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O2 sensor...

M

MOOSE16285

NAXJA Forum User
Location
Memphis, TN
O2 sensor... Woulod that affect the starting of my JEEP? I still need HELP! No spark created still! Here it is in more detail... When I did this, the water that got in the engine came in through the exhaust... Could this short my O2 sensor and if s, prolly a dumb question, must I need replace it?!
 
MOOSE16285 said:
O2 sensor... Woulod that affect the starting of my JEEP? I still need HELP! No spark created still! Here it is in more detail... When I did this, the water that got in the engine came in through the exhaust... Could this short my O2 sensor and if s, prolly a dumb question, must I need replace it?!
Click to expand...
What was the whole problem, and what year is your XJ?
 
90 XJ Sport 4x4 3 inch lift on 31s 4.0L engine and what happened... Take a look...

fxdjbc.jpg
 
MOOSE16285 said:
O2 sensor... Woulod that affect the starting of my JEEP? I still need HELP! No spark created still! Here it is in more detail... When I did this, the water that got in the engine came in through the exhaust... Could this short my O2 sensor and if s, prolly a dumb question, must I need replace it?!
Click to expand...
No it will not keep it from starting.
 
8700XJS said:
Shouldn't have opened the hood and let the water in...
Click to expand...

Are you bieng serious? ;) The bottom section of the engine bay isin't sealed in fact its open so the water level on the outside is going to equalize with the level on the inside. Hell, that isin't even a mud hole, you drove through a lake. Was SCUBA gear required for the recovery?

The oxygen sensor isin't used for start up and it shouldn't hurt it if wet. But, you probably got water and sediment in its connector so its all boogered up and corroded and it will need replaced (along with a lot of other stuff).

If you can crank the engine but can't start (assuming you dealt with any ingestion of water) I would check for fuel pressue and spark. Could be the circuit controlling the pump or sensors like crank & cam sensors that control the spark and injection timing.
 
Last edited:
8700XJS said:
Shouldn't have opened the hood and let the water in...
Click to expand...

I dont think opening the hood really made a difference man... Obviously form my picture the damage was done and alot was lost by that point...

I've already cleaned out all the mechanical stuff; engine, diffs, tranny, t-case... Fuel pressure is strong; knowing this by pushed the fuel line pressure relief in the engine compartment... Anyway, the O2 is not an input to the ECU?! I figured if any input was missing to the ECU it would not allow the start... I have alrdy replace the cps, distrubtor cap n rotar, spark plugs, wires, coil, ICM, Batt, all relays and all fuses... Mechanically, it sounds strong, new starter, oil, etc... Turns like a champ... It refuses to start due to the electricals... Coil does receive 12V but at crank will not amp to 33kV... Everything short of the wiring harness has been replaced... I dont think I'm ready to accept that as the problem... If anyone has submarined their Jeep before, and even if you didn't, and any idea how to get it started again, please let me know... I really really need this damn thing running again cause I got a ordinance violation twice already and 3rd time it goes byebye on my expense...

Another Q... Along side the relays in the passenger side engine area, toward the front, is a small metal box with a cable from the battery connected to it and quiet a few outgoing wires... What is this and what does it feed 12V to?
 
Last edited:
MOOSE16285 said:
I dont think opening the hood really made a difference man... Obviously form my picture the damage was done and alot was lost by that point...

I've already cleaned out all the mechanical stuff; engine, diffs, tranny, t-case... Fuel pressure is strong; knowing this by pushed the fuel line pressure relief in the engine compartment... Anyway, the O2 is not an input to the ECU?! I figured if any input was missing to the ECU it would not allow the start... I have alrdy replace the cps, distrubtor cap n rotar, spark plugs, wires, coil, ICM, Batt, all relays and all fuses... Mechanically, it sounds strong, new starter, oil, etc... Turns like a champ... It refuses to start due to the electricals... Coil does receive 12V but at crank will not amp to 33kV... Everything short of the wiring harness has been replaced... I dont think I'm ready to accept that as the problem... If anyone has submarined their Jeep before, and even if you didn't, and any idea how to get it started again, please let me know... I really really need this damn thing running again cause I got a ordinance violation twice already and 3rd time it goes byebye on my expense...

Another Q... Along side the relays in the passenger side engine area, toward the front, is a small metal box with a cable from the battery connected to it and quiet a few outgoing wires... What is this and what does it feed 12V to?
Click to expand...
That would be the starter relay.
Did you drown the ECU?
If the cps or TBS got wet there shot and those are need to start, the o2 is not.
 
