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So I floored it on the highway yesterday, and as soon as it got to full boost it felt kind of like hitting a fuel cutoff; got a stuttering and a loss of power, then the CEL came on blinking yellow.
I backed off and the car seemed to drive fine; light turned off. Got home and found it was idling a bit weird; smooth normally, then a slight shudder every 5-15 seconds or so.
AccessPort shows these codes:
P0003 Fuel volume regulator control circuit low
P0603 internal control unit keep alive memory (KAM) error
And my bluetooth OBD2 reader shows:
P0306 - cylinder 6 misfire detected
After resetting the ECU, idle went back to normal, but as soon as I'm on boost I get the same symptoms. Here's a short log of that. I notice that AFR and short term fuel trim spike on bank 2. So, what am I looking at here? I would think if it were a fuel pump or FPR problem it would affect both banks, but maybe I'm wrong about that; I guess one could be affected first...
Also FWIW I just looked back at some logs from before this problem, including one from a week ago, and they all show slightly higher stft on bank 2 vs bank 1 (like 1.1 vs 1.06) under full boost. But that's after building boost for ~ 1s, whereas this happens almost immediately and is obviously much more significant. (The log only shows it getting to 1.2, but on the AP it showed it hitting the 1.25 max. I backed off the throttle right away for obvious reasons, hence the short log.)
I assume you have already checked the low hanging fruit of boost hoses?
Other than fuel system related items, my past experience with ignition issues has been coils and sparks, since it is specifying a cylinder I would start with that cylinder and that side of the engine first.
Fortunately (or unfortunately) I have not had any issues like this in the 997, but I have had them in my Audi C4 S6. Each time it was coils.
I assume you have already checked the low hanging fruit of boost hoses?
Other than fuel system related items, my past experience with ignition issues has been coils and sparks, since it is specifying a cylinder I would start with that cylinder and that side of the engine first.
Fortunately (or unfortunately) I have not had any issues like this in the 997, but I have had them in my Audi C4 S6. Each time it was coils.
Ed
Boost hoses appear fine (and looking at the log it is building boost fine). Plugs and coils were all changed 10 months and < 2000 miles ago. I suppose one of the coils could have busted, but would that result in the AFR and fuel trims spiking under boost? I'm not a mechanic, but it seems more like a fueling problem to me. It also feels much more like hitting a fuel cutoff (like when you hit redline) than it does like a bad coil.
Another shoot from the hip suggestion: loose plug?
Also saw this:
Just had the call from OPC. There is a switch in the braking system that tells the 'brain' that the brakes are applied. This inhibits the throttle apparently. The switch was faulty hence the loss of power after braking and then acceleration. Sorted!
Thanks to all for your input.
And this:
What the P0003 code means
P0003 is a generic OBD-II code indicating an issue with the engine control module (ECM) reading signals from your fuel pressure regulator on your fuel injection rail mounted to your engine.
The ECM regulates your fuel pressure from your fuel pump going to your engine through this circuit and receives input on your actual fuel pressure, from the fuel pressure sensor. When the computer detects that fuel pressure it is not commanding to the fuel pump, it will set a Check Engine Light and this code. The code will affect fuel economy and possibly damage the engine.
What causes the P0003 code?
The fuel volume regulator control circuit low code may have several causes:
Possible corrosion in the sensor connector
A short in the sensor wiring to the ECM
A defective fuel pressure regulator
The ECM is damaged
I always ask, "What changed?" whether it's an IT problem or I have water on the floor of my house, and more times than not the answer to that question is the cause of my problem. The only issue I see is the 2K miles after the plugs/coils swap. Do you run a tune? Then maybe that post has something worthwhile.
I'll keep looking. I know what it's like to have a turbo with no power!
Yeah, it seems like there are a few possibilities. It's not the brake sensor thing, but it could be a coil gone bad (hopefully), or something more significant. Looks like time to take it to the shop.
You’re getting terrible ignition knock, timing is pulling out like crazy. This could be a cause or a symptom. When did you last get fuel? Have you checked fuel pressure? Bank 2 gets its fuel after bank 1 via the crossover pipe. You’re also close to the limit on injector MS, what injectors are you running?
You’re getting terrible ignition knock, timing is pulling out like crazy. This could be a cause or a symptom. When did you last get fuel? Have you checked fuel pressure? Bank 2 gets its fuel after bank 1 via the crossover pipe. You’re also close to the limit on injector MS, what injectors are you running?
The knock sense numbers are fine; that's comparable to what I had while tuning (by Sam @ bydesign), and what I've seen from others. It IS pulling the timing a lot; I think that's because of the AFR leaning out. And then it gets to the point where it can't increase fuel trim any further.
Stock injectors; only mods are exhaust and tune. Bank 2 being after bank 1 makes sense for it being a fuel pressure issue; I have no idea how to check fuel pressure though. Last got fuel a few weeks ago; there's about 1/4 tank now. Had no issues for the first 3/4, so it shouldn't be bad gas. Could be a bad fuel pump though?
What I mean by terrible ignition knock is the fact you’re down to 6 degrees of timing and zero in some spots and it is dropping very low overall timing - you’re getting knock (or what it thinks is knock).
There is a fuel pressure port on the feed line you can check. It should be at 3.8 bar.
You need to make sure both both pumps are working though.
Knock sums are fairly arbitrary and don’t necessarily track ignition knock events. You need to plot commanded ignition timing against actual and you can see the knock as dips. A timing curve should be very smooth.
You could just plot the timing on a graph and you’ll see the knock events.
Knock sums are fairly arbitrary and don’t necessarily track ignition knock events. You need to plot commanded ignition timing against actual and you can see the knock as dips. A timing curve should be very smooth.
You could just plot the timing on a graph and you’ll see the knock events.
Just FYI!
Can't timing be pulled for things besides knock? ie. AFR out of range?
it could be a cause or a symptom, that’s what needs to be sorted out. My recommendation is to check all the standard items first - fuel pressure, boost leaks, turbo actuators, etc.
Seems one of your fuel pumps is faulty. Try this: fill her up with fuel, reset the ecu and make a quick log just 2-3 seconds of WOT. If it makes a difference that donfirms it.
Which fuel pump is Primary depends on fuel level. Seems your "low" primary pump struggles till the second pump kicks in.
Seems one of your fuel pumps is faulty. Try this: fill her up with fuel, reset the ecu and make a quick log just 2-3 seconds of WOT. If it makes a difference that donfirms it.
Which fuel pump is Primary depends on fuel level. Seems your "low" primary pump struggles till the second pump kicks in.
I think it's actually the opposite. Right now it runs fine except at WOT/boost. So the primary pump is working, and (maybe) the secondary isn't. If I fill the tank, the pump that's primary will change, so if that other pump is faulty, the car might not run at all. It could be a good way to diagnose, but would also leave me stranded, and then we'd have to change a fuel pump with a full tank, which also wouldn't be ideal.
Anyway, I'm out of my depth, so will be letting a shop take it from here.
04-11-2018 | 01:42 PM
