Hello all,

I will start by saying I am somewhat new to forums and also new to being a "car guy" so go easy on me! This is a pretty lengthy story of a problem because I think I might have screwed something up at some point and idk when.

I purchased a 2003 Jaguar S-Type R(v8) with 145k miles and for the most part it drove fine. When I got it, the engine light was on and it had some error codes for misfiring cylinders(6 codes in all). It still drove fine except for if I tried to push it too hard, like passing someone on the highway. Then the dash would read "restricted performance" and the power would suffer. Also, it would take a good 10-15 seconds of turning over before starting. All other driving was fine. One day I decided to swap out all the spark plugs and ignition coils. The codes said that 4 or 5 cyclinders were misfiring and I always wanted to teach myself how to do it anyway. So I replaced ALL of the plugs and coils. I wiped the codes and drove a little bit but the engine light came back on. This time with less codes. I consider that a win. There was one code for a "random misfire" and then two codes. One for cylinder 6 and cylinder 7. Unfortunately, the condition remained the same. It would still enter "restricted performance" if I pushed it too hard at higher speeds. I was getting pretty tired of the excessive ignition time though so I thought I'd try solving that next. I had heard that it could be a problem with fuel pressure and one of the cheaper fuel things to do is get a new fuel filter. That takes us to today. I was able to swap out the old fuel filter, which looked to be original to the car. When I went to drive the car it STARTED with the "restricted performance" message on the dash. Just idling. When I put it in gear it struggles to go past 30mph. I have found that if I press the gas pedal hard it will max out revs at 1500rpm. There is a sweet spot though that I can barely press the gas pedal and it will build revs normally. I was curious about any new codes so I plugged in my code reader and to my astonishment ALL of the codes about misfiring cylinders were gone. Currently there are now only 2 codes. P0191(Fuel Rail Pressure Sensor Circuit Range/Performance Bank 1) and P1338(Fuel Pump drive circuit low/high voltage).

Is this because I changed the fuel filter? Now the car is practically undriveable. Should I put the old fuel filter back on? What happened to the misfire codes? I am so bumfuzzled about what to do.

TLDR: 2003 Jag S-Type R starts with "restricted performance" on and struggles to get up to 30mph. Codes are P0191 and P1338. Occurred immediately after replacing fuel filter.

Thanks for reading.

 

Maybe too easy, but did you put the filter the right way round?
It has an arrow on it to indicate flow direction from tank to engine.

 

Disconnect the battery for a half an hour or so to drain out all the electrical charge and clear the codes. Then start it back up and see if you have any check engine light or new codes. do you have any way to check your fuel trims or the outputs of your O2 sensors

 

Welcome to the forum.

For any fault codes, go here for the official Jaguar definitions and open the PDF for your model year:

JagRepair.com - Jaguar Repair Information Resource

You've got to be careful, as most scanners give generic code definitions that may lead you astray. Always go with the official Jaguar version.

For the two current codes (P0191 and P1338), that sounds like a fuel delivery problem. If you never had them before replacing the filter, I'd revisit the installation. Filters are cheap. I'd suggest getting a quality name brand filter and trying that. Perhaps your current filter failed and clogged itself internally. Who knows? I'd certainly be willing to gamble your time and money on a new filter before digging deeper elsewhere. Can't remember if the connectors are self-sealing, but if so, perhaps one is not fully seated and is restricting fuel flow?

Does your scanner read live data? Check the value for fuel pressure before starting the engine. I'm thinking you should see 55 PSI before engine start, as the pumps will run briefly to pressurize the injector rail when the ignition is first turned on. Don't quote me on the number for a supercharged engine, so maybe somebody else can confirm this. I think you should see 40 PSI at idle, but again am unsure about the number.

For your previous misfire codes: What brand coils did you install? We've had many tales of woe after the installation of Fling Dung eBay specials, or the white box house brand from the discount chains. For best results, you want to stick to a quality name brand such as Denso, NGK, Bosch, etc.

 

Forgot to ask:

Did you disconnect the battery at any point recently? That resets the computer back to factory defaults and would explain why the misfire codes disappeared, at least for now.

Once you get the current (fuel delivery?) issue resolved, and the car is somewhat driveable again, the misfire codes will probably return. Unless a particular cylinder shows a severe lack of power, the misfire codes require a little time before the computer will flag them. I think the logic is to avoid nuisance faults, so the computer wants a larger sample.

If the codes do return, you can try swapping the suspect coils with other positions and see if the fault follows. Then you'd know those coils were bad.

 

Thanks all for the responses,
I will try revisiting the fuel filter/checking live date/ and doing the battery disconnect thing.

Here's Hoping...

 

Okay, so I got back in there to double check the fuel filter installation. I've attached a picture of the old one and the new one, in case its the wrong filter all together. I installed the new one in the same orientation as the previous one. The wider side is on the left and the "flow" arrow points to the left when bracketed in place. No leakage. Car still limping :/ I've wiped the codes, but the same ones come back pretty quickly.

