2001 S-type 3.0
Initially trim was on negative 10 and now it has suddenly jumped to negative 50
I’m thinking it’s probably ECU that needs reprogramming and/ or clogged up VVTs (after engine got flooded ((dark oil)a few months ago)

I heard there were improvised steps to solve the problem …

Thanks in advance

 

Extremely unlikely. But check the TSBs etc / use Search.

Heard? Where? If Search won't find it, then forget it.

 

I used to do this regularly at the dealer 'back-in-the-day.

 

Great !
they want $150+ to reprogram it
Is there a way to waive those charges due to ‘recall’ or smth ?

 

Those two codes are fairly common with the early V6 engines. I've had them several times on my '02 V6 (approx 350k miles).

Are you in a time crunch, and have to get them cleared right away for an emissions test? That could be a bit of a problem, as it often takes a little time to clear the condition.

Two theories, both related to oil viscosity and how it affects VVT operation. Some have reported good results switching to a thinner viscosity. With higher mileage, thicker viscosity seems to work better. This thread should explain what you need to know:

https://www.jaguarforums.com/forum/s...bad-vvt-68687/


FWIW, I run fairly thick 10W-40 in my car. When I put off an oil change for too long (guilty as charged), the viscosity tends to break down and the first sign is one of these codes. A fresh oil change has always taken care of it for me.

If unsure whether you should try thinner or thicker oil, don't worry too much. It's not a permanent decision. Try one or the other and see what happens. But if dealing with a high mileage engine, thicker seems to work better.

 

Awesome !
I’m on it >

 

It's hard to imagine any required reflash hasn't been done by now!!

 

I wholeheartedly disagree. I’m imagining it right now. It’s not hard to do at all. While I’m busy imagining things, I’ve also imagined a world at peace, an end to hunger, and no more pollution.

Has the subject car actually been reflashed already? Probably, but who knows. But to actually imagine it one way or the other? Not hard at all. Oh look, a unicorn!...

 

Lol
y’all a funny bunch 🤔

 

Eh ?

 

 

I doubt 5W20 is right!!

Something is drastically wrong to cause those trims (*). Any other (engine-related) work done on the car?

(*) pretty sure they're the worst ever posted on the forum, by a long way, however I can't see it being the 5w20 oil

 

Dear sir , no comment on that …

 

Yeah, I was scratching my head over that one. Any other codes besides P1383 and P1388?

A vacuum leak causes high fuel trims, but they’ve gone the opposite direction. What does your scanner show for fuel pressure? If normal, verify with a mechanical gauge. My guess is the actual pressure is high due to a bad sensor. It’s easy to check on an early V6. There’s a test port (looks like a tire valve) near the front of the injector rail.

 

 

Please disregard P0125 (bypassed the thermostat a few years ago , takes a little longer to warm up and that’s all)

 

Oh and I’ve recently installed a brand new fuel pump and strainers from eBay , and it’s raised the trim from -30 to -50 🤔

 

Start by thinking how the amount of fuel is initially chosen. Trims are to tweak it (thus the name trims).

Basically it's the air coming in i.e. MAF value (which is checked against TPS and anything else for sanity) and tweaked a little using various sensors.

So, the PCM now has an estimate for the fuel wanted. (The MAF better be about right!)

It expects to add the fuel using injector pulses, so the injectors better work pretty accurately AND the pump better also AND the measurement of fuel pressure could do with being right.

You can get ideas from OnBoardDiagnostics.com - Engine Basics and many other places.

Something is WILDLY wrong on the car. Never seen an S-Type like it.

(Maybe disconnect the MAF and see what the trims do?)

 

My initial response:



My next thought was to look for my eleven-foot pole, as there's no way I'd touch this with a ten-footer.

Sorry, but your car is a mess, judging by all those codes. Some important, probably the primary source(s) of trouble. Most of the others are secondary codes, basically a normal response to certain uncorrected problems. What's primary and what is secondary? Hard to determine with any certainty, you just have to dig deeper.

Before putting on my miner's gear and/or drinking heavily, how in the world did you "bypass the thermostat"? Did you simply remove it? If so, your poor engine is going to be VERY unhappy. The S-Type thermostat is not a basic on/off device as on older vehicles. It's more of an either/or shuttle valve. Way more than you ever wanted to know here, including a pretty picture and technical details ad nauseum. See post #41;

https://www.jaguarforums.com/forum/s...3/#post1693028

In a nutshell, if you indeed removed the thermostat, the cooling system will essentially bypass the radiator at all times, with only minimal cooling. Now that I think about it, I'm not sure I want to know what you did. I would highly suggest putting the system back to normal and correct whatever fault was present (and likely still active) that caused you to "bypass the thermostat".

