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I'm new to this. Lol I just bought a wrx 2004 2.0 awd turbo. I'm already in love with it. It has 93k miles.

Ok so when I'm on the freeway and I'm going maybe like 70mph and I'm on 5th gear and I'm pressing the gas pedal like half way, and then I press it the whole way down the car takes off fast, but I feel like it goes fast then slows down alittle bit and then keeps going fast. Like I even hear the engine and turbo and it sounds like it feels, goes fast then it slows down a bit and then goes fast. It keeps doing that until I let go of the gas pedal. Why does it do this? Maybe I need A fuel system cleaner? Or spark plugs? Or what?

Again I'm new to this lol.
 

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Master Baiter
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You shouldn't floor the car in 5th gear.

Any modifications? Do you have a boost gauge?
 

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If the revs climb rapidly while the car is not accelerating, then dip, think clutch.

Otherwise: Vacuum leak, boost leak, spark issue, fuel issue, or normal.

Follow the links in my signature for info on the car, and see the maintenance/troubleshooting subfora.
 

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Um why not?
unless you're in the power band... there's a TON of load on 5th gear (which is the cruising gear) because it's overdriven, and a long ratio. Because of that load, the engine will be fighting to accelerate, but the transmission load is holding it back. The weak point between the two is the clutch. It's very bad on the clutch to gun it at low RPMs in 5th gear.
 

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Johnny88k said:
Lol I just bought a wrx 2004 2.0 awd turbo.
Johnny88k said:
I see. No mods on the engine. Just mods for handling. yes I have a boost gauge. How much should I boost it too?
 

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unless you're in the power band... there's a TON of load on 5th gear (which is the cruising gear) because it's overdriven, and a long ratio. Because of that load, the engine will be fighting to accelerate, but the transmission load is holding it back. The weak point between the two is the clutch. It's very bad on the clutch to gun it at low RPMs in 5th gear.
Sorry, but I'd have to disagree with that. As long as the clutch is fully engaged then it shouldn't be a problem at stock power levels.
 

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Sorry, but I'd have to disagree with that. As long as the clutch is fully engaged then it shouldn't be a problem at stock power levels.
Then why, when the clutch is beginning to go... is the first sign at WOT in the highest gear in low RPMs? That's the easiest way to dx (edit: dx = diagnose) a slipping clutch. No matter the power levels.

Here's a bugeye with a slipping clutch
 

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Then why, when the clutch is beginning to go... is the first sign at WOT in the highest gear in low RPMs? That's the easiest way to dx (edit: dx = diagnose) a slipping clutch. No matter the power levels.
Why is the first sign my 911 clutch is going at high rpm at high boost and it's fine at low rpm in the highest gear?
 

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The highest load is in the highest gear. That's because of aerodynamics, and the longer gear ratio. When you have a high load, it creates a large amount of exhaust gas, which spools the turbo, which in turn creates boost, and creates a large amount of torque. You'll always see the first signs of slippage at peak torque in the highest gear. If you're at a low RPM in the highest gear, and go WOT, then when you hit peak torque, you'll be slipping.
 

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( did you notice that the clutch in the video didn't slip until ~3200rpms? Which is where the car would start producing boost and torque )
 

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Then why, when the clutch is beginning to go... is the first sign at WOT in the highest gear in low RPMs? That's the easiest way to dx (edit: dx = diagnose) a slipping clutch. No matter the power levels.

Here's a bugeye with a slipping clutch
I had the same problem as in this video. It started in 5th at about 50-60mph when accelerating up a long gently sloping incline. As it worsened it would do it in 4th then at it's worst, in 3rd. It didn't slip in the lower gears because the mechanical advantage of the higher gear ratio made the car more willing to accelerate. In 5th the ratio is so high the car isn't as willing to move. I changed the clutch, pressure plate and flywheel and haven't had any problem since. I've even increased the power with a stage 1 tune and a catless uppipe and haven't had any issues since.

I agree with Sinister's theory. The lower ratio in 5th gear is for cruising and the load placed on the transmission and clutch under full boost (and max tq) in 5th is bad. Once the revs are higher (over 3,500-4,000), the motor is making more hp and there is less stress on the clutch.

My 1968 Cougar has loads of torque below 2,000 RPM so the clutch and transmission need to be strong enough to handle it. I've never seen a transmission or clutch rated to hp, they are tested to a specific tq rating. Unfortunately the motor in my Cougar makes more than my 330 lb/ft rated Tremec T-5z 5spd could handle and I broke the 3rd/4th shift fork while drag racing:( I'll be upgrading to a TKO 500 or 600 next. They handle 500 and 600 lb/ft respectively. :thumbup:
 
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