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Accelerating after speed bump - engine revs with little/no acceleration action


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AlyMarie
New User

Jun 21, 2016, 3:14 PM

Post #1 of 7 (1835 views)
Accelerating after speed bump - engine revs with little/no acceleration action Sign In

2004 Mustang 3.8L
Automatic Transmission
Rear wheel drive - 189,600 miles

Issue I am having only occurs (thus far that I have noticed) when going over a hump like a speed bump every time consistently I can make it repeat what it is doing without fail.

When driving forward over the speed bump breaking as I drive over it, as my rear wheels leave (when descending off the speed bump) and fully clear the speed bump (NO LONGER ON THE SPEED BUMP) it is only then at that small window when I begin to slowly re-accelerate forward on flat ground to continue driving it seems as if the car is not catching/accelerating (thought at first tranny slipping) like the engine is reving up and a second later it decides to catch and then start driving forward. (Tranny fluid levels are normal)

But the more I spent time last night driving over speed bumps and listening to it, i'm not sure if the noise i'm hearing from the front during the time its delaying to start accelerating as normal is the engine reving with no action/nothing catching - or a more grindy abnormal noise from the motor somewhere as the car struggles to start accelerating as normal.

Its like I can hear everything turning/stripping at a low yet louder than normal sound from my front end (I CAN FEEL THE SOUND SLIGHTLY IN THE GAS PEDAL AS WELL) it is NOT grinding from the wheels like breaks or metal grinding – its from the engine trying to commence forward and the car not commencing with it - no action from the wheels for a second or two...

It is only for a few seconds right after completely descending from the speed bump... and then the car is completely normal.. I can stop and go on flat ground no issues.


kev2
Veteran
kev2 profile image

Jun 21, 2016, 3:34 PM

Post #2 of 7 (1831 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In

start easy simple things first...
sure trans fluid is ok? checked HOT all gears selected before checking level?
might want to check for codes YES even if light is out.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 21, 2016, 4:19 PM

Post #3 of 7 (1824 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In

I doubt the speed bump itself that is the trigger. It's more likely the speed conditions and RPM that is triggering a downshift or something like that.

Do what Kev2 has suggested to get started.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



AlyMarie
New User

Jun 21, 2016, 4:50 PM

Post #4 of 7 (1818 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In


In Reply To
start easy simple things first...
sure trans fluid is ok? checked HOT all gears selected before checking level?
might want to check for codes YES even if light is out.


Yes I tested trans fluid hot with engine running... this was directly after a 40 min drive home from work. But I did not shift to all gears first... so I will do that as soon as I get home again today.

And no... there is no CEL or any other lights on for that matter. I believe that year of mustang the CEL only comes on for anything to do with Emissions? So w/out a CEL actually being triggered can an auto parts store still pick up codes? I was under the impression they couldn't - I know the manufacturer/dealership can hook the car to a computer and pin point issues - but that costs $100+ I was trying to avoid that Crazy

I will take it by my local auto parts store on the way home as well and have them check.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 21, 2016, 4:53 PM

Post #5 of 7 (1816 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In


Quote
I believe that year of mustang the CEL only comes on for anything to do with Emissions?


Not true at all. The computer monitors hundreds of circuits and systems. Remember, most any engine malfunction will effect emissions even though that is not the only thing monitored.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



AlyMarie
New User

Jun 22, 2016, 8:20 AM

Post #6 of 7 (1796 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In

I checked trans fluid levels again as instructed... levels are fine. It is due for a change and new filter as it felt slightly gritty. So I will do that this weekend. The speed bumps the other day was the first time not feeling the car accelerate until last night. I was driving home and and as I tried to accelerate it was holding back... I was pressing on the pedal but the car wouldn't pass 1000 rpms for about a minute then it didn't do it again the rest of the drive home. (40 min drive home) and then twice at a stop light the car was acting like it was wanting to stall out, rpms slightly dropping and raising for about a minute as well both times then went back to normal idle until light turned green.... I think she knows I want a truck! haha


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 22, 2016, 8:51 AM

Post #7 of 7 (1795 views)
Re: Accelerating after speed bump - engine revs with little/no acceleration action Sign In

Did you have it scanned for codes as suggested?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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