perplexed

mURS4 · 04-27-2012, 07:14 PM

So, hello and thank you for all the great info over the years.. 93 s4 is car in question btw. well two, but one may become a doner for the coupe!- ;p

On to the FUN!

Original problem with the car was a "fried" ecu. Bought a 2fer1 kind of deal, used the "good" ecu from wrecked car- viola! well kinda. swapped POS's as well. good as new-ish! Maintained and drove car for.. 4 or so months, when allunasudden.. NOTHIN. cruisen down the highway, NOTHIN. cycled key whilst rolling, nada.

SOOOO I just got through PATCHING in a FL kick-panel relay block, (three relays) and grounds. Turns out the pinch weld directly above it had shotty body sealant from factory. Which let water dribble down over the chassis directly in front of the door-fender seal, corroding the heck out of the two ground studs directly above the relays, rear 5 pin relay was obviously the main burner.

Got it all patched up, still no dice. Here's the kicker: The car sat for quite awhile for schedule reasons, and I really don't know when that relay block fizzled. I just know it had a dead short that created a -14v system next time I got around to the car, now, post patch-up, it seems to be just fine. (volt issue that is)

Here's a Q: IIRC, the tach had NO Signal when it died cruisen, even bumping it. Engine speed sensor? is this what sends tach signal? No rpm's whilst cranking aswell.. Seems from reading you need ALL THREE engine position sensors talking for spark. If it WAAAAS my cam position sensor, it should have got me home correct??

Jumped the fuel pump directly and she spins up. fp relay kicks at KOEO, but wont come back to life cranking. cps has EXACTLY 1000 ohms.

could the resistance in my existing ground wires be causing faulty grounds? (kinda nasty black-green innards, had to reaaallly try hard to solder them)

btw, I WILL POST FOLLOW UPS!! I WANT TO DRIVE THIS BEAUTY AGAIN!!

wow. it feels kinda good to vent.

UrS4boy · 04-27-2012, 07:45 PM

You have so much in there I don't know where to start. I presume the ground you talk about is the one in the photo below. As for your symptoms, although a failed cam sensor is NOT supposed to kill a running engine (because the G4 crank position sensor supplies a signal to the ECU that allows the ECU to continue to control a running engine), I know this is false. Sometimes a failed cam sensor WILL stop a running engine. You need the G4 Crank sensor, the G28 engine speed sensor AND the G40 cam position sensor ALL to work in order to start the engine. I think you need to pull the codes (go to SJM Autotechnik to find out how). Look for a 2113 blink code = cam position sensor.

In the meantime visit this live diagram and click on the labels for the G4, G28 and G40 to learn more:

http://members.shaw.ca/speedtek/UrS%...ice%20Map.html

scarman · 04-28-2012, 04:28 AM

The quandry here is the G28 engine speed sensor fault code displays as a false code when read with the engine not running, so other than checking the sensor itself you have no way to know if the code is genuine or not and a faulty sensor will prevent engine start.

Perhaps there will be other codes to point to the problem.

mURS4 · 04-28-2012, 12:20 PM

AH YES!! SJM's site is a real god-send us, and honestly I forgot the name of it, so thanks!! I will get the schematic for making another led-tester there and get some codes.

UrS4boy: it's the double ground studs in F-L (driver) kick panel, I believe there's a tall double wide, ABS, and one other stubby 5-pin relay.

My real concern with the patch-up is that the ground wire innards were nice and toasty. Literally black/green at times and seeming coated when soldering, only on a few of the larger gauge ones. An electrician friend of mine said not to worry, as long as I got them to take a solder. But we all know resistance is present with corrosion! oi.

I will try and whip up a blinker and pull some codes!

UrS4boy · 04-29-2012, 08:10 AM

Quote:

Originally Posted by mURS4

I will try and whip up a blinker and pull some codes!

Are you not in the US of A? All NAmerican UrS4s and UrS6s have a built in code blink light in the form of the Check Engine Light (CEL) in the dash. If you are elsewhere, e.g. UK, Europe, etc. then yes, you will very likely have to follow SJMs instructions on setting up an LED and a resistor (IIRC) to make up a blink light (or find a friend with a VAG 1552 code reader, etc)

mURS4 · 04-30-2012, 05:59 PM

Actually, no..
I'm just being a noob. I havent had to even LOOK at the CEL. Untill now. oi.

I was thinking back to my 200tq(10v) days. Starting a new gig today has kept me from getting over to the car as well, being that I live in a apt and the S is at my folks.

Looking at SJM's site, Im pretty sure the car even came with the $88 Audi "diagnostic jumper cable".

IIRC, In a no-start condition on the 200, you had to crank for something obnoxious like 30 seconds to get the codes out of it. Being that I'm still untrusting of the WHOLE power/ground system, I keep disconnecting the battery.. Therefore killing memory. Chance know if its the same way on the S4?

I'll just search through SJM's more, but yes, I was being a dumb..

UrS4boy · 04-30-2012, 07:39 PM

Disconnecting the battery will clear the codes in the ECU so pull the codes BEFORE you disconnect the battery.

mURS4 · 04-30-2012, 10:38 PM

I guess my q was is there a specific cranking time for a no-start condition, time for the systems to even recognize a problem. Or just KOEO initializes a self check of the modules, sensors etc.

For sure the ECU is at least talking, because the cel does cycle on/off before cranking.

Im almost hoping I dropped the crank position reference pin and just need to weld that sucker. codes first.. codes codes think codes ;p.

scarman · 05-01-2012, 04:58 AM

No, the codes are non-volatile, so they will be there when you turn the key on. If you have cleared them, they won't return until the ECU sees them again.

