Jbri22

Driving home today I went to accelerate and nothing happened I got no power. Let my foot of the gas and press down slightly and got a lil bit. She started sputtering a tad then came back to life for a couple minutes. This happened once or twice more until dying. Tried to restart and wouldn't. I pulled the connectors on the injectors and reconnected them and she started right up. Drove home and parked.

Haven't been able to pull any codes yet, will tomorrow. But thinking I need to replace my fuel injectors? Not sure what else it could be

tjwalker

Is the check engine light on? Even if no, connect a code reader or a scan tool to see if there are any pending codes. Codes are always valuable.

If it started and ran "normally" after your incidents, then I don't think the problem is fuel injectors. More chance that you have an intermittent electrical or sensor issue of some sort. Testing fuel pressure WHEN symptomatic also a good idea in the process of elimination.

Good luck and keep us updated!

Jbri22

So I should have given lil more detail. Few months ago I experienced sorta the same issue car would never completely lose power or die but would lose acceleration for a moment then come right back.

I drove to work today no problem, work across from napa, figured get it close was a good idea. Went to give it a test drive at lunch time and the issue came back up. Sputtering, struggling to get fuel. Trouble starting, eventually got back. Have not been able to pull codes yet. I am showing check engine light on.

Will update in cpl hours

Jbri22

98 xj, auto, 201,xxx

Jbri22

OK... pulled codes. PO 138:Sensor Shorted To Voltage(i was aware of this one and have had it for a lil while, need to replace o2 sensor

NEW CODES:
PO 118:ECT Sensor Voltage Too High Engine coolant temperature sensor input above the maximum acceptable voltage.
P0171 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

No idea about these....

tjwalker

1. If you have original oxygen sensors, replace BOTH of them. They aren't that expensive and if one is failing, the other one isn't far behind. Use only NTK sensors which are original equipment for your 98 XJ.

2. The P0118 is related to the CTS, coolant temperature sensor located in the thermostat housing. They can be tested for resistances cold and hot and then compare your results to a resistance chart which can be found in any service manual, but the procedure is kind of a pain. Most guys just replace them which is what I'd recommend. They aren't that expensive.

Then erase the codes, drive it and let us know if any SYMPTOMS or CODES return. Good luck!

Jbri22

So.. I have replaced both o2 sensors, change cts. Codes are all gone but problem remains.

I went ahead and changed my spark plugs and and grounds bc they needed it.

I am under the impression it is a fuel related issue. The jeep started sputtering and losing acceleration with a little under half a tank of gas. When it happens, it does the same thing when your running out of gas, chugging, cant accelerate but a little acceleration gets you a little bit of power. I filled er up with gas and drove it all weekend. couple hundred miles. Only to have the problem come back when reaching lil under a half a tank. Filled up and ran fine ok. Suspecting a fuel issue, I tested my pressure and got 40psi with it in the on position. After starting the jeep i got 44-46 psi.
Correct me if i'm wrong but i think it is supposed to be at 60ish turned on. With it running seems right.

So know i am thinking it my fuel pump, filter, or pressure regulator... Cant test the reg without dropping the tank since its a 98.

Let me know what ya think,
Thanks

tjwalker

Hold off on replacing that fuel pump assembly. On a 98, the spec for fuel pressure is 49 psi, plus or minus 5. 44-46 puts you within the recommended factory spec. I don't think the problem is fuel delivery.

If you have NO codes, (and be sure to pay attention to any codes that pop as they are likely related) then the next thing I would test is the "throttle position sensor". Directly involved in throttling up. How-to is shown below.

Keep in mind that you can have what are called "escapes" where you have an actual problem with a circuit, but no codes are popping for it. I have seen this many, many times. These can be difficult but you have to hunker down and test your way to a solution. Don't throw parts at it. Terribly inefficient and doesn't leave you with any beer money.
--------------------------------------------------------------------
The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics! It should be verified early in the troubleshooting process, when a transmission issue is suspected!

• Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".
• High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.
• Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.
• Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted accordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.
• Engine Misfire: A fault TPS can report values outside the denied acceptable range causing the ECU to incorrectly fuel the engine. This is noticeable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

GreaseMonkey17

The fact that the problem is only occurring at half tank or under and acts like it isn't getting gas has me curious . Have you filled the tank when it has happened to make sure it isn't actually empty ? You said when it hit a half tank after 200 mile trip the problem occurred my XJ doesn't get much more than 200 miles to a tank.

tjwalker

The possible half tank connection is a bit curious. I would keep your fuel pressure gauge in the cab and be ready to test fuel pressure again but be sure that you are under a half a tank and have just experienced the symptoms. Even then, testing may be a bit of a crap shoot if it is a problem that you only see under engine load. But I'd still test.

If you find that the problem is "consistent and repeatable" under a half tank, then you gotta look at "cause and effect" and it still could be fuel. Otherwise, it may just be coincidental.

Jbri22

Sorry for the delayed response. I work seasonally with long hours and dont get to much time off to fix my jeep, anyways.....

After the tps comment, coincidentally, the jeep threw a code (ps 123)-Throttle Position Sensor Voltage High, so i figured i would replace the tps. Replaced it 2 days ago and the jeep seemed to run just fine, better actually(shifting and throttle response seemed to be improved).

I was driving around today and sure enough, jeep starting sputtering. kept my foot barely on the gas enough to keep it moving with giving it too much gas bc that usually causes it to die. made it to a good spot to pull over and park her.

I went and borrowed a fuel pressure gauge from autozone and went back and tested the pressure. It now shows almost no psi with key in on position and when I can get her started, it struggles to start right now, it is showing about 5-10psi. I do not know if this because i cant really get the jeep started or the fuel pump is actually bad...

This makes me think its the fuel pump, or something located inside the pump.

I dont like throwing parts at the problem but out of troubleshooting ideas. Like always, any suggestions/ideas would be very useful.

Thanks.

Jbri22

oh... and the jeep is pretty much full on fuel. It was already close to full but after it died this last time, i went and filled up a gas can and put it in her and no changes.

Jbri22

any ideas yall?? bump

BlueRidgeMark

Sounds like an intermittent fuel pump. Time to replace it with a Bosch. Anything else is a gamble.