I REALLY want to get my 2003 XJR fixed and not show CEL codes! I finally got the after-market fuel pressure regulator installed but after about 40 miles of driving it threw these codes:
P0400 and B1121.
The P0400 seems to be something related to the ERG valve. I found an electrical troubleshooting guide that shows various voltages and resistance across certain pins to test it. Looking at the device and the rest of the parts around the valve, not sure how I could even get in there with a meter to get a reading. Besides the possibility of an electrical problem, perhaps the problem my be something like a blockage it the line? In any case, it is very cramped in that area.
Is the B1121 a pedal positioner sensor problem? I have an extra PPS connector that I could solder in if so but the P0400 is a bit more nebulous and problematic in my opinion. Any of you XJR guys seen these codes and can let me in on what it takes to overcome them? I cannot get a license tag until I clear these codes!

 

It can easily be sticking egr valve itself. Or block in the egr feed pipe, or the intake elbow hole for the egr valve is blocked. It is a bit hassle to remove egr valve and the pipe. But it can be done. Just replace new seals in the same time. p0400 is wrong egr flow. I assume that you have Aj27. As it is 4 coil steppermotor you can measure the four coils of it. But most likely they are ok and the valve is stuck and or it's gearing is broken because sticking valve.

 

Thanks a bunch Vauxi! I will do that this weekend unless something takes priority! Best, D

 

With a ELM - 327 live data reader you can see the error between the EGR command from the ECU and the EGR valve position Sensor

This is Parameter ID ...........EGR _ Error

The target value is 0 % through all engine ranges

You can put a meter on the position sensor return wire back to the ECU and get a at idle closed valve meter voltage value

Do you have the AJ27 or AJ28 engine ?

puting a meter on the stepper motor windings can be iffy to see a fault unless the EGR is heated up and tapping on the stepper motor but the windings are like this pic

so there are 9 meter probe combinations for the 4 pins and your looking for a open leg as a fault

 

Some members solved that by looking into the supercharger bypass Actuator valve.
However, you say you replaced that in your first post.

 

Hello Vauxi, Parker, and Randy S,

I did manage to get the EGR valve off the car and the tube to the exhaust does not seem to be blocked. Thanks for the marvelous schematic and trouble shooting information Parker though I cannot figure out how move the motor without power. Or perhaps there is way to get a correct reading in the position it's currently in?
I did not change the bypass Actuator valve but it seems like there's a bit of an adjustment that can be done though I'm not at all certain how to set it in the correct position or if by fooling with it the code may clear.
I have EGR valve apart up to this point, (see pix below) It does not turn but perhaps it will only move under electrical power. Also, I cannot remove the lower section / part because of the little button / valve that allows exhaust gas into the intake manifold and I don't want to break it off by forcing it. The section that has the water hoses is loose from the motor body but I cannot remove it entirely.
Is there a way to remove little end part without breaking the unit and look inside the motor? If so, what should I be able to observe or repair if I do get it apart? Not sure what my next step is on this..

Thanks guys! Someday I will have this car running without CEL lights and can get a license tag!


Valve disassembled. (to a point)

ERG valve disassembled.

 

I gave you some wrong information as you do not have a position sensor on the EGR to verify the correct position either by the EGR _ Error % or a basic meter reading on a sensor wire

But you do have 2 power source wires on the EGR as the 2 green wires and 4 yellow wires as the 4 wire stepper motor

Looking up the power wires as fuses may be involved

as long as the poppet seat is clean on the EGR valve so it can seal is probably the best cleaning you can do

 

Fuse # 10 / 10 amp engine management fuse box is the only fuse for both green wire power sources to the EGR

 

Checked the fuse though it's a 5A fuse instead of the 10A. Also on a better note, I went to the junk yard this afternoon and got one from a 2006 XJ8. Same part number and looks exactly the same. We'll see if that clears the code.....

 

EGR valve is installed and I drove the car about ten miles with no codes at this point so I'll report back when I get about 100 miles on it and can pass inspection.
Thanks a bunch guys!

