Acceleration cuts out for split second. Why??
10-13-2010, 02:39 PM
#1
1st Gear Member
Thread Starter
Join Date: Nov 2009
Location: Illinois
Posts: 59
Acceleration cuts out for split second. Why??
If I am driving for an extended period on the highway in 5th gear, (ex. 30+ minutes) and I drop to 4th or 3rd to pass somebody, every once in awhile the throttle/engine will cut for just a split second but then it will continue as normal. It does not happen all the time, just sometimes. It cuts while i am accelerating hard by the way, gas pedal pretty far down.
my car has about 58K miles on it but it has been doing this for a long time. Maybe since 20k? It obviously is not a big problem (or a frequent one) but just kind of annoying.
I read somewhere that it may be the crank sensor...but as the engine itself does not shut down completely or have any other problems, i doubt this....
my car has about 58K miles on it but it has been doing this for a long time. Maybe since 20k? It obviously is not a big problem (or a frequent one) but just kind of annoying.
I read somewhere that it may be the crank sensor...but as the engine itself does not shut down completely or have any other problems, i doubt this....
10-13-2010, 02:49 PM
#3
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
Are you rev matching when you downshift?
You're most likely hitting the rev limiter (The free spin, not the redline one) if you're not.
If you sit in your car in nuetral and bring the engine RPM up slowly you hit a rev limiter at around 3500 RPM. When you down shift, if you're not rev matching you are hitting this range pretty hard and fast which means the ECU is cutting the spark/fuel for a split second for what it considers iminent damage.
You're most likely hitting the rev limiter (The free spin, not the redline one) if you're not.
If you sit in your car in nuetral and bring the engine RPM up slowly you hit a rev limiter at around 3500 RPM. When you down shift, if you're not rev matching you are hitting this range pretty hard and fast which means the ECU is cutting the spark/fuel for a split second for what it considers iminent damage.
10-13-2010, 03:03 PM
#5
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Join Date: Nov 2009
Location: Illinois
Posts: 59
i don't think it has to do with the actual shifting process.
example
Lets say i have been going down the highway for awhile in 5th gear, no hard acceleration for awhile. I need to stop for some gas. So I get on the exit ramp...stop at the stop sign after the exit ramp. Upon acceleration the throttle will cut for just a split second and make the car jerk (its much more violent when it happens in 1st gear than 3rd or 4th).
In this example, I am not neccessarily accelerating hard or anything.
I hope this helps.
example
Lets say i have been going down the highway for awhile in 5th gear, no hard acceleration for awhile. I need to stop for some gas. So I get on the exit ramp...stop at the stop sign after the exit ramp. Upon acceleration the throttle will cut for just a split second and make the car jerk (its much more violent when it happens in 1st gear than 3rd or 4th).
In this example, I am not neccessarily accelerating hard or anything.
I hope this helps.
10-13-2010, 03:09 PM
#6
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Join Date: Nov 2009
Location: Illinois
Posts: 59
derf00, you may be on to something. I sometimes rev match, but not always. In the latest example I gave, well, I usually don't rev match when i am coming to a stop from highway speeds. I usually just put it in neutral and glide/brake to a stop.
10-13-2010, 03:12 PM
#7
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
Okay, that is TOTALLY different.
There was a thread about this floating around somewhere here that driving for extended periods of time caused the fuel pump to over heat or something and that caused that momentary lugging or loss of power once you came to a stop and went again or just slowed down for a short while.
I don't recall the fix but I want to say there was a TSB from ford on it. You might want to change the title of your thread to engine lugging after freeway cruising or something like that. Someone will pop in with the info.
There was a thread about this floating around somewhere here that driving for extended periods of time caused the fuel pump to over heat or something and that caused that momentary lugging or loss of power once you came to a stop and went again or just slowed down for a short while.
I don't recall the fix but I want to say there was a TSB from ford on it. You might want to change the title of your thread to engine lugging after freeway cruising or something like that. Someone will pop in with the info.
10-13-2010, 03:22 PM
#9
2nd Gear Member
Join Date: Mar 2006
Location:
Posts: 187
mine used to do the same thing. There ia a tsb out there about bubbles forming around the fuel pump but i could not find a dealer that would fix it They said they would have to duplicate the problem. So i got a brenspeed tune and intake and never had the problem again.
