b7 s4 epc cel and bucking

q_dubz · Feb 26, 2015

I'm at a complete loss on diagnosing this thing any further. This car will start and idle just fine, and leave the driveway and cruise just fine. All of a sudden i will lose all power as if the key was cut off for a TENTH of a second. The car will of course buck and the EPC and CEL light will kick on. Also if im running VCDS, i will lose comms with the module im logging (in this case engine). Its clear the ECM is losing power because if i had a check engine light pre-existing, it would be gone. It is very hard to reproduce this error but it is prone to doing it when shifting BUT NOT ALWAYS sometimes its just under slow accel. All this is kinda telling me a connection is lose but i've SCOURED and found every connection and come up empty. The only connection i can not find is ground connection 121. All it says is it's "Ground Connection 2 (in right front wiring harness)". I've replaced the Fuel and ECM relays.

Below are my codes, luckily the ABS module caught something

Code:

VCDS Version: Release 14.10.1 (x64)
Data version: 20150130
USRT
Tuesday,17,February,2015,20:18:44:00899

Chassis Type: 8E (8E - Audi A4/S4/RS4 B6/B7 (2001 > 2008))
Scan: 01 02 03 08 09 0F 11 15 16 17 18 25 36 37 45 46 55 56 57 65
67 69 75 76 77

VIN: WAUGL58E35A520761 Mileage: 146530km-91049miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 079-910-560-BBK.lbl
Part No SW: 8E0 910 560 K HW: 4E0 907 560 
Component: 4.2L V8/5V G 0010 
Revision: --H01--- Serial number: 
Coding: 0007711
Shop #: WSC 06335 000 00000
VCID: 2D51D6BAB412BD49F56-8078

No fault code found.
Readiness: 0000 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8E0-910-517.clb
Part No SW: 8E0 910 517 C HW: 8E0 614 517 BB
Component: ESP8 quattro H04 0180 
Revision: 00000000 Serial number: 00000000000000
Coding: 0004901
Shop #: WSC 06335 000 00000
VCID: 275D249296EE97190FA-8072

4 Faults Found:
01314 - Engine Control Module 
008 - Implausible Signal - Intermittent
01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30 
000 - - - Intermittent
01312 - Powertrain Data Bus 
014 - Defective - Intermittent
18265 - Load Signal 
P1857 - 000 - Error Message from ECU - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 8E0-820-043.lbl
Part No: 8E0 820 043 AM
Component: A4 Klimaautomat 2731 
Coding: 00000
Shop #: WSC 00000 
VCID: 6CD71BBE1C887441A28-5124

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels: 8E0-907-279-8EC.lbl
Part No: 8E0 907 279 J
Component: int. Lastmodul USA 0503 
Coding: 01023
Shop #: WSC 65536 
VCID: 3979F2EA235A11E969E-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8E0-959-655-94.lbl
Part No SW: 8E0 959 655 H HW: 8E0 959 655 H
Component: Airbag 9.41 H10 3230 
Revision: 91H10323 Serial number: 0036N000CWJ9 
Coding: 0032707
Shop #: WSC 06335 000 00000
VCID: 3C77EBFE7F6824C1728-8069

Subsystem 1 - Part No: 8E0 910 339 B
Component: BF-Gewichtsens. 02 0070 
Serial number: 6332DRB401818618G
Coding: 00032707

Subsystem 2 - Serial number: 6342DRB401829425F

Subsystem 3 - Serial number: 6352ARB4003B259CO

Subsystem 4 - Serial number: 6362ARB4003B62308

Subsystem 5 - Serial number: 63729RB4005238089

Subsystem 6 - Serial number: 63829RB400523AC9P

9 Faults Found:
01794 - Control Module - Incorrect Chassis (VIN) Number 
000 - - - Intermittent
00532 - Supply Voltage B+ 
002 - Lower Limit Exceeded - Intermittent
01316 - ABS Control Module 
008 - Implausible Signal - Intermittent
01639 - Crash-Sensor for Side Airbag; Rear Passenger Side (G257) 
014 - Defective - Intermittent
01316 - ABS Control Module 
004 - No Signal/Communication - Intermittent
01317 - Control Module in Instrument Cluster (J285) 
004 - No Signal/Communication - Intermittent
00474 - Control Module for Immobilizer 
004 - No Signal/Communication - Intermittent
01738 - Crash Sensor for Front Airbag; Drivers Side (G283) 
011 - Open Circuit - Intermittent
01739 - Crash Sensor for Front Airbag; Pass. Side (G284) 
011 - Open Circuit - Intermittent

