Jeep Wrangler Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter #1
I’m desperate to figure out what is wrong with my Jeep 1998 tj 6 cyl. 4.0 liter sport. It idles very rough
and stalls unless I rev the engine. If I’m driving, it will accelerate roughly and stall when I come to a stop (it seems to misfire and hiccup while I’m driving as well around 25-35 mph). Here’s the list of everything I’ve done. Please tell me what I’m missing (I’m losing my mind)
  1. Coil, plugs, wires and cap and rotor
  2. Cleaned all six fuel injectors
  3. Wrapped heat insulation around each injector and fuel rail (heat soak).
  4. Crankshaft position sensor, cam position sensor (distributor pickup coil)
  5. Replaced distributor ( possibly bad bearings)
  6. Complete Fuel pump assembly (pump, filter and regulator replaced (steady pressure at 45 lbs )
  7. Smoke tested for vacuum leaks fixed one small one but engine vacuum strong and consistent.
  8. Idle air control valve and throttle position sensor replaced
  9. Cleaned all ground strap contact points (battery to block, block to firewall and battery to fender)
  10. Added extra ground from battery to engine block
  11. Reconnected evap system hose that was loose and split.
  12. Cleaned and reattached alternator wiring
  13. Cleaned and tightened battery terminals- interstate battery is maybe six months old
  14. ran two bottles of techron fuel treatment through two full tanks of gas
  15. Seafiamed engine through the vacuum lines
Any help would be great. What could I be missing? ... Joe
Any ideas? I’m getting close to giving up ...joe
 

·
Registered
Joined
·
143 Posts
You should get the battery load tested anyway as batteries can be bad/dead on arrival.

If it doesn't do it immediately from a cold start and only starts doing it after at least 20 seconds, unplug the upstream O2 sensor. If it's causing a problem the engine will run normally when it's unplugged.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #7
You should get the battery load tested anyway as batteries can be bad/dead on arrival.

If it doesn't do it immediately from a cold start and only starts doing it after at least 20 seconds, unplug the upstream O2 sensor. If it's causing a problem the engine will run normally when it's unplugged.
I swapped out the throttle position sensor that I got the code on, then I disconnected the upstream o2 sensor ...BAM! It runs like a champ! What did I do? Can I leave it unplugged?
 

·
Registered
Joined
·
18 Posts
Discussion Starter #8
Can I just leav3vthe upstream o2 sensor unplugged and just keep clearing the p0132 and p0135 codes? Or do I need to replace the sensor to keep it running right?
 

·
Registered
Joined
·
492 Posts
I would replace the sensor...that way your not screwing around with constantly clearing codes

Sent from my SAMSUNG-SM-G930A using Tapatalk
 

·
Registered
Joined
·
143 Posts
The reason for asking whether the symptoms were immediate or not until after at least 20 seconds had passed was to determine if the problem was all the time or just in closed loop operation. The O2 sensors are only used in closed loop mode.

Disconnecting the sensor forces the PCM to run using programmed fuel tables, and since it runs OK with the sensor unplugged, it points to the sensor being the issue.

Before replacing the sensor, double check the wires haven't been damaged by touching the exhaust. If that has happened it might be a simple as repairing the wires.

If the wires don't have any damage, I'd just go ahead and replace the sensor. NTK are the OEM supplier so that's what I'd go for. They'll be no problem running with the sensor unplugged until it's replaced, and no need to bother clearing codes till then either. The code should go away anyway I think once the sensor's been replaced.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #12
The reason for asking whether the symptoms were immediate or not until after at least 20 seconds had passed was to determine if the problem was all the time or just in closed loop operation. The O2 sensors are only used in closed loop mode.

Disconnecting the sensor forces the PCM to run using programmed fuel tables, and since it runs OK with the sensor unplugged, it points to the sensor being the issue.

Before replacing the sensor, double check the wires haven't been damaged by touching the exhaust. If that has happened it might be a simple as repairing the wires.

If the wires don't have any damage, I'd just go ahead and replace the sensor. NTK are the OEM supplier so that's what I'd go for. They'll be no problem running with the sensor unplugged until it's replaced, and no need to bother clearing codes till then either. The code should go away anyway I think once the sensor's been replaced.
Thanks for the explanation and the help!...Joe
 

·
Registered
Joined
·
18 Posts
Discussion Starter #13
The reason for asking whether the symptoms were immediate or not until after at least 20 seconds had passed was to determine if the problem was all the time or just in closed loop operation. The O2 sensors are only used in closed loop mode.

Disconnecting the sensor forces the PCM to run using programmed fuel tables, and since it runs OK with the sensor unplugged, it points to the sensor being the issue.

Before replacing the sensor, double check the wires haven't been damaged by touching the exhaust. If that has happened it might be a simple as repairing the wires.

If the wires don't have any damage, I'd just go ahead and replace the sensor. NTK are the OEM supplier so that's what I'd go for. They'll be no problem running with the sensor unplugged until it's replaced, and no need to bother clearing codes till then either. The code should go away anyway I think once the sensor's been replaced.
Now I’m stumped again

I replaced the bad O2 sensor, cleared the codes went to a gas station and bought some gas. Then I restarted the Jeep, pulled out onto the road, it accelerated fine then started to hiccup again around 30-35 mph and continued all the way home. It was great until I stopped and got gas.

Could it be some residual gunk stirred up at the gas station or from the
Seafoam?

Is there some way to head fake the computer and just leave the O2 sensor disconnected
 

·
Registered
Joined
·
18 Posts
Discussion Starter #14
Now I’m stumped again

I replaced the bad O2 sensor, cleared the codes went to a gas station and bought some gas. Then I restarted the Jeep, pulled out onto the road, it accelerated fine then started to hiccup again around 30-35 mph and continued all the way home. It was great until I stopped and got gas.

Could it be some residual gunk stirred up at the gas station or from the
Seafoam?

Is there some way to head fake the computer and just leave the O2 sensor disconnected
I replaced the sensor with an NTK
 

·
Registered
Joined
·
4,846 Posts
Which part number NTK?


1997-1999
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)
 

·
Registered
Joined
·
325 Posts
Just an Idea were the IAC and TPS Mopar or Store Brand, Also maybe the IAT? IIRC it can mimic an O2 sensor failure
IAT OR INTAKE AIR TEMP SENSOR-This sensor reads the incoming air temp.The computer uses this information to calculate the proper injector pulse width and spark advance.
 
1 - 20 of 25 Posts
Top