I believe that with some ECMs knock sensors can cause the fuel trims to alter as well as retarding the timing but, as Plums said, the result would be to richen the mix not weaken it.

I don't see how things like the TPS/MAFS could affect one bank only.

The only sensor in closed loop that could make the ECM think one bank is rich is the O2 sensor and you've swapped these.
Question - have you checked on the relevant MCU pins that volts are getting there?
Have you checked at these pins that both O2 volts are the same when you get this problem ?
(I'm pretty sure you have but ....it is a long old thread.)

To try to understand what's happening can you say exactly what happens when starting from cold.

When the engine is first started the system goes into open loop operation.
The system remains in open-loop until the following three conditions are met:

Coolant temperature above 105°F.
Oxygen sensor has varying output voltage (indicating it is hot enough to operate properly).
A specific amount of time has elapsed.

so - do you get -ve STFT as soon as you start when the ECM is using fuel tables or is it only when the engine's warmed up and running closed loop?

 

Plums, Thanks for the ideas. When I installed the knock sensors, the thought did run through my head that the tightness of the bolt might make a sensitivity difference. I didn't have the PID specifications so I just "winged it." --- Perhaps this was not so good of an idea - because for the couple of days last month when the engine did seem to run well (after the fuel leak fix) I kept thinking I was hearing preignition pinging (mostly from the left side) at the onset of near full throttle acceleration. I may not have tightened one or both knock sensors enough.....

Just for the hell of it, tonight I may disconnect the new knock sensor's electrical lines and hook the old sensors back up (leaving them un-attached to the block) and gently test the car. I doubt that that will make a difference in how the car runs in closed loop mode - but it it will satisfy a curiosity.

When I find the exact tightening spec. I will have to REMOVE the #$%^&*^% supercharger and associated parts once again to re-torque them with accuracy !!!!!!

RE: Rebooting ECU and waiting while the TB and TPS sensor re-calibrate... Very good suggestion! I will do exactly that this evening - while I am reading the exact voltage the ECM is seeing via my Actron9185 scanner.

RE: Fuel.... I had the same train of thought on Sunday when I last drove the car. The tank was getting low on fuel and it had a dose of BK fuel injector cleaner in it (leftover from my attempts to establish that the fuel injectors are indeed clean.) I went to the gas station an put $50.00 worth of Uber-expensive pure (no alcohol) premium BP gasoline in it. Unfortunately, that made no difference in closed loop stumbling....


Steve, I have not traced those wires back to the ECU yet - I have to purchase a special "tamper-proof" torx driver set to remove the screw that holds the main harness connector to the ECU. I plan to procure those tools tonight.

Also, I will watch very carefully what the STFTs are when I start her up from cold - to ascertain that it is starting in open loop and then transitioning into closed loop. It heats up to 105 degrees pretty fast, so I will be sure to be alert from the very first of the start.

 

I did everything I said I would do in the last post - It's still broke

Checked more wiring points to the ECU harness than I could count - My eyes are crossed and my back hurts. They are all good.

I took the ECU apart for visual check - it looks clean and solid with no evidence of any burning or corrosion. In fact it looks brand new.

I did two hard resets of the ECU each time doing what Plums suggested (letting the TB and such reset before starting)

Steve: The Fuel trims were all at zero upon first start (like you and Plums expected) but engine was STILL missing badly from 1st crank. I let it idle for a moment and watched the scan tool. Within a minute the STFT bank 2 went from Zero straight down to -25%. When I revved the engine sharply STFT bank 2 would go to Zero and then back to -25%. It was missing like crazy.

I took ECU out and checked literally dozens of pins and put it back together and try the above procedure again: Same result.

Something MUST have taken a dump in the ECU !

Can a dearship re-flash the engine ecu? For less than a million bucks?

Anybody have a recommendation for after-market ECU repair?

 

I suppose the fact it runs badly when cold (open loop) pretty much rules out the 02 sensors.
Even so it would be worth checking that both O2 sensor voltages are getting to the ECM pins.
You say
When I revved the engine sharply STFT bank 2 would go to Zero and then back to -25%. It was missing like crazy.
was it missing when you revved up or only when you took your foot off?

These people
Dead or Faulty ECU? Here are a few ideas and solutions - Specialized ECU Repair
say they will test an ECM for $50 - worth calling + discussing the symptoms with them.

 

just to reverify, when the STFT is -25, the LTFT is also negative?

The torque spec for the knock sensors on a 2003 XKR is 20NM. But, the spec for a XJR same year is 31-40NM ... insert big shrug here. JTIS under "electronic engine controls".