-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 8E0-953-549.lbl
Part No: 8E0 953 549 Q
Component: Lenksáulenmodul 0601 
Coding: 02041
Shop #: WSC 06335 
VCID: 41899A0A4B8A492921E-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8E0-920-9xx-8EC.lbl
Part No SW: 8E0 920 981 Q HW: 8E0 920 981 Q
Component: KOMBI+WFS 4 H12 0040 
Revision: 0040 Serial number: 00000000000000
Coding: 0023201
Shop #: WSC 02301 444 10073
VCID: 3B75E8E2796623F97B2-5124

6 Faults Found:
01314 - Engine Control Module 
004 - No Signal/Communication - Intermittent
01316 - ABS Control Module 
004 - No Signal/Communication - Intermittent
01321 - Control Module for Airbags (J234) 
004 - No Signal/Communication - Intermittent
01771 - Control Module for Headlight Range (J431)
004 - No Signal/Communication - Intermittent
01304 - Radio 
004 - No Signal/Communication - Intermittent
01303 - Telephone Transceiver (R36) 
004 - No Signal/Communication

-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 8E0-920-9xx-8EC.lbl
Part No SW: 8E0 920 981 Q HW: 8E0 920 981 Q
Component: KOMBI+WFS 4 H12 0040 
Revision: 0040 Serial number: 00000000000000
Coding: 0023201
Shop #: WSC 02301 444 10073
VCID: 3B75E8E2796623F97B2-5142

6 Faults Found:
01314 - Engine Control Module 
004 - No Signal/Communication - Intermittent
01316 - ABS Control Module 
004 - No Signal/Communication - Intermittent
01321 - Control Module for Airbags (J234) 
004 - No Signal/Communication - Intermittent
01771 - Control Module for Headlight Range (J431)
004 - No Signal/Communication - Intermittent
01304 - Radio 
004 - No Signal/Communication - Intermittent
01303 - Telephone Transceiver (R36) 
004 - No Signal/Communication

-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr Labels: 8E0-959-760.lbl
Part No: 8E0 959 760 
Component: Sitzmemory R2 F 0305 
Coding: 00002
Shop #: WSC 00000 
VCID: 71E90ACA3BAA99A991E-4AE8

No fault code found.

-------------------------------------------------------------------------------
Address 37: Navigation Labels: 8E0-035-192-RNSE.lbl
Part No SW: 8E0 035 192 E HW: 8E0 035 192 E
Component: RNS-E HIGH EU H54 0650 
Revision: 03S Serial number: AUZBZ7E1501313
Coding: 0309137
Shop #: WSC 06335 000 00000
VCID: 2643299692E48E1134C-515E

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 8E0-959-433-MAX.lbl
Part No: 8E0 959 433 BT
Component: Komfortgerát T7B 3232 
Coding: 16232
Shop #: WSC 06335 
VCID: 0407531E14189C014A8-4AE8

