ok, i bought and stuck in a 2.8 out of a 93 s10. was idleing REALLY bad after i got it running so i plugged the vacuum leaks, replaced my lower plenum gasket and the upper plenum gaskets since those were both leaking. the cars still shaking bad, and it idles really low and eventually dies still. i cant figure it out, i didnt mess with my TPS when i swapped engines, my timings set correctly i believe. and i have no leaks now besides an exhaust leak where i dont have it sealed correctly at the donut gasket so im lost. help please?? i wanna get this car back on the road but i cant deal with all the shaking and it dieing. when the car idles about 550 it doesnt shake. its nice and smooth but its when it gets into the upper RPMS that it shakes. help??

 

should add that EGR is out and so is my charcoal canister

 

I had a misfire that caused my engine to shake under acceleration, I had a few wires touching the firewall grounding out those wires. I always check my wires twice to make sure they are properly installed. Make sure they are in 1,2,3,4,5,6 order starting with the passenger front spark plug wire. I wasn't familiar with these engines a year ago and was unaware that the #1 piston was on passenger side front unlike the v8's

 

checked the fireing order 3 times today, they are right, plug wires arent touching the firewall or anything so i dont think they are shorting out. i really want this figured out. i have a car show to go to in about 2 weeks so im hurrying to get this done lol, i still need my headliner and seat repaired, paint touched up, and windows tinted but i need this car running right before anything.

 

This might sound dumb but with the engine off can you move it from side to side? If you can you have bad motor mounts causing your shake. Another thing that could cause a shake is the harmonic balancer. Does the exhaust sound like it's missing at all? I hope you get your problem figured out. Did you get to hear the engine run before buying it?

 

the old engine didnt shake before i pulled it, and yes i listened to it run, my uncle had it but he ruined the transmission in it so he was gonna junk it before i told him i needed the engine, so i got to hear it run before i pulled it. and it didnt shake, it ran fine besides the valve cover gaskets gone lol. i dont have my driver side exhaust on all the way, i need to bring it over more so i can get all the way on the gasket. how can i check the balencer?

 

I'm not too sure but chances are it's probably still good. Did you use the flexplate that came with the engine or did you use the old flexplate? I ask because I noticed you have an 86 and they were externally balanced while the one in the 93 would be internally balanced.

 

the 93 was a manual so im using my old 86 plate, i was told that all the 2.8s were externally, only the 3.1s were different because of the crank, all the 2.8s have the same crank

 

I thought they started using neutrally balanced flexplate's in 88 and all pre 87 2.8's cars had externally balanced flexplate's. I think we found your vibration problem.

 

the balance is internal from 86 and up s10 2.8's.

 

so i need a new flywheel? great... also what about the idle/

 

You could always check the one you have installed with the dust cover off just turn over the engine by hand and see it there's a weight sticking on the side of the flex plate can't remember off hand which side has it though. If it does have a weight you have the wrong one if its all smooth all the way around then it's the right one. I may have an extra neutrally balanced one if needed.

Idle could possibly be your timing might not hurt to check it did you make sure it was at 10*btdc with the est wire disconnected?

 

i got a new flywheel and it will be here tomorrow so when i get outta school i gotta go to autozone and get it. and whats the est wire look like?

 

The est wire is a single wire that comes out of the wiring harness by the a/c-heater box on the passenger side you can't miss it.

 

also, what is 10*btdc? i have the star under the cap just before it meets the dizzy point thing

 

10*BTDC= 10 degrees before top dead center. All you got to do is slightly loosen the dizzy so that you can turn it, hook up a timing light and using the widest groove on the harmonic balancer you would make sure it lines up at 10 degrees which is the groove between 8* and 12* on the timing tab. Also the est wire is tan with a black stripe.