Hi guys,

As below in my signature (Not sure if I set it up yet), this post is about a 2002 S-Type R with some rad mods (no engine mods, mostly lighting and visuals).

I'm starting to fear my engine (even though the engine only has 28.000 miles on it) is going to die from the consequences of overheating.
I've laid out most of the story, and engine related service below.
I expanded the story from a list of bullet points so some sentences/paragraphs may read a little weird.

So in summary: my engine has been running fuel trims, both STFT and LFTF around 140% for quite a while now, I've done some troubleshooting/servicing as laid out below but the problem still persists, and I'm starting to feel like the specialst is turning a blind eye to a problem they're aware of.

Previously serviced:
- new K&N air filter -/+ 4000 miles back. Replacing a regular filter, which went in -/+ 15.000 back
- long life plugs -/+ 12.500 miles back
- MAF -/+ 10.000 miles back
- Oil filter with new engine, so -/+ 8000 miles back.
- 2 refurbished cats, about -/+ 1000 miles before the previous engine died, so -/+ 9000 miles back.
- The throttle body has been cleaned 3 times soo far, with not too much buildup on the 3rd time.
- (brakes, almost the car's whole suspension, 2 wheel hubs, etc. and all that fun)
I have not serviced coils. I ran them all through the tap and freezer tests, measured the primary winding resistance, but they were all very similair and I don't feel like I'm getting any missfires.

My previous engine almost made it to 250.000 miles at which point it died from a failed 'connecting rod bearing' (the one between the crankshaft and piston/caps).
The bearing failed from too much back pressure, presumably from driving the car on 2 clogged cats for too long, but as I'm writing up this post I'm begining to think it might've had something to do with the horrible mixture..

A Jaguar specialist rebuild the new engine (which cost me an arm and 2, if not 3 legs) replacing all gaskets and (thank god) the supercharger 'valley' hose, said rebuild was -/+ 8.000 miles back.
Seeing as the trims were pretty bad already when I got the car back with the new engine, I tried spraying down the whole top of the engine down with lighter fluid, but I'd only get any response when I sprayed some straight into the intake duct.

Prior to the rebuild I remember the engine running at 120% on both STFT and LTFT, but take these values with a grain of salt as they're from memory and quite a while ago.

I also noticed when I accelerate anywhere to 3000rpm+, you can almost immediately smell 'warm metal' (definitely not a sulfur smell, which I DO get on every cold start though),
which by my theory, is the aluminum block rapidly heating from the lean mixture.

I Replaced the fuel filter, when I broke one of the connectors clips so I put a piece of 'regular' fuel hose to replace the connector.
When I had the previous filter out I tried blownig some air through it, which could be done with hardly any resistance.
After replacing the fuel filter I disconnected the battery to clear the ECU to check whether I made any progress at all.
After my 3 mile test drive (slow warmup -/+ 1500rpm, very short periods of hitting 3-4000rpm to make sure the hose wouldn't pop off under pressure) the LTFT on both banks had already risen to 136% with STFT both at 128%.
Sadly the trims are still abysmal...

My personal theory is the injectors need replacement, as they may have been in for soo long, they're hardly putting any fuel into the engine.
I can support this with my MPG, which has slow crept up from 18-20, to 23.5 although I do have very favourable traffic, mostly highway and hardly any traffic jams.
But the bad part about them, they're beneath the intake manifolds, whom's screws are beneath the supercharger..

I have an appointment with the Jaguar dealer on the 6th of October as I feel they're the only ones I can still trust (although my wallet might regret this at a later stage..)

So if anyone has any idea what I should check next, or what dumb stuff I plainly missed, or if I didn't supply some critical info, PLEASE let me know.

 

Additionally:
- Both O2 sensors are working as they should (have had to change bank 1 twice in a year though)
- I've previously replaced the black disc on top of the engine (can't for the life of me remember it's name)
- The new engine burnt through one of the refurbished cats last week. So the problem is bad enough to wreck a cat in 6 months.
the cat wasn't clogged and since it was put in, the O2s have behaved as they should.
- I ALWAYS run on premium fuel as the car starts misfiring on regular (even though it's supposed to be able to run on regular)

 

I don't see it being the injectors. Maybe one of them, but not very likely.

How (what tool etc) are you measuring those trims?

 

i think you’re reading the wrong PID

 

I'm using the iCarSoft LR II (v12.40), an OBD reader which can also communicate with the Jaguar (and LR) modules.
I selected the JAGUAR menu, choose the S-type 2002-2003, selected the engine controle module and read the data stream for the below values:
- Long Term Fuel Trim Bank 1: 150% (I guess it's not liking the fuel line 'mod', as it used to be a steady 139-140)
- Long Term Fuel Trim Bank 2: 148% ( ^ )
- Short Term Fuel Trim Bank 1: 128%
- Short Term Fuel Trim Bank 2: 128%
(although somewhat redundant)
- Short Term Fuel Trim Bank 1 Downstream: 127%
- Short Term Fuel Trim Bank 2 Downstream: 127%

I checked trims while idling, at standard driving (1200-1800rpm) speed and at high rpms to check for leaks.
Idle locks the trims in at 133 ST, standard driving slightly lowers and stabilizes ST at around 122, but high rpms hardly changed anything compared to standard.

When I select the MY '02 - '03 engine module I can't ready DTCs, but when I select the MY '03-'04 I have one shot at reading DTCs, which gave me the following 2 (permanent) engine module errors:
- P1582 (flight record data)
- B1582, although it's somewhat vague, it's either "Dim panel increase input circuit short to ground" which seems highly unlikely, or "Fuel Composition Sensor Circuit Malfunction"/"Glow Plug/Heater Circuit 'A' Malfunction".

