All gears studder

Bond--007

Bond--007

New member
Recently replaced the upstream O2 sensor in my 97 TJ (with the help of JPNinPA & Greg92JeepXJ). Ran great for a few days. Now it's been getting colder at night, it seems like the TJ developed a studder in all gears until it gets warm (op temp 210*) when I try to run in the morning. Any suggestions
 

Any codes?

So how long does it take to get to 210? My jeep takes about a mile at 35 mph or so.

Have you completed general maintenance?
Check battery - load test?
Clean terminals and connectors.
Clean ground connections
Clean TB and IAC

With the last issue did you check or replace your plugs?

You might list all the parts replaced recently.
 
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JPN, no DTCs have been detected. It's gets to 210 in about the same time as yours. I haven't done anything recently other changing the O2 sensor a couple weeks ago (from the previous thread). Battery hasn't been load tested. Might run it over to AutoZone to have them test it. Terminals have been cleaned and sprayed with the protector. TB was cleaned recently and IAC replaced (when I was having the initial spudder in 1st and 2nd gear). Replaced the wires, plugs, cap, rotor a couple of weeks ago when I was tracking down the O2 sensor issue
 
You didn't mention your grounds. The opposite end of the ground cables are often an issue. Clean the contact point and the wire end with sandpaper or steel wool. It should be clean to shinny metal appearance.

You did change your exhaust intake gasket correct? Are the bolts torqued to spec?

If everything else you listed is in working order there is the TPS but being it is only when cold it is less likely.

Make sure the air temp sensor is clean.

I ask about the temp. There is a temp sending unit that may be going.

CoolantandAirTempChart-1.jpg
 

JPNinPA said:
You didn't mention your grounds. The opposite end of the ground cables are often an issue. Clean the contact point and the wire end with sandpaper or steel wool. It should be clean to shinny metal appearance.

You did change your exhaust intake gasket correct? Are the bolts torqued to spec?

If everything else you listed is in working order there is the TPS but being it is only when cold it is less likely.

Make sure the air temp sensor is clean.

I ask about the temp. There is a temp sending unit that may be going.

CoolantandAirTempChart-1.jpg
Click to expand...

I'll check the temp sensor to see what the ohm reading is. I drove the jeep in this morning and paid closer attention to the engine temp and issue. On initial take-off, the RPMs are high when the clutch is pressed in. Once the temp starts to come up, the idle smooths out. This morning it took about 7 mile at 40 mph to come up to the 210* op temp. Was about 48* this morning
 
Bond--007 said:
I'll check the temp sensor to see what the ohm reading is. I drove the jeep in this morning and paid closer attention to the engine temp and issue. On initial take-off, the RPMs are high when the clutch is pressed in. Once the temp starts to come up, the idle smooths out. This morning it took about 7 mile at 40 mph to come up to the 210* op temp. Was about 48* this morning
Click to expand...

Yep! You may have a thermo that failed open. When the thermo failed open it took app 5 mi on a 30 deg day to reach 210. No matter how cold it is now 1-1.5 mi. Not that this is your issue but it will perform better when at temp.
 
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JPNinPA said:
Yep! You may have a thermo that failed open. When the thermo failed open it took app 5 mi on a 30 deg day.
Click to expand...

Guess the thermo has a bearing on the PCM during open/closed loop? Guess I'm trying to understand why a thermo or temp would cause the studder. I had a thermo fail open in my 03 F-150 and it just took longer to warm up, not studder or stumble
 

It may not be directly related but needs to be corrected so the engine runs at optimal conditions. Your issue is open loop. Check the sending unit res as the engine warms. Like the o2 the readings can be erratic or just wrong and you could be in a too lean condition while in open loop.

Have you reset your PCM since correcting the O2 issue?

Also the battery and grounds?

You replaced the plugs with what brand and part number?

Also if you start the engine and rev the engine to 2K and back o idle a few times for 30 sec does the problem persist?
 
