tj loss of power

[stickynugs]

This is my first post on the forum because i can usually fix my 2000 jeep wrangler just by reading the post, but. 4.0L, 5 spd standard transmission, no hop ups at all. When i crank it up it has a slight miss at idle, when i take off it pulses like it isnt getting fuel . If i take off real easy it still doesnt but not as drastic. When the engine is warm it does the exact same thing but a little worse. At idle it doesnt run rough enough to die but it has a faint miss and i dont like it.

I have already done the following

fuel injector cleaning ( the pressurized cleaning at the mech shop)
changed battery
checked alternator
changed fuel filter and cleaned the tank thouroughly
changed air filter
changed spark plugs

I have only one idea left and that is the cataytic convertor. I would just like a few opinions before i take off the cc and hollow it out.
thanks

[laneiac]

Crank position sensor.

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[Jeepr89]

on the 2000 4.0 is there that gay dis system with three coils directly over the plugs???? If not ck to see if the spark is taking an easier path to ground and sparking out of the plug wires, to do this take a test light ground it and run it along each wire. that could be causing your problem. If you can't figure it out take it to a shop that has an ignition scope and ask them to hook it up to the scope this should almost pin point where the problem is at.
Evan

[stickynugs]

sorry i forgot to say the check engine light is NOT on. Wouldnt it be on if it were the CPS

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[nakedjeeper]

Not positive about the CPS, but my TPS went out without the check engine light coming on. It did throw some codes, but they didn't point directly at the TPS. The codes related to the symptoms like misfire or something.

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

	Throttle position sensor A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve. The sensor is usually a potentiometer and therefore provides a variable resistance dependent upon the position of the butterfly valve (and hence throttle position). The sensor signal is used by the Engine Control Unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).

[Bounty__Hunter]

Have the trouble codes scanned, there could be a pending code that's not triggering the MIL light.

A bad catalytic converter will kill your power, but not make the engine miss. A bad catalytic converter chokes the engine down even more as it heats up.

[_(OIIIIO)_Jeeper]

My 97 TJ 2.5L was doing close to the same...is the exhaust black at the tip? (running rich) If it is it will eventually "foul" an O2 sensor, which mine did several times before the actual culprit was found...
....the MAP sensor.
The MAP was sending false readings to the brain...was reading barometric pressure wrong....was causing the down stream O2 to show a lean condition....which the brain would pour MORE fuel to the TB....basically just went kaput! $90 for a new one and have not had a prob sence...got all my power back too! AND MY FUEL MILAGE WENT BACK UP FROM 4-5 MPG to 14-15 MPG!

PS how many miles you got on it...IF it is the cat it might be covered under emmisions warranty...somebody help me out here but I think it like 80K miles....?????

[Bounty__Hunter]

Federal Emissions Warranty is 8yr/80K miles. Covers the catalytic converter.

[Sparky-Watts]

Sounds more like a MAP sensor problem to me.....never replaced one on a Jeep, but I know on a Toyota Camry they're around $600.

[MerkL]

Test the fuel pressure. It sounds like you're not getting enough fuel coming up. It won't matter how well you clean the injectors if there is a bad fuel pump not sending enough fuel.

[Junkpile]

stickynugs.....good name ......care to elaborate on what it means? :wink:

[stickynugs]

you were the only one who noticed so you must know lol