got a studder when tring to accelerate so i replaced injectors, fuel filter, coil,plugs wires and distributor and catalyic converter,map sensor,cleaned throttle body, so now im stumped can figure it out inless its a timing issue any thoughts? and if its timing why all of a suddon would it change

 

93 5.7 manual

 

The last easy thing to check is the EGR valve, make sure it doesn't have a bunch of carbon deposits in it causing it to stick open. If the EGR checks out you may need to start looking at replacing the Opti.

 

well mine was helped greatly because i changed the o2. i replaced the wrong one. but it helped. my other one threw a code for a while but it went away. im replacing it Saturday. i can already tell that it will help. also go ahead and check the egr like slvr suggested but if your hesitation is bad this most likely isn't it. i had some egr issues but the hesitation was minimal. o2 can be much worse so can optispark.

 

Good point on the O2's, although those should be pretty easy to check. If you put a voltmeter across between the signal wire and ground you should see a rapidly changing voltage (nominally around 0.45V) while the motor is running. Just be careful not to burn yourself...

 

agreed ^

 

as for the timing it could a 101 things but unlikely. what is the mileage on your car?

 

disconnect the battery

allow engine to get comepletely cool

reconnect battery


drive car immediately when cold

does the stuttering still occur?

let's see if it's in closed as well as open loop so we can eiter suspect or eliminate sensors such as the o2's

it could be a vacuum leak and as for egr, disconnect the solenoid and see if it improves.

You may get a ses but you just want to check the stutter.

Does it occur at a certain speed or only at a certain rpm regardless of speed?

Does it occur at a certain speed but only in a certain gear? In other words, cruising at 45mph with the 4L60e tranny and slowly depressing the gas pedal and it stutters. If you put the car in 3rd and drive at 45mph it stutters less?

I'm just looking for as much clarity as possible

 

its got 152k miles, its only happins once it got hot/operating temp so thats why i thought the cat mighta been plugged, but it happins after it gets hot usualy not in 1st or second but occaionly it will if its been a long drive, i did reset the ecu after i did the ca2t which was the last thing i did but only happins when acellerating only happins above 2k rpm gets worse in the higher gears dosent happin when just cruising

 

i think it is easy to get at on yours... ( under the timing chain, in the cover )
you could pull out the crank sensor to see if it is craked looking or if it has lots of metal fillings stuck to the magent.
i had a 86 cavalier 355 000 km;s do that!
only after a 30 min drive it would start to buch a kick if i wanted to pass , and the tach was jumping around like crazy with the rpm of motor ( mostly zero , even on decel with standard )
cleaned of the iron fillings and it was fine again.
but if it is cracked at all or leaking oil threw the connector ...chuck it!