Could mud be fouling my CPS
06-23-2012, 11:49 PM
#17
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Good. Might try a different meter to verify. AC volts, right?
06-24-2012, 01:11 AM
#18
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Year: 90,84
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You might set it on ohms and mess with the leads, and also the dial and see if it jumps around allot. The leads definitely can be an issue. I guess it rounds off. (a .34, or .35 might read .3). Yea they can be a problem when it gets close. When mine was flashing a .2 now and then is when I had CPS trouble. Also btw, my new cps tested .4 (on a better meter), right when I put it in, then has tested .5 since...for what that's worth.
Do you have a bunch of mud in there? Is your inspection plate off?
Do you have a bunch of mud in there? Is your inspection plate off?
Last edited by DFlintstone; 06-24-2012 at 01:15 AM.
06-27-2012, 10:49 PM
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If you connect your meter leads, Do you get less than an ohm? And jiggle them and see it it changes.
My mud here actually DOES have iron. (its even rust color). Is your cover down there off? Is there a bunch of mud in there?
Off chance, sometimes when a production line screws up, they crank out a bunch of the same widgets, with the same flaw, at the same time. Unlikely, but it does happen. Having access to another meter sure would be nice...really you want that higher.
My mud here actually DOES have iron. (its even rust color). Is your cover down there off? Is there a bunch of mud in there?
Off chance, sometimes when a production line screws up, they crank out a bunch of the same widgets, with the same flaw, at the same time. Unlikely, but it does happen. Having access to another meter sure would be nice...really you want that higher.
Last edited by DFlintstone; 06-28-2012 at 12:21 PM. Reason: comma
I used Echlin #CSS980, Mopar will be fine.
07-01-2012, 07:04 AM
#25
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Year: 1988
Model: Cherokee
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So I checked my old CPS, coils and just for fun the dizzy and my buddy's xj ran some how I forgot to bring my volt meter so I couldn't compare readings. I'm thinking now I might have a problem with the ecu or of course wiring. So where do I start and can I have my ecu checked out or do I have to swap it
I have and am searching
https://www.cherokeeforum.com/f23/te...itings-136452/
Was hoping there was a cruisers ecu test
I have and am searching
https://www.cherokeeforum.com/f23/te...itings-136452/
Was hoping there was a cruisers ecu test
Last edited by Rustydog555; 07-01-2012 at 07:32 AM.
07-01-2012, 08:22 AM
#26
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Year: 1990
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I'm gonna give you 3 tings to do. Do them without taking any shortcuts or skipping any steps. Won't cost you diddly squat to do except a little time.
Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
Revised 11-28-2011
Renix Jeep C101 Connector Refreshing
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.
Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101.
The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together.
Revised 11-29-2011
I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals, and adding dielectric grease before plugging it back together. Be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else.
Revised 03/15/2012
Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
Revised 11-28-2011
Renix Jeep C101 Connector Refreshing
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.
Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101.
The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together.
Revised 11-29-2011
I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals, and adding dielectric grease before plugging it back together. Be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else.
Revised 03/15/2012
07-01-2012, 11:03 AM
#27
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Thanks I will have to go over everything again. I replaced the engine harness 2 years ago and dielectric grease every connection win I first got her she had sat for bout 7 years it's no dally driver and has had a rough life since I started abusing her kind of a love hate thing
Have had about every wire undone except the plugs going to the computer itself. Ill rubble check grounds and clean and grease as I go but I think I need to see what that little box looks like its probably been wet in the past.
Have had about every wire undone except the plugs going to the computer itself. Ill rubble check grounds and clean and grease as I go but I think I need to see what that little box looks like its probably been wet in the past.
07-01-2012, 12:07 PM
#28
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I've seen that C-101 connector get real nasty. (helping a buddy). I didn't now what it was called then, I just called it ugly!
Cruiser, that link he found is the page I did with your stuff, (same as in my sig)
Cruiser, that link he found is the page I did with your stuff, (same as in my sig)
Last edited by DFlintstone; 07-07-2012 at 06:04 PM. Reason: 1
07-07-2012, 03:06 PM
#30
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Was trying to post pix of my ecu had a water mark inside and was a reman got one out a 89 at looked like new starts right up thanks for all the help still don't know why I can't get but .3 volts from a Mopar CPS but must be my meter one day I'll try a good meter on one but for now I got a backup
Thanks again for all who helped and for reminding me that just because I don't know what's going on it don't make it an advanced problem
Thanks again for all who helped and for reminding me that just because I don't know what's going on it don't make it an advanced problem