Last edited:
JPNinPA said:
It may not be directly related but needs to be corrected so the engine runs at optimal conditions. Your issue is open loop. Check the sending unit res as the engine warms. Like the o2 the readings can be erratic or just wrong and ou could be in. Too lean condition when in open loop.

Have you reset your PCM since correcting the O2 issue?

Also the battery and grounds?

You replaced the plugs with what brand and part number?

Also if you start the engine and rev the engine to 2K and back o idle a few times for 30 sec does the problem persist?
Click to expand...


Have you reset your PCM since correcting the O2 issue?
I pulled the pos terminal off for about 2 mins after changing out the O2 sensor

Also the battery and grounds?
I used a multi-meter on the battery and was getting 13.2v without the engine running and 14.1 when the engine was running

You replaced the plugs with what brand and part number?
I got them from the local Chrysler dealership. I believe they are Champions

Also if you start the engine and rev the engine to 2K and back o idle a few times for 30 sec does the problem persist?
It does until the engine has reached operating temp


Before I left for work this morning (47*), I started the Jeep and let it idle in the drive way for 16 mins (was transferring files on the server at home and it took 16 mins to complete). When I jumped in the jeep to leave, I noticed the engine temp was ~ 180-190. Seems like the t-stat may be open since it wasn't up to temp within 16 mins idle time
 
Bond--007 said:
Have you reset your PCM since correcting the O2 issue?
I pulled the pos terminal off for about 2 mins after changing out the O2 sensor

Also the battery and grounds?
I used a multi-meter on the battery and was getting 13.2v without the engine running and 14.1 when the engine was running

You replaced the plugs with what brand and part number?
I got them from the local Chrysler dealership. I believe they are Champions

Also if you start the engine and rev the engine to 2K and back o idle a few times for 30 sec does the problem persist?
It does until the engine has reached operating temp
Click to expand...

The reset is important, otherwise it takes 500 or so cycles to gather new data. To clear adaptive memory:
Disconnect the POSITIVE battery Terminal and touch the connector to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM.

Voltage at the battery should be 12.6v off and 14.4 running. If you measured within seconds of turning the engine off and got 13.2 that is normal. If not there is something wrong.
Battery voltage is not the same as load testing the battery. Get it load tested.

Poor or resistive connections will cause performance issues and missing like conditions. The opposite side of the grounds are the biggest culprit.
Remove and clean both the wire side and the connection side with sandpaper units shiny, then reconnect.

What part number plugs? Pull them and inspect. Get the pn while you look and report back. Pics are great to help us determine any issues.

If you start the engine and have the issue them try revving the engine for a min or so. This will rule out a slow heating O2. And yes I realize you just changed the O2.

I list easy and basically free things to check and do. If you are unsure ask but do them if you want to resolve the issue.
 
Last edited:

JPNinPA said:
The reset is important, otherwise it takes 500 or so cycles to gather new data. To clear adaptive memory:
Disconnect the POSITIVE battery Terminal and touch the connector to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM.

Voltage at the battery should be 12.6v off and 14.4 running. If you measured within seconds of turning the engine off and got 13.2 that is normal. If not there is something wrong.
Battery voltage is not the same as load testing the battery. Get it load tested.

Poor or resistive connections will cause performance issues and missing like conditions. The opposite side of the grounds are the biggest culprit.
Remove and clean both the wire side and the connection side with sandpaper units shiny, then reconnect.

What part number plugs? Pull them and inspect. Get the pn while you look and report back. Pics are great to help us determine any issues.

If you start the engine and have the issue them try revving the engine for a min or so. This will rule out a slow heating O2. And yes I realize you just changed the O2.

I list easy and basically free things to check and do. If you are unsure ask but do them if you want to resolve the issue.
Click to expand...

