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1989 XJ odd running, then dying issue. Help.

G

GarageAlchemist

NAXJA Forum User
Location
Fargo, ND
My 89 Cherokee (renix) will start and run fine, but after coming down off of high idle it will start to sputter and die. If i give it gas rpms go back up and it runs good. If i put it in gear it will sometimes drive okay for a little bit but then starts to sputter and die again, and it doesn't matter if i give it gas when its it gear, just keeps on dying... It has a new fuel pump and filter... Any help would be great. I tried the local boards and searched and im about ready to :explosion
 
Auto or manual trans?

What is your idle--700-750, auto fully warmed up and in DRIVE.
 
i would, but i can't find which valve/sensor is which. I wanted to test iac,map, mat, and tps, but my haynes manual only shows HO motors and nothing to do with the renix. I know that makes me sound like a tard, but most of my expirence has been with honda motors, and i can't pick out which is which on the jeep.
 
i also didn't think that IAC didn't really jive with it dying when i put it in gear and would drive, being that it then doesn't even respond to throttle output.
 
Ok, when looking at the throttle body from the front of the engine on the left is the IAC with connector with 4 small leads. To the right of the IAC is the TPS, should be a four wire connector with the auto trans.

Think of the IAC as the idle and transition circuits combined.

Have you tested/adjusted the TPS?
 
i have not tested or adjusted the tps. What should i do with the IAC? i pulled it out while it was running, and the idle went way up, and stayed up, it did not die. When i plugged it in, it came down and then did its sputtering dying them.. And how do i test. adjust the TPS? is that something that could just all of a sudden come out of adjustment? Thanks for the help btw.
 
GarageAlchemist said:
i have not tested or adjusted the tps. What should i do with the IAC? i pulled it out while it was running, and the idle went way up, and stayed up, it did not die. When i plugged it in, it came down and then did its sputtering dying them.. And how do i test. adjust the TPS? is that something that could just all of a sudden come out of adjustment? Thanks for the help btw.
Click to expand...

Ok, when you removed the IAC you gave the engine a shot of extra air and that leaned out the mixture and increased the idle speed.

Here is what you should do: get some throttle body safe aerosol cleaner and clean the throttle body and the IAC passage, and the IAC itself. Be careful with the IAC, it can break. Use a toothbrush (M16 cleaning brushes are great) and q-tips to get it really clean, then mount it back up and see what you get. When it is mounted, engine running, you can unplug the IAC and see what reaction the engine has. Unfortunately as the IAC is a stepper motor you need a dealership tool to "exercise" it for testing.

Once you have the IAC done post back and we can cover the TPS.
 
MAP sensor is on the DS firewall, has a vacuum line running to it from the side of the throttle body.
 
Alright, i took out and cleaned the IAC. No change. Then i just started tinkering with the vaccume lines. I found that the one that went from the back of the valve cover to the intake mani was plugged. And when i pulled it off it would keep idling.. So i cleaned that out, and put it back on, and it would still die. So then i pulled off this vaccume line that went under neath the TB, i assume that this is the line that goes to the MAP sensor. I took some pics for reference.

This is the line

Jeep1.jpg


It comes from this

Jeep3.jpg


And goes under the TB, here, in the bottom hole...

Jeep2.jpg
 
now it will start and run again, but only as long as im holding the key on. Just like it did when i had to get one of the fusable links replaced.. but it is still not all the way cooled down, so idk.
 
GarageAlchemist said:
put in new map sensor, started and idled just fine! until it reached normal temp. then spit, sputtered and died again, now won't start..
Click to expand...

The MAP sensor provides input to the ECU, and the ECU adjust the fuel mixture based on those inputs. When the engine warms up the o2 sensor provides input to the ECU (closed loop) and that will also effect fuel mixture.

I would check the EGR system as jneary suggested, and the MAT sensor, as well as the vacuum lines, etc. for leaks.
 
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