Now What...

[SurfXJSnow]

So, i have this problem with my jeep that i cannot figure out.

When im just idling and coming to a stop the jeep seems very rough on the idle, and kinda shakes. This only happens at very very very low speeds without my foot on the pedal. Meaning, it happens with im just rolling with my foot off the gas. Feels and sounds like the engine wants to stall out. Engine performance kinda sucks lately as well.

I'm constantly pulling a P0301 code (Cylinder 1 misfire)

So what i have done is...

Changed all plugs, wires, cap, and rotor.
Swapped out cyl 1 fuel injector with a new one
Swapped out cyl 1 fuel injector wire harness with a new one
Cleaned and swapped out my IAC (idle air control sensor)
Swapped out my TPS (throttle positioning sensor)
Did a compression test. All came back within 5% of eachother.
Checked my fuel pressure and read about 49psi which is normal.
Ran a whole bottle of sea foam through the engine.

All of the above rule out ignition trouble, fuel injectors, fuel injector wires, fuel pump, fuel filter, TPS, IAC, bad rings/piston pressure...

So my question is... what now? Catalytic Converter? New ECM (Computer), Tranny issues?

Your input would be appreciated. I have wrenched on this thing every day for the last 5 days with no success.

 

[89xj]

what year?

 

[j33pownr]

Check your vacuum lines. I had a similar issue and it was because of two leaks. One at the intake and the other on the vacuum canister in the front bumper.

 

[cnugent]

My vote's for a vacuum leak too.

 

[ladywolf]

what about an idle air sensor/controller?

whoops nevermind. missed that.

 

[jeeperjohn]

Check to see if your engine mounts are toast. The stock mounts don't hold up well at all.

 

[SurfXJSnow]

checked all my vacuum lines, and engine mounts. Nothing there either =(

 

[Frank Z]

Tranny or torque converter.

 

[SurfXJSnow]

Tranny or torque converter.

where is the torque converter?

 

[89xj]

where is the torque converter?

between the engine and the trans.

 

[winterbeater]

We still don't know the year? Unplug map sensor to test if that makes it better.

 

[Frank Z]

It's 98.

Read it, Learn it, Live it!
http://www.pirate4x4.com/tech/billavista/PDFs/AW4_manual.PDF

 

[SurfXJSnow]

map sensor will be next then. im just afraid of hurting that little tiny rubber hose under it...

 

[Frank Z]

Just unplug the electrical connector.

 

[SurfXJSnow]

Just unplug the electrical connector.

going to do it now... what should i expect? should i drive it with it unplugged? CEL is back on. should i wait until i pull the codes again tomorrow?

 

[Frank Z]

Just unplug it and then see what it does.

 

[Frank Z]

http://www.babcox.com/editorial/bf/bf90222.htm

Most late-model automatics have some type of lockup torque converter to improve fuel economy. If the lockup fails to engage, there will be some slippage and fuel economy will drop. Causes here include a bad lockup solenoid, incorrect sensor input information to the transmission controller or PCM (typically a speed sensor) and hydraulic control problems. If the lockup fails to release, the engine may shudder and die when coming to a stop. Causes here include a faulty lockup solenoid, a sticking lockup valve, grounded lockup solenoid wiring or a missing lockup solenoid spacer plate screen.

 

[SurfXJSnow]

http://www.babcox.com/editorial/bf/bf90222.htm

now............ thats something i need to have checked by a pro. sounds just like my problem..

thanks FRANK!

 

[winterbeater]

If you are talking about torque convertor not releasing, my Lincoln has similar symptoms occasionally while warming up. If I pop it into neutral, it smooths out immediately. If you pop your XJ into neutral, does it smooth out and maintain proper rpms?

 

[SurfXJSnow]

not sure. its dark as hell outside right now. im going to try that tomorrow. whats that mean if it smoothes out in neutral? torque converter?