I had a small exhaust leak where the exhaust pipe connects to the exhaust manifold after replacing that pipe and cats. The replacement pipe and cat was aftermarket (davico I believe) and there was a small bump on the flanged end of the pipe where the pipe was originally welded. So the flanged end didnt seal to the coned exhaust manifold outlet well enough. I got cat efficiency codes instead of lean codes. I smoothed out the bump with a file and all was good. But there was no strange exhaust leak sounds and I could see much of any soot there bc the location is hard to see when all clamped into place

 

What a CAR centered weekend. Sheeeesh!

So, I did the smoke test and found only one leak that I could see. DIY smoker was great btw. Used one of those can openers that only curls back the lid (a large can of crushed tomatoes - so tomato sauce was on the menu) of the can to open allowing for a nice seal after. Some atf, a pinch of gass, a bunch of ripped up card board and a bike pump with make shift attachments and tubes. Worked perfectly and smoldered smoked for an hour... Thanks youtube!

The one leak was around one of the injectors. Removed, replaced o rings and seals of all 4 on that side. Sealed!

Exchanged the plugs for the O2 sensors LH to RH both upper and downstream. Car didn't like that much on next start up BUT it seemed to be making adjustments, threw a bunch of misfire DTCs, then leveled out.

The steady 19.5 LTFT on bank 2 dipped down, but ONLY to about 15.0 at the lowest. And, it remained on bank 2 despite the sensor swap - which I don't understand. Bank 1 sensors plugged into the bank 2 did not effect the LTFT numbers as my HIGH numbers on bank 2,,, remained in bank 2. I was/am puzzled.

I only idled the car, didn't drive it for any duration. Maybe LONG term fuel trim means exactly that? And it will take some time to slowly ease out? At least the pegged 19.5 isn't just "stuck" giving a false reading. At least the O2 sensors seem to be ok. At least I found a significant vac leak.

But what now? At this point the car registration expired, I MUST have an inspection and proof if it before I can renew the registration. I am frustrated with this machine!

​​​​​​

 

So the car is going back and forth into open and closed loop. Runs aweful when in closed, much better in open.

The lean code has not reappeared BUT the 19.5 trim DID shift to the other RH side. I swapped all the sensor plugs.

My only codes are for misfire when running (trying to run) in closed loop.

Is it the 02 up or downstream sensor on the LH bank that reads the amount of oxygen in the exhaust?

I'm not getting DTCs that indicate a failed O2 sensor. Just the misfire and seeing the data on the OBD going from opened to closed loop.

 

You probably already know this, but the lean code takes multiple reps to set (2).

So, the LTFT swapped when you swapped the sensor plugs? If so, swap them individually (in pairs, one function) until the LTFT shifts, and that is a big clue problem. By the way, what are your STFTs at idle?

 

You need to do a hard reset when switching sensors and then turn the ignition on for 30 sec, before starting. The ECU will then revert to factory settings. It will take up to a half hour for the fuel trims to stabilize.

 

That's ^^^^^ the best news I've heard all day. It's like the car is looking around and going crazy trying to make sense of things. And I ain't just saying this, I was thinking of the hard reset myself to try and help answer the car questions and the confusion caused by the swap.

I'm embarrassed to post the pic I have. Mind ya, this is NOT what it looked like the first time I hooked up the battery, started the car, went on maybe a 24 mile drive a few days after I put in the new motor. All I had after the was the single lean code on the LH bank.

After swapping the sensors, things went haywire. I didn't know of the hard reset, and silly me, I did the smoke test and clean up of the FInjectors (I'd found a leak on the LH injector rail and replaced seals) and the swap of the upper and lower O2 plugs at the same time! Dumb. I should have done the injectors, took a look at what resulted and then reached back and did the swap if things didn't look right.

The photo below is and OBD screen shot after walking up to the car cold, sensor plugs still swapped and starting the car and letting it warm up at idle naturally. This is the second time it went this way today.

