monstercherokee

I go to take off and it bogs down and it pops in the throttle body then picks back up?

Marcucco

Backfires in the manifold mean the fuel air mix is getting ignited in the intake somehow.
A valve is stuck open or not closing tight, there's some serious carbon build up issues,
or it's radically out of time. (plug wires crosse up)
Sorry for the bad news.
My first guess would be a valve sticking open when the engine is cold.

Marcucco

oops

monstercherokee

It runs real good new head motor no wires are crossed

Marcucco

Think about it.
You need fuel air and a heat source to cause ignition.
There shouldn't be more then a tiny amount of fuel in the manifold if the valve timing is correct, and there's nothing in the manifold to cause ignition.

One of a couple of things could be happening in your engine.
There's some carbon build-up above the intake valve that's getting hot enough to ignite the incoming fuel air mix.
Or
The valve is open (at least slightly) when the cylinder fires.
Or
The spark plug is firing with the intake valve open.

It's not a death sentence or anything, it could be one of those things SeaFoam could cure.
But I'd want to take the rocker cover off because the easiest/cheapest answer, going by what you posted, is that a valve is sticking open when the engine is cold and it loosens up once the engine warms up. You might want to get that problem diagnosed/solved before the valve gets stuck good and the piston crashes into it

Marcucco

You could also pull the plug and see if maybe theres a build-up on the head of the piston that might still be hot enough to cause ignition when the fuel/air mix hits it.
This would indicate you're running a mixture that is too rich.

monstercherokee

It did it with the old engine and head.. its all new and its done it once a day ago

Marcucco

Look buddy, I get it, you just had a bunch of work done.
But the Jeep still isn't running right so obviously something got messed up or skipped over in the rebuild, $h!t happens, somebody screwed up.

The bottom line is this, you've either got a stuck valve or a timing issue.
You can go back an talk to the people who did the work,
or you can try and track the problem down yourself,
or you can ignore it until the valve sticks hard and punches a hole in the top of the piston and hope they make good on the warrantee.
Your choice.

eae0164

Or...it could be an issue with the IAC, TPS, or CPS too. Mine runs like that right after I reconnect the neg. Battery cable after changing parts, until the ECU relearns all of the sensors. It will only do it just after it warms up, and only 1 or 2 times until the ECU calibrates.

monstercherokee

I did all the work all of its been tested and it runs like a Cadillac no issues. Timing is dead on and everything checks out fine looks like you need to brush up on your mechanics buddy the old motor did the same thing so not a motor or head issue.... thank you

monstercherokee

That maybe my problem

rrich

Not symptoms of CPS or IAC but could be TPS.

Crossed wires, bad cap, even plug wires run too close together - cross induction - or lean. TPS can cause it to be too lean.

Pull off one plug wire at a time - snap the accelerator hard. See which cylinder does not make it backfire.

If no particular cylinder is the cause, very likely TPS - defective or misadjusted. A scratchy TPS can act like a bad accelerator pump on a carb. It will run OK unless you try to accelerate.

Something in common with all cylinders.

Something you had on the old engine and re-used again.

Let us know what you find.

monstercherokee

Intake and throttle body that's all I reused