Subsystem 1 - Part No: 8E1959801F
Component: Tõrsteuer.FS BRM 1315 

Subsystem 2 - Part No: 8E1959802E
Component: Tõrsteuer.BF BRM 0205 

Subsystem 3 - Part No: 8E0959801A
Component: Tõrsteuer.HL BRM 0205 

Subsystem 4 - Part No: 8E0959802A
Component: Tõrsteuer.HR BRM 0205 

17 Faults Found:
01331 - Door Control Module; Driver Side (J386) 
49-10 - No Communications - Intermittent
01332 - Door Control Module; Passenger Side (J387) 
49-10 - No Communications - Intermittent
01333 - Door Control Module; Rear Left (J388) 
49-10 - No Communications - Intermittent
01334 - Door Control Module; Rear Right (J389) 
49-10 - No Communications - Intermittent
01317 - Control Module in Instrument Cluster (J285) 
49-10 - No Communications - Intermittent
01320 - Control Module for Climatronic (J255) 
49-10 - No Communications - Intermittent
01336 - Company Data Bus for Comfort System 
37-10 - Faulty - Intermittent
00962 - Alarm via. Tilt Sensor 
35-00 - - 
01369 - Alarm triggered by Hood Switch 
35-00 - - 
01371 - Alarm triggered by Door Contact Switch; Driver's Side 
35-00 - - 
01574 - Alarm triggered by Door Contact Switch; Rear Right 
35-00 - - 
00955 - Key 1 
35-10 - - - Intermittent
00956 - Key 2 
35-00 - - 
01403 - Glass-Break Sensors; Rear 
36-10 - Open Circuit - Intermittent
00532 - Supply Voltage B+ 
37-10 - Faulty - Intermittent
00466 - Control Module for Steering Column Electronics (J527) 
49-10 - No Communications - Intermittent
00457 - Control Module for Network (J519) 
49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 55: Headlight Range Labels: 4F0-910-357.lbl
Part No SW: 4F0 910 357 E HW: 4F0 907 357 E
Component: AFS 1 H01 0010 
Revision: 00000001 Serial number: 
Coding: 0000019
Shop #: WSC 01041 444 52566
VCID: 285F27AE9BF09861060-807D

Subsystem 1 - Part No: 8E0 941 329 A
Component: AFS-Modul links H05 0030

Subsystem 2 - Part No: 8E0 941 329 A
Component: AFS-Modul rechtsH02 0020

1 Fault Found:
01314 - Engine Control Module 
004 - No Signal/Communication - Intermittent

-------------------------------------------------------------------------------
Address 56: Radio Labels: 8E0-035-192-RNSE.lbl
Part No SW: 8E0 035 192 E HW: 8E0 035 192 E
Component: RNS-E HIGH EU H54 0650 
Revision: 03S Serial number: AUZBZ7E1501313
Coding: 0309137
Shop #: WSC 06335 000 00000
VCID: 2643299692E48E1134C-515E

No fault code found.

End-------------------------(Elapsed Time: 07:11)----------------------

Also this happens with the MAF unplugged as well. Granted its not as bad, it still does it between shifts and at throttle tip-in.

dafrazi · Feb 26, 2015

Have you checked the battery and the battery terminals? I have seen wobbly batteries and loose battery terminals cause the type of problem you are describing.

q_dubz · Feb 26, 2015

dafrazi said:
Have you checked the battery and the battery terminals? I have seen wobbly batteries and loose battery terminals cause the type of problem you are describing.

Yes.

Also important to note, that EPC/CEL turn on as well for a brief second.

q_dubz · Feb 26, 2015

Also a lot of those codes are from disconnecting the battery. The ones that come back are always the ECM and steering terminal 30s which refer to the bolt connections under the dash. Checked those and disconnected all additional after market accessories .

roth · Feb 26, 2015

I would focus on the ECM. The best way to check it is have the engine running and experiment with moving / twisting / the harness because it is prone to doing it when shifting BUT NOT ALWAYS sometimes its just under slow accel. You might get lucky that way and fine broken shorted wire in the engine harness. Another thing you could do is to move the connectors on ECM, there might be some corrosion there. So, if the engine does not die, still unplug and check them for signs of any moisture.

Also do you have any coolant leaks???

BR, Andey

q_dubz · Feb 26, 2015

Negative on the corrosion, moisture and coolant leaks.

This problem overall started over a year ago. I'd just be humming along the highway and out of nowhere it would just cut out for a split second, but it was such a rare occurrence I could never track it down and I always got the power terminal 30 code. Its just recently it started doing every time I drive.

I've ordered a new MAF and CrankPS and will install them when they arrive. I've removed and opened up the TB and checked that for corrosion.

q_dubz · Feb 26, 2015

by rare occurrence I mean weeks/months apart.

