stallingg problems....please help daily driver

I am having problems with my 95 xj 4.0 it will start fine when it is cold but when it gets up to normal running temp it starts sputtering and will eventually die.At first I thought it was water in the fuel so I drained the fuel and added heat...still does the same thing. Replaced fuel filter fuel pump plugs wires cap rotor crank shaft position sensor MAP sensor still same problem. It also will back fire when up to operating temperature and it smells as well. I am out of ideas.....HELP
 
Long time since I have posted about my problem....I didnt for a while untill my jeep died after going through puddles. I have waterproffed all conections with dielectric grease. the bottom of the "idk the actual name" power unit that the coil bolts to, has a few hair line cracks the the bottom where the soft rubber material is, but I applied grease to the bottom of that and it still died. After talking to a friend that offered to help drive it through his creek crossing and tracking the problem down, I came up with a thought.....the NSS could that be getting wet and causeing the no start problem? also it seemed that when I unpluged and pluged the CPS a couple times it started shortly after. the CPS is new, just put in a few hundred miles ago. thanks for any info!
 
NSS = NO CRANK, not NO START.

CPS/CKP crank sensor has to generate a signal to the ECU/PCM or you won't get spark.

The ICM--ignition control module--has the coil clipped to it. You can take it apart, clean the contacts and treat them with dielectric grease.

Critical grounds for the ICM, ECU, and other engine management items at the DIPSTICK tube. Make sure those grounds are clean, take the surfaces down to bare metal, treat them with anti-corrosion material (any hardware/paint store), and make sure they are TIGHT.
 
ok, i get spark, the ICM I took off and cleaned very well and dielectric greesed it. the only thing is the grounds. would the craks in the ICM in the ruber cause any of it?
 
posa88xj said:
ok, i get spark, the ICM I took off and cleaned very well and dielectric greesed it. the only thing is the grounds. would the craks in the ICM in the ruber cause any of it?
Click to expand...

Might. Any salvage yards near you?
 
an hour away....I pulled the one from a parts jeep i have, same year, but it too has a few cracks...would anything get hurt if i put a plate on the mounting bralet to cover the hole in the bottom to prevent splashing up to the base of the ICM?
 
Shouldn't hurt anything.

You might consider covering those cracks with RTV or a silicone based adhesive.
 
I will do that.....Also the cam sensor is in the distribitor right? I just thought might be a possibilty, if it got wet, wouldnt work, but after cranking a few time it would dry out right?
 
posa88xj said:
I will do that.....Also the cam sensor is in the distribitor right? I just thought might be a possibilty, if it got wet, wouldnt work, but after cranking a few time it would dry out right?
Click to expand...

Take the cap off, if it has moisture in it dry it out--don't spray any flammable product in there or you could get a rude surprise when you try and start it!

You can test the synch sensor (cam sensor, CPS/CMP) with an analog voltmeter, or just use a NOID light in the injector harness to see if you are getting a signal.
 
Well today, I found a guy with a snap on scanner that is able to scan renix systems...one thing I found out today was the coolant sensor on the block near the motor mount is broken, like the leads came out, so its telling the computer everytime its on that my temp is 246.....also this might be my stalling problem as it shorts out the leads.....the other thing is my exhaust manifold is gone to hell, it leaks so bad now, and the guy that had the scanner, thinks it could be possible that enough moiseture get into the exhaust and messes up the O2 sensor.
 
Wow, split personalities--busted CTS telling the engine it is hot when its not, leaking exhaust fooling the o2 sensor into telling the ECU the engine is lean (when it isn't) so the ECU is increasing the injector duration to try and compensate for the lean condition, making things worse.

Cool!
 
Yup.....just to test the theory of it being the broken sensor leads, I dunked the broken end into water, and sure enough it died several times everytime I dunked it. but after I unplug the broken end, it starts up after a try or two. I am so Happy to figure this out.
 
joe_peters said:
NSS = NO CRANK, not NO START.

CPS/CKP crank sensor has to generate a signal to the ECU/PCM or you won't get spark.

The ICM--ignition control module--has the coil clipped to it. You can take it apart, clean the contacts and treat them with dielectric grease.

Critical grounds for the ICM, ECU, and other engine management items at the DIPSTICK tube. Make sure those grounds are clean, take the surfaces down to bare metal, treat them with anti-corrosion material (any hardware/paint store), and make sure they are TIGHT.
Click to expand...


Got a question for you. I just bought a 1990 XJ and it has no spark. Frome reading this post it sounds like it would be one of 2 things, the coil or the CPS. what do you think?
 
Grounds, CPS/CKP crank sensor, B Latch relay, or coil are the usual suspects.

CPS/CKP crank sensor, should have 200 ohms resistance + or - 75 ohms, 125~275 ohms range.

B Latch relay provides the 12 volts for the coil input and also for the 3-second prime of the fuel pump when you turn the key to the ON position.

The clips where the coil clamps to the ICM (ignition control module) should be cleaned and treated with dielectric grease.

Renix, 87-90, are hyper sensitive to ground issues. There are critical grounds for the ICM, the ECU, and the o2 sensor at the dipstick. Make sure these are clean--down to bare metal--treated with an anti-corrosion material and very tight. Also, the head to firewall ground is the one and only unibody ground on the early XJs. I recommend replacing the braided strap with a 4 or 2 ga cable.
 
joe_peters said:
Grounds, CPS/CKP crank sensor, B Latch relay, or coil are the usual suspects.

CPS/CKP crank sensor, should have 200 ohms resistance + or - 75 ohms, 125~275 ohms range.

B Latch relay provides the 12 volts for the coil input and also for the 3-second prime of the fuel pump when you turn the key to the ON position.

The clips where the coil clamps to the ICM (ignition control module) should be cleaned and treated with dielectric grease.

Renix, 87-90, are hyper sensitive to ground issues. There are critical grounds for the ICM, the ECU, and the o2 sensor at the dipstick. Make sure these are clean--down to bare metal--treated with an anti-corrosion material and very tight. Also, the head to firewall ground is the one and only unibody ground on the early XJs. I recommend replacing the braided strap with a 4 or 2 ga cable.
Click to expand...

This is the info that I am looking for, thank you for the input. FYI, I do have fuel to the injectors, just no spark.
 
I believe this is correct:

http://autorepair.about.com/library/graphics//42276757-b.gif

There has been some discussion on this before, with multiple answers. Up until now I have been too lazy to look again, but I will go check mine and post back later.

EDIT: Ok, on mine, three relays only (no a/c), the relay closest to the firewall is the oxygen heater relay, in the middle is the B Latch relay, and the closest to the front grill is the fuel pump relay, and of course that doesn't match the graphic. I have confirmed this by pulling the relays with the engine running.

EDIT 2: Ok, the Chryco published FI training guide has them in a graphic as closest to firewall a/c; next is the B Latch; then fuel pump; and closest to the grill is the oxygen heater relay.
The FSM graphics showing the relays has a single base point with four arrows running to the relays and a list of the relays at the single point--worthless.
 
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