UrS4boy · 05-01-2012, 06:18 AM

Quote:

Originally Posted by scarman

No, the codes are non-volatile, so they will be there when you turn the key on. If you have cleared them, they won't return until the ECU sees them again.

Ummm...Sorry Tom, beg to differ. Codes are cleared by pulling the constant ECU power fuse in the red fuse holder above the ECU . Therefore, if the battery is disconnected the codes will also be cleared.

http://www.sjmautotechnik.com/troubl...20v.html#fcser

04-27-2012, 07:45 PM	#2
UrS4boy AudiWorld Super User Garage is empty, add now Join Date: Feb 2001 Posts: 18,210	You have so much in there I don't know where to start. I presume the ground you talk about is the one in the photo below. As for your symptoms, although a failed cam sensor is NOT supposed to kill a running engine (because the G4 crank position sensor supplies a signal to the ECU that allows the ECU to continue to control a running engine), I know this is false. Sometimes a failed cam sensor WILL stop a running engine. You need the G4 Crank sensor, the G28 engine speed sensor AND the G40 cam position sensor ALL to work in order to start the engine. I think you need to pull the codes (go to SJM Autotechnik to find out how). Look for a 2113 blink code = cam position sensor. In the meantime visit this live diagram and click on the labels for the G4, G28 and G40 to learn more: http://members.shaw.ca/speedtek/UrS%...ice%20Map.html __________________ Naturally, IMHHEO(tm), Dave F. aka the Librarian Car and Mods: 93 S4, 1.8t coil pack conversion (First in world using integral POS coil packs (??)), CF (OE), S6 steering wheel, RS2'd, Samcos, MRC, TDS-1, Apikol FMIC, Eibach/Bilstein, BIRA Sys 1, relayed FP Click here to link to the UrS FAQ Thread Start Uncle Dave says "You want my 'high horse, elitist' opinion ?(IMHHEO(tm))Then just post something stupid." Unofficial Chief Cat-herder Vancouver UrS-car club

04-28-2012, 04:28 AM	#3
scarman AudiWorld Senior Member Garage is empty, add now Join Date: Sep 2009 Location: Knoxville, TN Posts: 612	The quandry here is the G28 engine speed sensor fault code displays as a false code when read with the engine not running, so other than checking the sensor itself you have no way to know if the code is genuine or not and a faulty sensor will prevent engine start. Perhaps there will be other codes to point to the problem. __________________ Tom '95 S6 '95.5 S6 avant

04-30-2012, 07:39 PM	#7
UrS4boy AudiWorld Super User Garage is empty, add now Join Date: Feb 2001 Posts: 18,210	Disconnecting the battery will clear the codes in the ECU so pull the codes BEFORE you disconnect the battery. __________________ Naturally, IMHHEO(tm), Dave F. aka the Librarian Car and Mods: 93 S4, 1.8t coil pack conversion (First in world using integral POS coil packs (??)), CF (OE), S6 steering wheel, RS2'd, Samcos, MRC, TDS-1, Apikol FMIC, Eibach/Bilstein, BIRA Sys 1, relayed FP Click here to link to the UrS FAQ Thread Start Uncle Dave says "You want my 'high horse, elitist' opinion ?(IMHHEO(tm))Then just post something stupid." Unofficial Chief Cat-herder Vancouver UrS-car club

05-01-2012, 04:58 AM	#9
scarman AudiWorld Senior Member Garage is empty, add now Join Date: Sep 2009 Location: Knoxville, TN Posts: 612	No, the codes are non-volatile, so they will be there when you turn the key on. If you have cleared them, they won't return until the ECU sees them again. __________________ Tom '95 S6 '95.5 S6 avant

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04-28-2012, 12:20 PM	#4
mURS4 AudiWorld Newcomer Garage is empty, add now Join Date: Apr 2012 Posts: 8	AH YES!! SJM's site is a real god-send us, and honestly I forgot the name of it, so thanks!! I will get the schematic for making another led-tester there and get some codes. UrS4boy: it's the double ground studs in F-L (driver) kick panel, I believe there's a tall double wide, ABS, and one other stubby 5-pin relay. My real concern with the patch-up is that the ground wire innards were nice and toasty. Literally black/green at times and seeming coated when soldering, only on a few of the larger gauge ones. An electrician friend of mine said not to worry, as long as I got them to take a solder. But we all know resistance is present with corrosion! oi. I will try and whip up a blinker and pull some codes!

04-30-2012, 05:59 PM	#6
mURS4 AudiWorld Newcomer Garage is empty, add now Join Date: Apr 2012 Posts: 8	Actually, no.. I'm just being a noob. I havent had to even LOOK at the CEL. Untill now. oi. I was thinking back to my 200tq(10v) days. Starting a new gig today has kept me from getting over to the car as well, being that I live in a apt and the S is at my folks. Looking at SJM's site, Im pretty sure the car even came with the $88 Audi "diagnostic jumper cable". IIRC, In a no-start condition on the 200, you had to crank for something obnoxious like 30 seconds to get the codes out of it. Being that I'm still untrusting of the WHOLE power/ground system, I keep disconnecting the battery.. Therefore killing memory. Chance know if its the same way on the S4? I'll just search through SJM's more, but yes, I was being a dumb..

04-30-2012, 10:38 PM	#8
mURS4 AudiWorld Newcomer Garage is empty, add now Join Date: Apr 2012 Posts: 8	I guess my q was is there a specific cranking time for a no-start condition, time for the systems to even recognize a problem. Or just KOEO initializes a self check of the modules, sensors etc. For sure the ECU is at least talking, because the cel does cycle on/off before cranking. Im almost hoping I dropped the crank position reference pin and just need to weld that sucker. codes first.. codes codes think codes ;p.

05-01-2012, 06:18 AM
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