studder

[200plus]

ok so im driving down the road and every so often when im either down shifting to second or upshifting to second i get to about 2500 rpm and i have a NASTY studder and its like my car just wants to die but never does. it drops the rpms down real low. i can step on the gas and it doesnt do anything for a like 3 seconds then it rev back up agian. the only time it happens is when i drive my car to where ever let it sit for like 3 hours or more and then go driving agian. i cant figure out what it is i have changed the throttle cable plugs throttle position sensor and i still dont know... can anyone help me?
Thanks
Jamie

[Classicrocjunkie]

thats what we call granny shifting... its like shifting through all the gear before 40mph... If you have an idiot light in your car, don't shift according to it. I yell at my g/f all the time with her 96 cav... she shifts way to early and her car bogs down and just runs shitty... when you shift too early it causes more stress on the engine becuase it has to work harder in order to get up to proper speed... lemme give you an example...when your riding a mountain bike and you start in the highest gear possible.. and try driving it up a hill... thats your engine while in to high of a gear at low speeds... when you hear your engine start to strain you down shift.. same thing on a bike.. you down shift to make it easier... try letting your RPMs get higher before shifting.

[200plus]

no dude its not like that it basiclly lunges forward with such a jerk that my head almost hits the steering wheel

[godenm]

i know exactly what your talking about, it does it only when the car is usually cooled off,& if you try to stay on the gas when it does this it will try to die, like the fuel (injectors) has been shut off. its actually pretty damn embarrissing!!! i hav tried just about every thing to stop this on my car, the only thing that has really helpped is to keep the IAC valve cleaned and to spray carb cleaner down throttle body to keep it clean;i usually do this about once every couple of weeks.that and try to let your car warm-up for a few minutes befoe driving it ,that usually helps too. sorry i dont have a better answer for you, alot of people have this problem w/ cavaliers, maybe run down some old threads and get some more ideas

[Classicrocjunkie]

Check your injectors, plugs and make sure the connections on the battery aren't croded... last winter when my car was starting up in the cold, it was misfiring in #3... i some how sheard the wire off and i bought new cheap ac/delco plugs and wires... problem solved. I also brought it in for a fuel injector cleaning

[200plus]

it is the o2 sensor

[godenm]

what makes you say its o2 sensor?

[Classicrocjunkie]

O2 sensor either in your exhaust manifold, or behind your cat would cause a check engine light to turn on and you would be running rich all the time.. black smoke out the exhaust very often... it not that!

[200plus]

my studdering stopped when i put the o2 sensor in so im guessing its that

[200plus]

so i have found out it isnt the o2 sensor. my car decided to do it after i put on an intake, header and a flow master muffler. i cant find out what it is but the machanic at work said it is probably going to be something with my ignition... so im hoping its either going to be my wires or coils. please someone help me find out what the hell it is
thanks

[mattcurry]

another thing to check is your fuel pump, one thing that many people overlook when experiencing studder/'rough idle' symptoms. If the pressure output of the pump is off even slightly, it can cause these 'studder' symptoms. For the problem you're experiencing, it could very well be the backpressure caused on the fuel pump when shifting, especially in the lower gears. There may be a faulty valve in your pump cutting your fuel supply for a couple seconds between shifts. It could also be a matter of dirt/residue build-up somewhere along the line. This is usually worse before you're up to normal engine temperature.
The best solution would be to run some line cleaner and fuel treatement through, check the fuel pump output pressure, and the Easiest, most-overlooked method of prevention for this is to never let your car sit with less that 1/4 tank, you're just asking for fuel pump problems, and this also keeps you from shooting any dirt in your tank through your system, which is why running a tank right down can be extremely hard on your car. About %80 of the customers through my shop neglect to do this, and i've seen way too many problems because of it

[200plus]

could it be cause by my wires or coil cuz its not contiunious it only happenes sometimes.

[Classicrocjunkie]

How big of a muffler/intake did you put on.... 3' maximum intake tubing and since your car dosn't have a turbo, you shouldn't really be above 2.75-3.5" or you can loose back pressure... this maybe an odd ball guess.... check you battery connections and the ones on your plugs...

[200plus]

2 1/4 all the way back to a flow master muffler 60 series commin from a header

[200plus]

intake tube is 2and3/4 or 3