logs from the DSMLink later today.
If anyone has ideas please let me know
Edit: Here is the logging data from DSMLink during warm idle - I'll have cold idle in the morning:
Battery: 13.58v - 13.72v
A/F Ratio: 14.99 - 15.60
Timing: 9.1deg - 14.4deg
All injectors show enabled
Injector Duty - 1.8%
Front O2 varies from .12v - .80v every 1.79seconds
'97 GS-T
Denso 720
Walbro 255 (rewired)
NGK Platinum plugs
Stock wires
DSM Link
264/272 cams
Issue:
During cold startup or when the car has been sitting for more than 6 hours - the car will miss and stumble as if its not running on all cylinders.
If I wait about 30 seconds while its 'coughing' everything will begin to smooth out and the engine will begin to run normally.
If the car has been sitting for less than six hours (engine still warm to the touch) - startup and idle is very clean.
Once out of the driveway its drivable - unless accelerating up an on-ramp - where the car will buck and surge until I let off the gas.
I have noticed at night that during the cold start sequence the interior lights will flicker and the Walbro's hum will oscillate up until that 30 second point where everything begins to stabilize.
Work Performed:
Thus far I have changed out the plugs - checking for any contamination in each cylinder bore - very clean.
Swapped around plug wires.
The Walbro is rewired and has a clean source of power coming directly from the battery.
I had the electrical system checked by a garage (battery/alt/starter) and all readings show normal charging/use of the system.
Where help needed:
I'm stuck at this point on what would cause the car to act so poorly when cold - better when warm - and the bucking/surging when accelerating up an incline.
I plan to get some logs from the DSMLink later today.
If anyone has ideas please let me know
Edit: Here is the logging data from DSMLink during warm idle - I'll have cold idle in the morning:
Battery: 13.58v - 13.72v
A/F Ratio: 14.99 - 15.60
Timing: 9.1deg - 14.4deg
All injectors show enabled
Injector Duty - 1.8%
Front O2 varies from .12v - .80v every 1.79seconds
