Intake does not need to come off, just the black metal brackets that hold the wireloom in place. The coolant lines (if it's that side) can just be pushed out of way to remove the rail. Each rail is mounted with two screws if i remember correctly, but the rails themself cannot be easily separated from eachother. You shouldn't need to either, just pull the complete rail you're after straight up so you can remove the injector from the rail.

I have no idea how to bleed the fuel system, maybe som info in the service manuals?

 

Thanks Anders for your input on removing the injector rail. I ordered injectors and working on how to release the fuel pressure.

My initial thought on releasing the pressure was to remove the rail with the injectors and cycle one of the injectors with a momentary switch to bleed it down, but I'm not sure the pressure would pop one off the rail before I could bleed it down. My other thought was to go through a starting sequence with the fuel pump disabled via a fuse or other.

Dave

 

 

Hi @boxercupdave ,

Good video above.

I might add one caution. I am not sure about this platform but on some cars (my Bentley CGT W12 was a hard learned example) the fuel pump is activated for a few seconds to pressurize the system when the driver's door is opened. So, if that is the case here, and if you're leaving battery connected, then I would suggest leaving the fuel pump relay out (unplugged) until AFTER all your work is completed.

On one repair I was doing on my CGT, a coolant tstat replacement which is located under the intake manifold, I had the manifold off and injectors out. I innocently opened the driver's door, not knowing, and showered the top of the engine with raw fuel as the system tried to pressurize.

On my DB11, V12, I can hear the fuel pumps activate when I use ign accessory position, but not sure about your MY.

Best,

 

Well today I started the process of trying to remove the injector rail or at least be able to more it up high enough to do an injector swap.

My V8 had the fuel pump relay as pictured in the same place as the V12, so pulled it and tried to start the car. This should have removed pressure from the rail. I will still be wearing safety glasses when I open up the rail in case.

I'm a bit stuck by two of the brackets. The bracket retaining the hoses that parallels the intake and is mounted by two nuts/studs to the valve cover and two bolts to the intake is free but I can't remove. There is another bracket that rests on top of it towards the rear, this is holding one leg of the bracket on one of the valve cover studs. I can't see how to free this rear bracket enough to allow the other bracket to move up and over the stud. I suppose I could try to lever the rear bracket but was trying to resist.

 

Today I was finally able to remove the bracket that hides the injector rail on bank two. The other bracket that sits above it on the valve cover stud is also held on by another stud and nut to the most rear of the valve cover, and a 10 mm bolt in the block just below the valve cover. I didn't remove the nut and bolt fully as I was sure I'd get them back in some backed them off to give enough flexibility in the bracket to raise it over the stud.

I will also need to source some of the clips/tie wraps that hold the looms in place as I had to cut them.

Dave

 

Dave I am really enjoying your journal. My sincere hope is your deep dive is to the issue. My luck is typically I get to my end goal and it is not the issue. But it appears you have been properly methodical. Keep up the good work and posts!! Rooting for you

 

I did get the bank 2 fuel rail pulled out the way enough to remove all injectors on that side. The most rear one was very tight and getting the clip back on tried my patience (had to step away a few times). All 4 injectors were replaced on this bank while I had the rail free, as the time doing it myself paid for the injectors and at 60k miles I think it was the thing to do.

Did this fix the problem? No I still have a miss at idle and I did clear the code but I'm sure it will return. I checked for misfires on both the new Thinktool and older Autel MaxiDiag and both show no misfires. With it idling a bit rough at idle I would have thought a misfire would have been counted on at least one cylinder. Getting a bit frustrated.

I was only able to work on it this week as we have a sick cat so stayed in town to take care of him. Soon I'll be back up to Arkansas to work on the house. At least up there my vehicles are basic and easy for me to work on. Just rebuilt the carbs for the Chevy K10 pickup and my old track day corvette. Timing light, Tach and a vacuum gauge is usually all I need.

Anyway I would like to figure the Aston fault out before giving up to the local dealer. Emissions inspection expires this month so wont be able to drive it until resolved.

Dave

 

What is the actual fuel pressure while running? Does it maintain fuel pressure after shutting down the engine?

 

Fuel pressure is 56 lbs when running. I will have to check run vs shut off pressure tomorrow as battery is too low (left glove box open the other day).

I only have only fuel pressure value to read on the scan tool as the other is always zero. I believe the V8 only has one common pressure value to check. Both banks run off fuel rails that are connected together and I didn't see each rail having it's own regulator.

Dave

 

Today the battery was back up to normal level so I was able to look at fuel pressure and observe as high as 73.49 psi when I turn the ignition on and averaging around 56 psi with engine running.

Can anyone confirm if the V8 has a single fuel rail regulator that regulates both banks? On my Thinktool scanner when performing a data stream report, I get Fuel System Status Bank 1 is 1 and Fuel System Status Bank 2 is 0. If only one shared fuel rail regulator I would assume this is correct.

Even though I tried spraying carb cleaner around the air intakes and vacuum hoses previously checking for leaks, yesterday I ordered a smoke machine to more thoroughly test for vacuum leaks. In the near future I'll look again for a leak if nothing else is found.

Dave

 

Got a chance to spend some more time on the car and my Autoline Pro smoke leak detector was delivered a few days ago. I order the leak detector with their kit that includes extra rubber cups for blocking off pipes and I'm glad I did. I found that two of the tapered cups fit the two inlets just after the filter and before the airflow sensor. The cups are different sizes but enough overlap in size worked great.