 

Drove the car about 50 miles and got the P0300, P0301, P0302, etc. including the dreaded P1316. The P0400 is gone but I still need to figure out these other codes. They were some of the code's that came with the car including the knock sensors. Replaced them and figured that would clear these other codes. I did replace the fuel pressure regulator and set it a 40lbs. The engine runs smoothly without missing or hesitating in any way. Not sure where to check at this point. Will continue to fool with it though...Any new advice is appreciated. Getting a bit discouraged with this car. Had it over six months and can't get it to stop the CEL codes....
Best, D

 

40 PSI the correct fuel pressure ?

Do you pick up the codes only at idle where the injector pulse width is shortest ?

 

Parker, that was a great win by the Chiefs on Sunday !!! I'm a Chargers fan but root for the AFC West Team(s) in the playoffs. Maybe one of these years the Chargers will join the rest of the division and win an SB ... LOL

Back to the subject, I'm running my adjustable FPR at 41. I have a the Eurotoys larger lower pulley, the Mina Gallery intake, and Nameless 200-cell cats, and it does fine. I initially set the FPR to 39, but that seemed to cause a little bit of a rough idle, so I bumped it up and the idle smoothed out. Engines without any mods probably should stick to the 39.

I also had a P0400 code last week after a Costco run of 30 miles. I put in a new EGR valve a year-and-a-half ago, and also had to have the connector pipe welded because it had a crack. So, Dave, check that pipe; I didn't notice the crack until I was putting everything back together. My ultimate goal would be to remove the EGR, but that's going to have to wait until winter is over.

 

Hello, The code popped up while driving but not going fast. It happened after about 50 miles which is about the about the same mileage as with the original pressure regulator. No P0400 code so I hope that's behind me now.
I set the pressure at 40PSI when the car was idling and the vacuum hose was attached; perhaps I could lower it a bit and see if that helps. The car has a completely stock engine and runs very smoothly so I'm not sure why it gives me the misfire codes. If it is misfiring it's unnoticeable to me.
It may be a few days until I report back...I'll be driving J2 unless my wife needs it. Next weekend I plan to replace the rear end on J3 so I'll have my car back on the road.
Thanks again for the kind advice.
BTW: that was a great game! Not a huge football fan but was kinda hoping the Chiefs would win. I'm really a baseball guy, As a radio sports reporter once said; "The four most beautiful words in sports, Pitchers and Catchers report!" Tomorrow is the actual day for most teams but it means Spring is not far away...

 

The fact that the misfire codes are on one bank and not both points to a bad knock sensor as there is history on them with your V8 model

if you were under fueling it would be on both sides effected by an underling issue

there is a specific fuel injector power source relay, and you might have a compromised splice as it branches out to left and right banks

all your injectors have raw B+ power " sitting " on them and the ECM provides a timed individual ground to open

swapping knock sensors would be a cheap try but easier said then done

 

Replacing the knock sensor is inexpensive and easy.

 

That is interesting advice about the relay, Did not think about looking into that! Just to let you know, I get the P0300, P0301, P0302, P0303, P0304, P0305 and all cylinders up to P0308 then the P1316. But your explanation of the operation is enlightening. I do wonder what is telling the EU that it has random misfires? The knock sensors? Seems it would also throw the knock sensor codes if so but I may certainty be wrong.
When you mentioned "under fueling", are you thinking there may not be enough fuel pressure? I'd be happy to adjust it up or down to get this resolved!
There is a little flap valve in the supercharger manifold that I don't actually know what it does. What is it and is there any chance this is not adjusted correctly and may be the cause this problem? When I bough the car it had all the above codes plus the knock sensor code. I measured the knock sensors with a meter and one was extremally high resistance. Much more that the usual (I think) 2m ohms. The other was what I'd expect having changed a few on my other cars.
I will look into that relay and perhaps it may be the trouble? Wouldn't that be great!
In the mean time, I only have six bolts holding the rear end in my red VDP (J3) and hope to finish the swap this weekend...

 

Which engine do you have ?

AJ27R ?

see page 59

AJ27_EMS_OBDII.pdf

 

see also page 18 of the pdf

 

see page 67 of this AJ27 Doc, 43.5 PSI

Does not mention fuel pressure after the FPR on page 65 functional diagram.

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