random miss or cough - but showing no codes......

A6 All/ S6 All
#1

Hey All,

pretty new issue, I had a rough running drive with lumpy idle so scanned her and came up with a
1 Fault Found:
000402 - Fuel Pressure Sensor (G247)
P0192 - 002 - Short to Ground - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 11
Reset counter: 255
Mileage: 114644 km
Time Indication: 0
Date: 2018.10.22
Time: 11:57:48

I checked the loom to the pressure sensor I could get to (top of the motor on teh coolant res side) cleared the codes and she went fine.

Now every other drive it has a cough or miss. Normally a single event - with no MIL light or codes at all…completely clear. When it happens it feels like it pulls the cam timing and thus performance but unsure as there is no code to check this.

Any ways these cars can have a miss without recording anything? is this the way the crusty injectors show?

to repeat she stutters once (after its warm about 10min in) with nothing recorded.

#2

I replied to your PM you sent me. Did you get it? I wasn’t sure if what I sent actually went anywhere

#3

I have experienced something similar that I characterize as a “stutter” for the last couple of years.

It seems to be completely random other than it only occurs in warmer temperatures. From late fall to early spring, it never happens. I could be driving down the highway at a constant speed and all of a sudden, it stutters for a split second. It may not happen again for a day, or a week or longer but sometimes it will happen several times in quick succession. If I am rolling down the road, the momentum of the car will carry it through but if I am at a stop light with my foot on the brake, the engine will stall.

If it happens a number of times in a row, the EPC light will come on and the car goes into “limp” mode. I occasionally get the same HP fuel sensor fault that you are getting.

Last year, I spent a lot of time logging with VCDS with the hope of picking up some sensor data from one of these “stuttering” incidents. Below is ten seconds worth of data of the actual and target fuel pressure readings along with the injector time.

http://audirevolution.net/addons/albums/images/921055308.jpg

You can see that the actual fuel pressure follows the target closely except for a single dip where the actual fuel pressure dips to 20bar

There must be something off in the time stamp as the indicated injection time increase in reaction to the indicated drop in fuel pressure is reversed. In reality, the injection time would increase after a decrease in fuel pressure occurs. The indicated drop in fuel pressure to 20 bar is the result of a momentary short to ground on the ecu input from the sensor. I verified this by intercepting the signal wire and then touching it to ground briefly while the car was idling. It produced the same stuttering event.
If I grounded it and left it grounded, the engine would stutter and then recover. You can drive it in this state but you will have no power. I was also able to get the engine to stall by connecting and disconnecting the lead to ground in rapid succession.

I believe in my situation, there is an issue at the ecu connector. Since I have the engine and all the electrical out of the car right now, I can take the opportunity to replace the entire wire including the terminals in the connectors at both ends.

I should note that I had also replaced the sensor early on in case it was shorting internally. It did not resolve the issue.

1 Like
#4

^^^ I think you should change your name to Professor eng92. This is good stuff thank you.

#5

OK Gurus,

So I had some weird stutters that would come and go, now they come every drive. Its a cut in power that is like the key is being momentarily turned off and then on again.

Sometimes scans record one of the three below, sometimes more than one and sometime nothing at all (stutters happen just no codes pop up)

Each time fuel pressure either sensor or regulator is the king trouble maker,

Fuel Pressure Sensor (G247)
P0192 - 002 - Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 3
Reset counter: 255
Mileage: 119329 km
Time Indication: 0
Date: 2019.02.07
Time: 07:48:32

008852 - Fuel Pressure Regulator Valve (N276)
P2294 - 004 - Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 118806 km
Time Indication: 0
Date: 2019.01.31
Time: 07:51:35

000402 - Fuel Pressure Sensor (G247)
P0192 - 002 - Short to Ground - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 11
Reset counter: 255
Mileage: 114644 km
Time Indication: 0
Date: 2018.10.22
Time: 11:57:48

008852 - Fuel Pressure Regulator Valve (N276)
P2294 - 004 - Open Circuit
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 118806 km
Time Indication: 0
Date: 2019.01.31
Time: 07:42:27

The presvious responses didnt really give any intel on how to fix this…anyone changed this out or had sim issues?

many thanks

#6

Also - this normally happens only one or 2 times during easy driving, it never happens when you are at 100% throttle - only when adding 20-30% throttle normal driving

#7

The G247 sensor is under the manifold so I would eliminate the easier to access possibilities first.

There is a black 14 pin connector at the back on the left hand side of the engine. It is the harness connection to injectors 1 thru 5 and the G247 HP fuel pressure sensor.

Pins 11, 12 & 13 are the sensor ground, signal and 5V sensor power supply connections respectively. You can check 11 & 13 using a meter with the key on. However, your issue sounds fairly intermittent so you may not find any irregularities with simple voltage measurements. I would look for signs of corrosion on the pins.

I do not think the fact that you do not see the issue at 100% throttle is meaningful. You spend 99% of your time at lower throttle openings so any issue that is seemingly random is much more likely to occur during normal driving.

#8

thats awesome intel - Yes I cleared the faults and then brought up the live Fuel pressure figures and went for a drive and yep not a discrepancy to be seen.

Ill keep a good aye and do some investigating next weekend (away this week)

#9

Yeah for sure check the sensor and the wires.

Not sure what the ECU does at WOT it is going to go into open loop so how that effects the reporting of the fuel pressure I don’t know code wise. I would think you should be able to log the car obviously but the fact that the car cuts out means that there has to be an actual fuel deliver issue IMHO

#10

So I did find the black connector as stated below. Mine only had 13 wires to it, but that could be my country’s factory setup. Conducted the pin clean and reset. This gave me a couple of days without a stutter. But it did return. Now I have had loom / wiring work done on my things as someone has messed with the throttle body wiring, we have re wired that portion. We also found that my Ecus have been replaced at some point. They are stamped with 2014 date codes.

After some research it seems that this type of sensor (fuel pressure sensor) saying it had short to ground means its getting an intermittent reading. So dodgy wiring or connection is more likely as apposed to faulty sensor.

So I inspected the wiring there and connectors to the ecus. I pushed the plugs home into the ecus. It didn’t feel like they were not home or partially out.

It appears that this has resolved the issue. No stutters since pushing the ecu plugs inwards.

I’ll keep all updated. She’s getting a service tomorrow.

Big thanks to the support