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Could an o2 sensor cause this?

N

NVRwheels

NAXJA Forum User
Location
Cary, NC
My XJ died the other day while wheeling. It wasn't getting spark but was getting fuel so I replaced the CPS and still no spark.

But today when I crawled under the heep I noticed on the front o2 sensor wiring all 4 wires were cut like they got caught on something and tore.

Could this cause my no spark issue?

thanks,
Jake
 
Well, a shorted o2 sensor can play havoc with the ASD relay and that relay provides power to the coil.
 
NVRwheels said:
Can I just splice the wires back together or do i need a new o2 sensor?
Click to expand...

Just splice them together, you won't be the first one to do it! :cheers:
 
Year, details?
 
CharlesS said:
Verify a fuse didnt blow when one of those O2 sensor wires shorted to ground....
Click to expand...
X2, fuse or relay, or wire even. I smoke the main fuse link on mine when the 12 volt heater wire to the O2 sensor internal heater shorted out to the exhaust manifold.
 
Ecomike said:
X2, fuse or relay, or wire even. I smoke the main fuse link on mine when the 12 volt heater wire to the O2 sensor internal heater shorted out to the exhaust manifold.
Click to expand...

What year is your rig? Where's the main fuse link on that thing? My 2000 has two relays in that box on the pass side of the fender. One says front o2 and the other says back o2 but my 98 doesn't have that.

Sorry about the hijack...
 
My rigs a 1996 with a 4.0 ax-15 and 231
Checked all the fuses visually and they looked fine.

All check out the relays and wires tom. and report bak.
 
well put new cap/rotor and a ignition coil still nothing.

Double checked fuses and swap all relays and still nothing.

I'm gonna return the cps and try another incase this one is faulty but after that if it doesn't start I'm stumped.
 
While on the subject of the CPS - before I hang an oscilloscope on the leads to mine, what waveform does a good one show? sinusoidal? rounded pulse? square wave? square pulse?

(if you think it'd keep from derailing, feel free to pm)
 
NVR - When my O2 sensor harness dropped onto the rear driveshaft a few years ago, it did the same thing ('96). I replaced cps (mistakenly), spliced the harness, and then found that there's a 30amp mini fuse in the Power Dist Center on the passenger side wheelwell. If it's blown, no starty.

With that being said, and seeing that Joe and Jon are watching this thread, I'm going to hijack a little.

This morning, at 6:45, in the blizzard we were having here in Denver, my Jeep stopped dead, just like before. I drove on the starter to get off the road, and went back this afternoon to diagnose.

Checked fuel pressure (42 psi), CPS per Tim_MN, and all the fuses, and swapped relays. That same 30a fuse is bad. My O2 harness is still intact, so I'm wondering what else can pop this fuse. It's fuse F20 per the FSM, which I have, but honestly can't read the wire diagrams all that well.

Just turning the key to the on position makes it blow, not even the starting circuit. :dunno: Help!

Steve
 
Sounds like SteveT is on to something there. If all else fails I would dig into the harness to see if the CPS wires got damaged in the rip and pull contest that took out the O2 sensor wires?
 
Steve,

When Hugo's rig stopped dead in it's tracks on Jenny Creek, he'd blown one of those fuses. Replaced it and same thing -blew right upon making contact in the terminals. He had corroded battery cables and one clamp was a bit loose. We cleaned the clamp and post a bit, then left the battery disconnected before replacing the fuse again. Once the fuse was in, I put the battery clamp on swiftly to keep the sparking to a minimum. Tightened the clamp and it fired right up and as far as I've heard - he's had no further issues.

Go clean your battery clamps and posts, grab the cables and bend 'em around to break up any internal corrosion, leave the positive clamp off, replace the fuse, then reconnect the battery. Hopefully that'll help.

I'm thinking that when the cables get corroded, something that's drawing through that circuit is blowing the fuse. We never did trace that circuit on Hugo's rig that day, but the fix worked.

:dunno:
 
Steve, F20 powers the ASD relay. You could remove the relay and see if it still blows the fuse, if so it is something downstream of the relay shorted whether wire or component. The ASD relay powers the injectors, the 02 heaters, ignition coil and alternator. Disconnect components one at a time to find the short. To save on fuses rig a test light into the fuse socket, if it glows as brightly as when hooked across the battery there is a short present.
 
YELLAHEEP said:
Steve,

When Hugo's rig stopped dead in it's tracks on Jenny Creek, he'd blown one of those fuses. Replaced it and same thing -blew right upon making contact in the terminals. He had corroded battery cables and one clamp was a bit loose. We cleaned the clamp and post a bit, then left the battery disconnected before replacing the fuse again. Once the fuse was in, I put the battery clamp on swiftly to keep the sparking to a minimum. Tightened the clamp and it fired right up and as far as I've heard - he's had no further issues.

Go clean your battery clamps and posts, grab the cables, throw them in the trash and replace them with a set from BigOffroad, leave the positive clamp off, replace the fuse, then reconnect the battery. Hopefully that'll help.

I'm thinking that when the cables get corroded, something that's drawing through that circuit is blowing the fuse. We never did trace that circuit on Hugo's rig that day, but the fix worked.

:dunno:
Click to expand...

There, fixed it.

I'll give 'er a shot tomorrow, if it's still where I left it.

Thanks
 
Something to keep in mind. When my O2 sensor wires got trashed with an encounter with the drive shaft, it pulled a huge current that was high enough, and shorted long enough to melt wire insulation!

Mine is Renix, and it was not fused like yours, all the Renix had was a 100 amp fuse link near the battery. SMOKIN! When it goes to ground.
 
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