Fuel Related Issue at Start Up

[rubbndubbn]

I had posted about this in another thread but thought I should make my own so I don't steal theirs.

I am having issues with fuel pressure at start up. I copy and pasted from the other thread the issues I have dealt with. I would love some advice on what to do next or look in to. I may just throw in the towel and take it to a shop as its my wife vehicle and she needs it back sooner rather than later. However if I can figure out the issue Id fix it. Just at this point in time I don't know the cause so I'm just throwing parts at it in hopes to fix it.

Its a long story so Ill do my best to keep it short...

Went out one day to start the LR4 and it started as it should idles at 1200 then downshift to about 800rpms and then starts to shutter and stalls out. Start it up again does the same sequence. 1200 rpms shifts down and stalls out. Always on the third start it starts again at 1200 and then shifts to 800 and idles out and I can drive the car as intended. However I get a CEL and performance reduced. I can drive about a mile or two and the performance reduced goes away. I can then turn the car off and back on and I have all my power back but still have the CEL.

Codes have ranged from

Fuel pressure at the rail low
Fuel pressure at the rail high
Misfire on all 8 cylinders
random misfire detected

I am unable to clear codes with GAP. It says clearing failed and all codes return.

I have replaced both sensors and no change. Actually when I replaced the upper fuel sensor I got more codes (misfire on all cylinders). I put the old sensor back in and only get a code for Fuel rail pressure high. On the GAP it says desired fuel rail pressure is 10,000kpa but Im usually sitting at about 15,000 kpa. Have also done the AC/Fuel pump relay switch with no change.

To add to this just yesterday my voltage was sitting at 15.0V (people on the LR3/4 Facebook groups think this isn't that high) which seems high for my car usually is 14.3-14.7V. Battery checks out good after sitting for 24 hours its got 12.26V

Any advice or lead I will pursue at this point in time because I'm giving myself the weekend to find the issue. If I come up empty, off to the shop it goes sadly.

Attached photos of above mentioned issues.

 

[Longtrail]

I learned the hard way never to rule out the battery on these things although I can't explain the stalling, here's the thread I started on this topic as an FYI:

P0232-24 (28) Fuel pump A - secondary circuit high - General signal failure - signal stays high

Hi Folks, following my recent Timing Chain endeavor, I'm getting the following code which returns immediately after it's been cleared: "P0232-24 (28) Fuel pump A - secondary circuit high - General signal failure - signal stays high" But unlike others, the truck runs absolutely fine, I've not...

www.landroverworld.org

 

[rubbndubbn]

I learned the hard way never to rule out the battery on these things although I can't explain the stalling, here's the thread I started on this topic as an FYI:

P0232-24 (28) Fuel pump A - secondary circuit high - General signal failure - signal stays high

Hi Folks, following my recent Timing Chain endeavor, I'm getting the following code which returns immediately after it's been cleared: "P0232-24 (28) Fuel pump A - secondary circuit high - General signal failure - signal stays high" But unlike others, the truck runs absolutely fine, I've not...

www.landroverworld.org

Headed out soon to have it checked. I’m guessing I’m due up for one. If that some how solved my problems I would be beyond ecstatic but I’m not very hopeful!

Battery checks out good.

 

[itsaguything]

12.26v is a battery at less than 30% capacity. It needs replacing.
Your generator is working overtime trying to keep up with demand and charge the battery fully, which it will never be able to do.

 

[gsxr]

12.26v is a battery at less than 30% capacity. It needs replacing.
Your generator is working overtime trying to keep up with demand and charge the battery fully, which it will never be able to do.

If measured at the battery, with the ignition off, this is correct - 12.26v is significantly undercharged.

 

[rubbndubbn]

12.26v is a battery at less than 30% capacity. It needs replacing.
Your generator is working overtime trying to keep up with demand and charge the battery fully, which it will never be able to do.

