ohecht
NAXJA Forum User
- Location
- Richmond, VA
Apologies in advance for this incredibly long post, but I wanted to get all the information out there to see if anyone can help. I really can't pinpoint a potential source of this weird problem so I've included the whole story in order and everything I think might possibly be relevant.
I've owned and cared for this XJ for 23 years and 347,000 miles and never had a problem even close to this...very frustrating as I'm going through CP sensors at an alarming rate and the risk of getting stranded is way too high for a car we've trusted for all that time (I'm now test-driving it to and from work carrying around coveralls, latex gloves and the tools to swap the sensor in about 5-10 minutes).
It's a 1995 XJ Sport, 4.0, manual transmission. I've been running the same CPS for 15? years with no issues. Here is the series of events that started this set of issues, but they seem only possibly related at best, so I really need some help from experts with similar experiences or other ideas. The car does have a Grand Cherokee alternator that puts out a lot more amps than stock, but that's been in there for more than 3 years so if it's the cause of this problem, something changed after all that time.
Here's what happened: I replaced the existing Banks header with another Banks header...(probably the 5th or 6th time I've done that job as they crack a lot and I was getting them under the lifetime warranty for a while until they reduced it to 5 years). During that replacement, I also had the intake manifold cleaned in a tank at a machine shop, and I replaced the fuel injectors with some aftermarket, "4-nozzle" injectors. I included a link to those injectors below. I also replaced the FPR (OEM). I also installed Brown Dog motor mounts (rubber) as I'm hoping stiffer mounts will reduce the tendency of the headers to crack as often.
The only issue during the replacement was that the double-nutted mount where the CPS wiring harness had a metal mounting tab unscrewed at the bottom nut, so that harness got pretty twisted before I noticed - I made a mental note to maybe expect problems with that part of the harness, but didn't think it would be this bad and persist after I replaced that part of the harness (which comes with each new sensor).
When I test drove the car, the check engine light came on. The code was for the idle control circuit and the engine was idling high. I drove home thinking it was a loose connector or that the cleaner I sprayed in the throttle while it was apart might have hurt the motor (but that's never happened before either). It also crossed my mind that the idle valve was on that same twisted harness, but it's not...those wires go into a bundle along with the injector wiring across the top of the valve cover, but the part that got twisted was between the CPS and it's connector so separate and "downstream" from anything else in the system.
As I was trying to get the idle valve to work by checking all the connections, starting the car, etc., it suddenly wouldn't start any more. I was now getting Code 11 for the CPS (no signal during cranking). Weird, but I was half expecting an issue there, and when really working on that harness (even resoldering what looked like sketchy parts of the individual wires) without any luck, I went and got a (Duralast) CPS from AutoZone. Put that in along with a new idle valve, and the car seemed fine...no codes, low idle...everything worked again. Then it died on my wife...luckily only about 20 feet from our driveway after she'd been driving around town all day...maybe about 60 miles since the CPS replacement.
I let it sit for a while as I was tired of messing with it. A few days later, the car actually started again when I tried it just to check it before messing with it again. My son took it out for another test drive and it died on him about 30 minutes later. I got a new CPS (warranty from AZ) and now the car is running again and has been fine for a commute and a few errands today. I did get Code 11 on the last start, but the car actually ran absolutely fine even with the CEL on due to that code, so now I'm worried the next CPS is starting to give up.
I've read about leaking heat from the header causing CPS issues, but the header should be crack-free and tight...it's certainly leaking a lot less than it was before when cracked and there is no evidence of any leaks with the new header and its connections...the header mated up fine to the block and to the downpipe. It's also been about 40 degrees here lately and the car has been used for mostly in-town driving so I don't feel like it would be super-heating anything even if there was a small exhaust leak.
The battery (2105 Optima Red Top) did have an issue during all of this where it lost charge and couldn't even do more than click the solenoid within about 6 hours of being on a sophisticated AGM trickle charger/conditioner. So I'm keeping an eye on that and might need to replace it. That said, I've put new red tops in this XJ about every 5 years for the past 20 years and had plenty of issues when the batteries were on their way out, but never had an issue when the CPSs were temporarily and then permanently burned out.
One other weird cause I've been considering is a change in the injector impedance? It seems like a long shot, but could some interaction between the new and non-stock injectors and maybe the non-stock GC alternator be burning up sensors? It seems really weird to me that both the idle valve (probably stock @ 23 yrs and all those miles) and now multiple CPSs are going out so quickly after this seemingly unrelated repair. I might put the old injectors back in just to see if all these issues magically go away.
Could that metal mounting tab on the CPS harness I had in the car for 15 years be a weird heat sink of some type? That CPS was also aftermarket...it was one of those with the holes ovaled out to trick the ECU into advancing the timing back when I had a Jacobs ignition and adjustable MAP sensor on the car. The mount was a piece of metal wrapped into the harness with electrical tape (not electrically connected to anything) and mounted to one of the injector rail studs on the intake manifold. None of the replacement, even OEM CPS have that type of mount. It can't be a ground as the manifold is aluminum and I don't think makes for a good ground...nothing else is grounded to it. I've made sure to route the wires for all the replacement CPSs as far away from the header as possible.
Sorry again for the incredibly long post, but I wanted to get all the information out there at first as I have such a wide set of possibilities to consider...that's what is so frustrating about this particular issue...probably one of the most frustrating I've had in terms of trusting this car that's served us so well for 23 years and almost 350k miles!
