I have 2003 cobra with new mmr 4.75 stage 2 cams and whipple 2.9. The car starts bucking at 1000 till 1500.I tried all possible soultion but no success. I changed all sensors and fuel filter. I noticed that while datalogging the spark advance the timing will drop from 20s to 7 or 9 when it start bucking. What could make the pcm to pull timing! Do you think it could be vacuum lead that makes it lean and the pcm starts pull timing.:shrug:
low rpm bucking/hesitation issue
- Thread starter recky2000
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Has the car been tuned/dyno'd? Or is it just a base tune for break in? I'm having a similar problem...new built motor, custom cams and a 2.3 and it cuts out bad down low trying to accelerate at all. It's most likely a fuel issue in the tune and the tables need to be adjusted to compensate for the increase in airflow throughout the rpm range. What are the fuel parameters showing in the datalog?
it is just a base tune. what fuel parameter should i datalog?
Do you have a wideband? That's the easiest way to check...mine dances allover the place from 14-17 down to 12 and back up...it's allover. When it cuts out, the a/f spikes up to 15, 16 even 17. Mine bucks and cuts out pretty good so the wideband picks it up right away. If yours is somewhat of a smaller cutout then the wideband may or may not pick it up
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