WhitePheonix

Ever since I got the car back from the dyno I noticed that the acceleration tends to be non-linear, meaning that it will accelerate, then it feels like something kicks in and accelerates even harder. Even though I havent hit the pedal any harder. I especially notice it when I shift from 4-3 and accelerate. Any ideas to what it may be?

z289899

Possibly clutch slipping and then finally gripping which would make it feel like it all of a sudden wants to pull harder.

locosteelersfan

Clutch is the first thing that comes to mind.
Could be something Ignition related that isn't
giving consistant spark-anything from the coil pack
to the plug. How often are you getting it?
Are your RPMs linear or jumpy?

Iv_z28

It can very well be the tuning - when computer jumps from one fuel cell to another and tuning is messed up (like when you have a ported MAF), that's exactly the effect you get.

DANSLS1GTO

It sounds like you may have an issue - but you know that normal acceleration is going to be non-linear, right? Look at torque and hp curves - none of them are linear - you acceleration is going to be some combination of them. Could it be as simple as taking better advantage of the power band w/ the new tune?
Dan

jpbgto

iTrader: (4)

that's vtec yo
jk

z98

No.

Your acceleration matches your torque curve EXACTLY (not counting wind resistance).

Your horsepower curve has NOTHING to do with it.

jRaskell

iTrader: (1)

What was done with it on the dyno? As was already said, if it was dyno tuned, this could be a side affect of that tune. Take it back and tell them what you're experiencing. Take them for a ride, have them pluged into the PCM to see what's going on.

If it was clutch slippage, it'd be accompanied by the RPMs rising, then dropping suddenly just as you got the surge of accel (the engine revs higher as the clutch slips, then when it finally grips, it pulls the engine back down to matching RPMs, a good portion of the sudden surge of accel is usually attributed to the momentum of the engine internals. Very similar to just revving it and dumping or slipping the clutch) Most people with experience driving sticks will easily recognize this kind off behavior, so I doubt that's your problem.

WhitePheonix

There was no pcm tune, the car was just dynoed, thats it. I have already had the damn clutch replaced once, I really hope its not that. It happens during a constant acceleration meaning, its after I have already shifted, and I keep the pedal constant.

WhitePheonix

BTW, I dont notice it all that often, a couple times yesterday, its like the rpms are jumpy, almost seems like more fuel is dumped or something.........On a side note the shifter doesnt seem as heavily sprung either. My 2-3 shift doesnt feel nearly as tight. Whatever the hell that means

kyle97

iTrader: (10)

Your not running your a/c right? The compressor solenoid engauging/releasing can cause an abrupt change in the feel of the acceleration.

WhitePheonix

No A/C.....I dont know what it could be, but I never noticed it before the dyno runs

WhitePheonix

Do you think it could be something with the computer, would disconnecting the battery and resetting the pcm help?

locosteelersfan

Describe jumpy RPMs.
If its going up high and you don't seem to be moving
any faster, its the clutch slipping. Do they wander up
then drop back without upshifting.
Unplugging the battery can't hurt but probably won't help
either, try it anyway.

WhitePheonix

Ok guys sorry for such a vague description. This is what happened to me a 1 hour ago.

I was lightly accelerating up to 45mph. At that point I was in 4th gear around 3000 rpm. At this point I took my foot off the gas and let the engine rev down to 1700 rpm. I then shifted into 3rd. After I shifted I applied the throttle at around 1/2 WOT. As the rpms climbed around 2600 rpm the engine felt like something kicked in and it begin to rev harder even though the throttle was constant. I don't know if this is normal, but I never felt it before and it didn't seem right.[/B]

VIP1

How about the O2 sensors. Is that the only time that the engine feels odd? Has mileage worsened? I guess another possibility would be the MAF sensor.
--VIP1

WhitePheonix

Thats really the only time I noticed it, I havent dont anything to the MAF, I know I touched the screen a couple of times when I put my lid on a couple of weeks ago. Is what I described seem out of the ordinary to you guys

locosteelersfan

From that description it just sounds like your hitting
your powerband. So it just seems to be pulling harder?
Its not missing or anything? You just seem to have more
midrange power? Am I understanding this right?

How long have you had the car?

WhitePheonix

Its pulling harder, but its not smooth, Again like something is kicking in aka. more fuel. But the throttle is constant. Im just concerned because the car always accelerated very smoothly. I have had the car since last august, but it wasnt driven from last nov-april

zamboxl

iTrader: (1)

ok get a new cluch.