Wow, man... that's too bad! I really hope you get your Jeep out of there soon.

MOOSE16285 said:
Anyway, the O2 is not an input to the ECU?! I figured if any input was missing to the ECU it would not allow the start
Click to expand...

Well, not exactly. The oxygen sensor is used by the ECU, but not during cranking. Think of it this way: there's no combustion if the engine hasn't started, so what's the oxygen sensor going to measure? In fact, the sensor isn't even used for the first few minutes of engine operation, since it needs to reach a predetermined temperature before it operates properly.

Hmm, isn't the coil tripped during cranking by the distributor? Did you check that?
 
langer1 said:
That would be the starter relay.
Did you drown the ECU?
If the cps or TBS got wet there shot and those are need to start, the o2 is not.
Click to expand...

Judging from the pic, water is up to the driver window. Now don't the renix jeeps have the ECU under the dash so it looks likely.

Anyway there are four necessary sensors for it to run and the others are more auxiliary. They are the CPS -which I read in your post has been replaced-, the cam pos. sensor (under distributor cap), the TPS and the MAP (which I it fires up without) then theres the IAC which is output not sensor input.
 
langer1 said:
No it's not, it triggered by the ECU from data gathered from the CPS and the CKP signals.
Click to expand...

Thanks for clarifying, langer1. My vote goes to a faulty CPS, too.

MOOSE16285, you mentioned that you already replaced the CPS. That sensor is located on the bellhousing of the transmission, but it's underwater. Did you replace it right after you got stuck?
 
iroc86 said:
Thanks for clarifying, langer1. My vote goes to a faulty CPS, too.

MOOSE16285, you mentioned that you already replaced the CPS. That sensor is located on the bellhousing of the transmission, but it's underwater. Did you replace it right after you got stuck?
Click to expand...
I just thought he was out now, could be wrong though.
 
langer1 said:
No it's not, it triggered by the ECU from data gathered from the CPS and the CKP signals.
Click to expand...

cam shaft position sensor was replaced a month ago, i went fishing in my jeep in august... My CPS is on the bellhousing and was bought n replaced from Advance... Distributor rotates but i do not understand the tripping thing. What do you mean by tripping and what is a CKP? I get no spark at all. The ECU is indeed under the dash but I have confirmed it DOES work... So, throw me some more suggestions, i really appreciate the help guys!
 
MOOSE16285 said:
cam shaft position sensor was replaced a month ago, ... Distributor rotates but i do not understand the tripping thing. What do you mean by tripping and what is a CKP? I get no spark at all.
Click to expand...

Whoops, sorry for not clarifying what I meant. By "tripping" I simply meant "activating" -- for example, I was inquiring whether the HV coil was activated by the distributor or some other source. Since you weren't getting the plugs to spark, it might be worthwhile to check the part that makes the coil work. As langer1 pointed out, it's the ECU that activates the coil when a number of sensors match the proper parameters. But you're sure that works, so move on to the next thing.

CPS and CKP are the same thing -- the crankshaft position sensor.

I'd make a fairly large wager that the CPS is at fault, like others have mentioned. The CPS tells the ECU the position of the crankshaft (oddly enough ;)). It uses this information to determine where the pistons are relative to their stroke; this is how fueling is synchronized. If there's no signal, the ECU won't allow the engine to start since the fuel injection system isn't designed to operate this way. Think of it as a fail-safe.

It's very possible that water has shorted out the sensor (it wouldn't be the first time, in my case). The trouble would come with replacing it, since your Jeep is submerged in water.
 
I may have missed it but have you double checked your connections on everything? Check the CPS and the wiring. I believe there was an upgrade for the crank sensor at one time. It bypassed the harnass and plugged right into the computer.

good luck
chris
 
The o2 sensor doesnt have any input when the truck is cold, so that wouldnt stop it from starting.

Just for clarifaction.
 
Even with purchasing a NEW CPS two months after the fishing experience, you still believe this to be the problem? Should I return the new CPS than? I dunno if I still have a receipt. Bought it from Advance. Will they have this on their computers? Guess I'm redoing the CPS again for Thanksgivings! I had to rebuild the Jeep last year a week before Christmas. My dad and I finished it Christmas morning and went ice drifting the rest of the morning! That was alot of fun! Anyway, good memories. What is this harness bypass and where can I purchase one? Is the CPS a common failure prone item? And should I go ahead and replace the O2 since I was rather deep in water? Take a look, here's the view from the inside...
hrbtkh.jpg

hrbtlf.jpg

hrbuy1.jpg
 
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