Hi Paul,

I think that you do need to get those plugs back in the right sockets. I'm not sure how the US setup operates but I'm sure the ecu must be looking for different parameters from the upstream and downstream sensors. Perhaps other US owners can take a pic of their plug sockets and identify which should be the upstream and downstream connections then at least you can get them back to original positions. I'll try and have a look at my UK car and see if I can give any feedback on the position of the upstream plugs that my car has.

Paul

 

Relax, you are fine with what you did.

As long as upstream sensor and downstream sensor still report to one another, it doesn't matter which sensor is where, all four sensors are the same. You get into trouble if you switch banks so that the sensor upstream is no longer communicating to the correct downstream sensor.

Again, I just wanted to see if the closed bank would move over once you switched places with the oxygen sensors, upstream with upstream, downstream with downstream.

Be careful playing around with these, you should label all four harnesses as well as sensor pigtails to keep yourself in line.

When working with these sensors, always work on one sensor at a time.

 

Vee,

Thanks,

I just finished cleaning the Jag all up and am going to take it for a ride.

Will report back later today as to what happened.

Thanks

Softball60/Paul

 

Vee,

Tks for clarifying. Just for my interest, could you explain what the ecu does with the signals from the upstream and downstream sensors on US cars and how they relate to each other?

Thanks

Paul

 

Thanks to the both of you for being interested in my issue!!

Just a few minutes ago I took her for a ride....Cold...No time for warmup!!

I realize it was just one time............BUT ......NO LIGHT, probably come back to burn me. I will monitor for the next week and report back.

One (1) thing I didn't mention...Old Age!! is that the O2 sensors were extremely easy to remove...Very little effort to break loose....Makes me wonder if I didn't have a poor ground, so that when it was cold..maybe not so good grounding.

Also, Wouldn't the Engine Trouble Light come on if the wires were crossed when I put them back together since the signals would be wrong or non existent.

This time I really made sure they were tight...Could it have been that simple??

ptjs1,

I spent a year in Dundee, Scotland living in a bothy on the grounds of the richest man in Scotland.

Great time and love the Brits,
Spent several weekends in Glasgow looking at antique English Sports Car. This was back in 2001...Boy, were the Rolls Royce really inexpensive back then....Almost bought one but the wife said no!!!

Thanks

Softball60/Paul

 

I suppose anything is possible. You may have swapped a lazy oxygen sensor with one that will do some heavier lifting as well.


The upstream oxygen sensor does all the heavy lifting. It reads the oxygen concentration in the exhaust (pre-cat) and sends those signals to the ECU so it can make the proper fueling change. The downstream sensor is more of a dummy check sensor. As long as the oxygen value is always lower than the upstream sensor, the ECU is happy and doesn't send you a trouble code. (It should constantly read a near zero oxygen level, so it would look closer to a flat line, where as the upstream will look like waves)


Switching the upstream and downstream sensors may have bought you some time, where a lazy sensor is taken from the busier upstream position, to the easier downstream function. I suppose that could have been the issue. (I would start setting aside some money for sensor replacement, at least the upstream ones) Like I said before, the Jaguar OB2 system is reluctant on sending out accurate codes.


If you're going to use anti-seize, make sure it's the night-temp rated nickel type AND make sure you use it very sparingly. It won't take much of that to destroy the head. Apparently anti-seize and oxygen sensors don't like each other.

 

Will keep you posted!!

Softball60/Paul

 

Vee,

Tks for that. Quick question: if Paul has swapped over the plug connections of the upstream and downstream sensors, won't the ecu now think that the exhaust is cleaner pre-cat than after and get confused?

Paul

 

No. He didn't relocate the harness connections on the car, he just switched oxygen sensors. It's really no different than if Paul had bought one new oxygen sensor. The placement is the same.


WHat Paul really needs to watch out for is if he mistakenly uses the harness from the Bank 2 downstream sensor and plugs it into the Bank 1 downstream sensor. The harnesses are too far apart to mix n upstream harness with a downstream.


He'll know if he goofed as the car will run awfully, like it's panting and shaking.

 

Ah, I see! I assumed that Paul had just swapped the wiring plugs OR swapped the sensor locations but left the wiring plugs intact. I hadn't interpreted that he'd changed the sensor locations AND the wiring plugs!

Ditto your warning about copperease. If there's any contaminant on the head of the sensors it can ruin them.

Cheers

Paul

 

Vee,

Two (2) days and NO ENGINE LIGHT!!..............Probably the kiss of death.

I get the impression you know your stuff.

My next project assuming no more light issues is to completely replace all of the old bushings for both the front and rear, also the ball joints.

I get a rear end bang when I turn right and go up a drive (Sounds like something is bottoming out).

I get a small metal sound (Ball Joint?) when I pull into the garage and hit the approach small bump.

I've read good and bad regarding Poly Bushes. I am not a race car driver so the standard rubber bushings I feel would do just fine.

The car also does a small amount of hulla hoop when slowing down just before stopping.

I would appreciate your comments and also where I could buy like a complete front or Rear's worth of bushings.

Most like Ebay sell individual pcs. for a specific part on the suspension.

I was thinking that it might be more cost effective to purchase a complete kit.
Since I am discussing something other than the original Engine Light issue, should this be a separate thread.


Thanks

Softball60/Paul

 

I've responded in bold.

 

Vee,

After driving ~6 days with the oxygen sensors switched and immediately after startup the engine light finally came on again.

The last two (2) days I have let it warm up and no light has come on.

I guess I will purchase new oxygen sensors and report back.

Softball60/Paul

 

Same code?

 

Yes, Same Code

 

You never did check to see if the other bank would go into open loop? Can you undo the switch you did then go back and do the swap that I originally suggested?

 

I had already switched the sensors w/o any markings.

We are heading up North tomorrow for 10days.

When I return I am just going to purchase 4 new sensors and see what happens. These must have been original as they are Lucas?

If no light then maybe it was the issue. If I still get Engine light then maybe you were correct with your first suggestion......ECM!!!

If it is the ECM I don't understand why the car runs super!!!! w/or w/o Engine Light.

Thanks

Softball60/Paul

 

Denso is OEM, but I found that even those are marked NTK.

I have Bosch, you don't neee OEM on these cars for the O2 sensors.

I just wanted to see if the Closed Loop bank would move with the sensors. That would be a strong indicator.

I wonder if one of your exhaust manifolds are cracked. I'm not sure it could prevent your banks from going to open loop though.

 

Currently in Charlotte, NC.

Car is extremely quiet!! Does not sound like an exhaust leak of any kind.

Thanks

Softball60/Paul

 

To Vee and others that were interested in my delima.

As you stated Vee it's probably a lazy O2 sensor. Replaced all and no more issues for at least one (1) week.

Thanks for all your help and interest.

Now I will post another entry regarding Suspension.

Thanks

Softball60/Paul