Light bulb time .. did you perhaps get the O2 sensor connectors reversed? This can cause big problems because the ECM does not know any better. The sensors can be wired to either connector, but they have to stay that way. There is actually a place in the Jag dealer software to set which one is which. If you reversed them, then unreverse them since you do not have the special software. You will then need to do yet another reset. To zero the LTFT in tcam, you have to do what the jag tech help desk terms a "full hard" reset. Do the usual reset, then leave disconnected for 15 minutes.

 

Plums, about a century ago in this thread maxwdg said
I haven't pulled the valve cover and checked the valve timing because the car ran perfect for a couple of days just after the original fuel leak repair - so the assumption would be that the valve timing is still correct.

 

So who mentioned valve timing?

The only thing remotely possible would be the use of the acronym "TCAM" which was used to reference the persistent memory where the ECM stores its LTFT data. Nothing to do with valve timing at all. TCAM is not a reference to a camshaft or cam timing.

 

If he'd got the O2 sensors swapped it wouldn't have run to start with.

 

Steve, It runs bad (Miss Fires) from the instant it's started.

When the car is in the garage and running in PARK the only time it's not missing is when I SHARPLY whack the throttle and the TPS reading indicates that I opened the throttle more than... Let's say 50-60%. It revs up nicely and the STFT ad LTFT goes quickly to Zero but as soon as the engine hits 4000RPM the non-load rev limit function comes into play and I know not to push it any further, so I back off the throttle and the -25% STFT comes rushing back along with the miss firing at idle.

FWIW, the LONG term fuel trims on the last start up (after the computer had reset) were showing ZERO again... Zero LTFT Bank 2 as the engine tried to idle with the STFT Bank 2 pegged at -25% as usual.

Plums, Thank you for the torque spec on the knock sensors. And I understand the thinking, but I was mega mega mega careful to get the O2 sensors connected to the correct harness when I refitted them. Buy the way, on my 2003 the O2 sensor's plugs and sockets are color coded (grey and black) making misplacement unlikely....

In the what more could go wrong department: On the last start up test the small "Powerhouse" pulley started backing off (moving forward about 3/8 inch) on the supercharger input shaft!!!! This caused the belt to move forward and rub on the tensioner bracket, fraying the NEW goodyear Gatorback belt I installed with the small pulley only 3000 miles ago.

My theory: The missing causes a bit of a jiggling/clunking sound from the supercharger. When the engine is not missing, there is no clunking - only smooth Jaguar V8 yummmmm sounds. I think that the small crankshaft speed variations caused by any engine that is missing, slows the rotation down enough that when the next cylinder fires and pushes the crank, it "hits" harder than usual creating a mi-nute-but-abrupt acceleration of the crank... Which is no doubt transmitted to the supercharger pulley - causing the slight clunking from the shaft and/or impellers. That rattling or clunking could be acting somewhat like an impact wrench on the pulley - thus, in time, loosening it on the shaft. Does that sound plausable?

That pulley, made of stainless steel, as many of you know is only pushed on after heating it up - relying on cooling contraction to create an "interference fit" to stay in place... Same as the factory pulley. What a dumb idea. IMHO

I tried to use a 2x4 board and a hammer to lightly "tap" it back into place - but it wouldn't budge...NOW I get to try to heat the pulley up sufficiently to expand it enough that I can push it back on the shaft - all without getting the shaft so hot that it ruins the bearing seal !!!!

I have angered the Gods, I tell you.

 

Try logging the lambda voltage. This might tell you whether the sensors are any good at all. When all is golden and warmed up, it should read 1.0v. In the thread titles "Black plugs ..." posted by Pers, his sensors never got above .40v which is in the lean part of the curve and the ECM was pushing fuel in. He replaced the sensor and all was golden. Last post in the thread was this morning so you should be able to find it.

How about a good old fashioned plug reading?

 

It'll run ... just very badly. It would probably run with completely borked sensors, but the ECM will go into degraded mode or rely only on open loop.

Now, what about the supposed reference to valve timing?

 

The point is that it ran perfectly for two days before this happened.
If he'd crossed the O2 sensor leads it would have run badly from the start.

 

I think the C-4 option is gaining ground here.
I'm probably telling you something you know already but the safest way of doing this is to heat a lump of metal up as hot as you can get it and apply it to the front face of the pulley. That way you'll be transferring heat into the pulley where it's needed. Obviously a quick quench as soon as you get it back in place.

 

The IDS can log some more data, that may help in diagnosing the issue.

 

That was a long time ago. After searching the *other* thread, the timeline was:

Followed by one return trip to work where it did not act up.

Have you figured out why you thought a suggestion was made about valve timing in your post at #46?

 

Plums
Post #29 in this thread
AVOS, I have thought about cam timing but put that out of mind when the car ran so well for those few days... You have reminded me to check that sensor and it's wiring for possible problems. That IS the pigtail harness that goes into the back of the valve covers or heads, correct?
I'm not concerned about timing, just pointing out that it worked to start with so he must have put it back together correctly.