Jack@European_Parts · Feb 26, 2015

OK

Lets check some things related to EPC that can be sporadic.
How is brake fluid level in reservoir?
Have you verified brake and clutch switch function in VCDS advanced blocks for behavior not seen by the ecu?
Does it do it with MAF unplugged?
Is intake boot from air box to TV secure and not torn underside slightly?
Is ignition switch in proper order?

I would try running additional ground straps and power overlays to see if related to interruption for testing.

Does car completely stall/die or just idle with no response?
How is fuel pump duty cycle looking?

Man I have one hell of a cold that is kicking my ass this week..........

q_dubz · Feb 26, 2015

Brake fluid is a little high.

Brake switch and clutch switch ill double check.

This happens with the MAF unplugged as well. Granted its not as bad, it still does it between shifts and at throttle tip-in.

Airbox >TB is good.

No idea if the IGN switch is faulty. It all seems fine and turns over and starts every time.

Fuel pump duty cycle I could check.

It doesn't completely die because it catches itself so fast. Like I said it only happens for a 10th of a second. I'm gonna need to make a video it seems. Re-Read my post and try and picture what I'm saying. Its kinda hard to describe.

roth · Feb 26, 2015

q_dubz said:
Negative on the corrosion, moisture and coolant leaks.

This problem overall started over a year ago. I'd just be humming along the highway and out of nowhere it would just cut out for a split second, but it was such a rare occurrence I could never track it down and I always got the power terminal 30 code. Its just recently it started doing every time I drive.

Well my friend, T30 is the battery power that you are obviously loosing. That is your problem or you got T30 on ECM but ECM itself is bad.

q_dubz said:
I've ordered a new MAF and CrankPS and will install them when they arrive. I've removed and opened up the TB and checked that for corrosion.

Waste of time and money.

You got wiring diagram for this car?

BR, Andy

q_dubz · Feb 26, 2015

roth said:
Well my friend, T30 is the battery power that you are obviously loosing. That is your problem or you got T30 on ECM but ECM itself is bad.

Waste of time and money.

You got wiring diagram for this car?

BR, Andy

yep I have diagrams. I would love to just swap out ECUs but audi spot welded this super awesome anti-theft bracket across one of the connectors.

Jack@European_Parts · Feb 26, 2015

Please also check the engine speed sensor for contamination of oil ingress like candle wick to connector.

The fact that improvement is seen when the MAF is disconnected is a dead give away that maybe trims are off.

Please check the trims with VCDS and see if we have an air leak........isolate all possible false air in addition to intake boots .......such as brake booster, N80, and LDP circuits.
I would also like to know if we have a fuel issue for delivery. PSI and volume checks are mandatory.

A gasket is less likely but could be part of the issue.

I would be in pretty close agreement with Roth and that a tone out with a draw carry ability of the harness is needed.
A lot can be said for wiggle tests but to verify with a load light or alternate tester is advised.

Pull that stupid tamper proof off.

It would not be the first time I have seen a bad ecu seeing a corrupted G28 signal for this condition and car.

q_dubz · Feb 26, 2015

Jack you got a # I can reach you at? I'd like to call you after work.

-Quintin@USRT-

Jack@European_Parts · Feb 26, 2015

Dude I am sick as a dog....... so talking today is out but you can PM me or email me at vwemporium@aol.com or ask stuff here so others benefit from the data.

q_dubz · Feb 26, 2015

True, ok no worries.

Alright last I checked trims they were around -1% at idle and -2% at cruise. If it were a leak I'd surely see some sorta lean related code, no?

What channels should I log for fuel pump duty/psi? I can try. Remember every time this glitch occurs all engine module logging stops.

Jack@European_Parts · Feb 26, 2015

Monitor the terminal 15 and 30 at the ecu if that is the case, with a recorder or test light that can be watched.
Also monitor ignition switch conditions....

When I get ghosts I log everything I suspect with recorders and VCDS.

Is terminal 15 relay and ecu supply relay ok?
I know you said you changed some.