 

can you take a photo of the scanner screen showing the trims just to make sure it is reading the correct data point i did not know the ecm could correct to such a high trim...just thinking out loud and not judging your diagnosis
...do you have access to another code reader to verify your data...a reader that can do obd2 generic will work...i have the icarsoft i930 and it has the obd2 feature that is not vehicle specific....if yours has that feature try using it...on mine it is listed as obd2 diagnosis....you can also read the actual o2 sensor outputs as milliamps...that is what the ecm is using for the trims.....negative amps = positve trim and vice-versa

 

I think the tool is making a mess of reporting the values, i.e. is wrong or at best very misleading.

 

There's more than one way to read fuel trims on an iCarSoft. I usually use an i930 & the first time I got readings like yours. Trying to remember but I think it's OBD>Data Stream & then scroll down & select the trims to view from the list. You can also select a graphic display & this will also give you maxima & minima.

 

OBDII Diagnose>Data Stream>Select Items

Scroll down & select LT & ST trims for both banks

Press ESC

 

Below I've posted two pictures, the first showing the result from the "Engine module", and the second with a test reading using OBD2.
As Jagv8 quickly pointed out, the tool IS either making a mess of the value, or presenting it in a very misleading way. (peak to peak, worst case or something?)
So atleast rhe trims aren't nearly as bad as I had previously thought. Although they're not perfect, they're doable, and I can look into the problem with peace of mind knowing it's not a ticking timebomb.



Fuel trims as measure by reading through the Jaguar ECU using an iCarsoft LR 2.


Fuel trims as measured by OBD2 using an iCarsoft LR 2.

 

not the worst trims in the world. smoke it up

sulfur and metal smell is probably from aftermarket cats

 

I think you need to check the PB vacuum connection on the SC intake elbow. This is a guaranteed failure due to a very poor design of the vacuum fitting.
I have a detailed thread outlining several ways to fix it and where it is.
Vacuum Leak from PB Vacuum Line

Might be worth a look as you have replaced just about everything.
.
.
.

 

good call. My trims on my 06 str always have a positive for longterm. I think the more you goose it contributes to that. I think smoke will reveal something small because the trims are not that bad as xalty states

 

Take a look at IAT1 and IAT2 temps. If those are in line I'm thinking an exhaust leak upstream of the 02 sensors or a vacuum leak.
btw, when IAT2 temps get too high you'll see both enrichment and a reduction of timing.

 

if you can add one more photo of the trims with vehicle fully warm and hold about 2500 rpm for about 15 to 30 seconds

 

I see yo mention a new MAF sensor.
Please tell me its a genuine Denso ?
Plus one on the vacuum elbow.terrible design work there !

or pcv pipe or connections.
also wise to check the evap canister .
these can fail also .
I have had wild trims from bad catalytic converters too .
you can monitor your fuel trims whilst spraying invert gas around all the vac connections.
Manifold charge cooler couplers ect .
The trims will jump all over the place when you find a leak..
also check your Digital obd2 and also physical fuel pressures . If your fuel pressure regulator has failed or lost its vacuum line you will always see wild fuel ltrum‘s.
and in my experience a failed fuel pressure sensor/regulator will lie to you via OBD2.
so best to back it up with a physical pressure test also from the Schrader valve.

 

Sorry for the 3(?) days absence, I tried spraying the brake booster connection with some carb cleaner but didn't get anything that noticeable on the trims combined with the fact that is was cold and late I decided to give it a rest until the dealer appointment.
So the dealer appointment was this morning, I practically gave them a paper saying "smoke test rear of engine please", and after 30 minutes they came back telling me the engine had been "heavily modified", and they couldn't work with it (LR 3 plenum (intake elbow to TB right?) and the Mina intake elbow), so all they did was reset the ECU which hadn't been done by the specialist whom put the engine in (presumably).

My god, look at ALL those modifications. I hardly recognise 'er

So I'll have to do the smoke test myself, which I'll try this evening using a propane torch and some left over fuel hose, mostly focusing on the brake booster connection.

Below are the LTFTs with a warmed up engine running a steady 2000rpm, which clearly shows a vacuum leak. (Did the test previously, STFTs didn't change that much IIRC, so didn't include them here)

LTFTs with the engine running at 2000 rpms, clearly showing a vacuum leak


The new MAF is an original Denso and I've got proof

An actual Denso MAF

I'm going to buy a fuel gauge this Friday to make sure the OBD reading (atleast somewhat) matches the gauge's fuel pressure, after that I'll report back (unless I find something noteworthy in the mean time)

 

I think you are on the right track. Those trims are a bit high but not too terrible. I do not know if you will find a small leak without actual smoke or something visibly broken or cracked. Keep at it you are close. One thing for sure is to take of the windshield cowl and crossbrace for extra viewing space. You can drive the car without the cowl if you want. The x brace is more of a mount than support and you can reattach the wiper arms also. I did this for a couple weeks when i was chasing a vac leak and a coolant leak near the firewall. You hear a lot more engine noise for sure and an extra is a nice supercharger whine

 

Last weekend I tried searching for the leak, with the crossbrace and windshield cowl removed, using propane but as @scottjh9 pointed out, I didn't find anything. this weekend I'll be going to a tuning garage which can do the smoke test for me.
(and I'll discuss mods/tuning and all with them of course)
The OBD fuel pressure closely matched the fuel gauge's pressure, so this seems fine aswell.

I think the ECU knows something, which it REALLY doesn't want me to know.
The car has driven for months without the MIL ever turning on, but since I've been diving into the trims using OBD (not the useless "150%" reading from the module), the MIL turns on every time I idle for more than 10-20 seconds.
So either I moved something while prodding around making it worse, or the car is trying to redirect my attention away from it's dark secret!

 

Is this new? I didn't see any previous mention of the MIL. What codes are present?