 

OK, after dumping the radiator and pulling the fans AGAIN (Blahhhh) I got the pulley back in place last night. I heated the stainless pulley for about 30 sec with my OxyAcety torch and pushed it right back flush with the S/C shaft then blew air on it to cool it quickly. I then got an allen head stainless 8mm x 1.25 bolt, turned a washer to the exact size of the front of the pulley out of some 1/16 stainless sheet, used a drop of permatex red and bolted that pulley to the shaft. It better not come off now, Yo!

After re-assembly, I hooked the ECU back up to the mega-point harness, connected the battery, let the TB do it's buzzing and whirring thing and fired it up. I was monitoring it's every sensor with the scanner. It started in open loop and wasn't missing for about 30 seconds. I watched the O2 lambda voltage start to go up. Around 30 sec it went into closed loop and started miss firing (as usual) with the STFT Bank2 moving quickly to -25%. The LTFTs were both at Zero.

I revved it a couple of times and watched it go briefly into open loop, but as it returned to idle, it went back to closed loop, mis-firing and -25% on bank2 stft. It threw the CEL as usual - Nothing new there.

Then something unexpected happened - I revved it to about 2800 rpm and held it for a few moments and while I watched the O2 sensors voltage go up to about .75 to .80 volts (still in closed loop) when I noticed that it was running real smooth. I let off the throttle and to my complete surprise, it idled smooooooth! It went into closed loop and all the fuel trims hovered around Zero while the engine played like a jag is supposed to run - nice and docile. I revved it to 3 - 4000 rpm a few times and marveled how it would go into open loop for a moment and then settle right back down. The Lambda on both sensors would run up to about .7+ volts when it was held at a decent rpm and then drop down to .1v when it would idle.

Still running fantastic, I let the engine come up to full operational temp (about 200 degrees) and then shut it down to check the codes and erase the CEL.

I read the usual (as of lately) codes of p302,304,306,308 and 1314 and I was excited to start it up again.

Well, that was the end of my fun... When I started it back up, it immediately
started miss-firing, bucking and threw the CEL. I attempted to re-create the same result as I had in the last test-run, so I held it at 2800 rpm for a few seconds and it went into Restricted Performance! That was the first time I had seen that warning when the car was not under load.....

The STFT bank 2 was at -25% as usual for this condition, but I noticed that the LONG Term Fuel Trim Bank 2 was now hovering around -14% and slowly rising. I watched the O2 voltages and they would rise and fall with the rpm but I did see that the bank2 Lambda seemed to go a bit higher than bank 1 did. I got out of the driver's seat and walked over to the ECU that was resting on the right fender and pushed and wiggled a few wires around at the connector trying to get it to suddenly smooth out - but Nope! Not gonna happen today. It was just gonna continue to run bad, period....

It was 3:00am - so I shut the engine off, disconnected the battery and walked, head down, out of my "little shop of horrors."

Anybody see any trends here? I was happy to have it run decently for a few minutes but now I'm worried that an intermittent problem will be EVEN harder to find.

At this writing It's 2pm on Saturday - and Plums, I'm going to do a plug reading first thing before I do anything else today.

 

You mention a "mega-point" harness. Is this the connector at the ECU?

If so, perhaps the fresh reconnection operation plus the revving at 2800 rpm temporarily made all the right connections and the car got happy. But, on the second try, something had disconnected again. The problem has been seen on other bulk connectors on the car where it is is difficult to maintain that many connections because they are all in the same physical block. You might be able to feel for it by reconnecting again if you have a great deal of experience with these connectors. The real test is to back probe the connections with a DVM while the connectors are mated. The tests and expected values should be in JTIS under the diagnostics section of the "electronic engine controls" section. You could probably limit your tests to those that affect the fueling on the problem bank.

BTW, the response curve on the sensors is higher voltage=richer, lower voltage=leaner.

Going to open loop under heavy throttle is expected behaviour.

After reading your post for the umpteenth time ... your ECU is resting on the fender ... try clipping a jumper wire between the ECU case and a chassis ground in case that is a required ground path. The top bolt heads of the shock tower are usually pretty good. Make sure that it is a good ground point by measuring resistance between the chosen ground point and the top of the SC hat. If there is resistance, find another ground point candidate.

 

To be crystal clear, the point is that your correction addressed to me concerns an assertion that was never made by me in any of my posts in this thread.

 

As said, with the IDS you can measure more, and also more detailed, which definitely would help in diagnosing.

The O2 sensor needs to be hot to operate well, so if the heater wouldn't work, it would probably give bad results at idle, but better results at a higher RPM as the exhaust gases heat up the O2 sensor.

So might still be an area to focus on.