Blew my turbo yesterday, swapped it, and now no fog lights.

[USAF Long]

I blew my turbo but it had been making noise for like a week. I had another K03 so I rented a u-haul trailer and towed the car to my friends house with my truck. Took us 6 hours to swap it in a 1 car garage with hand tools. We pulled the front bumper off to put the car in service mode. After putting it back together I hooked up the fog lights but they don't work and the dash says fog light bulbs out. Do I need to reset the battery? We fired it up without the headlights and foglights on the car to make sure nothing was leaking.

[daverdfw]

I blew my turbo but it had been making noise for like a week. I had another K03 so I rented a u-haul trailer and towed the car to my friends house with my truck. Took us 6 hours to swap it in a 1 car garage with hand tools. We pulled the front bumper off to put the car in service mode. After putting it back together I hooked up the fog lights but they don't work and the dash says fog light bulbs out. Do I need to reset the battery? We fired it up without the headlights and foglights on the car to make sure nothing was leaking.

did you leave the harness disconnected on the driver side? there is a connector that goes from the car to the bumper, and then it goes to both fog lights, Check to make sure its completely engaged.

[USAF Long]

I'm 99.9% sure that was reconnected.

Also on the way home the car sputtered and wouldn't accelerate or boost, but wasn't misfiring. No misfire codes. I had to pull over on the highway and shut it off, restart. It revs but won't boost. Only codes are the rear O2 heater circuit failure and rear O2 something else... I have a test pipe so those codes are normal.

[old guy]

Check and make sure one of your boost hoses hasn't come loose.

[USAF Long]

Everything looks good, no leaks, no loose hoses. I put on a silicone turbo inlet, new DV, and new PCV. New clamps on all connections. Does the N75 have a specific setup? We put it back the way we thought it was routed. One line from front banjo on turbo to one side, other side to wastegate port, and 3rd port into turbo inlet.

[old guy]

Make sure the long port is plugged into the TIP. Also make sure the harness plug has a good connection.

[USAF Long]

I think that's how I have it but I will double check it. Does it matter if I have the wastegate and charge pressure hoses in the opposite ports?

[old guy]

Yes it does because of the restrictor on the charge pressure port.

[USAF Long]

I'm going to run new vac lines from the turbo to the N75 and report back. According to the Torque app on my phone my car is requesting like 6-9 psi at part throttle but I'm not getting it. No underboost code though.

Reset the battery and still no change. Lights still not working. Going to unplug and check the connector for the fogs on the left side behind bumper also.

[USAF Long]

So last night I ran new vac lines to the turbo nipple, the N75, and the wastegate actuator. They were correct but they are brand new now. Still no damn boost. We did pull the headlight and unplug and reconnect the fog harness, now my fogs work.

Today, on the way to a car show I was driving down the road and reset my fault codes with the Torque app on my phone. Car immediately stalled. I pulled over, it would crank and fire, hunt for idle then stall.

I did the throttle body adaptation, reset battery for 5 minutes, turned key on and let it sit for 5 minutes, and still nothing. My friend came to get me in his B7 avant and we unplugged the MAF and my car fired right up and idled smooth. WTF??

So I have a spare MAF I can swap the electronics from, but still no boost at all.

[old guy]

Did you by any chance monitor your LTFT's with TorquePro prior to resetting the ECM? I don't think you have a MAF sensor problem. I think you have false air entering somewhere after the MAF and as a result you were running some very high fuel trims. When you reset the ECM the fuel trims reset to zero and your engine leaned out to the point where it wouldn't run. Unplugging the MAF sensor reverts you to programmed fueling maps based upon throttle position, MAP sensor, IAT etc.

That source of false air is also probably what is causing your no boost condition. Are you sure your DV is installed and working properly?

[USAF Long]

I will pull and inspect the DV. Thanks for pointing me in this direction. Might be time to buy a new 710N. I have a Evolution Motorsports valve that I've never seen anyone else run.

[USAF Long]

Update:

Got the belly pan off and the lower turbo to IC crossover pipe hose had blown off. My friend who helped me swap turbos didn't put the hose on far enough and clamped it behind the lip on the pipe. It blew off as soon as I boosted on the highway. Fixed it, plugged MAF back in, cleared codes. Now it runs great again. I feel stupid for not checking this before trying to troubleshoot the N75 but I couldn't lift the car at my apartment in my car port.

[old guy]

That would be Post Number 4 ;-)

Glad to hear you got it figured out!

[USAF Long]

I miss having a garage. My apartment has a policy where you can't work on your cars on the property. So I had to wait til I could get it somewhere.