Car will go in and out of loop, OBD saying that the closed loop failed and it goes open. Things smooth right out in open loop. Then it tries closed again, goes bad and returns to open. Cycle like.

This is keeping me up at night and I am sooooo grateful y'all are answering! Jus say'n

 

I see negative fuel trims, were they negative when you started the thread?

 

I don't believe so... I had STFT and LTFT trims on bank 1 that varied pos to neg, as they do, I think. I'm ashamed to say that I never really paid much attention to my fuel trims before and am on a bit of a learning curve with it all. On bank 2, before swapping plugs for the O2 sensors (and I only would have swapped the ONE set if I knew whether it was the up or down stream sensor responsible for reading lean or rich - I still don't know) the reading seemed PEGGED at (+)19.5 no matter what. Bank 2 STFT if I remember were all high and all over the place. But,,, for all intents and purpose, the car felt to be running normal.

When I started the tread (not having seen the fuel trims) the only DTC I had was a a solid p0174, bank 2 lean... I guess it was so bad that it sent the car into "Restricted Performance" after any period of driving. But, the only code.

At some point I think I mistakenly mis-reported a code, a code that popped that basically said that I was getting ZERO information from the O2 sensors. Later I remembered that I had removed fuse 14 (I think it's 14) from the RH fuse box momentarily with the car running which thru the code. That DTC has never returned.

After the smoke test and possible fixing of the air leak, I'm looking for to going back, doing a hard reset, returning plugs to their appropriate sides(should I?) and starting her up to see what happens...

I am super open to any other thoughts, suggestions and ideas. This is no no no fun.

 

By plugs do you mean the oxygen sensors? If yes, I would return them with a hard reset and start from there.

 

Yes. Thank you for the suggestion! It'll be a couple of days maybe, but I'll be going the way you suggest.

 

Then, there's this :

Oxygen Sensor removal - The cable lead to ????-Resolved - Jaguar Forums - Jaguar Enthusiasts Forum
https://www.jaguarforums.com/forum/x...esolved-79384/

I just read some of this thread suggesting that the plugs need to go back EXACTLY,,,,, like they were removed...?

For mine, when putting everything back together when placing the engine I kinda got the sense on the loom that the sensor leads that were most on the RH,,, and and those most on the LH sides of the loom went to right and left CATS... Then, a black plug and a grey plug each side. imagining that it would make sense to construct and lay out the loom that way. Am I fool for making that assumption?

 

Jay
The upstream o2 monitor the air/fuel mixture and the ecu in closed loop uses this info to fine tune the fuel trim

The downstream o2 monitor the catalytic converters

 

Thanks, Day! That's what I had thought, and read. Thank you for confirming... Really. Working on these things,,, my ability to second guess and doubt myself drives me nuts.

I have to remember,,, there is NO reason that I should know how to swap and engine in an older Jag, considering that 3+ yrs ago I had never even driven in a Jaguar, nevermind work on one.

I've GOT to get this sorted.

Good thing (I guess) about this news is that the up stream sensor wiring saw no rubbing or scraping on the sides of the trans when the motor was going in and out. Could have gotten contaminated though, I guess. We shall see.

 

Dead sensor,,,,? Downstream?
and can I trust the labels placed by the torque pro OBD monitor as accurate? I don't want to remove and change the wrong sensor.

I get NO sensor codes. Strange.

I guess I ask because it give NO reading for the upstream (?) sensor - there is a label on the OBD but inactive? I thought that strange. The uppers are pretty costly (130$) but the lowers not so bad. What a thing!

Call me dumb (and I suuuure can be) but I JUST found this voltage readout on my scanner, smh


The bank one voltage fluxed between near 0 and near 1 from what I could tell...

 

May be a sensor with an open circuit, or faulty wiring/connection.

 

Thanks Man. From what you can tell, which. Up or Down, Bank 2...?

