J757 relay location

[JerseyShoreA4]

Quick question. I know the relay is under the ecu. There are two 614 relays under there and one is the fuel pump relay and the other being the 757? Which is which?

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[JerseyShoreA4]

Long story short, I have a ton of codes, n75, n80, misfires, lean fuel etc etc. I replaced a bunch of parts and I'm now turning to electrical problem. Got a 4 pin relay numbered 644 that they say is the proper one for my problem but under the ecu, both are 614. I'm assuming it's one of those two

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[mtroxel]

[JerseyShoreA4]

Thank you! The pins on the 614 are different thicknesses than the 644. Should that effect them? That's the relay I changed and it didn't do a damn thing. I'm ready to wrap the car around a tree if I don't figure this out soon

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[JerseyShoreA4]

The car is in fact harder to start with the 644 relay than with the 614 in

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[mtroxel]

Are you actually seeing symptoms (hard starting, bad mileage, hesitations, etc.) or do you just have a bunch of codes? And if so, are you considering a goofy ECU?

[JerseyShoreA4]

Doesn't do well over 2500 rpm, need to let off gas a little to up shift most of the time (Tiptronic unfortunately), in limp mode, hard to start but once it's running and driving it's smooth as long as I drive like a 90 yr old lady. Large bridges are no good. I can hit one at 80mph and be doing only 50mph by the time I hit the top and the motor will be screaming in 3rd or 4th gear trying to make it over the bridge.

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[JerseyShoreA4]

Thanks for responding too, I almost edited thus thread to something about air ride or wheel fitment because that seems to be the only thing that gets responses anymore. Not like it used to be years ago when I had my b6

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[mtroxel]

OK, so the codes are not lying. I think you've got to VCDS that thing. Find out if there is boost, log fuel trims, look at timing, etc.

[mtroxel]

I almost edited thus thread to something about air ride or wheel fitment because that seems to be the only thing that gets responses anymore.

[Silveravant]

ECS now shows a 643 relay. The ones in my car were 614. I think the part has been updated. When my 614 was bad all the codes were for low voltage, had p0458, p0245, p2294, p2401, p0031, and p0036. Old relay looked/tested fine, but when i replaced it my EPC and limp mode problem went away. Maybe the relay contacts were dirty.

[JerseyShoreA4]

I've been asking around to people local for vcds and everyone has fallen through on me. I have an eBay cable and it's not reading on the b7, would only read my b6. The mechanic that pulled codes for me didn't get anything for advance timing or anything timing related for that matter but because it wasn't vagcom, I don't trust it 100%.

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[mtroxel]

For all the stuff you got going on, you wonder about something big like timing, boost, fuel supply. Don't know how much you've spent on parts, but VCDS is $350. I used mine all time time.

[JerseyShoreA4]

I've considered buying it and tossing the eBay vagcom cable.

The codes that were pulled were:
P0031 b1s1
P0034 b1s2
P0087 fuel pressure too low
P0089 fuel pressure performance
P0171B bank 1 lean
P0243 turbo wastegate (soildA? Don't know what the mech wrote)
P0300 random miss
P0304 #4 miss
P0444 evap system purge valve open

Over the past few weeks I've installed a new hpfp, cam follower, purge valve, n75 valve, 4 coil packs and plugs. I have a new diverter waiting to go in but the top bolt is a bitch, a new 034 high flow cat with new o2 sensors but that bottom bolt is also a bitch. Lol. I replaced the fuel pump relay at the beginning of the summer but when that didn't work I parked the car and it sat. Last night was the j757 relay which made things worse. I've reset the ecu by doing the key in the ignition/gas pedal trick and that only gets rid of the cel for about 20 or so miles. Epc never goes off. The new relay last night turned the epc off for about 30 seconds

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[JerseyShoreA4]

I dont have a boost guage but i put an aem cone filter on and can hear the car building a little boost and the diverter is working but doesn't sound like it's working properly. Actually sounds pretty pathetic.

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[mtroxel]

Ouch. Low fuel pressure codes lead to lean codes.....no shit!
And that might lead to misfire codes.....no shit!

But I can't connect the rest of those dots. Maybe someone else knows better than I, but I keep wondering ECU or other electronics flakey-ness. Check this thread, he had a mess of codes and found wet relays that solved most of it all.

http://www.audizine.com/forum/showth...terday-2-0tfsi

[JerseyShoreA4]

Yeah I read a similar post to this with someone else having water in their ecu. Mine is bone dry unfortunately. Wish it was that easy to figure out. Lol. I haven't taken the valve cover off yet to check the cam but the cam follower wasn't horrible when I replaced it. It was worn and a little pushed in but wasn't worn through. I've been suspect of cam or timing and praying it's neither but I don't know what else to check. Maybe the ecu is toast? Would vagcom really tell me that though or is that me basically finding someone that would swap an ecu and see what happens?

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[mtroxel]

Yea VCDS wont tell you if the ECU is bad. It only tells you what the ECU is complaining about. But at some point if you get enough codes out of the ECU that don't make sense, ya gotta wonder about bad wiring, bad ECU, bad harness plugs, water, etc.

If you get to that point, about the only way to diagnose an ECU is to pop another one in.

[JerseyShoreA4]

Is there a diagram that will show what fuses control what at the ecu? Behind the relays? I checked the dash fuses and the only one I saw out is the cigarette lighter fuse which I believe a car charger came apart in there a while back and shorted that one.

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[mtroxel]

Check your PM

[Charles.waite]

1) just get VCDS.

2) Look those codes up here: http://wiki.ross-tech.com/wiki/index...ry:Fault_Codes
You'll get lots of Audi specific help there.

3) Stop replacing parts. Usually when you have more than 2-3 electronic failures in one region, its bad wiring or a bad relay/fuse. the component is often fine, but the signals aren't getting to the proper places.

4) Get VCDS

5) the Bentley has all the fuse/relay locations listed as well as their purpose (tahts what the screengrab above is from)

[JerseyShoreA4]

I found that the 15 amp fuse in the brown socket next to the ecu which I'm guessing was the engine electronics fuse 3 was blown. I replaced that fuse but I'm still getting the epc light, cel and limp mode after doing the accelerator reset trick. Left the battery unplugged for a few minutes to try and reset that way too but I think I was too impatient.

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[Okedokey]

I found that the 15 amp fuse in the brown socket next to the ecu which I'm guessing was the engine electronics fuse 3 was blown. I replaced that fuse but I'm still getting the epc light, cel and limp mode after doing the accelerator reset trick. Left the battery unplugged for a few minutes to try and reset that way too but I think I was too impatient.

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You need to short the power leads that go to the battery to discharge the circuitry.

[Charles.waite]

You need to short the power leads that go to the battery to discharge the circuitry.

Yup. Aka, disconnect the positive and negative wires on the battery and touch them together. That will discharge the system.

[JerseyShoreA4]

So after a hard reset the epc came on immediately. Went and had someone clear them and epc came back right away again. Guessing vagcom is purchase in the near future.

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[Charles.waite]

That light will come of for a few miles I believe and will clear on its own.

[JerseyShoreA4]

I drove it about 30 or 40 miles yesterday after trying to clear everything and it stuck around and stayed in limp mode. I have to trace the rest of the wiring I guess and see if there is anything else funky going on. Really frustrating.

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[mtroxel]

My EPC light is always on after I disconnect the battery. Honestly, it goes out by the time I'm backed out into the street.

I had another thought. Sometimes you get electrical flakey-ness from bad grounds. Subaru has those braided grounds from the heads to the body. If those are bad (and they go bad on that flat 4) you get some pretty weird electrical stuff.

[JerseyShoreA4]

Hmmm we are getting some snow right now and I've been busy all weekend with my boys. I'll check the grounds in the next few days. I'm also going to change out the fuel filter. Who knows what my ex did to this thing when I wasn't watching. She was probably running it on regular for all I know.

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[JerseyShoreA4]

I poured seafoam into the tank today also to see if I can clean out the system a little

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[Tenedorr]

Did you ever figure this out?

[JerseyShoreA4]

Wow i havent gotten a notification on this thread to see your post. Car comes back this week. Sent it in to a shop and ended up being multiple things. Intake cam was replaced. Cam tensioner, chain and chain tensioner, pcv valve, diverter valve and a few other odds and ends. Another grand in parts basically. Started with 15 codes when it went in to the shop. After all was replaced there were still 5 codes and no boost. Ended up being a relay under the ecu went bad. No codes now and it pulls like new. While it was there my 034 highflow cat was installed. The diverter is a forge diverter now and new o2 sensors went in too. Cant wait to get it back. Next project is replacing the motor in my touareg in my friends garage one coming weekend. VAG problems. Smh