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I have 2 codes on my 07, P0174 system too lean bank 2 and P0430 catalyst efficiency below threshold bank 2, Note that from other threads I'm calling bank 2 the left side of car when sitting in it (drivers side in US)
I've had the P0430 show up every so often over the years but I suspect this is due to 200 Cel cats. When I bought the car I didn't realize it had RSC cats on it, oh well live and learn.
In the last few weeks the car started to have a miss at idle and maybe a slight impact in acceleration. I thought at first it might be the Bank 2 front 1 sensor and I had some spares put buy. NTK part OZA816-EE1 for sensor 1.
I have an older Autel 802 scanner which does provide real time logging and found bank 2 short fuel trim was at 8.2 to 14 % where bank 1 short fuel trim was 0 to 5.5%. I did a test by changing out bank 2 senor 1 to the new part and saw no change.
I needed to change the air filters so at the same time pulled the MAF sensors and cleaned them. No change on bank 2. I then swapped the two MAF sensors from side to side with no change to bank 2. I'm not sure if the sensors operate together or if the MAF sensor on the left side of the car is just for bank 2, May scan tool only shows one MAF in the menu.
The scan tool has basic graphics and when I try to graphic both sensor 1 sensor outputs, the bank 2 is too far out of range so I have to graph individually.
O2B1S1 displays a saw too pattern which is correct.
O2B2S1 displays an erratic pattern (not clean). OSB2S2 seems to show the same.
I'm contemplating ordering a more up to date tool from Think Tool or Topdon which should allow for easier trouble shooting and can be used on my other vehicles.
Any feedback on where to look next would be helpful.
Have you check to make sure one of your air box is not damaged as I believe it happen to someone that more air was going though the damage air box and throwing errors due that the right and left side didn't match
With a P0174 (and not an accompanying P0171), you want to look for air entering the intake path PAST the MAF (which will show as vacuum) somewhere in the intake path on Bank two. This could possibly be a bank 2 intake manifold gasket or any other place past the MAF. Since you swapped the MAFs, with same results (good tech trick), you are then getting more air into the left bank than the sensor is reading which causes the P0174.
BTW, you used the correct way to ID left/right (sides) relating to anything on the car (and any car), engine compartment, trunk, etc,. Left/Right is always IDed sitting in the car, looking out the windshield (left hand or right hand drive, doesn't matter). Lefts and rights do not change when you walk up to the front of the car looking at it backwards and when facing the engine bay.
Sorry it's taken me a while to respond, but I was in Arkansas building our retirement home and coverage is not the best. Plan is to install a cellular modem in the near future.
Airbox - The airboxes are good. I did have to repair some broken tabs on each airbox after purchasing the car and first air filter service. I've since broken one off my self due to a higher than expected curb.
Intake track - I didn't see any leaks but will check again while I have access. I was leaning to this not being an issue as it was my thought that after the MAF sensors the air is combined prior to the throttle and both would show lean.
Intake leak - I did spray carb cleaner around the vacuum hoses/lines in the intake area but may not have gotten it low enough on the intake to find a track leak. Bank 2 rear is also not as easy.
I'll be in town for a week so will be periodically working on it.
So I was finally able to speed some time on the car this afternoon.
Brought the car up to temp and sprayed carb cleaner on and around the plastic intake track from the MAF and also on the bank to intake manifold area where it bolts to the plenum and the heads. I was monitoring the front O2 sensor and the sensor operated with no change from the cleaner. Based on that I don't think it's a leak on the intake side as of now.
I still was monitoring the O2 sensors on Bank 2. Sensor 1 of Bank one moved up and down from ,around .02 to .8 which seems normal. Sensor 2 down stream is only operating in the .765 to .830 range which is not correct. I think it should track O2 sensor 1. My older Autel MaxiDiag Elite will allow me to view and graph both, but will not allow me to change the scale separately so thinking I missed this before. I didn't see the higher O2 sensor 2 until I only view that sensor.
My thoughts were that sensor 1 would be for mixture only and sensor 2 was for cat performance only. Maybe sensor 2 is also used as an input for mixture control?
