big problems with 91 s10 2.5

i have a 91 s10 2.5 vin code e i have had a new engine put in it and ever since i have had alot of problems with the engine jumping, sputtering, bad idle, backfiring, missing through driving range.when i put the new engine in i put a new water pump, distributer, clutch presser plate and throw-out bearing, and i also put a new cap, rotor, plugs, and plug wires. since the engine has been in i have replaced all the electronic sensors and i replaced the egr valve and solinoid along with the muffler and catalitic converter.i have also had the valves checked and the hydraulic lifters repaced because ever since the motor was new it has had a tick in the valves.i had my mechanic check the timing and it was way way off and when he put it in time it wouldnt hardly run.he put the timing back where it was and it seems to have plenty of power but its still acting up backfiring, and it still has that jump and hesitation in it.im about to change out that distributor again because ive had people tell me it may be a short in the module or the halls effect switch.well thats about all i know if anyone has any advice or idea about it that would be greatly appreciated.thanks

Wrenchdude

I hate to say it, but for all that work you put into it, you should have gotten at least a better motor to begin with :dunno:
My only suggestion is check to make sure the timing marks are right (???). If those are not right, that might be what is up with the timing, but that is a world of hurt for ya man, sorry to hear about that.

maybe your timing chain slip a nocke, i know it has to be top dead center for timing to be exact. actually i would check for a plugged exhaust system first maybe the converter might be pluged. hope this helps.

nevermind i should of read a little further.

It Sounds Like The Timimg Chain Is Off A Tooth. Was This A Rebuilt, Or Just A Good Used Engine?

thanks for the advice ill check to make sure top dead center is really top dead center still have changed out that distributor yet i think theres something wrong with the halls effect switch or mabey the module.anyways thanks for the advice any or ideas let me know

yes it was a rebuilt

Hey Dude, I Just Saw In Your Original Post, That You Have The Halleffect Switch In That Picumup. By All Means, Check That Sucker Out. I Have Had A Milenium Of Problems With Them Damn Things. I Have A `90 S-10,2.5L,And Put A 93 Distributor In It Just To Get Rid Of That Trouble Maker.

personaly i would throw a smallblock v8 into that puppy and be good. Just make sure it is carbarated and half your problems will go away (though when fuel injection is running, it is a better running motor)

Was This Motor Rebuilt From The Ground Up? Were The Cylinder Walls Bored Over? If This Is The Case, You Have To Understand That Your Engine Is No Longer A 2.5l It Is Bigger But Your Computer Doesnt Know That. So At Cold Startup (open Loop) Your Computer Is Adding Fuel And Timing Curves For A 2.5l Until Your O2 Sensors Are Hot Enough To Work And The System Goes Into Closed Loop (read The O2 Sensors To Calibrate Fuel And Ignition Curves). This Is One Thing You Will Need To Be Aware Of. First I Would Check The Cam Timing And Then Make Sure Your Distributor Is In Time. You Will Need A Timing Light And An Extra Buddy To Help You Do This. As For The Engine Displacement You Will Need To Find Out The Actual Displacement Of The Engine And Have A Special Computer Chip Made For It. I Had The Same Problem With A 1990 Firebird 3.1l
Good Luck!

on a 2.5 there is no timing chain worry about. the timing is pretty fool proof on these motors. the cam and crank are goined by two big gears that simply mesh together. the only thing you have to do is line the dots up.

Sounds like a timing thing to me.

Did you remove the timing wire on the PCU under the dash when you set the timing.