1987 xj problems

[JEEP_cannible]

Ok I have had this thing about 8 years.In that time I have had a few small problems.Then last summer my daughter was dirving it when the stearingcolum went to sh-t.It was spinning all the way around.I replaced the colum no problem.Now all kinds of things are going to sh-t.I replaced the distributer cap,rotar,and plugs the other day.It was running better than it had in a long time.Then it stopped starting with the key.I installed a pb in the sistem,and it started with the key.Then it quit again,and i'm using the pb.Well yesterday I replaced the ignition switch,and same issues persist.While putting the dash back togeither I had a no start issue.Today I took the dash back apart.I ran checks from the cpu,ignition coil,sensers,cps,sparkplugs everything I could stand to do in the cold.While checking the spark(plug wire off) it started and ran just fine.With the dash all back apart of course.Now I'm afraid to put the dash back togeither.That the no start issue will come back.Its an 87 auto trans,4.0 L.
Any ideas,and sorry for the long post.Do these thing ever get any better as transportation.I never had this kind of BS with my 70's wagoneers.Maybe I should put my 78 back on the road,but gas prices would kill me.

 

[joe_peters]

Ok--clarity is required.

Crank, no start OR no crank?

 

[JEEP_cannible]

Joe I had both just not at the same time.Yesterday was a no fire issue from the dash reinstall.The no crank issue with the key is still there as well.Even after replacing the ignition switch thats why I have the the pb switch installed.

 

[JEEP_cannible]

One problem down so far.I have the dash back up togeither,and the thing starts with the remote switch,and runs.The running part is a good sign right?
Joe I replaced the ignition switch yesterday because I had an extra.So I'm guessing,but wouldn't the starter relay be the next in line? I'm also guessing the NS switch isn't a problem,because it just started in drive on me.Supprise,supprise maybe I should put it back in park after reinstalling the dash.:laugh3:

 

[87manche]

no crank- I would suspect the neutral safety switch long before anything in the column. Search it and you'll find a detailed thread about how to remove and clean it.

 

[ifixit8]

If it started in drive then the nss is shot! that should not happen as a safety. the whole point of the switch. I'd say replace that and you will be good.

 

[JEEP_cannible]

I think the previous owner/bodyshop bypassed it all togeither,but its something to look into.Some of this thing is really mickie rigged.I know good and well its from the bodyshop/previous owner.
Just like the heater fan motor.Its not even for a jeep so its definetly not the right one.On the bright side they didn't hack anything to put it in.

 

[joe_peters]

Yeah. Path is key, key cylinder, remote rod, ignition switch, starter relay, NSS/clutch safety switch (starter relay ground interrupt), solenoid, starter.

Battery and main cables along with the harness between all of the above are things to consider.

On the starter relay there is one large lug--the Renix PDC--and 3 male spade connectors: IGN--12 volts from ignition switch; SOL--12 volt feed to solenoid when relay is energized; GRND--the ground that is interrupted to prevent cranking if not in Park or Neutral. You can jumper a ground to that GRND terminal on the starter relay for a quick bypass in an emergency.

Not fixing the NSS is absurd and leads to more problems. The NSS has other duties besides preventing starting, it tells the TCU what gear has been selected, and it controls the backup lights. If the NSS is bad you may (likely) end up with transmission issues.

Lets a**ume for now that the crank, no start issue is resolved. You should repair the no crank issue so that it is back to OEM. While I personally don't have a problem with a vehicle that can start in any gear (learned to drive on trucks/tractors/motorcycles in the late 50s), however most lawyers and juries do. Loaning a vehicle to ANYBODY in an unsafe condition leaves you open to all kinds of problems.

Heck, I won't let anybody but my Son drive my XJ, he is an experienced wheeler and knows the handling characteristics of lifted vehicles and lockers.

PS--Old School thing: when you have multiple problems just break it down and take care of one thing at a time. Yes, things today are less easily defined due to interdependence/interactions of subsystems, but fixing one bad sometimes rewards you by eliminating other issues, or at least you have narrowed the list of possibles.

Good luck.

 

[JEEP_cannible]

Thanks Joe,
Yea I would like to have everything back to OEM if its at all possible.Thanks for the Info Joe,and I will be checking into the NSS switch asap.I'm hoping that NAPA will have a replacement.If not then its off to the junkyard,or dealer.I think the relay is the problem and a quick fix,but not the only problem for sure.

 

[joe_peters]

Thanks Joe,
Yea I would like to have everything back to OEM if its at all possible.Thanks for the Info Joe,and I will be checking into the NSS switch asap.I'm hoping that NAPA will have a replacement.If not then its off to the junkyard,or dealer.I think the relay is the problem and a quick fix,but not the only problem for sure.

I would definitely hit the salvage yards for an NSS--little buggers are EXPENSIVE, North of $100 (I think the cheapest I saw online was $130).

 

[JEEP_cannible]

Ouch, Thanks Joe thats good to know.I may try the cleaning idea first then.Remove any,and all the jumpers.Clean it up reinstall it,and check it out before I just go get a new one.Thanks again Joe

 

[joe_peters]

Keep us posted on how it goes.

