98 with power loss

Hello
I have been trying to fix this for some time.
Feels like i'm not running on 6 cylinders. Gutless


>1998
XJ 4.0
5 speed
Stock
177K

Jeep dealer couldn't find problem and didn't want me throwing money at it. Since I reset the PCM Jeep dealer couldn't review any history.
No codes

Power loss, struggles to accelerate. Same in each gear
Idles well no dips, spikes etc.
Power loss seemed to come suddenly about 2 years ago after a wash, but 2 years later I'm sure I'm forgetting some details.

Drives dependably, always starts with no recent hiccups.

What I've done to date.

No codes/stored
Fuel trim both short and long term are with in spec.
New Cat, muffler
New Crankshaft sensor
New O2 (Bosch) up and downstream
New plugs, wires, distributer
Throttle body cleaned
IAC cleaned
New TPS sensor, then replaced back to original when it drove same.
New MAP sensor then replaced back to original when it drove same.
Fuel pressure is 49 at rail
Compression 150, with very slight variation
Vacuum tested good
Plugs looked fine after 2k replaced. Not rich. All consistent with each other.
No back fire
Gas milage bad
Fuel injectors cleaned
Tested spark- all good
Tested fuel injectors with noid light- all good
Coil is original and within spec
Besides O2 codes (which were both replaced) no other stored error codes
Ran gutless before upsteam O2 showed code. Was replaced with same result.
When O2 showed code it also blew the 15 amp @PDC. After new O2 and fuse it was back to normal gutless.

From my Torque app I get error message but I've read that error was pretty common.
TiD: $11 CID: $01
Min:56
Current:13
Test result said "not Ok"

When checking temp at header, cylinders 2/3/4 seem to be running cooler 250f to 400f (+-50). This was only thing that i could find.

Again this was a sudden change. Has not gotten worse nor improved.

Thanks in advance

All the replaced sensors are genuine Jeep, and not crappy Chinese knockoffs with a "Lifetime Warranty" ? Cheap parts are cheap for a reason.

You should be using NTK or genuine Jeep O2 sensors. Many threads on the different Jeep forums point out how the original poster had running/driving issues when using Bosch O2 sensors. After long and frustrating searches for the cause, replacing the Bosch O2 sensors cured the problems.

Make sure there is no wire harness damage or intermittent short circuits, and no corrosion or damage at the O2 sensor wire plugs pins. I would test or replace the Coolant Temperature Sensor.

When problem started XJ had original os sensor. Was not throwing code.

>After long and frustrating searches for the cause, replacing the Bosch O2 sensors cured the problems.

Yeah not having a Jeep sensor makes me anxious but I have no difference with bosch, which was installed after CEL very recently.

I'll check into the Coolant Temperature Sensor. Haven't looked at it.

If you installed a Bosch O2 replacement for a failed sensor, I wouldn't expect any change. O2 sensor have a service life of about 150,000 miles. Weak/worn sensors often do not throw a CEL code, but will cause a 30-40% drop in gas mpg's.

Do you think the Bosch is just copying what the original was doing. Which was possibly giving the pcm a bad reading?

Make sure there is no wire harness damage or intermittent short circuits, and no corrosion or damage at the O2 sensor wire plugs pins.

It is well proven in numerous threads on various 4x4 Forums that Bosch O2 sensors and Jeep 4.0L do not play well together. YMMV.

mack14 said:

Hello
I have been trying to fix this for some time.
Feels like i'm not running on 6 cylinders. Gutless


>1998
XJ 4.0
5 speed
Stock
177K

Jeep dealer couldn't find problem and didn't want me throwing money at it. Since I reset the PCM Jeep dealer couldn't review any history.
No codes

Power loss, struggles to accelerate. Same in each gear
Idles well no dips, spikes etc.
Power loss seemed to come suddenly about 2 years ago after a wash, but 2 years later I'm sure I'm forgetting some details.

Drives dependably, always starts with no recent hiccups.

What I've done to date.

No codes/stored
Fuel trim both short and long term are with in spec.
New Cat, muffler
New Crankshaft sensor
New O2 (Bosch) up and downstream
New plugs, wires, distributer
Throttle body cleaned
IAC cleaned
New TPS sensor, then replaced back to original when it drove same.
New MAP sensor then replaced back to original when it drove same.
Fuel pressure is 49 at rail
Compression 150, with very slight variation
Vacuum tested good
Plugs looked fine after 2k replaced. Not rich. All consistent with each other.
No back fire
Gas milage bad
Fuel injectors cleaned
Tested spark- all good
Tested fuel injectors with noid light- all good
Coil is original and within spec
Besides O2 codes (which were both replaced) no other stored error codes
Ran gutless before upsteam O2 showed code. Was replaced with same result.
When O2 showed code it also blew the 15 amp @PDC. After new O2 and fuse it was back to normal gutless.

From my Torque app I get error message but I've read that error was pretty common.
TiD: $11 CID: $01
Min:56
Current:13
Test result said "not Ok"

Was there a code associated with the error message?

Those Torque app readings are strange to me. What do they mean?


When checking temp at header, cylinders 2/3/4 seem to be running cooler 250f to 400f (+-50). This was only thing that i could find.

Again this was a sudden change. Has not gotten worse nor improved.

Thanks in advance

Click to expand...

.

No code


The torque reading is I think data from O2.
I don't know what it means and I wasn't able to get info on it.

mack14 said:

No code


The torque reading is I think data from O2.
I don't know what it means and I wasn't able to get info on it.

Click to expand...

See if you can get one of the auto parts stores to hook up their code reader and see if they can find a code (that is to say you haven't cleared the history), maybe a pending code.

Edit: You may have to show them where the DLC is.

Update

I unplugged the temp/sensor. I didn't clear CEL

Tonight I check to see code PO118 which made sense as its the temp/sensor
But I also had:
PO138 O2 (bank1 sensor2) "circuit high voltage
And pending PO135 (bank1 sensor1) "heater circuit"

Could both of these be linked to disconnecting temp sensor?
Or could this be more info to power issue.

Google the CEL trouble codes, and check/test/inspect the typical issues that will be listed for each code.

Did you ever find your issue?

I'm running into something similar that just started last night. Mine occurs over about 2100 RPM is is such a huge power loss that it decelerates and it sounds like I installed a cold air intake at that point too. At idle all seems good and when I rev it without load it seems fine. I suspect something in the intake or exhaust is loose but it was all to hot to dig too far on the side of the road last night other than a quick check to see if something obvious had come loose. So I limped it home and will work on it tonight.