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westrope65, ASE Certified Technician
Category: Car
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Experience:  ASE
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hesitation in 93 jeep wrangler while driving

Resolved Question:

cleaned fuel system,complete tune-up,replaced fuel pressure unit,fuel pump & strainer,fuel filter,plug,wires ,cap. problem comes and goes
Submitted: 8 years ago.
Category: Car
Expert:  westrope65 replied 8 years ago.

Hi, welcome to

Have you looked at the pick-up coil? and teh crank sensor?Also have you tried to get the engine codes?

Here is general procedure for getting engine codes by using the flash method.

Turn the key from off to on three times within five seconds. Then watch the CHECK ENGINE lamp. When you hit the proper rhythm ( this varies some from vehicle to vehicle and takes a few tries sometimes ), the MIL will stay lit longer than normal, go out and then start flashing.

Count the flashes. There will be short pauses between sets of flashes to indicate you're going to another number. The last set of flashes will always be 5-5, or code 55, which means end of test. All the codes will have two digits to them. You can repeat this as many times as needed to get a feel for how it works. If the PCM or battery has been disconnected within the last month or so, the first code you'll see is 1-2 (code 12) which indicates a recent loss of memory. be careful not to misread numbers so like 1-2 becomes a 3 or 2-3 becomes 3-2. Do this a few times to check and always write them down for future reference. Remember these codes do not say parts are bad only that they got or receive a bad signal. SO it maybe part before or after them that needs to be replaced.

Click image to see an enlarged view
Fig. 1: Electronic engine control component locations-2.5L engine shown


The camshaft position sensor, or CMP sensor is located inside the distributor. The ECU uses the CMP signal to determine the position of the No. 1 cylinder piston during its power stroke. The ECU uses this information in conjunction with the crankshaft position sensor to determine spark timing among other things.

The CMP sensor contains a Hall effect device which sends either a 0.0 volt or a 5.0 volt signal to the ECU depending on the position of the distributor shaft.

If the cam signal is lost while the engine is running, the ECU will calculate spark timing based on the last CMP signal and the engine will continue to run. However, the engine will not run after it is shut off.



  1. Insert the positive (+) lead of a voltmeter into the blue wire at the distributor connector and the negative (-) lead into the gray/white wire at the distributor connector.

Do not unplug the distributor connector from the distributor. Insert the voltmeter leads into the back side of the connector to make contact with the terminals.

  1. Set the voltmeter on the 15 volt AC scale and turn the ignition switch ON. The voltmeter should read approximately 5 volts. If there is no voltage, check the voltmeter leads for a good connection.

  2. If there is still no voltage, remove the ECU and check for voltage at pin C-16 and ground with the harness connected. If there is still no voltage present, perform a vehicle test using tester M.S.1700, or equivalent.

  3. If voltage is present, check for continuity between the blue wire at the distributor connector and pin C-16 at the ECU. If there is no continuity, repair the wire harness as necessary.

  4. Check for continuity between the gray/white wire at the distributor connector and pin C-5 at the ECU. If there is no continuity, repair the wire harness as necessary.

  5. Check for continuity between the black wire at the distributor connector and ground. If there is no continuity, repair the wire harness as necessary.

  6. Crank the engine while observing the voltmeter; the needle should fluctuate back and forth while the engine is cranking. This verifies that the stator in the distributor is operating properly. If there is no sync pulse, stator replacement is necessary.

hope this helps.______________

Customer: replied 8 years ago.
my problem is not that it wont start every time its hesitation while driving,when this happen I can pull over an stop the motor,restart an drive on no problem or keep on driving an it will go away until it happens again (1 hour,day,week,and even months)before it comes again.and Idid replace the coil already
Expert:  westrope65 replied 8 years ago.
Yes I understand and read your symptoms. I think you should use the key method to check for codes and then maybe look at what it points to or try testing the two sensors i mentioned
Expert:  westrope65 replied 8 years ago.
DId you get the codes? Did they point to a problem?

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