Just trying to figure out why my car wont get up and go at highway speeds.

Its the TA in my sig. H/C M6 4.10 Gears. Does has a small vacuum leak that I'm fixing and it does need a tune. Brand new Opti.

I know the car has a rear main seal leak but i figured it wouldn't cause it to lose this much power.

Down low it has great power and 5th or 6th is really were you notice no power at all. For example a rather stock SRT4 wanted to race. We went from a 50 and my car took off like it was a 4 cylinder! And he just slowly pulled away.

Could my problem be just what i stated above or do i need to be checking out something else?

 

"And it does need a tune"

 

I second that... Don't overlook the obvious stuff, please.

 

With your 4.10 ring & pinion, in 5th gear at 50MPH, your engine is turning just under 2000 RPM. There's no way you're going to have much power under these circumstances. So, if I'm following this OK, all I think you need to do is use a lower gear on the highway... ?? 5th and 6th are overdrive gears, really just meant for cruising.

 

i completely agree.... 4.10's arent your normal highway cruizing gears, they accelerate like no other, but dont expect the same top end. if your gonna be highway racing, might wanna stick w/ 373 or even lower, and of course the tune

 

What I meant was, he should be using 3rd or 4th gear for acceleration on the highway, not 5th or 6th

 

Well i know i shouldn't be racing in 5th or 6th from a highway roll but there is NOWAY that its running right.

I know my 97Z with just LT's took off faster.

And when i raced a SRT4 from a 50. Either took off in 2nd or 3rd.. Think it was 3rd.. And the car didnt go anywhere at all.. He was pretty much stock and was slowly pulling away, and i was bearly catching up to the car in front of me(which was going the speed limit).

So you think a tune would throw it off THAT bad?

 

I would definitely take care of tune-up and vacuum leak issues first... but my guess (and it's just a guess) is that a bad tune-up (alone) would not cause a car with all the mods you have, to run that poorly.