HI,
I just replaced the Catalytic Converters due to them being burned up or melted and in pieces. I am looking for the root cause of this and my OBD II diagnostics is telling me that the fuel pressure is 39 PSI or 275 kPa. Can anyone tell me what the pressure should be in this system? Thanks for reading.
Jim

 

Jim,

I've moved your question from Jaguar Forums Feedback & Suggestion Center to S-Type forum. Members here with the same model will be able to help.

The Feedback & Suggestion Center is for posts about the forum and not for tech questions.

Graham

 

There is no set fuel pressure. So it helps to understand the fuel pressure will change depending on what the engine is doing. Expect to see the pressure jump around as you rev the engine.

But 39 psi is in the range I would expect.

The cats getting damaged is usually do to driving around with too much fuel going thru the engine. Most likely with a check engine light on and flashing.

That's why the manufacturer's put the flashing in. To try and get people to stop driving it in that condition because additional damage is being done.

Have you changed the coils and plugs? All of them?

Is the car still mis-firing?
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If anything that may be low but ignore it for now and look at any codes then at fuel trims.

 

The reason I mentioned the fuel pressure is that I am not experiencing any codes but am getting high temps on the cats front to back. Inlet temps are around 2350 deg F and outlet is about 2700 F. Readings on the OBD are as follows.

RPM @ 1730 RPM @ 730
Load PCT% 32 43.1
ETC C 99 91
SHRTFT1 -3.1 0.8
LONGFT1 -1.6 0.0
SHRTFT2 3.1 -6.3
LONGFT2 -3.9 8.6
FRP 276 kPa 273
Spark adv 19.5 9.0
IAT C 5 4
MAF (g/s) 9.78 4.18
TP% 18.4 16.5
O2B1S1 .625 7.85
SHRTB1S1 -3.9 -1.6
O2B1S2 .425 .870
O2B2S1 .240 .415
SHRTFTB2S1 -3.1 -8.6
O2B2S2 .435 .395

 

WQell that didn't come out like I wanted. There was seperation between the collums when I put it in.

 

BTW I just purchased this Jaguar and the previous owner erased the codes prior to my purchase. When the light came on I purchased an OBD II and found the cat codes and no other listings. There have been no missfire codes presented either in my OBD or on the system from what I could tell. Previous owner did tell me he had replaced 3 of the coils along with the plugs recently.

 

They're clear enough, don't worry about that.

I hope someone with your engine or at least a 3.0 knows what typical values would be.

I see nothing too weird except bank 2 trims are a bit + and at revs go -

I wish I knew what sort of Load to expect for that engine. I take it those values are when parked?

When running CL, the PCM essentially trusts the MAF if it's not a daft value, adjusts a bit for IAT / ECT, sticks in fuel that ought to be roughly right, and tweaks it based on what the O2 sensors say.

Diagram: OnBoardDiagnostics.com - Engine Basics

I suppose the owner may have fixed whatever caused cats to crumble/block. Once blocked they tend to run hot as the gas can't get out soon enough. They also mess with trims a bit as nothing's really working as designed.

My sig has acronyms...

 

Thanks for the feedback so far folks but I am still seeking further inmformation about this. I drove the car last night and then this morning for the first time since replacing the cats. While replacing the cats I disconnected the battery so the codes have been reset. I had the check engine light come on again and its the cat code for bank 2. This O2B2S2 sensor is the one running low. My OBD II is not picking up any missfires and I have used starting fluid aound the intake manifold checking for vacuum leaks. Any thoughts as to what I need to look at next? I am wondering if the O2 sensor could be giving bad readings without throwing a code for this, is this possible?
Thanks,
Jim

 

Yes, it's possible. If it's low without apparent cause then ... well, swap it but maybe low is OK and it's the other that's wrong?

The O2 S2s are there to do final fuel trim and check cat function. When I had a car more like yours (without upstream widebands as my STR has) and graphed the O2s the S2s had long wavelength unlike the rapidly switching S1s. I guess your era car will be similar but it's a guess.

 

Looking at you figures

LTFT1 – 1.6 0.0
LTFT2 – 3.9 8.6

You say that you have no codes and the cats have been replaced? I assume the plugs and coil packs are ok! I would look at an exhaust leak or the purge valve.