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Hesistation at highway speeds 80 plus.

ricio1991

ricio1991

New member
I have a 2004 grand prix gtp comp g with 101k miles. Car runs totally fine until you get to 70 to 80mph then it starts hesitating and seems clogging to change gear. I took it to a shop and i test drove it and showed him so i accelerated hard and the check engine light started flashing. We t back to the shop and mechanic ended up checking engine everything looked fine then checked transmission fluid and it was dark and smelled. So diagnostic answer was lets do a filter and replace fluid and then from then will determine if rebuild needed. Should i get a second opinion I'm thinking of selling thats why i ask. Plugs and wires were changed 10k miles ago. Mechanic said it had bcm codes and no other codes. Could it be the transmission it changes gears great before highway speeds


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It was dark and smelled? Usually not good.

You leave out a lot of nfo., but you have a 10 yr old car with 100k, was the tranny ever serviced? Where are you and what type of driving? Best thing to do is do a tranny pan drop, change filter and fluid and look for debris in pan. Don't be lazy and flush the tranny. Go from there.
 
flashing cel usually leads to needing a tune up, or a clogged cat.

the tranny, drop the pan change the filter add 8 new quarts of fluid. do not flush it if the fluid looks dark and stinks bad. or bye bye tranny asap most of the time.

maybe add 1 qt or lucas and 7 qts new tranny fluid.


any chance its slipping in and out of OD? 4 th gear hubs go bad in these trannys. 04 was hit or miss if it got the new upgraded hub or not from the factory.
 
I think the transmission is bad because 1st second third works amazing. When u get to 70 plus it starts slugging. Catalytic converter was changed already plus pcv and fuel filter about 90k. Its been acting up for a while like it would take a while to accelerate on 3rd gear. I would have to let go off the gas or something to let off. Been hearing alot about this trans. What do u guys think?


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Not serviced yet but odd thing is that it only does it in high gears/rpms


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try the pan drop and filter change with a qt of lucas trans medix. it may hold up for a while.

trans wont cause the cel to flash tho. thats a major thing that should be checked into. maybe its got bad plug wires, burnt on the manifolds or something.
 
So i have an update. I started using 91 octane now only and the problem appears to be resolved, doing transmission fluid and filter now. Going to test drive and see if octane difference could of cause hesitation.


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Yeah but its still rough! So i have to look for another solution at idle. But when running seems fine! I have to determine if its misfiring still at wot! Just have to find the right freeway not to get caught and try again.


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No but no check engine light on. It just idle the needle 8 and it goes up and down little bit tho i have a video i just dont know how to upload it


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Cool i will. So i test drove it accelerates great even to 90. I put seafoam in it too see if it works. Ill put the video up


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