I also watch a break out box that lights the paths hooked to the ALDL.......sometimes you get an indication.

q_dubz · Feb 26, 2015

Jack@European_Parts said:
Monitor the terminal 15 and 30 at the ecu if that is the case, with a recorder or test light that can be watched.
Also monitor ignition switch conditions....

When I get ghosts I log everything I suspect with recorders and VCDS.

Is terminal 15 relay and ecu supply relay ok?
I know you said you changed some.

I also watch a break out box that lights the paths hooked to the ALDL.......sometimes you get an indication.

I replaced the ecu and fuel pump relays. Which one is the terminal 15 relay?

Also I don't have access to any fancy electrical equipment except for my digi-multimeter

roth · Feb 26, 2015

q_dubz said:
I replaced the ecu and fuel pump relays. Which one is the terminal 15 relay?

Also I don't have access to any fancy electrical equipment except for my digi-multimeter

You have a code for loosing power on terminal 30, which is the battery +. So, why are you checking terminal 15, key on?

BR, Andy

q_dubz · Feb 26, 2015

roth said:
You have a code for loosing power on terminal 30, which is the battery +. So, why are you checking terminal 15, key on?

BR, Andy

I was responding to Jack.

Just looking into all options. I'm thinking that there is a short to one of the other things that tap terminal 30 which is sapping power to the ECU.

jyoung8607 · Feb 26, 2015

q_dubz said:
The car will of course buck and the EPC and CEL light will kick on. Also if im running VCDS, i will lose comms with the module im logging (in this case engine). Its clear the ECM is losing power because if i had a check engine light pre-existing, it would be gone. It is very hard to reproduce this error but it is prone to doing it when shifting BUT NOT ALWAYS sometimes its just under slow accel.
...
Also this happens with the MAF unplugged as well. Granted its not as bad, it still does it between shifts and at throttle tip-in.

This will be a fun one. I'm mostly in agreement with Andy and Jack... power, ignition switch (a sub-case of power) or ground, or possibly a defective ECU. You have no engine DTCs and you say they're lost during the event, which implies power loss or perhaps a brown-out. You also say the EPC and MIL lights come on. Do they only come on briefly solid and then go out? That would be consistent with the power-on lamp test.

Things I would try:

Wiggle the ignition switch while the engine is running. Gently move the key back and forth, twist, push and pull gently to see if you can trigger an event. If you can, then you know it's the ignition switch.
Monitor and log T15 ignition state from somewhere, like address 46 MVB 015. If you catch T15 state changing at the time of an event, you know you have an ignition switching problem somewhere. If you can't catch it happening, it doesn't totally rule it out but it argues against it.
Monitor and log T30 voltage as perceived by the ECU, MVB 004 field 2. Look for sane and stable values that are reasonably close to what you measure at the battery with the car running. Watch this value while you wiggle around various bits of engine wiring harness and ground wiring. You may see variances here that show you power problems before you brown-out deeply enough to crash. If you see a problem here, be aware it could be power-supply or it could be grounding.
You say that disconnecting the MAF makes it somewhat better. This is hard to understand. If you have a borderline power/ground situation, I suppose the MAF element heater might be the current demand pushing you over the edge. You could try to disconnect more demands, like the O2 sensors and the SAI relays, and see if that gives you a further improvement. That's grasping at straws, but this is a weird one.
Use your multimeter in DC voltage mode to check potential between several points on the engine and a good body ground. You should see no more than a few millivolts. If you see more, run a temp test ground to even them out, and then take another test drive.

Jason

***b7 s4 epc cel and bucking***

Verified VCDS User

Verified VCDS User

Verified VCDS User

Verified VCDS User

Verified VCDS User

Verified VCDS User

Verified VCDS User

Gone But Not Forgotten

Verified VCDS User

Verified VCDS User

Verified VCDS User

Gone But Not Forgotten

Verified VCDS User

Gone But Not Forgotten

Verified VCDS User

Gone But Not Forgotten

Verified VCDS User

Verified VCDS User

Verified VCDS User

FoRT

b7 s4 epc cel and bucking