 

I'm having a bit of difficulty following here, since I think you started with a P0171/P0174 and now have a P0171/P0175 with the HO2 sensors swapped (that makes no sense to me). And now, a bunch of misfires. Did you swap side to side (i.e. left to right) or upper and rear? I also wouldn't worry about closed loop/open loop. It cannot keep closed loop if it uses all of the available trim to one direction, so it's not surprising here. I'd start with the codes.

In any case, here's the relevant bit from the 2nd ed workshop manual for the lean condition (P0174 is basically the same)


P0171/P0174 Issues

So, comprehensively, there's fuel and there's air and there are sensors and there's the ECM. Go ahead and rule out the ECM until you've ruled out everything else. Also, did the ECM work before the engine swap? If so, hard to believe it would be the culprit.

So, for fuel, you've got both banks lean, so this rules out many of the single injector conditions, etc. So, for system wide issues, check the fuel pressure on the rail.

If (since?) this is okay, proceed to check the vacuum lines and intake system. Many ways to do this, best way is smoke, but common sites are
1. Intake hose (both ends and the middle)
2. Full load breather
3. Part load breather
4. Vacuum lines on either side of the throttle elbow
5. Finger trap vacuum line for the brake booster into the throttle elbow
6. Oil dipstick (both around the dipstick and the dipstick tube into the engine)
7. At connections to the cam covers
8. Around the cam covers
9. The intake (the intake could be broken, and/or the gaskets could be leaking
10. The exhaust before the cat.
11. etc.

If the system is sealed (which you have checked with smoke?), then there are 5 sensors of interest. MAF, ECT, IAT, TP, HO2S. There are electrical tests you could try to check continuity/resistance of the system in the 1999 Workshop Manual (tests starting on p. 1564). But, at first, you appeared to have a system problem, not a single bank problem, so I wouldn't do anything with the HO2 sensor at first because there are two of them (you could swap the two upstream ones, but I'd expect it would tell you nothing since both were already lean. Oddly enough, one trim went to rich.). In any case, what are the odds both are bad/cut wires/etc to the H02 sensors?

You can easily check ECT with your scanner by seeing if the reading makes sense for the notional engine temperature. TP? Possibly, but since it's happening at idle, what are the odds? So, the first bet once you get here is MAF/IAT, both of these are in the MAF sensor for you. There's another for the SC versions.

Note that the ECM also performs checks on these sensors and does not appear to be reporting sensor problems.

If you get to here, I'd try a new MAF sensor for grins.

The problem with all of this is that you may have disturbed wires. So, the pinpoint tests (continuity/short tests) in the Workshop manual may make sense here. That would rule out/in wiring issues and would probably take less time than you've taken thus far diagnosing this.

Good luck with it, and Merry Christmas.

 

You started with P0174 code only with the ltft pegd at 19.5 on bank 2..You report bank 1 ltft seams to be normal.
Your concern was you may have damaged an o2 sensor or wiring on bank 2.
The swap of sensors behind the tb (bank 1 to bank 2 and bank 2 to bank 1) is a way of getting conformation that you have or dont have a bad o2 sensor, with or with out having o2 sensor codes, If the o2 sensors are causing the p0174 ltft 19.5 this would move from bank 2 over to bank 1, yes it will take a littel time for the fuel trim to adjust and a hard reset would make this adjustment faster but will also clear all on board diagnostic settings and could be problematic when getting car registration inspection.

I use obd fusion and it took some time to get the correct setting to read the sensor 1 data...
I had to look through the pid's and select the correct one, then i could see all data for the 02 sensors

The pid that worked for my upstream sensor read..
O2 SENSOR LAMBDA WIDE RANGE (CURRENT PROBE) (BANK 1 SENSOR 1)
O2 SENSOR LAMBDA WIDE RANGE (CURRENT PROBE) (BANK 2 SENSOR 1)
and i set the number of decimals at 2

I would spend a bit time to get the torque pro reading the sensors correctly
Hopefully you had the correct sensors in the correct plugs behind the TB at the very start of all this..

