1987 xj problems

[box_goblin]

I had very similar issues, and it was the cable from the Coil to the Dist-Cap that was the culprit -- the connector to the wire inside the boot was not tight, so it would work every now and then. It puzzled me for a long time because every time I pulled a spark plug out to test it, it worked... Not saying that's the case here, but it is one of the quickest and easiest things to check; and for me it was easy to overlook. I'd recommend swapping a cable from one of the plugs to the coil-cap and see if you then get a clean, strong start.

 

[JEEP_cannible]

Funny you should mention this Box because I just replaced the cap,plugs,and rotor.I have had some of the same issues all ready with the new cap.I added it to the list to check again just the same.
Thanks Rod

 

[JEEP_cannible]

Damn it Joe!!! I should have seen this sooner.I saw a post you made on up grading some electronics.It had an up grade for the Batt + ground cables.I added the #4 ground to body first.I didn't have any #4 red wires to upgrade the rest yet.Then I really didn't look that far in my auto electrical boxs yet.
I decided to just try to start it after the new cable.Yea it started and now I have spark again.Now I'm wondering what will happin it the morning.Today it was a scarry 67 degrees today here in OK in December.Tomarrow will tell the hole story.One way or the other the upgrading will get finished tomarrow.
Thanks Joe for all the help.

 

[joe_peters]

That's me, just like a broken clock--I still manage to be right twice a day!

Hope that does it for you. Some real good advice from the others on checking the CTS and MAT sensors too.

Post up and let us know what happens.

BTW--its 29 degrees here right now and heading for 25!

 

[Ecomike]

Global warming is alive an well in Houston, we hit 78 today here.

 

[cruiser54]

Damn it Joe!!! I should have seen this sooner.I saw a post you made on up grading some electronics.It had an up grade for the Batt + ground cables.I added the #4 ground to body first.I didn't have any #4 red wires to upgrade the rest yet.Then I really didn't look that far in my auto electrical boxs yet.
I decided to just try to start it after the new cable.Yea it started and now I have spark again.Now I'm wondering what will happin it the morning.Today it was a scarry 67 degrees today here in OK in December.Tomarrow will tell the hole story.One way or the other the upgrading will get finished tomarrow.
Thanks Joe for all the help.

Bad grounds? Whoda thunk it?

Glad it started for ya.:roll:

 

[JEEP_cannible]

Ok joe it didn't start so is there a way to check the MAT sensor.I have an idea on the CTS all ready.

 

[joe_peters]

Yeah the MAT sensor varies resistance by temperature.

This website has info on all of the Renix sensors, values and testing: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

 

[joe_peters]

Ok joe it didn't start so is there a way to check the MAT sensor.I have an idea on the CTS all ready.

Is it NO SPARK again?

 

[JEEP_cannible]

I haven't really had time to check that yet Joe.Its tipical OK now its around 20 degrees out side.I'm pretty sure its getting gas I can smell it at both ends.

 

[Ecomike]

Ok joe it didn't start so is there a way to check the MAT sensor.I have an idea on the CTS all ready.

Just disconnect the MAT and CTS, test ohms across the two sensor leads. At 20 F they should be 13,500 ohms. At 40 F , 7500 ohms, 70 F 3,400 ohms. You can pull the MAT and test it on the stove in boiling water, and ice water. At 212 F it should be 185 ohms.

The CTS can not be pulled with out loosing the coolant in the block. They both should have the same resistance at the same temperatures.

 

[joe_peters]

Try this, if you can:

Take a hair dryer or heat gun and warm up the ICM/coil. You could even put a 100 watt bulb close to it if that is all you can muster. Give it about 5 minutes of that and try and start it.

EDIT: cross-posted with Ecomike--test the resistance of the MAT and CTS first.

 

[Ecomike]

I haven't really had time to check that yet Joe.Its tipical OK now its around 20 degrees out side.I'm pretty sure its getting gas I can smell it at both ends.

Once flooded they are hard to dry out and un-flood, especially in cold weather.

 

[JEEP_cannible]

Ok Joe get this one LOL.I went out pulled the #4 plug wire put a phillips in it held it about an 1/4 inch away from a ground.Jumped it across the polls on the starter relay,with the key on.Its about 8 degrees colder than the first attempt.It started right up while i was cranking it over.So now I have spark again,and it started.I replaced the plug wire turned the jeep off after getting a hell of a good shock.The joint in my finger is still stiff lol.Then turned the key back on,and it started up a secound time.Then a third,fourth,and even a fifth time.WTF is the deal here LMAO.I do think I have a vacume leak.I was hearing a whistle from under the hood.So I have to track that down too.

 

[JEEP_cannible]

Oh yea when this thing has spark it has spark lol.No need for a hotter coil even if they did make one.Finger is still stiff,and switching lol.I was going to try the hair dryer trick on the coil,but didn't need it.I keep thinking I have a short somewere in the system,but no idea wear.

 

[JEEP_cannible]

Ok 40 mins later,colder,and guess what it started again.Maybe I fixed it?????

 

[box_goblin]

Oh yea when this thing has spark it has spark lol.No need for a hotter coil even if they did make one.Finger is still stiff,and switching lol.I was going to try the hair dryer trick on the coil,but didn't need it.I keep thinking I have a short somewere in the system,but no idea wear.

I'm guessing the hair dryer on the coil was to simulate heat and test for thermal failure (meaning it would fail after being hot...)

 

[joe_peters]

I'm guessing the hair dryer on the coil was to simulate heat and test for thermal failure (meaning it would fail after being hot...)

His rig seems to start Ok when it is warmer.

Wanted him to warm the coil to see if that would alleviate the no spark condition.

 

[JEEP_cannible]

I don't get it Joe.The weather was even colder today,and she started right up the first try.Maybe the new ground took hold. LOL
Thanks again Joe + everyone for all the help.

 

[joe_peters]

Well, keep us updated on this thread if it goes South on you.

Good luck.