Mikeythrash

So me and a friend "XJWonders" put on a 03 grand cherokee manifold,703 injectors and new NGK plugs.Before that is also got new cap,rotor,wires.Iac sensor seems fine.everything is pretty much clean inside and out has a new head was cut at the machine shop from having blown head gasket months ago "the was fixed awhile ago" has new coil basically the whole freaking thing has been rebuilt and we'll we are still at square one very rough,shaking,sounds like it's gonna stall coming to a stop at idle.misfires around 40-45 mph rpms jump back n forth like crazy then at around 70-75 does it again go back down to 45 and the jeep vibrates like crazy. He did say my battery was too small could that cause roughness? My fuel pressure is good and we did a compression test which also came out good. No light no codes as of yet since we did the swap but still running like crap.i am actually nervous to drive it cause I feel like I am going to break down also has a new CPS as we'll.

RTorrez1

First of all what year and engine size??? Have you checked it for codes?

Mikeythrash

My fault 96 cherokee 4.0 6 cyl and yes we checked multiple times after we did it nothing and I drove for awhile still no CEL came on.we checked for pending codes and nothing.but it's Definitely missing and running horribly.

RTorrez1

I would start by checking the plug wire and make sure that you didn't get a couple of them mixed up. That is if you haven't already.

Mikeythrash

Hmm like wires In the wrong spots I am pretty positive there good

XJwonders

We didn't do compression test. That was a vacuum gauge that we hooked up.

By the way, here's how u check the firing order to make sure the spark wires are hooked up correctly.

Mikeythrash

Running like a champ super smooth no engine light for over a week now.smooth at idle as well.

RTorrez1

How did you fix it, What was the problem?

Mikeythrash

Well it got the ngk plugs, upgraded the manifold cleaned the iac sensor. It eas still rough for about a week after that was done then this past week or more we checked the light it said 3 and 6 were missing but immediately after that the light went off.and it has beem running awesome since then ive drivin it alot amd still no light no rough idle it doesnt sound all cammed out like it did before.so I am guessing it just needed to be drivin a lot for the computer to pick everything up.