Good luck and happy xmas

 

Happy Holidays... Thanks for the posts...! Really

The MAF is reading 5.2 at idle in P.
Around 5.9 - 6.1 in D...
Both at idle.
Which I think is dead on? Yes?

The previous screen shots, with all the misfire codes, are right AFTER swapping all of the O2 sensor plugs, all LH to RH and, all RH to LH. Started. Car didn't like that AT ALL. Popped all those codes. I didn't KNOW about doing a hard reset before running the car after swapping the sensors. I assume thats why the car started and ran as it did,,,, ton of misfires and codes. From what I could see, and it took a while of rough running and clearing TDCs being set off, it seemed like the problem followed the sensors to the RH bank. High numbers in trims on the RH with lower numbers on the LH.

The day I swapped the O2 plugs I also did a smoke test and found only one source of smoke. Fuel injector seal. Replaced seals. Also replaced the main intake seals around all 8 intake ports and checked everywhere else. No more smoke. I DO get a little bit of a change in idle IF I take some carb cleaner and spray it around the LH front of the plastic of the intake at idle. Don't know why. But I didn't get any smoke there. I do have a second plastic intake house (and throttle body),,, but I would rather avoid that swap if possible.

After, I put all plugs back to "normal" did the hard reset, started it up, and, for a while, this were going well. I think the ECU was having a hard time keeping up with proper fueling and making adjustments though. Trimming. After driving quite a bit the night before last, trims on the LH bank becoming increasingly high positive numbers on OBD.

With ZERO volts on a sensor. What I'm trying to pin down.

In this last post, I was messing around with the OBD,,, scrolling down the list of "active" sensors. I had just driven about 20miles, mostly highway, and the car increasingly began running worse and worse. CEL and restricted performance by the end of it. System LEAN Bank 2... Trims 25% stft, 19.5% LTFT... Pretty much pinned.

Looking through the list of "active" sensors I found ZERO volts on one of the sensors (see above)... That, while the corresponding sensor on the other side is producing the wave in the graph you can see.

ZERO volts. I understand the upstream sensors work in amps?

I didn't find a LIVE reading similar to the one above for the Bank 2 sensor 1 anywhere.

Can I trust that this reading (zero volts) is the bank 2 down stream sensor? That this sensor is dead despite no codes? Should this be the sensor I need to aim at changing? I'm not a rich man and don't want to be changing the wrong sensors (there is a price difference between up and down denso sensors) AND it's not an easy job to do in the first place.

And yes, when swapping the engine, for the downstream sensors, despite taking my time and being careful there was little I could do to stop the end tips of the sensors from coming into contact with and scrapping the side of the transmission on engine pull and engine place. Thought I may have gotten away easy,,, but it seems I may have not.

Thanks for all the help.

Also, if it IS my problem, is it possible to get to these sensors on the 2002 thru the fire wall, where the HVAC drain ports are, as Mertz mentioned? Or, am I not that lucky?

 

Yes. The ECU, sensors and trims were within thresholds before the engine swap. I was driving the car. No faults. Though MPG was low and the engine seemed tired with 215k miles. No codes related to O2 sensors and lean or rich. Sensors were probably on there last legs with the ol engine. And, the ECU was probably used to the messy sensors. I think (once everything is sorted) the 37k miles engine will introduce the ECU to efficiency that it's not used to. I did hard reset the systems but maybe the ECU is shocked and confused by new numbers, lol

Honestly, even though this set of problems has gotten me in a funk and frustrated (only because living in NYC and having a bad inspection sticker, which results in me NOT being able to renew the registration, can cost me $130 a day in tickets), I am VERY pleased at how how successful I was at swapping the engine... If one code is all I am getting after, I have to see that as a success. I've NEVER done anything like swapping an engine in an ol jaguar XK8 before. And, btw, the 2000 S Type engine swap went very well too. SType is up and running. No faults.