Missing, surging and bucking

Tiny
BOYDBALEX
  • MEMBER
  • 1995 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 108,000 MILES
My jeep has a missing or bucking problem, its does not do it all the time, mainly when the engine warms up, and it feels like a fuel starving problem. Under mild acceleration and steady throttle it starts to buck and surge. If I push the gas pedal to the floor it will accelerate just fine. The fuel pressure is steady at 40psi. It did have a code 52. I've changed the following parts: O2 sensor, fuel filter, spark plugs, plug wires, dist cap and rotor. Help.
Wednesday, November 25th, 2009 AT 1:57 PM

11 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
This sounds like the throttle body needs to be cleaned but to be sure here is a guide to help.

This guide can help

https://www.2carpros.com/articles/engine-hesitates

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:
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Wednesday, November 25th, 2009 AT 2:20 PM
Tiny
MERCEDESTECHIE
  • MEMBER
  • 2 POSTS
It is a "lean" condition prior to full warm-up.I posted a question to this site with the same situation and I was asked to "ohm the CPS (crankshaft position sensor) and get back to him" Apparently he was unable to connect the dots or read thoroughly. I'm a 30 plus year tech with euro cars, and I thought a Jeep tech might have seen this before. Good luck on finding the answer here.98 "lean" Jeep
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Saturday, December 12th, 2009 AT 10:18 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Have you checked the crank possition sensor? If not unplug it and ohm it get back to me with the reading. It is on the left (drivers side) near the top of the engine on the back side just under the back side of the intake.

The CPS and the KS sensor will cause the same problem for the above problem
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Saturday, December 12th, 2009 AT 10:53 PM
Tiny
CHUCK CALABREZE
  • MEMBER
  • 1 POST
  • 1995 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 185,000 MILES
My 1995 Jeep Cherokee hesitates and surges around 2000 RPM in drive. It idles fine, performs perfectly while accelerating, but while cruising it runs roughly. Give it gas while it's running rough and it smooths out--no backfiring, nothing. I noticed the rear breather CCV tube doesn't reach the valve cover and has been extended with a piece of garden hose and therefore has a vacuum leak. Would this cause the problem?
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Are you refering to the PCV hose? If so, that shouldn't cause a miss. Has the check engine light come on? Have you ever had the fuel pump pressure tested? Have you checked for other vacuum leaks? EGR?
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
MICHEAL P
  • MEMBER
  • 2 POSTS
  • 1995 JEEP CHEROKEE
  • 200,000 MILES
AS we drive it hesitates and lunges like its starving for fuel or air. T seems to be missingI.
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Is the check engine light on or flashing?
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
MICHEAL P
  • MEMBER
  • 2 POSTS
Yes, the check engine light is on. Do you think it is the O2 sensor? Will a mechanic's computer tell me if it is the O2 sensor?
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
IF the light is on, then there is what is called a "trouble code" stored in the computer. That information is obtained by using an OBD 2 scanner. From that code, the tech can tell where the problem is coming from.

As far as having the computer scanned, try a nationally recognized parts store. Most have scanners and will do it for free.

Let me know what you find.
Joe
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
RJMIDBON
  • MEMBER
  • 1 POST
  • JEEP CHEROKEE
Jeep, Cherokee, 1994, 207,000 miles 6 cylinder surges when I drive at nearly any speed it use to do it only when first accelerating but now does it all the time as I drive I changed the distributor cap and rotor button when I had this same problem before and it fixed the problem I changed the distributor and rotor cap but this time it did not fix the the problem can you give me any kind of starting place your help will be greatly appreciated
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the actual fuel pressure with and w/o vacuum rule out the fuel pressure and get back then will go into the electronic controls, then the exhaust system
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Sunday, November 17th, 2019 AT 11:47 AM (Merged)

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