JPN,
As always, I appreciate the help. Since I'm off tomorrow, I'll begin working on the items you listed. I pass an AutoZone on my way home from work. I'll stop there tonight, get the battery load tested, and report the results. I will also use the multi-meter on the battery again "cold" and then after engine is started to see what numbers I get. I'll flash the memory tonight (same procedure I did previously before the O2 change). I did find a diagram of the ground connections (http://www.blackgto.com/jeep/98wiring.pdf). The link states it's for a 98 TJ, but I thought all TJs were the same (97-06). After your previous post about the coolant temp sensor, I started crawling the web. I did find several posts/threads about people having the same issue with the sensor being bad and the PCM causing the engine to stumble (adjusting for bad sensor input). I called the dealership for part # of the sensor and price.... $ 56.45:cry:. They did give me the part number so I cross referenced it online and went ahead and ordered one ($23.50 + free S&H)
 
Killing me dude. Free n easy first. Detail!! :)

Measure the res of the temp sending unit (on thermo housing) over the temp range before you commit the purchase and it sounds like your thermo will not let it get to 210. It needs to get to165. To fully come out of open loop.
Make sure the temp sending unit is the one in the thermo housing with wires going to the PCM. Earlier models used two one for the readout and one for the PCM.
 
Last edited:
stopped by AutoZone today and had the battery load tested. They tried 3 times and it showed fail on the test. Before buying a new battery, I'm pulling the battery out of my truck and run it for a few days (battery is less than 6 mos old).
 

Bond--007 said:
stopped by AutoZone today and had the battery load tested. They tried 3 times and it showed fail on the test. Before buying a new battery, I'm pulling the battery out of my truck and run it for a few days (battery is less than 6 mos old).
Click to expand...

Take it to another place. Sometimes they just don't know the proper load. If you want a recommendation the sears diehard platinum P1 or P4. They are pricy but worth it in the long run.
Make sure your truck battery has the minimum 550 CCA for the jeep.
 
JPNinPA said:
Take it to another place. Sometimes they just don't know the proper load. If you want a recommendation the sears diehard platinum P1 or P4. They are pricy but worth it in the long run.
Make sure your truck battery has the minimum 550 CCA for the jeep.
Click to expand...

The truck battery is 850CCA. I'll run the jeep tomorrow to the Advance Auto here by work to have them load test it also
 

Bond--007 said:
stopped by AutoZone today and had the battery load tested. They tried 3 times and it showed fail on the test. Before buying a new battery, I'm pulling the battery out of my truck and run it for a few days (battery is less than 6 mos old).
Click to expand...
Maybe it sounds like I'm shooting down the auto zone guys again, but now I just do not trust them to be giving me information even when they are useing their meters to check the battery and alternator.
I had gone to autozone about a week ago to have my battery and alternator checked. The guy put his meter on it and told me the battery was 100% charged but no good. :scratch: He said he couldn't check the alternator cause the battery was no good. I'm like this don't make any sense. I went to a diffrent autozone the next day and they put their meter on it and told me the battery was good but had a low charge and couldn't check the alternator with the battery like that. So I just decided to run the vechicle like it is and see what happens, a week later and no problems, so be careful dealing with those guys.
 
The truck battery is being put in tonight (needed the truck this morning and didn't want to swap the batteries and run a risk of being stranded)
 
ok guys, just swapped out the truck battery. Before finalizing the install, I touched the positive cable to the negative post for 30 secs. Finished the install and fired the jeep up for a quick run around the block. Took off from the driveway and first didnt stumble but as soon as I shifted into 2nd, it stumbled but not as bad as before. Weather permitting, I'll be checking and cleaning grounds tomorrow evening
 

*UPDATE* The jeep has the same studder in all gears until it is warmed up to operating temp. I'll be going through the grounds this weekend to clean them up. If the problem continues after the cleaning, this leads me to the (1) Coolant Temp Sensor, (2) PCM, or (3) the heater curcuit for the O2 sensor, causing it not to heat up quick enough
 
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