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Idling problems along with other questions

E

ethernet

NAXJA Forum User
Location
Springville, UT
Just got my XJ back from the shop after quite an ordeal. Anyway to the point. Before I took it in it seemed to be running alright. But now it will not idle properly. It has a 5 speed it in.

When I am driving down the road and come to a red light I will down shift and then put it in neutral as I coast to the light. However by the time I get to the light the engine has died. What would cause this? Is the timing off? It seems to be running pretty rich. Would that do it?

Another question I've got. Down by where the O2 sensor plugs in there is some sort of sensor that plugs into the block. What is that? Is that part of my problem?

Any input would be much appreciated. I am not much of a mechanic but love a good challenge and learn and catch on pretty quickly! Thanks!
 
What year? It sounds like it may be a RENIX(87-90) and the sensor on the side of the block just above the oil pan is the knock sensor. There is a CTS(coolant tempurature sensor) more toward the front of the engine closer to the intake/exhaust manifold. The Knock sensor you can live with out if you run good gas and keep it tuned, later XJ's deleted this. The CTS must be hooked up or you will never go into closed loop and it will run rich/rough.
 
You got it right. It's an 89.

Now I am just trying to remember where this sensor was at... The plug that went onto that sensor came down the same way as the O2 sensor. I'm pretty sure its the knock sensor that isn't connected. Do you have a picture or diagram or something so I can clarify? It might be the CTS. I dunno...
 
ethernet said:
You got it right. It's an 89.

Now I am just trying to remember where this sensor was at... The plug that went onto that sensor came down the same way as the O2 sensor. I'm pretty sure its the knock sensor that isn't connected. Do you have a picture or diagram or something so I can clarify? It might be the CTS. I dunno...
Click to expand...

The knock sensor will have a plug on it that is exactly the same as the fuel injectors have, the CTS has a 2 prong Nycopac connector. Here is a pic of my 90' just before dropping it in, The sensor with the pigtail hanging from it is the CTS, the sensor with the shinny nut in the middle of it just above the oil pan is the Knock sensor.

engine2wb9.jpg
 
ok... So it was the CTS. When I unplugged the wire from the sensor I just pulled on it. I guess there is a little metal retainer clip you are suppose to take off and then pull the cable. I'm not sure what I broke if anything. Guess I will have to look when i get it back from paint. How hard is it to replace the whole sensor? Probably have to drain all the coolant and then replace it right?
 
ethernet said:
ok... So it was the CTS. When I unplugged the wire from the sensor I just pulled on it. I guess there is a little metal retainer clip you are suppose to take off and then pull the cable. I'm not sure what I broke if anything. Guess I will have to look when i get it back from paint. How hard is it to replace the whole sensor? Probably have to drain all the coolant and then replace it right?
Click to expand...

Yes, Ive done it with coolant in it but you have to work fast and you will still loose some coolant. If the connector is popping apart just use a zip tie to hold both halves together. The knock sensor does have a metal clip that holds it on the sensor just like a FI connector does.
 
hmmm... friend of mine is painting it. Maybe I can squeeze in his shop sometime when he isn't too busy...

I have a parts Jeep. Maybe I will just pull the CTS out of it and take it with me just in case. If I damaged the connector and can't use a zip tie on it could I cut off the connector from my parts Jeep and splice it in?
 
ethernet said:
hmmm... friend of mine is painting it. Maybe I can squeeze in his shop sometime when he isn't too busy...

I have a parts Jeep. Maybe I will just pull the CTS out of it and take it with me just in case. If I damaged the connector and can't use a zip tie on it could I cut off the connector from my parts Jeep and splice it in?
Click to expand...

That will work as well, polarity does not matter on the temp sensors on the RENIX.
 
Make sure all of yur grounds are connected as well while your under the hood, poor grounds are another thing that will make a RENIX do stupid stuff. You should have one strap from the firewall to the head drivers side and i think 3 connected to the block on the dipstick tube hold down bolt. And of course the ground from the battery to the block. I added a battery to chassis ground with the side post on my Optima red top.
 
ethernet said:
Thanks for all of your help! Saved me alot of headaches and troubles!!
Click to expand...

No problem! I've been to the school of hard knocks on the RENIX and unfortunatly class is still in session. I'm having issues of my own right now!
 
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