I connected up the smoke machine today and found no leaks on the intake track of bank 2 up to where they combine. I was about to turn it off when I did notice some smoke starting to come out of the bank 2 valve cover where the breather hose connects. This hose goes from the bank 2 valve cover around the front of the engine to the oil tank. The fitting on the valve cover seems to have a hex like it might unbolt. I'm not sure it the hoses come out of the fittings using quick release tools.

I know this needs to be addressed but I'm not sure how this would effect just bank 2. I often wonder if I'm not chasing two problems like a bad injector (replace all 4 on bank 2) and maybe a bad plug/coil.. The miss at idle reminds me of a plug not firing, but there are no misfires reported. I would also think a bad coil or plug would show up as rich, if an injector is still allowing fuel to pass.

Dave

 

so I do have some new data points using the new scan tool in real-time mode, however before I validate this data I'm worried the long term trim is not being cleared.
- Does anyone know how to clear V8 long term trims. I can't drive the car on the street so hoping it's not by miles driven.

Data without confirming the long term trim has been cleared:

• Bank 1 and Bank 2 cat temps are 920 to 980 degrees F
• From cold long term fuel trim bank 2 is 15 to 18%
• With car running and coming up to temp Bank 1 LTFT is -5.469% with Bank 2 LTFT 10.156% (captured during the warm up cycle)
• Sensor output voltage B1 S1 is going between .1 to .85 V and B2 S1 is .1 to .87 and both are cycling between these voltages at the same rate.
• Bank 1 STFT is going between .3 to -5% and Bank 2 STFT -7 to 5% so more offset and over a larger range.
• When I hit the throttle B1 LTFT seems to jump between 0 to -10% while Bank 2 LTFT 14 to 12% so little change on Bank 2 when warming up and hitting throttle

Once the car warms up fully (engine cooling fan comes on I see both LTFTs drift more negative. I assume this is just like a choke and the ECU is pulling fuel out.

• Over the same period I see Bank 1 LTFT go from -5 to -6.25% while Bank 2 LTFT goes from 10 to 2.344%. So Bank 2 comes down further than bank 1 but also the rate of change is greater.
• With B1 LTFT at -6.25% S1B1 voltage goes from 0 to .8 V and with B2 LTFT at 2.344% S1B2 also goes from 0 to .8V and both sensors seem to track each other.
• As the car continues warm B1 LTFT settles at about -7.031% with B2 LTFT drifting towards negative but stops around 1.5%. Going in the right direction but Bank 2 is still 8% higher.
• Also when arm and I hit the throttle B1 LTFT goes from -7 to around 0 % and B2 LTFT goes from1.5 to 12%

Anyone have some input on these values? I would like to reset LTFT and try taking the same readings again.

Dave

 

Hi Dave,

I did a quick read here and unable to elaborate right now, but let me answer the part about clearing fuel trims.

The quickest way to clear fuel trims is to disconnect the battery for a period of time. I cannot estimate how much on this system, but I can give you a sure way to get it done pretty quickly.

Disconnect the battery.
Take the positive cable (REMOVED FROM THE BATTERY) and ground it. You can do that grounding it to the chassis, or with BOTH cables removed from the battery, touch the positive and the negative cables together for about 3 minutes.

This will drain the latent capacitance from the system and essentially erase volatile memory.

Reconnect the battery now and LTFTs memory should be gone.

I've also reset FTs when I flash a new tune, but that's not an option for you here, I'm betting.

I will try to get back to you after I can spend some time absorbing what you've written. One Q for you - Do you have two MAFs or one?

I have rebalanced FTs on built engines I've tuned and there are a couple of options using the EMS data tables. One is to manipulate the MAF curve output, another is by manipulating injector data. Again, these might not be options for you without a deep DL tool and access to the data tables via a hack SW. So, I think getting you to your next steps and first clearing FTs and restarting from zero is a good exercise. See how FTs relearn.

BTW, when doing a hard reset with the battery disconnect, other memory losses will occur too. TCM learned shifting will be lost, not a big deal.

 

I wanted to add some additional info about the car:

• I purchase in 2012 with 30K miles and it now has 63K
• Car came with RSC catalyst and air filters. Not aware of a tune on the car.
• I first changed O2 sensors at around 40K miles if I recall correctly (haven't gone back to look at notes)
• I have a spare set of aftermarket catalytic converters from Appleby performance that have not been but on the car.
• Get the periodic catalyst performance codes which usually clear by themselves or I clear with a tool. Was getting a performance code on Bank 2 before the P0174 code came up.

I do need to change the plugs and maybe the coils at 63K miles but I would have thought this would have caused a rich issue or misfires (no misfires on tool unless its not reading them properly). I noticed a misfire started while out the last time I drove the car (check engine had been on with cat performance code). When I got home I read both cat performance code and now a new P0174 code. Don't think a bad cat would cause this as B2S1 is before the cat unless a clog could cause a lean condition up stream.

Could it be an issue with cam advance on bank 2? Not sure if the engine retards or advances the cams at idle.

Air pump or EGR. I would think EGR would effect both banks. Air pump could effect one bank but have not found any details on the V8 specific system and how it operates plus no codes for this.

Over the last 15K mikes I would sometimes get a mis I could sense at idle that would come and go and never found the cause. With the mis at idle there all the time now this points to a hard failure of some sort.

Dave