Renix 1990 xj stalling when slowing to stop especially at turns. All electricity goes out- starts right up again after turning the key. I’ve done most of Cruisers tips and am now looking at the CPS

questions;
-I only get 0.25-0.3 from the CPS, can cleaning it up help that much (automatic), I know it’s supposed to be at least 0.5?
-is the full electricity fall out indicative of the CPS or something else?

I know it’s been handled before, just need to get these answers before I buy yet another expensive part adding to the hole in my pocket.

 

Elaborate on "All electricity goes out". There is no power until you start it again? No interior light if you open the door? No fan, turn signals, radio, headlights? Typically I would be asking about fuel pressure, Ohms of grounds, and TPS settings, but that is an interesting symptom.

 

I cannot be 100 sure right now but I know that the dash shuts off and the servo goes away. Pretty sure that all lights go out but have only tested in daylight to not push my luck. I checked the TPS after cleaning the throttle body etc and all checks out. Bad voltage on CPS as mentioned, but not sure of that would create this behavior? I also have a ballast resistor that is completely shot that I am about to remove.

 

I see you have done most of Cruiser's tips. If you are measuring CPS voltage per Cruiser's tip 7, you will also see in that tip a method to increase voltage by oversizing one of the bolt holes on the CPS flange. Can it also be assumed that "TPS checks out" means you verified that it was set at 17% of the reference voltage per Cruiser's tip 8? If your rig is actually losing electrical power as you near idle speed, then that would definitely cause you to lose voltage to the ECM and subsequently the CPS as well. You're going to have to understand that phenomenon a little better. If your ballast resistor is suspect, that is an easy one to jumper out. At least you can rule it out as a contributor to your problem.

 

Yes, I measured the tps and it was ok to Cruiser #8 instructions. I have a very cheap meter so don’t know exactly how accurately though. Thanks for clarifying the drilling out part, I never understood what hole Cruiser was referring to but then again I am still yet to get the right tools to get the CPS off at all. So the drilling is actually done on the CPS flange that comes off, making it possible to get it closer to the bell housing with the attachment bolt?

If it should be the ballast resistor creating problems- would it make more than the fuel pump go nuts? Would it also make the power to dash etc disappear?

I am going to bypass the resistor and check the 108 and 107 grounds as recommended next, in case it would be a ground to ecu problem.

 

Drilling the hole on the CPS flange will allow the pickup to get closer to the tone ring of the flexplate. The ballast resistor wouldn't be responsible for anything beyond low fuel pressure. If you can, follow Cruiser's tip #5 and get an Ohms reading before and after cleaning grounds that would be good data. How does your XJ run otherwise?

 

Yes will do number 5 as well for sure.
I haven’t had the chance to use it much since I bought it. Been working on abs delete, power windows and locks, steering, stereo etc. Finally I was getting out of the garage and new challenges arises haha.

it always starts up after two cranks and idling around 800-1000 quite steady. Sometimes a bit ”searching”. Some kind of knock is going on wich is also on the list. What I noticed on my short drives is that it doesn’t seem to change gears quite as it should, revving up too much and being a bit weird I think, but this is my first xj so hard to tell what’s normal.

I’m not 100% sure about the vacuum since I patched up one cracked hose there might be leaks in other places too. Front rubber hose (PCC? CCV? CCTV?!) is cracked by the elbow and taped up. New vacuum lines are ordered and on their way. Just cleaned up the throttle body and all sensors, improved all grounds etc.

 

Ok so I have no eliminated the ballast resistor and after much agony managed to get the bolts off and removed the CPS. I have a new one from SMP that I hope would be good quality. Since my jeep always started I’m not sure if the CPS has been my problem though, even though it showed only 0.25 Volts.

would a shot CPS cause the electricity to the dash to shut off or just the fuel pump?

wish me luck tonight!

Just wow

Dirty CPS

The wire also had a part where the wire was exposed due to wear, would short out if touching metal no?

One of the factory clips holding the CPS wire in place also crushed it. Oh well

 

If your Jeep was still starting before, even with the CPS showing only 0.25V, are you sure the CPS is the root cause? Also, just to clarify — can a faulty CPS actually cause complete electrical loss to the dash, or would it typically just affect engine timing and fuel delivery?

 

When its "stalling".. whats it actually doing? Does it slowly die down and shut off, does it lug or struggle or is it more instant?

Is this a AW4 transmission? Is it possible that the torque converter is staying locked?

The fact it only happens when slowing down is what really gets me. You certainly may have other things going on - like the CPS but for it to ONLY happen when slowing the vehicle is weird...

 

It’s a 1990 automatic 4w transmission. So what happens is that it just quits- no pre warning at all. I think the shifting is a bit off as well, it feels like I had to push a bit too far before it shifts but I haven’t had the chance to drive it much. It idles ok I would say around 800-1000, pretty evenly.

everytime it has happened it has been after slowing down and making a turn which might suggest something mechanical affected by shifting balance?

the feeling is that everything dies but the most obvious things are the engine, the dash and the servo. After coming to a full stop and hiding my face for the much annoyed people behind me, I need to turn the key back and start again, which so far has worked (4 times by now)

I don’t now much about torque converters, would locking up have this effect?

I can add that I have worked on the brakes and have not fiddled around too much with the adjustment if the white switch by the brake pedal rod after swapping brake booster. From my understanding it has to do with the cruise control and also torque converter?

 

Wow,.. ok.

Unrelated to your shutting off issue.. Sounds like you may need to do the TV cable adjustment.

If you google "cherokee TV cable adjustment" you'll find a couple of youtube videos that show exactly what to do. Takes 30 seconds and really makes a difference in drivability.

 

great will do, thanks!
could my problem be ignition switch related maybe?

 

Thinking about the fact that it dies when you turn and that the wiring harness is 35 years old I would have the thing running (idle is fine) and start wiggling and pulling on every piece of wire and connection you can get to and see if you can get a reaction.

 

^^^ THIS. Sometimes.. its the simple things that make the most sense. That is experience talking right there.