Tomorrow I will swap the number 2 sensor in bank 2. Easy enough to do as the car is up in the air and I have the part on hand.
downstream O2 sensors are not switching back forth like the upstream sensors do. They are monitoring the performance of the CATS. So if the cats are performing then more oxygen is steadily present in the exhaust stream.
the other thing about downstream sensors, most EMSs are programmed to check the output of those every so many miles, not constantly. I’ve seen on some models every 50 or 100 miles.
too bad you cannot find the P0174. It is not too complicated. It is more air, Oxygen in the airstream PAST the MAF. That is key as the MAF reported an air volume to the ECU but when combustion occurred the O2 sensor is constantly reporting lean (not oscillating like it should). Can’t be an air leak before the MAF as it would report that extra volume.
I should add one more possibility to a P0174, and that might be a clogged or dirty fuel injector(s) that isn't(aren't) delivering. That too would create a more constant lean condition at the O2 sensor on that side. If you're sure you've covered every possibility for a vacuum leak past the MAF, then, you might need to look at fueling. Remember the EMS is striving for a constant stoichiometric balance so either fuel or air can upset the equation.
I don't think so but the SAIR system is separated after the pump into right and left exhaust manifold and might be an issue? I know that these units can go bad in a number of different ways with the valves, pump and what not. If I remember correctly they are quite closely monitored by the ECU for faults so should have a code for this if that was the case.
Either way I would think that the exhaust would push into the intake manifold rather than the other way around, but I just thought I would chime in with this.
So this morning I went to the local garage that I get to do oil changes on my other vehicles as were in a town house with limited space as most of my of my tools and lift are in Arkansas. FYI - I do the Aston oil changes myself.
The owner offered to have one of the guys put it on their more comprehensive Autel scanner. They were very busy so I did not get to observe and all I got back was it's the fire box under the intake. I've tried looking it up and found nothing (maybe under a different name?)
I will also look up SAIR. I assume this is like the old air injection pumps.
This afternoon I ordered a ThinkTool ProS scan tool and a small hand held O-scope. Its supposed to support Aston Martin so we'll see. At least it should support a lot more ODBll capabilities. Been watching a guy on his Pine Hollow YouTube channel use the same tool on a lot of brands and it seems very useful. This is taking me back to another lifetime when I ran and engineering lab and had access to a number of tools.
The SAIR pump and valves is under the intake manifold. It's not to bad to get to in the scheme of things. I have gone there twice, first time to change SAIR pump and second time to put back pieces I forgot the first time.
But I'm a bit surprised that you don't get any code more closely related to that system since it closely monitored.
I received the Thinktool ProS scanner and hand held oscilloscope.
I hooked up the scanner and it only shows the P0174 code nothing related to SAIR. Not to SAIR may not be a problem but I don't' have a diagram of the system to review how it works.
The scanner has Aston Martin as a selection but only lists 2011 and up for Vantage so I had to view through ODB2. Maybe they will update in the future for other car modules as there must have been a change after 2010. The scanner does give me a much better view graphically of the ODB2 outputs so much better here.
Today I used the O-scope to view the signals to all 4 injectors on Bank 2. So the signal is there, but this does not mean that one or more are dirty or clogged. I may purchase 1 or 2 replacements to swap out for testing but not there yet. Want to identify the cause vs. parts changing too much.
May work on it some tomorrow then back up to Arkansas Monday.
Needed to move the Aston over to its side of the garage and bring my wife's vehicle in but before I did that I tried unplugging the injectors on bank 2 one at a time. The car is idling a bit rough from this issue but did observe a change when the front 3 were unplugged and improvement when plugged back in. The most cylinder could not be check as it got too hot. Tomorrow I will try that one by unplugging when cold then push back in when running to see if there is a change.
Fuel sources have been a little on the sketchy side out there since covid.. especially if you're not using a top tier fuel source, even then....
One simple thing to try albeit a little in the level of an "elixir", try a bottle of Chevron Techron in with a tank of gas. It's good to follow the dilution instructions, but BC you are trying to possibly push through a cluttered injector, maybe go a little higher concentration...but don't go crazy here. It is either going to make a difference relatively quickly, or not at all. I've had it work sometimes to clear injectors, and other times not.
Use the Techron in the BLACK bottle and not the one in the blue bottle (I think the blue bottle is marked as injector cleaner) the Techron in the black bottle is the same as in the blue only in a higher concentration.
Tried running some Techron concentrated with no luck. It may have helped prior to the injector becoming fully clogged.
Does anyone have any info on what is required to remove the injectors/rail? I'm mechanically inclined so I think I'm up to the task just have no experience with this engine or fuel system. Hope I can remove the rail without having to remove the intake. If I don't get a response to the this post I may open up a new one just on injectors service.
05-22-2023, 04:10 PM
