Hey everyone, just something that's been catching more of my interest a bit lately. I don't if it's just my car because it's under powered or something else.

Anyways, when I'm at a stop (stoplight or stop sign) and I floor it or launch my car, it seems to bog down, then once it gets past 20-25 mph it picks up and climbs on the speedometer. Rarely I'll chirp the tires off the line.

Top end is pretty good, 40-45 mph kinda bogs too, but 50-60 mph in 2nd gear taking off just puts your head back in the seat.

How can I have more "oomf" from a start? As in, some wheel spin, and feel some power and not have it bog down when I take off and then pick up speed past 25 mph?

Tires are at appropriate psi
I've done some performance mods

It seems to always have been like that lately, but I just want more oomf off the starting line. Any Ideas?

 

What Engine do you have?
What mods have you done?
How many miles?
What condition is your Cat?

 

I have the 3.4L LA1 207ci

Oil Catch Can
Milzy TB Cooling Bypass mod
Fender well CAI
Summit Racing Down pipe w/high flow cat
U-bend Delete*
Resonator Delete*
* = replaced with straight pipe
going out to a flow master 40 series muffler

Miles = 113,728

Rest is just aesthetic mods.

I don't have a cat, just a dog LOL

Sorry, my humor got the best of me lol

My cat is good, had the exhaust worked on 2 years ago in march.

Perhaps it may be the oil catch can...the hoses collapse under the heat and pressure, but they inflate when I give it gas.

 

Honestly, I couldn't tell you. You've done most everything. I'm sure someone here can give you a lead or two. Only thing I can think of is a better transfer. If there is such an animal?

 

For the most part, those mods help with basic air flow, maybe fuel economy and sound. Sounds like you want more of a "punch" to the car. For that you need more going on.

Some suspension mods, help reduce rubber recoil. Cheapest mod, instead of getting poly radiator mount bushings, flip your current ones. They are designed to let the engine rock back and forth. The concept is a very small amount of lost power at the wheels on launch. I have poly radiator and dog bone bushings. The change is minimal (I never did the flipping of the rad bushing, but I think you would yield 90% of the same result and it just costs a little time). Could explore some other poly bushings elsewhere (again, changes are minimal).

L67 coils. Yes, they work on a 3400. My Grand Am and wife's Impala BOTH have them (so does my L36 in my Monte). Again, minimal change, but helps improve throttle response. I did not notice the gains as much when I put them in, but when I put a 3100 back to stock coils, I hated it (the L67 does yield a little gain. Target that as a $30 mod, much more then that and I really don't think it's worth it).

A basic tune would probably help push it a little harder (as I understand, the factory leaves room for change). Then it can also be dialed in to do a bit more at the times you want it.

Beyond those small and cheap items, I would think you would have to start looking at more serious mods. Cams, super/turbo charges, ported heads and intakes, perhaps different valves..... Possibilities increase upon how much you want to spend.

 

I had a 95 Buick Regal GS with similar symptoms... When I got it, it would spin the tires no problem, then it got sluggish sometimes and spuddered under WOT, any speed... Changed the cat and all was good...It was clogged... Worth checking out before replacing...

 

It sounds to me like the hoses are collapsing due to improperly installed catch can/excessive vacuum or very cheap/thin walled hoses are being used. At idle manifold vacuum is high. Restricted flow in the hose is causing it to collapse. When you open the throttle manifold vacuum drops and the hoses return to their normal diameter. I would double check the installation of the catch can and check for restrictions.

 

I've heard about flipping some bushings, but I'd rather replace with better and more sturdier ones

The cat isn't an issue, it was replaced with a summit racing downpipe w/high flow cat that's 2 years old lol

It's installed correctly, the only restrictions are the hoses. They are a clear, steel braided hose. They are pretty stiff when you first get them, then once the heat gets to it, it softens them up pretty badly to where it's like silicone.

I definitely need HIGH temperature hoses.


Extensive mods (Heads, cams,etc) are out of the picture. My next car (EVO X/STI) is roughly a year away, so major mods are out unless i'm' saving this car for a build lol