Link to new injectors: https://www.ebay.com/itm/Set-of-6-FACTORY-REMAN-Bosch-Upgrade-Injectors-1991-98-Jeeps-4-0L-0280155703/201436597666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
Thanks in advance,
Olivier
I've owned and cared for this XJ for 23 years and 347,000 miles and never had a problem even close to this...very frustrating as I'm going through CP sensors at an alarming rate and the risk of getting stranded is way too high for a car we've trusted for all that time (I'm now test-driving it to and from work carrying around coveralls, latex gloves and the tools to swap the sensor in about 5-10 minutes).
It's a 1995 XJ Sport, 4.0, manual transmission. I've been running the same CPS for 15? years with no issues. Here is the series of events that started this set of issues, but they seem only possibly related at best, so I really need some help from experts with similar experiences or other ideas. The car does have a Grand Cherokee alternator that puts out a lot more amps than stock, but that's been in there for more than 3 years so if it's the cause of this problem, something changed after all that time.
Here's what happened: I replaced the existing Banks header with another Banks header...(probably the 5th or 6th time I've done that job as they crack a lot and I was getting them under the lifetime warranty for a while until they reduced it to 5 years). During that replacement, I also had the intake manifold cleaned in a tank at a machine shop, and I replaced the fuel injectors with some aftermarket, "4-nozzle" injectors. I included a link to those injectors below. I also replaced the FPR (OEM). I also installed Brown Dog motor mounts (rubber) as I'm hoping stiffer mounts will reduce the tendency of the headers to crack as often.
The only issue during the replacement was that the double-nutted mount where the CPS wiring harness had a metal mounting tab unscrewed at the bottom nut, so that harness got pretty twisted before I noticed - I made a mental note to maybe expect problems with that part of the harness, but didn't think it would be this bad and persist after I replaced that part of the harness (which comes with each new sensor).
When I test drove the car, the check engine light came on. The code was for the idle control circuit and the engine was idling high. I drove home thinking it was a loose connector or that the cleaner I sprayed in the throttle while it was apart might have hurt the motor (but that's never happened before either). It also crossed my mind that the idle valve was on that same twisted harness, but it's not...those wires go into a bundle along with the injector wiring across the top of the valve cover, but the part that got twisted was between the CPS and it's connector so separate and "downstream" from anything else in the system.
As I was trying to get the idle valve to work by checking all the connections, starting the car, etc., it suddenly wouldn't start any more. I was now getting Code 11 for the CPS (no signal during cranking). Weird, but I was half expecting an issue there, and when really working on that harness (even resoldering what looked like sketchy parts of the individual wires) without any luck, I went and got a (Duralast) CPS from AutoZone. Put that in along with a new idle valve, and the car seemed fine...no codes, low idle...everything worked again. Then it died on my wife...luckily only about 20 feet from our driveway after she'd been driving around town all day...maybe about 60 miles since the CPS replacement.
I let it sit for a while as I was tired of messing with it. A few days later, the car actually started again when I tried it just to check it before messing with it again. My son took it out for another test drive and it died on him about 30 minutes later. I got a new CPS (warranty from AZ) and now the car is running again and has been fine for a commute and a few errands today. I did get Code 11 on the last start, but the car actually ran absolutely fine even with the CEL on due to that code, so now I'm worried the next CPS is starting to give up.
I've read about leaking heat from the header causing CPS issues, but the header should be crack-free and tight...it's certainly leaking a lot less than it was before when cracked and there is no evidence of any leaks with the new header and its connections...the header mated up fine to the block and to the downpipe. It's also been about 40 degrees here lately and the car has been used for mostly in-town driving so I don't feel like it would be super-heating anything even if there was a small exhaust leak.
The battery (2105 Optima Red Top) did have an issue during all of this where it lost charge and couldn't even do more than click the solenoid within about 6 hours of being on a sophisticated AGM trickle charger/conditioner. So I'm keeping an eye on that and might need to replace it. That said, I've put new red tops in this XJ about every 5 years for the past 20 years and had plenty of issues when the batteries were on their way out, but never had an issue when the CPSs were temporarily and then permanently burned out.
One other weird cause I've been considering is a change in the injector impedance? It seems like a long shot, but could some interaction between the new and non-stock injectors and maybe the non-stock GC alternator be burning up sensors? It seems really weird to me that both the idle valve (probably stock @ 23 yrs and all those miles) and now multiple CPSs are going out so quickly after this seemingly unrelated repair. I might put the old injectors back in just to see if all these issues magically go away.
Could that metal mounting tab on the CPS harness I had in the car for 15 years be a weird heat sink of some type? That CPS was also aftermarket...it was one of those with the holes ovaled out to trick the ECU into advancing the timing back when I had a Jacobs ignition and adjustable MAP sensor on the car. The mount was a piece of metal wrapped into the harness with electrical tape (not electrically connected to anything) and mounted to one of the injector rail studs on the intake manifold. None of the replacement, even OEM CPS have that type of mount. It can't be a ground as the manifold is aluminum and I don't think makes for a good ground...nothing else is grounded to it. I've made sure to route the wires for all the replacement CPSs as far away from the header as possible.
Sorry again for the incredibly long post, but I wanted to get all the information out there at first as I have such a wide set of possibilities to consider...that's what is so frustrating about this particular issue...probably one of the most frustrating I've had in terms of trusting this car that's served us so well for 23 years and almost 350k miles!
Link to new injectors: https://www.ebay.com/itm/Set-of-6-FACTORY-REMAN-Bosch-Upgrade-Injectors-1991-98-Jeeps-4-0L-0280155703/201436597666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
Thanks in advance,
Olivier