 

[JEEP_cannible]

Joe any ideas????
The no fire problem is back,but get this.Its only happining when the weather is cold.Do you think it could be a flooding problem? Its never done this before,and its never been cold blooded.In past years it has always fired up fast,and easy.I replaced the plugs,cap,and rotor a couple of days ago.Went out tonite with the temp drop,and it wouldn't start,The last three days have been alot warmer,and no problems starting at all.It started right up when it was warmer out today now nothing.The only mod I have made is a cold air intake,and new filter.I wouldn't think that would be the issue,but anything is possible.
Thanks for any help

 

[joe_peters]

Ok, by "no fire" do you mean actually no spark or it just cranks and won't run?

Ok, our Renix XJs have to "spin up" to 300+ RPMs before the crank sensor can generate a strong enough signal to get the ECU to trigger a spark. At the same time the battery must be able to provide 9.0+ volts or the engine management system won't work. Starters don't care about volts as long as there are enough AMPS they will work.

When the weather turns cold the battery and starter get really stressed, and marginal components--those that work fine when it is warmer--start causing problems.

I would start by fully charging the battery and then having it load tested after it sits outside overnight--test the battery when it is at its weakest moment. I have put batteries in the freezer and then tested them hours later--my Wife does NOT like it when I do this. At least I no longer overhaul carbs in the kitchen sink, and we are currently working on a compromise about the drill press on the dining room table. Women can be so fussy sometimes.

While the battery is charging clean the main cables on both ends. Renew the grounds at the dipstick tube--those are for the ECU, the ICM/coil, the o2 sensor and others. Check the ground strap from the back of the head to the firewall--that is the one and only ground for the unibody and all of the other little grounds have to flow through it. If you still have the braided strap replace it with a 4 or 2 gauge cable. For all grounds strip the metal down to shiny bare, treat with an anti-corrosion agent from any paint/hardware store, and make the connections TIGHT.

Ok, battery fully charged and load tested, main cables cleaned on both ends, all grounds renewed--does it start now? If not, put a voltmeter between the battery's terminals and observe it while cranking--is it maintaining 9.0+ volts? It should be if it passed a load test. Next step is a voltage drop test on the main cables--they can be corroded under the sheath and you not know it. Here is info on a voltage drop test: http://www.aa1car.com/library/voltage_drop_testing.htm

Ok, that should get you going. Here is a good read on how to improve the cables/charging in the poorly designed XJ system: http://www.olypen.com/craigh/charge.htm

Remember, with bigger cables it will crank better/faster and charge better.

Post up and keep us informed.

 

[JEEP_cannible]

Thanks Joe,
I just replaced both batt. cables when I started having this problem.I also added a ground to the body from the batt.I still need to check the strap at the back of the head.I completely forgot about that one.I should replace the battery too.Its been setting on my work bench for over a year.It was new just never used.
It was for duel batterys do to the amp.It never got finished,because I never needed the extra battery.I should just do it the tray is all ready there,and I have everything to set it up.It will give me more cranking power,and help with a voltage drop.
Thanks Joe

 

[Ecomike]

One other thing to check is the CTS and MAT if it only happens when cold. I had spark and fuel, but no start once. I had that problem once and it was a bad MAT, Manifold Temp sensor. Joe has you lined up with all the other usual suspects.

 

[JEEP_cannible]

God I love this.Its about 10 degrees warmer+bat.charger on 52 amp boost,and still wont start.Its cranking over like no tomarrow go figure.I did find that ground strap Joe,and its still the flat strap.Not for long though thats getting changed today if at all possible.Then its back to the drawing board.

 

[joe_peters]

Ok--lets do BASICS.

Compression
Fuel
Air
Spark
At the right time
In the right quantities

When cranking, what is missing? Put a spare spark plug into a spark plug wire and ground the steel body of the plug to the engine. Have a spare set of hands crank the engine over--consistent, HOT, blue, SNAPPY spark?

Post up.

 

[JEEP_cannible]

Ok joe its a no spark issue.All last week I had spark,and now nothing.WTF is the deal with this thing.Ok now I have a bunch of things to check again right? The funny thing is I have power at the coil wire with the key on.The Batt is fully charged.So start checking grounds first? Then the NSS ?

 

[Ecomike]

Ok joe its a no spark issue.All last week I had spark,and now nothing.WTF is the deal with this thing.Ok now I have a bunch of things to check again right? The funny thing is I have power at the coil wire with the key on.The Batt is fully charged.So start checking grounds first? Then the NSS ?

For a no spark you can work backwards from the HV coil to the CPS, or start at the CPS.
Since you have power, cranks, and no spark:
CPS....ECU.....ICM.....HV Coil on the ICM and the wiring in between is the path I think. I am having the same problems. Mine seems to come and go, now it is the ECU, or ECU to CPS wiring it seems. Last week it was the old 1989 CPS on it's last legs. CPS sends a signal to the ECU, ECU processes multiple signals and data, and sends a signal to the ICM telling it when to fire the HV coil. ICM needs a good ground, 12 volts, and the ECU firing signal, and needs a good ICM and good HV coil. Bad CPS is common, or so I am told. ECU needs 12 volts and CPS signal to fire the ICM for sure, not sure if any other sensors are required to get the ECU to fire the HV coil and injectors.

You might find the notes in my current thread enlightening:

http://www.naxja.org/forum/showthread.php?t=1050783

Lastly, the current theory on Jeep gremlins is that they are nomads, they like to move around a lot, and they hate to stay in one place for very long!!!

Edit: I don't the NSS is involved in a no spark issue. I would check the CPS first.