First gear lurch/lag

[Valkyrie14]

This has bugged me from the first time I drove my car. When I am in first going from a full stop at a low to normal speed the car hesitates and then lurches forward when the clutch is about 3/4 of the way released.

When I am at a place where I can go faster I give it more gas and all is well. But when I am behind someone at a stop sign or stop light it always heaves forward. My kid makes a comment everytime!

If this is just part of the deal then I can live with it, but if there is something I can do I will do it tonight!

[Moto-Mojo]

If this is the same program that the automatic uses, your car (computer) attempts to match the engine speed with the vehicle speed. It almost never matches up quite right, it just lurches forward like you say. You are expecting the classic downshift resistance of deceleration but what you get is the opposite. It’s in the programming. Crazy, I know. Why, I’m not sure.

I think they ‘attempted’ to avoid the decel lurch where you go forward. But what they created was you going backwards!

[CamaroCracka]

I have it too. Two things that helped are lower gear ratio and aluminum driveshaft. What makes it more annoying is when the Prius in front of you wants to drive like it's trying to hit 70mpg.

[Moto-Mojo]

It has a name and has been discussed here before. Seems odd that it can’t - or doesn’t, get tuned out with a tune mod. I’m tuned but it’s still there.

Update: apparently it’s called, “rev hang” or rev matching And can be Googled, etc...

[Avenging Orange]

Mine does it...mostly when cold. The other half of the time it's the 2 piece drive shaft and drivetrain slack. Also, it something you had to work around when cammed.

[Valkyrie14]

Rev-Hang...awesome. Well I can add gears and driveshaft to the wishlist.

[Greenhornet2]

I am not sure what you are talking about. When my car had the stock cam I had no issue at slow speeds. With the rough idle cam I get lurching at very low rpm but that is the nature of having a cammed car. You can raise the rpm higher and slip the clutch a little more if needed. Not sure if your car is cammed or not. If it's not you may need a better tune. If it's cammed you are feeling the lurch of the rough idle

[Valkyrie14]

Originally Posted by Greenhornet2

I am not sure what you are talking about. When my car had the stock cam I had no issue at slow speeds. With the rough idle cam I get lurching at very low rpm but that is the nature of having a cammed car. You can raise the rpm higher and slip the clutch a little more if needed. Not sure if your car is cammed or not. If it's not you may need a better tune. If it's cammed you are feeling the lurch of the rough idle

Not cammed...yet. I have played with throttle/clutch combinations with my feet to make the slow acceleration smooth. Occasionally I get just the right mix, but mostly I either rev the engine to high and everyone around looks over like, “where do you think your going?” Or I creep and then the rev-hang hits like I jumped a curb.

It is just a thing, I think I am at the end of what my current tuner will do for what I paid. Waiting for another mod to find another tuner. Going to back to my original tuner and get a street tune. Probably after my cam. He also has a dyno and I might throw down the cash to get a real rwhp number verified.

[Greenhornet2]

Originally Posted by Valkyrie14

Not cammed...yet. I have played with throttle/clutch combinations with my feet to make the slow acceleration smooth. Occasionally I get just the right mix, but mostly I either rev the engine to high and everyone around looks over like, “where do you think your going?” Or I creep and then the rev-hang hits like I jumped a curb.

It is just a thing, I think I am at the end of what my current tuner will do for what I paid. Waiting for another mod to find another tuner. Going to back to my original tuner and get a street tune. Probably after my cam. He also has a dyno and I might throw down the cash to get a real rwhp number verified.

Sounds like a tune issue, I never had any issue like that on stock cam. It drove like stock before I added the cam. I would pay Jannetty to do your tune.

[Norm Peterson]

Originally Posted by Valkyrie14

This has bugged me from the first time I drove my car. When I am in first going from a full stop at a low to normal speed the car hesitates and then lurches forward when the clutch is about 3/4 of the way released.

When I am at a place where I can go faster I give it more gas and all is well. But when I am behind someone at a stop sign or stop light it always heaves forward. My kid makes a comment everytime!

If this is just part of the deal then I can live with it, but if there is something I can do I will do it tonight!

I'm thinking that your tune may need to have throttle tip-in response dialed back a bit. Too aggressive + forced induction may be throwing too much response at you when you're driving gently, but may not be ramping up as fast when you're running harder.


Norm

[hudson773]

sounds to me that you are not pushing in the clutch soon enough when you come to a stop. rev hang and rev match are 2 different things. the only common denominator is "rev"

[JuniEdith]

Most probably it is an issue with the transmission fluid .Check the transmission fluid level first. Low fluid can prevent the transmission from shifting properly. It’s important to find out why the fluid is low and fix any problems. It could be a leaky seal or other mechanical defect. Otherwise, adding new fluid won’t ultimately solve the problem.
Transmission fluid that has aged and lost some of its frictional properties can also lead to poor shift quality. When your vehicle’s computer tells the transmission to shift gears, hydraulic pressure squeezes a series of plates together inside a clutch pack to connect the engine to the transmission output shaft and route power to the wheels.

[gtstorey]

Originally Posted by JuniEdith

Most probably it is an issue with the transmission fluid .Check the transmission fluid level first. Low fluid can prevent the transmission from shifting properly. It’s important to find out why the fluid is low and fix any problems. It could be a leaky seal or other mechanical defect. Otherwise, adding new fluid won’t ultimately solve the problem.
Transmission fluid that has aged and lost some of its frictional properties can also lead to poor shift quality. When your vehicle’s computer tells the transmission to shift gears, hydraulic pressure squeezes a series of plates together inside a clutch pack to connect the engine to the transmission output shaft and route power to the wheels.

Pretty sure he has a manual.