Thoughts?

 

Does the arrow on the new filter point in the correct direction towards the engine? We still don't know how the old one was installed? Unless you might have a picture?
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Do you have a scanner that can read live data? Or a basic code reader?

If the former, what is the reading for fuel pressure?

 

I've attached pictures of the old and new fuel filter mounted in place. The arrows point towards the engine. I've also attached a picture of the live data. I don't know what I'm looking at so I don't know if anything looks abnormal. Hope that helps.

 

Your second screenshot shows FRP (Fuel Rail Pressure) at 177 kPa at idle. Factory specs are 300 kPa at idle, and 500 kPa at wide open throttle.

Your reading shows the fuel pressure over 40% low. Next step is to figure out exactly why. I'd be interested what pressure you'd see if you try to rev the engine. I bet it drops even lower, if the supply can't keep up with demand. Can't say this is the entire problem, but it certainly needs some attention.

More troubleshooting details here in the factory service manual:

http://www.jagrepair.com/images/Auto...M-Workshop.pdf

Fuel pressure specs are on page 2435 of the PDF. Search for P0191 and P1338 for details on how to troubleshoot low fuel pressure.

 

Thanks for posting that manual. Seems like I could try replacing the fuel rail pressure sensor... Any one have any videos on that? I'm not entirely sure where it even is/how to get to it.

 

You are far more likely to have an actual low pressure condition, not a bad sensor.

This sensor provides feedback to control the pump operation. At idle, the computer adjusts the pump speed to put out the specified 300 kPa, but you're only getting about 60% of that.

If the sensor was out of whack, the computer would happily regulate the pump to this inaccurate value, but would think the actual pressure was correct. Instead, you're seeing a very low pressure reading. You're at a disadvantage as 2003+ models don't have a test port for a mechanical gauge. If it did, I highly suspect you'd see the actual pressure (low?) agrees with the scanner value (low).

Is the current filter the same one installed when this latest problem started? Kind of a long shot, but I wonder if it was bad from stock, with a partially clogged output. Rather than gamble on a sensor, I think another filter FROM ANOTHER SOURCE would be a much better option. If no improvement, then you've got a spare. Careful not to get another filter from the same vendor, in case of a bad batch. I do not care to discuss how I learned this...

 

When I had a bad fuel rail pressure regulator I was getting P0193. With your code and other symptoms I think it points to a weak fuel pump.
The sensor is so simple to change I don't think anyone needs a video?
It has 2 bolts and an electrical connector and one vacuum hose attached. It's at the rear of the engine on the driver side.
Have you looked?

Some cars have the Shrader test ports and my old 2005 S Type R did. I think they dropped this test port in 2006? If you car has one it will be at the rear of the engine on the passenger side with a tire valve setup to attach a fuel pressure gauge.
Again take a look at your car and report back what it has?
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i have an 06 str and really wish they would have left the test port. I imagine they just decided to trust the ecm reading or devised a real expensive way to access the fuel rail

 

I decided to double check all the fuses and relays just to be certain that they weren't the problem. I found one blown fuse. It seemed like a long shot that it was causing my low fuel pressure, but I figured no matter what it did, it shouldn't be blown and I should replace it. When I looked it up, to my astonishment it was fuse F47 "Rear Electronic Module, , fuel pump driver". That seemed fairly related to my problems. So... I put in a fresh fuse. I turned my car on and... the problem is worse! It use to just run in limp mode which sucked but, at least I could drive it to a mechanic when I give up. Now it turns over for a long time before starting and struggles to idle. It hovers around 250rpm-500rpm and spikes up occasionally to 1k and the whole car shakes.

I guess the only things left to rule out are a bad fuel rail pressure sensor or a bad fuel pump?... >.< Any way to do that?

 

Have you checked the new fuse? If the old one had blown, there's a good chance the new one did also.

You may not think so, but you are making progress. You found a fault directly related to the apparent fuel delivery problem.

On the supercharged model, were you aware you've got two electric fuel pumps? Maybe one is marginal and other keeps blowing fuses. Wiring diagrams here:

JagRepair.com - Jaguar Repair Information Resource

See figure 03.6. One pump is driven via the RECM. The second pump is driven by a dedicated Fuel Pump 2 Module, found only on supercharged models.

I know you're just itching to change the fuel pressure sensor, but please see my previous comments on it. It seems to be accurately reporting low fuel pressure. For whatever reason, the pumps and related plumbing cannot deliver the 300 kPa to which the computer would happily regulate the pump output. Even if the sensor was inaccurate, you'd still see the 300 kPa value if the fuel delivery system could keep up. Instead, it's falling well short of this goal.

 

I found this video. I think I'm going to give this a shot. Seems like a cheap enough thing so I won't be too heartbroken if it doesn't work.
Wish me luck!