Flat spot/Hesitation?
4/6/08, 09:53 PM
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Flat spot/Hesitation?
GT, 5spd manual, Brenspeed XCal2 stock tune with 4.10 gears. Here's what happens. I'll be driving along in say 3rd gear, for a while, and then punch the throttle. The engine flat spots and occasionally backfires slightly then pulls normally. I've already had the fuel pump tsb done as well as this is not related to long cruise times. If I punch it and it flat spots/hesitates, wait for the power to come on then punch it repeatedly afterwards, the throttle responds fine.
Any clue what's going on here? Brenspeed tune, factory tune, Normal throttle delay? If it's the normal throttle delay, why does it work fine with repeated throttle punches after the initial throttle punch? If I remember correctly, I think it does the same with the Brenspeed 87 octane performance tune. I don't run that tune when it's below freezing though because the throttle's too hard to control till the engine is hot(closed loop). I won't be running that tune till June.
Any clue what's going on here? Brenspeed tune, factory tune, Normal throttle delay? If it's the normal throttle delay, why does it work fine with repeated throttle punches after the initial throttle punch? If I remember correctly, I think it does the same with the Brenspeed 87 octane performance tune. I don't run that tune when it's below freezing though because the throttle's too hard to control till the engine is hot(closed loop). I won't be running that tune till June.
Last edited by Lime GT; 4/6/08 at 09:55 PM.
4/7/08, 04:54 AM
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If your talking air filter, no. Fuel filters original with 22,000 miles. Don't have a laptop to data log.
Thought that was it so I turned the switch off. It's somewhat better but still does it. If it was carbureted I'd say it feels like a bad accel pump or vacumn advance. It usually catches me by surprise. I'll have to take note if it's rpm related next time.
Thought that was it so I turned the switch off. It's somewhat better but still does it. If it was carbureted I'd say it feels like a bad accel pump or vacumn advance. It usually catches me by surprise. I'll have to take note if it's rpm related next time.
5/25/08, 05:43 PM
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I've had it happen to my car as well, but without any backfires. I just attributed mine to the engine loading up due to slow driving on a 93 octane tune
It seems like after that initial hesitation it doesn't happen again as long as you "wring out" the enging rpms. Go back to cruising for a while and it will happen again on initial full throttle accelleration. Though, I don't know if it should be doing it or not.
It seems like after that initial hesitation it doesn't happen again as long as you "wring out" the enging rpms. Go back to cruising for a while and it will happen again on initial full throttle accelleration. Though, I don't know if it should be doing it or not.
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