Car loosing power at high PRM in 3rd gear

[The Green GT]

Today I was going home from school and there was some moron is a prelude who kept wanting to race me. I got fed up and just let him in my dust. When I hit about 110 which is about where I shift out of 3rd, the car felt like it was loosing power. My shift light flashes on for a split second and then would come back on.
Its actually almost always done this IIRC. Is the powerband in 3rd just not as long?

 

[cbarr300]

with what u have I'd say that's getting out of ur powerband. What rpm are you at when ur shifting?

oh yeah, what gears and do u have that zex yet?

 

[The Green GT]

Pretty much stock except exhaust and CAI.

Im not sure of the RPM. I have a tach from a 4.6 and it goes to 8K so its off a little. I have my light set at like 5200-5300 though. It feels like it has a hard time getting there when its almost there.

 

[cbarr300]

unless ur fuel pumps going bad I think ur prolly just starting to run outta power. Have u changed the fuel filter and maybe used some injector cleaning. How about the usual tune-up? plugs, air filter, etc.

If all those things are good then I have no idea

 

[The Green GT]

Everything is pretty new. The fuel pump has been pissing me off lately though. I think Im gonna change it. But its dosent loose power like that in 1st and 2nd. Im guessing its just the powerband.

 

[Guero]

110 in third seems way to high!!! should be more like 92. If i did it right thats more like 5950 rpms!!!!

 

[The Green GT]

110 in third seems way to high!!! should be more like 92. If i did it right thats more like 5950 rpms!!!!

Its 110 in my car. Remeber, I have 2.73's.

 

[Guero]

5300 rpm. your 300 rpms over which you might feel since the rpms are longer as supposed to 1st and 2nd

 

[The Green GT]

Whats the link to that gear claculator?

 

[cbarr300]

if I'm not mistaken the car's seeing more load and needs more fuel. Maybe, just maybe, ur pump can hold up pretty good in first and second...but once u get to top end on third it just can't supply the fuel u need. Maybe u could get a fuel pressure gauge off a buddy and run it in the car just for diagnostic purposes

luck

 

[Guero]

Its on the EEC Analyser. I know theres a site for it to let me look.

 

[The Green GT]

if I'm not mistaken the car's seeing more load and needs more fuel. Maybe, just maybe, ur pump can hold up pretty good in first and second...but once u get to top end on third it just can't supply the fuel u need. Maybe u could get a fuel pressure gauge off a buddy and run it in the car just for diagnostic purposes

luck

But 5000 RPM is 5000 RPM no matter what speed you are going. Wouldnt it get the same amount of fuel at the same RPM regardless of speed?

And I have been needing to do some tests on my pump anyway.

 

[Guero]

if I'm not mistaken the car's seeing more load and needs more fuel. Maybe, just maybe, ur pump can hold up pretty good in first and second...but once u get to top end on third it just can't supply the fuel u need. Maybe u could get a fuel pressure gauge off a buddy and run it in the car just for diagnostic purposes

luck

Wouldn't be easier for the Pump to keep up in third high rpm since it happens slower, than in 1st and 2nd were it happens quicker. Just a thought, not sure

 

[cbarr300]

hmm..u bring up a good point. It would just seem like it'd take more fuel to push a car at top end in 3rd than top end in first. I could be wrong on this thinking though.

maybe grady or jt can chime in eventually

 

[cbarr300]

at top end in third that pumps gonna have to be putting out more fuel longer. You stay in the upper rpms longer in third than you do in first. I'm thinking, granted the pump is the problem, that the pump just can't flow the volume of fuel needed in the upper rpms for as long as you need it to.

Think about it. In first you rip through it and shift. second: you rip through it somewhat slower since the gears are higher (numerically lower). Third: The gears are getting higher once again...so you can't rip through it as quickly and therefore ur gonna be at the higher rpms for a longer time. Maybe the pump can supply enough fuel for the first and second gear rips..but at third it just can't CONTINUOUSLY flow what it needs to. Plus u have things working against you the faster you go..such as wind resistance.


again....I could be 100% wrong on everything I just said..I'm definately no genius and am still somewhat green when it comes to cars.

 

[The Green GT]

I think you could be right. But now I nee to hook that DMM up to my pump and see what its doing in real time.

 

[cbarr300]

eh, sounds good in logic

now u just need to find a way to see what the pumps doing at higher rpms. You might as well go ahead and get an interior fuel pressure gauge. Ur gonna want it with that nitrous set-up ur plannin. I think you can find a cheapy at pepboys but if you have the extra money on hand might as well get an autometer to see what's goin on

 

[Guero]

but the rpms happen slower higher in 3rd, thus giving the pump more time to make more pressure or keep up. Now im just thinking to my logic. But i have clue of how it really works

 

[HISSIN50]

Yep - more fuel for higher (numerically) gears. So while first might not ping or crap out, 3-5 can.

Eric, if you can monitor FP in real time, that'd be telling. Unless you have a midget friend who doesnt mind riding sidesaddle (under the hood), maybe a buddy has a gauge you can borrow and set upon the cowl (I think you could fish a braided line through the rubber adjacent the hood hinges).

If this is a new feeling, it also could be the very early signs of some other issue (ignition, etc).

I might see how it does tomorrow (dont hurt anything though) to see if there was a glitch.

Good luck.

EDIT: there were about 3 posts since I loaded the page to reply.

 

[Guero]

Damn it i was wrong!!!!!!!!!! Its your fault hissin and all your "smartness"!!!!!!!!!!!!LOL!!!!!!!!!!jk