So this is what I found out. As mentioned I went out opened the door popped the hood check voltage and got 12.26.

The next day with the hood up and almost another 24 hours later I checked the battery and it was 12.64. This confused me so I then went and opened the drivers door which “woke up” the car and I retested the battery and it was sitting at 12.16 now. Also started the vehicle after that and it’s charging 15.01v at the battery so definitely 15v.

I ran to the auto parts store in the vehicle and had it tested and they said it was a healthy battery.

I put the battery on a trickle charger overnight. It’s telling me that it’s 100% charged as well. Im thinking my battery is not my issue.

I called a LR specialty shop some what local to me to see what the HPFP replacement would cost because I am leaning toward this is the issue though I have no way to prove that. They want $3000 for the replacement. Ouch!

 

[Longtrail]

Ouch... New battery at Costco was $170 but mine failed the test at the local AutoZone so it was a no brainer... Perhaps try a battery and return it if that's not the issue, it's a lot cheaper than $3K.

 

[rubbndubbn]

Well did some live value stuff this morning and I’m not 100% confident it’s my hpfp because they seem to be doing there job based on what I can see.

I did clear all the engine adaptations and was able to actually clear the engine codes for the first time in 3 weeks. Wasn’t able to go drive around yet but will see what it says when I can.

When I talk to the Land Rover shop the tech mentioned looking at my crankcase ventilation. Looked it over and didn’t see anything glaring but did go ahead and ordered two new PCV caps with seals as preventative maintenance since that’s an easy job and I’m sitting right at 100k miles on the truck.

 

[jlglr4]

If it’s your PVC, typically your fuel trims levels will be way high showing a lean condition. A lean condition can point to a fuel pump issue as well, but if you are not showing lean, I don’t think the problem is the PVC.

The fuel rail pressure looks way out of wack to me. 0 psi desired at 650 rpms, then the same 1450 psi desired at the next three rpm levels. And the actual rail pressure stays pretty similar at the first three rpms, and drops to 42.1 at the last. It should be increasing with increasing RPMs. I have some old readings, and looks like my rail pressure is at about 680 psi at idle (620rpm) and increases with RPMs to somewhere around 2800 psi at about 1500 rpm. Desired is always slightly different, but the two values follow each other pretty closely. Yours are not following each other at all.

The lp fuel pump duty cycles look high at 52% . I don’t have my own numbers to compare, but I think that’s pretty taxed out from what I recall. Still, I don’t think a failing LP pump would account for these strange fuel rail pressure sensor readings, and maybe the lp is just maxing out because of problems with the high pressure side.

You mention that both sensors were replaced - I assume you mean the low pressure sensor and the rail pressure sensor. That would have been my first guess. Could be a wiring issue someplace with those strange zero readings.

I think HPFP would be my next guess. As I understand it, the fuel pressure regulators are built into the pumps - I think it uses pulse width modulation signals from the ecm to determine how much fuel to deliver with each ****** of the pump. If the regulators are no longer working, the rail pressure will not be adjusting giving you sometimes more pressure than desired and other times less pressure than desired. Moreover, if the car can detect that it’s not able to control the regulators, maybe it’s defaulting to some kind of scheduled desired pressure. I don’t know - I’m guessing. Again - could be the wiring to the HPFPs rather than the pumps themselves.

I’d look around for evidence of rodents anywhere in the engine compartment - bit wires obviously, but also little food scraps, nut shells, ****. Also, if you had a sunroof drain problem that caused any flooding in the passenger side in the past, maybe some corrosion is creeping up.

 

[itsaguything]

@rubbndubbn . And battery capacity test is irrelevant unless, the battery is cold, and resting for a 6 hour period. (The very same process used at any reputable dealer) But glad to see following a complete charging it holds 12.6v after a 24 hour rest. Correct, your battery is good.
FWIW, an automotive battery can not ever maintain 15v. You are reading the charging voltage which is not the battery voltage.

Cheers!