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Nasty Acceleration Studder

S

surfmon

NAXJA Forum User
Location
Pensacola, FL
99' XJ 4.0
This has gotten consistently worse over the past year.
After sitting for anywhere from 1 hour to all night, starts up fine. When I accelerate it bogs down horribly and clears up when I give it more gas. Seems to only happen right after startup. When it clears up it is so fast it jolts me back in my seat.

new o2 sensors
new cat
new plugs/wires/coil/ etc.

I am leaning toward TPS or Fuel pump.
any ideas?

Also, since pulling my motor last spring, my check engine light will not go off.
How much is a code reader??

Thanks
T
 
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i had the same problem, i replaced both, the bog went away. i really dont think i needed to replace the tps, but i guessed that first and since i hooked it up, the parts store would not take it back.i bet its the pump, and check for oil blow back in your filter. mine did that real bad cuz id punch the gas then the blow back would happen in conjunction w/ takin off.
 
surfmon said:
never used a reader, thats not how I roll

no ideas??
Click to expand...

Keep on guessing then sooner or later you'll replace the correct part.

A code reader is better than the "Eney Meany Minny Mo" this is how I roll.
 
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langer1 said:
Keep on guessing then sooner or later you'll replace the correct part.

A code reader is better than the "Eney Meany Minny Mo" this is how I roll.
Click to expand...
While I agree that reading the codes is an almost obligatory first step in something like this, I would point out that at least on a 99, the short list of things that cannot be detected by trouble codes includes fuel pressure and delivery problems, as well as mechanical problems with injectors and secondary ignition problems, all of which are among the possible causes of an acceleration stutter. Therefore if no codes come up I would suggest a vacuum gauge first, to see if it can sort out between ignition and fuel problems, and then perhaps an extension on a fuel pressure gauge to see if readings change under road conditions.
 
I have the same problem, and it happens exactly the way you described it. I rented a code reader and got a P135. So i repalced the O2 sensor and now get a P135 and P132. Both codes are O2 senosr related.
 
abrogate said:
I have the same problem, and it happens exactly the way you described it. I rented a code reader and got a P135. So i replaced the O2 sensor and now get a P135 and P132. Both codes are O2 senors related.
Click to expand...

No the o2 sensor readings are off because the engine is running poor.
Code readers are a good tool as long as you understand it mean that you need to start at the o2 sensor and determine why the reading is off, a bad sensor is only one of the possibilities.

Running rich or lean is another one. A poor running engine will throw o2 sensor error codes.
 
I've got the exact same issue on my 1989 renix...Still working on the issue.

http://www.naxja.org/forum/showthread.php?t=96937

I think my next new parts are a new TPS and o2 sensor.

The common parts to the old and new XJ here are the o2 and the TPS...

If you go to Autozone they'll read the codes for you for free...my 89 has no codes so that would be a good first place to start and it's free.

Randy
 
surfmon said:
no, cant afford a reader or anything else for that matter right now
Click to expand...

As mentioned above, take it to any autozone, they will pull the codes off the computer for free for you.

On another note, now that the weather is starting to cool off a bit, I'm beginning to have the same problem. When I first start it after it's sat over night or long enough to cool off, as i first take off it bogs down...almost like its got a dead spot...give it some more gas and it takes off, and then it's fine the rest of the trip.

I've been chasing an on and off P0135 problem since march...but i can't catch the damn sensor acting up...every time i hook a DRO tool up to it, all the sensors read fine....i'm not replacing it untill i can catch it shorting out.

I was going to pop the tps off this weekend and clean it out....do you think that would help the surging? This only happens when the weather turns cool/cold....spring and summer i don't have this problem.

oh ya and the specs...99, 4.0,AW4....bout 84K and some change on the clock.
 
I have the same problem on my 99 but it's intermittent,maybe once a month,maybe 2 days in a row.Only lasts a couple seconds though.Advance Auto Parts also will test the codes for free.Mine isn't spitting any out but maybe yours will.
 
I have a similar problem in my 90 XJ.

When I start the engine the RPM's go up to 2000 and then back down to 7-800. Then while accelerating from a light it will bog down and feel like it is conking out. It will then come back and be fine. It does this intermittently.

Replaced the CPS, had fuel system cleaned, new Fuel pump (it might be bad having it checked tommorow)

I put in an IAS and TPS I got from Pick'n'Pull all to no avail.

I then changed the spark plugs to Champion and at least it would not conk out when this happens.

I have not changed the O2 Sensor, could this be a part of the problem?

LTK
 
I am having the same issue with my 98 sport. It started the day i bought the stupid thing which was 2 days ago LOL. While under the XJ checking everything for leaks etc. i found the O2 wires by the transfer case have been tore apart and were tied up in a knot. I then wondered why the check engine light never came on and found someone removed the light bulb ( nice people) So i fixed all the wiring and went and bought a obd2 scanner from advanced for 98.00 on sale. it had a 118,135,138 IIRC. so I cleared the codes and drove it 10 mi or so and the light hasn't popped back on but the studder was there the last 3 times i took off after firing it up. Im leaning toward fuel pump or fuel pump strainer. once the tank empties down im going to drop it replace the strainer and filter and hope for the best!!
 
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