Engine General question about my 99 rolla

General question about my 99 rolla

Okay I have this question I need to ask. I'm not sure if its normal or not, but whenever I step on the gas real hard then let off, the car seems to jerk. Anyone know what causes this? is that a problem or is it normal?

what kind of jerk is it? like a jerk forward or like a jerk trying to slow down....sorry its hard to explain.

Auto or manual?

maybe an engine mount that could be bad.......Do a test open hood than get inside and start it and gas and brake it at the same time if you see the engine twist/left. you can tell if it is bad if it looks like the engine will roll right over..it sounds funny but it works

Its like when you are at a complete stop, then you stomp on the gas and kept on it for a little while then release the gas. Its like a jerk backwards. It doesn't happen all the time, but from time to time I would feel it. This happens only when I do heavy driving and the car is auto.

What causes the motor mount to go bad? Is that expensive to replace? easy to replace?

over time they do go out and being hard on your car

Hm, I can't really imagine the problem. Are you sure it just isn't upshifting? Say you're in first gear on your auto and you jolt it, when it either hits redline or you let off the gas, it upshifts to the next gear. I couldn't imagine a car downshifting when you let off the gas.

most of the time they dont vibrate.The only time I punched it and let off there was a jerk...........thats becouse the engine slams down or you have a fudged up tranny

Well my friend told me its not the motor mount because its not vibrating. He thinks when I step on the gas, I'm hiting my rev limiter and when I let go, the gears compensate by switching gears. The feeling of jerk is kinda like going from a higher gear to a lower gear type so that's what he thinks.

Do you have a tach? If it's auto, it shouldn't be near the limiter when it shifts..

Try changing the transmission fluid maybe that might solve the problem.

Uhhhhh....I don't get any of that. Something about valves, rings, pistons, torque convertor, ECU.

I think what you're describing is normal to an extent. It's shift-shock and you're never going to be rid of that completely. It gets A LOT worse with when the transmission fluid needs changing. You're probably feeling the transmission shifting gears if it's kind of a jolt. Check your fluid and change it if it's not pretty and clear cherry red.

If you hit the gas hard enough to cause the transmission to downshift and then you let your foot off the gas really quick, sometimes it will cause the car to suddenly slow down (kind of like you just hit your brakes real quick). In that case, the transmission just hasn't had enough time to upshift. That's engine braking for ya and it's normal and healthy.

Trav

OOOOOOO i think i know what ur talking about....ok on an auto...dunno bout on other cars, but on toyotas if u floor it real quick then let off the gas before it has time to catch on the gear, itll down shift and the engine speed will go up. if u stop before u actually start to accelerate, but right after u floor it really quick, ur transmission kinda chanages its mind and ur car shakes a little bit....is that it?

if u dont understand this go on the road and cruise @ about 40 mph....then quickly--not fast as hell, but maybe for a second or less--press ur accelerator pedal to the floor and release it...dont back it down slowly, just let it fling back.

yeah something like that. Its like when you step on the gas, you can hear the engine starting to roar then deny it the full roar when you let off the gas, it leaves you with that jerk.

sounds like you've got some sticky valves or your pistons could be wanting to keep going fast but when u let off they slow down quicker than usual....it could be some unusual piston wear......if the feeling that your describing feels like when you downshift....it could be something w/ your torque converter but thats if its an auto...and you could probably add the piston rings as a possibility as well....and just like the post above, your ECU could be a factor....i kno that ECUs adjust themselves to the driver either around the first couple thousand miles or quite frequently depending on the car.....if its driven in a way that the ECU usually doesnt respond to, then yea your ecu could act up and try to counter or even adjust to that...that was the case w/ my friend's 02 ram...that truck ran perfectly until he put an intake and flowmasters on it and started racing it...after a while, his ecu adjusted the RPM redline of his truck and shifter gears quicker, which in his case was a good thing....wish my car did that...

Whew! I'm glad you said that =)