Once that is corrected, work on whatever faults remain. I highly suspect many of the faults currently active are caused by improper operating temperature. The poor computer can only respond the way it is programmed. It has no idea you've jury-rigged an important part of the overall engine control system.

You may as well pour yourself some coffee and slog through this for more details on the thermostat and temp sensor:

https://www.jaguarforums.com/forum/s...rature-186873/

On the early V6 models, the temp gauge is NOT reading coolant, but the metal of the left (US driver's side) cylinder head. The needle is also deliberately misleading, and will park in the center position during the normal range from about 180-230F. The early V6 models also have a very slick system to prevent engine damage in case of an overheat, alternately cycling cylinders on an off to allow you to reach safety at reduced power even if all coolant was lost. You don't want to cripple this important feature by jury-rigging the cooling system. And don't just slap a new thermostat in there and hope for the best. Read the link above for my tale of woe with thermostats bad right out of the box. Take a few minutes to test one before installation. The QC on thermostats available (OEM, aftermarket, doesn't matter) is pretty poor. Test first to save yourself some grief.

Sorry if I seem harsh, but these engines are super reliable in stock trim. I've got over 350K miles on my '02 V6, and it still purrs like a kitten with minimal upkeep. You start throwing a wrench in the works by disabling and bypassing stuff and who knows what will happen. Oh, wait, we do know. You end up with faults galore, smoked catalytic converters, etc...

 

You sure that's all? No more surprises? I'm not seeing the P13888 you mentioned earlier? Is that on the next page?

In my previous rant, I mentioned how some codes are the primary faults, and others are secondary or normal responses to a primary fault.

For example. codes P0420 and P0430 are what you can expect to see when catalytic converters are damaged by running too long with an overly rich fuel mixture. You may have cooked all nine lives out of those cats.

Same with P0172 and P0175. That's just saying both banks are running too rich, as you already know. These two codes don't really isolate the root cause. It's just the computer's way of saying, "I'm trying to trim back this rich fuel mixture but I can't go any further."

Not entirely sure about P1383 and P1388 for the valve timing, but I also suspect that is a normal reaction to an excessively rich fuel mixture. Don't quote me on that, maybe you really do have a problem with valve timing. It's what you had initially mentioned, but maybe put that on the back burner and clear up the known bad stuff first.

The bad stuff. likely the primary faults: P0125 and P1121.

Now when I say "bad stuff", I don't mean insurmountable faults and your only recourse is to set the car on fire, report it stolen, and collect the insurance money. I just mean faults you shouldn't ignore. These may be very easy to correct, and at least some of the others will then come into line.

Official Jaguar OBD definitions are here:

http://www.jagrepair.com/images/Auto...os/PE20001.PDF

Don't rely on the definitions provided by any scan tool, as some are not accurate for Jaguar. Always search by the 5-digit code and get the official scoop.

P0125: CHT Sensor response insufficient for closed loop fuel metering control

Note my overuse of cute little emojis to get your attention! Oy vey, this code is a biggun, as Al Bundy would say. Now I'm not 100% sure how the computer responds to such an input fault. I do not know if the engine stays in open loop (think rich fuel mixture ) or if a stored value is used as a backup. But either way, this fault is YUGE! Fix your poor cooling system and make the computer happy. We don't even know if this is an actual temperature problem or indication only. Maybe both, who knows? Don't make the poor computer work with one hand tied behind its back.

P1121: TP Sensor signals inconsistent with MAF Sensor signals

Hmm, as previously suggested, this could be a fault with the MAF. Per the OBD guide linked above, this could be a problem with either the TPS or MAF. How to know? Not really sure, but I'd go with a basic tenet of troubleshooting: Fix the known faults first (P0125) and see if this one clears up. For all we know, it could caused by the poor computer trimming back fuel so much that it can't make any sense of it, and so suspects the MAF or TPS values are inaccurate. They could be perfectly fine, so don't just throw a part at it.

Look through that guide again for the possible causes of codes P0172 and P0175. Two of the possibilities:

• Fuel pressure sensor failure (high fuel pressure)
• PCM receiving incorrect signal from one or more of the following components: ECT or CHT Sensor, MAF Sensor, IAT Sensor, IP Sensor, EFT Sensor, TP Sensor(s), TACM

So in addition to fixing P0125, get a mechanical gauge on the injector rail. Make sure the actual pressure agrees with what your scanner says. If the fuel pressure sensor is inaccurate, the pump will be commanded to put out the desired pressure, with no way of knowing the pressure is actually way off, possibly high in your case.

Then note the second possibility above, of the computer receiving inaccurate values from the long laundry list of sensors. Hmm, we already know the cooling system is jury-rigged and throwing code P0125 for a CHT sensor value problem: