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Wants to be TheFlipperGray
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7,339 Posts
Discussion Starter #1
Hey all, looking for some PW advice since AZ is slow right now..

I was dropping off some old B5 parts and slid on a small patch of black ice during heavy rain/snow. I got control of it quickly and drove away fine, but after that I have lights all over the place and am in limp mode. There are 5 codes, so I was hoping for assistance before just throwing parts at it.

P2138 - Throttle/Pedal Position Sensor/Switch "D/E" Voltage Correlation
P0106 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal
P0237 - Manifold Pressure / Boost Sensor (G31): Signal too Low
P0102 - Mass Air Flow Sensor (MAF/G70): Signal too Low
P2128 - Accelerator Position Sensor 2 (G185): Signal too High (PENDING code)


Some notes:
- max boost is around 2-3lbs
- intake and intercooler piping is intact, no vacuum leaks (reading 22inHG0
- no rough idle or misfires, runs relatively normal
- can't accelerate up hill, pedal can be pushed a bit or a lot and speed doesn't increase (not sure if because NA 1.8..)
- cleared the codes and unplugged the battery for a few hours, to no avail. Codes returned, and was still in limp mode.

I don't think five sensors can just go out at the same time, so if anyone has ideas I'd like to hear them. I researched each code individually, but I'd rather have some help before I starting throwing parts at it. Any input is appreciated.

Thanks,
Aaron
 

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Maybe pull the connector for the ABS controller? I know that's been responsible for all sorts of fascinating bizarro issues before. I can't imagine any "real" problem that is going to cause every sensor entire intake system (except your IAT, curiously enough) to pack up and go home at once.
 

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Wants to be TheFlipperGray
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7,339 Posts
Discussion Starter #3
Ironically enough my ABS light went off driving to a friends house. So one down, two to go.

Someone suggested I check the 02 sensors and connectors, as a short in that line can cause all of those codes. I'll do smaller things too like swap MAFs (should have an extra around here somewhere) and TB adaptation. But I'll pull the plug on the ABS module as well to see what happens.
 

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Wants to be TheFlipperGray
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Discussion Starter #5
I love how this is one of those weird five sensor problems where there's no definitive answer and even has the pros stumped because there isn't a solid haha. Well I don't love it, I just find it amusing that I get these issues.

Thanks Steve, I will take a look at all the fuses tomorrow. I'm not sure why I didn't think to do the obvious sooner. There has got to be something electrical that ties all these systems together. 02 sensor is one, fuses very well may be another.
 

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Wants to be TheFlipperGray
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Discussion Starter #6
If there's one thing that can cause irratic electrical signal behavior, it's heat.

Anyone know what wires are within this loom, the one resting happily on the very hot cat?

 

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Wants to be TheFlipperGray
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Discussion Starter #7
The loom is connected to the MAF, so this is likely the cause of my codes.

But I'm concerned about whether or not I can cut out any melted wires and solder new wire in, or if it's too late and I need this section of the wiring harness.
 

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RETIRED Super Stealth Moderator
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27,902 Posts
it's never too late, Aaron. I'd take the time to remove the melted wiring, and solder new wiring in - use heat shrink on each individual wire, as well as over the entire section of harness. you obviously need to change the run so it's not sitting on the cat, as well...but you know that.

how did it get there in the first place?
 

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Wants to be TheFlipperGray
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Discussion Starter #9
I think one of the clips popped out (the plastic tapered cone shaped ones that fit into a plastic circular housing) when I spun. The car did jerk very suddenly and very fast so it's very possible.

Wiring is the one thing I am more than confident in (all those circuits/electronics labs come in handy with VAG car ownership), so I will solder in new wires and heatshrink them, then put them back in the loom and cover with electrical tape. I already moved the loom out of the way with VW/Audi tool #3 - zipties, so I'll be sure to keep it off the cat from now on.

So I'll cut open the loom after work and report back. Thanks for the reply, Jay :thumbup:
 

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who woulda have thought?

some burnt wires... i'm sure i've seen a few fires here and there and something like this very well could have caussed them.. consider yourself lucky!
 

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Wants to be TheFlipperGray
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Discussion Starter #11
Yeah, I'm glad nothing caught on fire. I'll consider myself lucky when I can boost again! I'm sick of daily driving this car without a turbo.

But I knew it had to be something strange because there's no way that five sensors will just go at once, coincidentally.

I'm not sure when I can do the wiring. I changed a tire in my apartment parking lot and got in trouble, I changed my valve cover in the parking lot and got in even more trouble. I might have to wait until Friday to get this done when I can go to Worcester. She'll have to be a slow DD until then...
 

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I feel your pain re: apt parking lot, all we have are cramped garages...so I did some stuff out in front of the leasing center on a Saturday. They didn't appreciate it.

GL with the soldering!
 

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Wants to be TheFlipperGray
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Discussion Starter #13
I have to wait until I can go to Worcester where me and a buddy have a garage, or my parents house in Auburn. This is one downside of the city life :(

But thanks man, I'll be sure to update the thread with results after I can dig in.
 

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Administrator
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can't you just pull into a vacant lot somewhere to get it done? At least patch them up temporarily until you can do a clean job....
 

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Wants to be TheFlipperGray
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Discussion Starter #15
I could, but my soldering iron and heat shrink are in the garage. I don't want to dig into it and half ass it with electrical tape in a parking lot. She's driving fine, albeit without a turbo, so I don't think more damage can be done in the few days before I can get home. I don't want to find be stuck in a vacant lot in the middle of Boston if I make any kind of electrical mistake.
 

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Moderate Moderator
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16,486 Posts
I once used a computer UPS to power a soldering gun out on the street for a couple quick solders. It worked great. The amount of solder time you'd get would depend on the capacity of the UPS and the hunger of the soldering tool.
 

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Wants to be TheFlipperGray
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7,339 Posts
Discussion Starter #18
UPS.. or USB?

I have an old fartsy one I snagged from my electronics lab before graduation.. nothing fancy.
 

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Moderate Moderator
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Uninterruptible Power Supply. USB power probably won't provide enough watts to do soldering. I unplugged the unit from the wall and carried it out to the curb. Plugged the soldering gun into it and it provided 120vac to power the gun. This was an APC ES-750 supply and a 100/140 watt gun. I made two or three solders in cold weather and it put out enough power to heat the gun like it was plugged into a wall outlet. I don't know how many solders I could have done on one charge. This was an older unit with the original battery pack. APC ES 750VA Power-Saving Battery Backup, 100V
 

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Wants to be TheFlipperGray
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Discussion Starter #20
Ohh that makes sense. I have a few power supplies lying around, but I'd still rather wait until I'm out of the cold and wet weather and in a nice warm garage with wall outlets.
 
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