Before I start, I have researched and look up my issue. Found plenty but there are never any solutions. The post just kind of die. Ok so I have been going after this for about a month now. I have a 2001 Jeep XJ. Changed out to banks torque tube headers. Have been having a issue where when it starts up it runs rough in idle. The engine sounds like a rotary which is strange. It will warm up and go into a closed loop setting but still continues the rolling idle. I have 12 port fuel injectors from k suspension. And NTK copper plugs gapped to 35. Once I get driving the engine will begin to bog down with it is getting the right air to fuel ratio. Not to mention when I am going up hill or floor the gas it will not pass 3000 rpms. Almost like it is hitting a rev limiter. I have check TPS, MAP, IAC, Crank and cam sensor. All were replaced due to needing tune up anyways. Check fuel pressure and replace fuel pump. Ran fuel pressure gauge and got all the air out of the line. I have codes for misfires p0300, p0303 and p0304. I have check to ensure I don’t have any cracked head symptoms. No milky oil no oil in coolant ( verified by testing the coolant at local shop. It stickers to open loop and runs like absolute pooooooooooo. Replace upper precast and all four o2 sensors with NTK sensors. I am at a loss. PLEASE HELP.

 

Make sure no wire harness wires have been melted.

Did it run like **** before doing injectors and header.

Does it have a vacumn leak. Lightly missed intak with starting fluid. Lightly so it doesn't suck it in the air filter.

 

The header have been on for a few years. It was running crappy before the new injectors. I was running 4 port and when I moved to Alaska is when it started being retarded.

I have done a check in all vacuum lines with a propane test. Including the evap canister and intake.

Are you talking about the wire-harness near the fire wall side of the engine. I checked there. I had one exposed wire on the back of the coil pack but I isolated and repaired that.

 

Im winging it.
any crucial harness any that could be grounded out.

Did you put wrench on manifold/exhaust bolts. Verify everything is mechanicly sound. Vacumn leaks, compression, pull plug wires make sure its firing on all 8.

Go back to basics before messing with computer crap.

Did you say how many miles on it?

Unplug 02 sensors see what happens

is the factory exhaust on it? I'd assume not since it has big money in bank's header
Wondering about a severely plugged converter

 

Milage is 178000. I have unplugged the o2 and nothing changes. I think that means they are bad but not 100%. Exhaust is flow master with universal cat. ( was low on money when I needed the last replacement. Still don’t know why I need the third cat that has no o2 sensors to it). It is firing on all 6 plugs. Have tried to tighten manifold and exhaust. Help slightly but not much. Going to do compression tomorrow. Just trying to get a point in the right direction. Thanks for the responses so far. Sometimes talking to someone else helps bring to light something I may have missed.

 

Your catalytic converter may be clogged.

 

can a clogged cat force misfires????

 

It can cause P30X errors. Put a pressure gauge on the down stream O2 bung. should be no more than .5lbs or so, anything over that and the cat is clogged.

 

can cats clog in 2 weeks. Sorry forgot to mention up above upper precast are brand new. Lower cat next to transmission is still at there. Is that the one you think is clogged.

I need to see if I have a attachment to get it the o2 hole

 

Sorry needed to clarify you'll need reading from upper and lower - I'd check both uppers and both lowers (I assume your '01 has 4). If cats are new those might not be the problem.. are they OEM?

 

You noticed a change after checking manifold bolts?
does it fall on its face if you give it to much throttle accelerating.

Due to it getting slightly better after tightening bolts. Id redo a vacumn leak test with starting fluid.

After hear that I think id be inclined to get a new gasket and redo the header job. It may have part of tge old gasket under the new one or even just crud that may not have been cleaned off.

Sazall exhaust off ahead of the un needed cat. Go for a test drive. Weld or clamp on cat delete pipe.

KISS

keep it stupid simple.

 

As for the acceleration, basically when I’m under a load( hills or any type of slight incline it seems like it bogs down, but never to the point of dying. Also when I give it gas it get to around 3k and starts to bounce like it’s hitting a rev limiter. That is the part that is most confusing. Was thinking about doing that to the unneeded cat. Need to go get some piping and get that ready. I’ll redo the vacuum test and see what I get. Is there a difference doing it with propane and starting fluid??

it’s hard doing work in 10 degree weather and my Jeep won’t fit in my garage. The joys of living In Alaska!!

 

The word you are looking for is, "mist".

 

So I fixed a vacuum line coming from the carbon filter near gas tank. Still have all issues in addition to a high idle now. My TPS is reading between 90 to 99 % open with no touching to the throttle. The TPS is brand new ( I know that doesn’t mean it’s good but yeah). If I unplugged the TPS the idle goes back down to normal. About to turn it into a DIY fire pit.

 

Starting fluid is just what ive used i missed (mist) it picks up on small leaks.

What about IAC unplug that sensor. Im not computer smart i just start un plugging stuff looking for change for the better or worse