TJ cranks then dies and sounds weird

labgeek

labgeek

New Member
Joined
Jan 13, 2022
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9
Location
Granbury, TX
BLUF: Please provide top 3-4 things to start with to diagnose my issue.
My TJ cranks, but doesn’t catch/fire unless I give it a lot of gas by pushing the gas pedal and then immediately dies. I can keep it going by pressing the gas pedal but when i stop, it immediately dies. Also, the engine doesn’t sound normal when cranking and when i keep it going with pedal. Also, using the same key that i always have used, so i hope this eliminates the SKIM issue that i have seen in previously Posts.
Specs: 1999 4.0L automatic.
Upgraded: K&N filter
160K miles
Purchased already with body lift


What have i done so far:
1) charged battery, nothing changed.
2) Looked at other posts and didn’t see anything that mentioned an odd noise.

My background: slightly mechanical, but i haven’t worked much on cars/Jeeps/trucks. I don’t have code reader or anything like that, just normal tools. I have owned my jeep for about a year. I have never owned a TJ previously.

Thank you very much in advance for taking the time to reply. Hopefully i will add value to this group and give back.
Rusty
 
Your jeep is a computer on wheels. Unless something suspension/axles/trans/tcase breaks you won't get anywhere without a way to talk to the computer.

You are making assumptions and trying to take shortcuts.find out how to properly diagnose and repair your jeep and follow those prcedures.its a simple logical process. Skipping steps and trying to cheat by guessing will only cost you more money and time.
 
labgeek said:
BLUF: Please provide top 3-4 things to start with to diagnose my issue.
My TJ cranks, but doesn’t catch/fire unless I give it a lot of gas by pushing the gas pedal and then immediately dies. I can keep it going by pressing the gas pedal but when i stop, it immediately dies. Also, the engine doesn’t sound normal when cranking and when i keep it going with pedal. Also, using the same key that i always have used, so i hope this eliminates the SKIM issue that i have seen in previously Posts.
Specs: 1999 4.0L automatic.
Upgraded: K&N filter
160K miles
Purchased already with body lift


What have i done so far:
1) charged battery, nothing changed.
2) Looked at other posts and didn’t see anything that mentioned an odd noise.

My background: slightly mechanical, but i haven’t worked much on cars/Jeeps/trucks. I don’t have code reader or anything like that, just normal tools. I have owned my jeep for about a year. I have never owned a TJ previously.

Thank you very much in advance for taking the time to reply. Hopefully i will add value to this group and give back.
Rusty
Click to expand...

Is the Check Engine Light on?
 
Rickyd said:
Your jeep is a computer on wheels. Unless something suspension/axles/trans/tcase breaks you won't get anywhere without a way to talk to the computer.

You are making assumptions and trying to take shortcuts.find out how to properly diagnose and repair your jeep and follow those prcedures.its a simple logical process. Skipping steps and trying to cheat by guessing will only cost you more money and time.
Click to expand...

Thank you for the advice! Makes sense, i will see about getting a code reader/computer on it.
 
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Usually, you do not need a code reader or fancy computer to pull the codes.

Watch the video. Do the test. Record the codes (if any). Then let us know what, if any, codes are shown.

 
Crom said:
Usually, you do not need a code reader or fancy computer to pull the codes.

Watch the video. Do the test. Record the codes (if any). Then let us know what, if any, codes are shown.

Click to expand...

Thank you for the video. I performed the test and did not see any codes. However, it did not show “done” as it did in the video, so not exactly sure if the test is working on my TJ, so i included a video for one of the tests that i did. I tried several times; faster, slower, etc.
thank you for your help.
 

Attachments

  • 59F0151F-264A-4387-9FAD-F59DD846BC17.MOV
    26.8 MB
You need 3 things for the engine to run. Spark ,fuel & compression.
You say it makes a funny noise when cranking, can you describe? Does the crank sound even or is it cranking fast, slow,fast,slow? Did your battery go dead? For how long?
 
If it did not read DONE it failed to run the test.

I usually reach under the steering column with my left arm and press the button that keeps the key from going into the ACC position. With the button held in I switch from ACC to RUN three times rapidly (not sure at the moment if I stop at the RUN or OFF position on the third time, I think I stop in the RUN position). That usually gets the jeep to run the test.

If that does not work you can pick up an OBD2 from a local auto parts store.
 
Crom said:
If it did not read DONE it failed to run the test.

I usually reach under the steering column with my left arm and press the button that keeps the key from going into the ACC position. With the button held in I switch from ACC to RUN three times rapidly (not sure at the moment if I stop at the RUN or OFF position on the third time, I think I stop in the RUN position). That usually gets the jeep to run the test.

If that does not work you can pick up an OBD2 from a local auto parts store.
Click to expand...

Yep, i don’t have a button under the steering column and cannot seem to get the test to run. I will see about getting a OBD2.
 
NskLJ said:
You need 3 things for the engine to run. Spark ,fuel & compression.
You say it makes a funny noise when cranking, can you describe? Does the crank sound even or is it cranking fast, slow,fast,slow? Did your battery go dead? For how long?
Click to expand...

The funny noise is a higher-pitching “zing” noise. The crank speed is normal. My battery might have gotten low or died, it would only have been about 3 days.
 
UPDATE: i was able to get it to start and stay running (still sounds different). I couldn’t test drive it right now, but was able to let it idle for a couple of minutes. However, there is water with black soot coming out of the tailpipe.
 
labgeek said:
UPDATE: i was able to get it to start and stay running (still sounds different). I couldn’t test drive it right now, but was able to let it idle for a couple of minutes. However, there is water with black soot coming out of the tailpipe.
Click to expand...

Check the coolant to see if it’s low, the water and soot is probably the cat doing it’s job. I asked about the battery if it was dead the computer could of lost its memory and that’s why it would not idle.
 
NskLJ said:
Check the coolant to see if it’s low, the water and soot is probably the cat doing it’s job. I asked about the battery if it was dead the computer could of lost its memory and that’s why it would not idle.
Click to expand...

I checked the coolant and it was good, however, i think you were correct about the battery. i replaced the battery and it is good now. thanks a ton!
 
thanks for all the help. There were no error codes and it seems everything was because of a bad battery. i was surprised by the weird noise and did not understand this could be caused by a bad battery.
 
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