shyttle
New Member
- Thread starter
- #1
So here’s the main issue. Whenever RPM is steady between 1800~2500 the car has a bump/lunge feel every 2~3 seconds. It only occurs when holding the throttle steady. Acceleration/deceleration/WOT are solid.
Background:
This is a 2015 GT MT82 non-PP with 33k miles. I purchased the car about 8 months ago with a few mods already done. It had a Cobra Jet intake with a GT500 throttle body, factory injectors, stock headers and straight piped when I purchased it. It was remotely tuned by a well known company (came with a SCT tuner, don’t want to name drop the tune company). I had the car inspected by a local mustang guy that was recommended by a few shops locally. Everything checked good and he noted the “bump” and mentioned that it was most likely the tune because the TB can be tricky to tune correctly. Nothing out of the ordinary noted while watching the dash gauges… AFR, etc… looked good (I know they are not the most accurate readings)
Fast forward a few months. I upgrade the exhaust to a Corsa Extreme and upgraded the suspension to Steeda Ultrlite springs with Pro-action struts/shocks. Once the car was lowered it felt like the “bump” had disappeared. I really don’t think it disappeared, I believe it was just covered up by the linear springs. Up until this point there were no local tuners for Fords but a reputable GM focused shop had recently started dyno tuning Coyotes so I decided to finally have it re-tuned to take care of the issue.
Re-tune got an additional 19 whp and a smoother torque curve compared to the original remote tune. However, the “bump” is much more noticeable now. I brought the car back to the tuner, assuming it had to be associated with the tune. They data logged the car while replicating the issue and noted that all data looks good and there is nothing happening in the engine that is causing the “bump”. They told me it is most likely driveline “slack” that I am feeling. To me, this doesn’t explain why it is more noticeable with a different tune unless more power = more “bump/lunging”? However, all my power gains were in the higher RPM range so it still doesn’t make sense to me.
Has anyone experienced what I am talking about? I have read post after post about clunking and lunging at low speeds while the car is cold but I haven’t experienced any of those specific issues. Only the slight bump/jerk/lunge while cruising no matter what the engine temp is. 35 MPH in 3rd gear is the where I really feel it but it is there in any gear while in the 1800-2500 rpm range. If I drive steady at 3k rpm, the issue is not present.
Could driveline slack actually cause what I am feeling? Any recommendations what to do from here, or do I just need to suck it up and live with it?
Background:
This is a 2015 GT MT82 non-PP with 33k miles. I purchased the car about 8 months ago with a few mods already done. It had a Cobra Jet intake with a GT500 throttle body, factory injectors, stock headers and straight piped when I purchased it. It was remotely tuned by a well known company (came with a SCT tuner, don’t want to name drop the tune company). I had the car inspected by a local mustang guy that was recommended by a few shops locally. Everything checked good and he noted the “bump” and mentioned that it was most likely the tune because the TB can be tricky to tune correctly. Nothing out of the ordinary noted while watching the dash gauges… AFR, etc… looked good (I know they are not the most accurate readings)
Fast forward a few months. I upgrade the exhaust to a Corsa Extreme and upgraded the suspension to Steeda Ultrlite springs with Pro-action struts/shocks. Once the car was lowered it felt like the “bump” had disappeared. I really don’t think it disappeared, I believe it was just covered up by the linear springs. Up until this point there were no local tuners for Fords but a reputable GM focused shop had recently started dyno tuning Coyotes so I decided to finally have it re-tuned to take care of the issue.
Re-tune got an additional 19 whp and a smoother torque curve compared to the original remote tune. However, the “bump” is much more noticeable now. I brought the car back to the tuner, assuming it had to be associated with the tune. They data logged the car while replicating the issue and noted that all data looks good and there is nothing happening in the engine that is causing the “bump”. They told me it is most likely driveline “slack” that I am feeling. To me, this doesn’t explain why it is more noticeable with a different tune unless more power = more “bump/lunging”? However, all my power gains were in the higher RPM range so it still doesn’t make sense to me.
Has anyone experienced what I am talking about? I have read post after post about clunking and lunging at low speeds while the car is cold but I haven’t experienced any of those specific issues. Only the slight bump/jerk/lunge while cruising no matter what the engine temp is. 35 MPH in 3rd gear is the where I really feel it but it is there in any gear while in the 1800-2500 rpm range. If I drive steady at 3k rpm, the issue is not present.
Could driveline slack actually cause what I am feeling? Any recommendations what to do from here, or do I just need to suck it up and live with it?
Sponsored
