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Stumped, please share your thoughts..thx

ezeman

NAXJA Forum User
Location
Denver
Ok, I have been at this trying to figure this one out for a few months. I have read a bit, but cant seem to put my finger on this problem or serious of problems. the backdrop: 96 xj, 142,000 miles, intermittently goes into bad idle, dies at stop signs, turning, etc. Runs fine at highway speeds. Problem started some time ago, cleaned TB, replaced IAC, TPS, replaced MAP last week. Also did rotor, cap, wires, plugs, within 6 months ago. The other odd problem is intermittently, when i step on the gas hard, the car almost 'feels like' its shutting down of r aquick second at 3100 rpm, then starting up once it dies down to around 2800 RPM, if I kepp it floored, it maintains this pattern cyclicaly. THis problem has been around off and on for a few months, but has been consistent for the last few days now, along with the crappy idle. Any help you can give is most appreciated as I am truly stumped. I dont think is fuel related, and I have a new coil and CPS on hand, which I think I will try to install next?

E
 
Sounds like the computer is shutting off for some reason. Is there a way you can determine whether it shuts the injectors or the ignition, or both?
I'd double check all grounds in the engine compartment and the distributor indexing, to begin with.
 
Can you pull a code ? I can,t believe that a CEL isn,t burning bright.It also sounds like mine did when the distributor wore out.
Wayne
 
Only code I have ever gotten has been Code 14, which is currently showing. I got Autozone to read it further a few weeks ago, they said voltage high. I replaced MAP last week, problem was gone for 4 days, then it shows back up this week, but even worse (the idle problem), with the exception that it doesnt seem to now be missing at 'cruising speeds' I have to give it gas at every slow down now to keep er goin'

Thanks for help in advance also :)
e
 
A question for others: Could leaky injectors, or high fuel pressure cause this problem?

Have you checked the plugs to see what the electrodes look like?
 
I had a similar problem on my 96 last month. I was pulling several codes & started replacing everything. I replaced the CPS, TPS, Coil, rotor, cap & wires. The problem turned out to be the 'other' CPS (camshaft position sensor). It's code 54, which says 'replace distributor SYNC'. The parts guy at Chrysler told me that an SYNC was a rotor, which caused a good $200 worth of uneeded parts in my case.

Good luck,

Paul
 
Wayne, I did pull code, its 14. This problem has been intermittnet for a few months, but seems to be staying prblematic here this week. I got this same code for the last few months, no others.

I will check the plugs tonight, after work. When I changed them 2 months ago, I saw no signs of anything 'foul' haha

Paul, what 'other' CPS, I am only aware of the Crank Position Sensor, is there something else I should check? Did you change this out and it fixed your problem? I would like to circumvent the $200 throw-some-parts-at-it mentality I have recently taken

Thanks again!
e
 
The 'other' CPS is the camshaft postion sensor (on the distributor). Mike R. confirmed that this is indeed what is called a distributor SYNC. It solved my problem.
I also had a code for the 'normal' CPS (crankshaft postion sensor), which I changed out & which did not solve my problem.

Paul
 
I had similiar problems with my 96 (hesitation, especially when cold, rough idle, tendancy to want to stall at lights etc etc)

mine though, i attribute to my severlely cracked exhaust manifold (which i was aware of).

i installed a new borla header and downpipe and the engine runs fantastic now

if you are still at a loss.....check for exhaust leaks (I'm sure if they are really bad you will know it though)
 
Here's a dumb thing to check, but why not try retorquing the centre five bolts on your manifold? They seem to be the most likely to come loose, and they'd cause all sorts of strange troubles if they do...

Loosening manifold bolts is a common problem with inline six engines, just because they're so damn long. Add in our "sidedraft" heads and having an aluminum intake and a steel exhaust held down with the same set of bolts, and you're going to be tightening those bolts down every now and then.

If you take it all apart, here's a tip:

Replace the steel bolts with silicon bronze 3/8"-16x1.25" (available from Fastenal) and use LocTite 272 to retain them. Make sure all bolts and nuts have Belleville Spring Washers installed (if you don't have them, get them from MSC Direct or Small Parts, Inc.)

This is pretty simply, and goes a long way to keeping everything tightened up under the hood. LT272 is the only grade that will work with exhaust heat.

Belleville washers take some of the clamping duty off of the bolt heads, and makes for more consistent clamping accounting for the different expansion rates of aluminum and iron/steel

Silicon Bronze is a copper-based alloy, rather than iron. Why is this important? Heat-soaking an iron part and allowing it to cool is a process called "annealing" - used to relieve stresses after hardening or machining. Eventually, this can (and usually will!) soften the bolts slightly. Also, the "bending" action of the different expansion rates will work a bolt loose - all the more so if it softens (as it will bend more.)

Going to a copper-based alloy results in a bolt that will actually get slightly stronger each time it heat-soaks and cools - between that and the Belleville washers, you should have no trouble maintaining torque on the bolts.

How do I know? How do you think I put these things together when I have to take them apart, Grasshopper?

Sorry - but while the 242 is one of the best engines I've met, that doesn't mean there isn't room for improvement (damn Accountants - they should leave the engineering department alone. I don't mind paying for good engineering...)

5-90
 
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