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Discussion Starter #1
Hey gang,

Finally got the Mk2 1.8T back on the road. First light test drive went OK. On the second drive, I had issues after getting into moderately heavy boost. A couple miles into my drive, the car started to lose throttle input after I got into boost pretty good (75% throttle). I would push the pedal 3-4 times before it registered the input, and in order to keep it moving/running, I basically had to give it 80% throttle and slip into the clutch to leave stoplights (read: I looked like a complete goober). I limped it home, fighting the throttle input and near stall issues. There's a serious delay/hesitation upon pressing the throttle, sometimes not registering at all. *the car has a cable throttle, not DBW*.

I scanned it with Torque (no VAGCOM), and this is what I came up with:

P0122 - TPS low input
P1338 - Cam sensor (I found the issue and corrected this)
P1426 - Fuel tank vent valve (I noticed the tank is wet on the pass side below the filler; doubt this would cause limp though)
P1473 - EVAP control open circuit (all the EVAP **** is deleted; again, I don't think this would cause a limp mode)
P1543 - Throttle actuation potentiometer (another TB/TPS code...)
P0107 - *pending fault* MAP/barometric pressure sensor (I need to verify that the person who swapped this carried the barometric sensor over)

The car uses an AEB wire harness and ECU, and I don't care about check engine lights (I don't have one wired up, and there's no smog here). Just want to focus on the trouble codes that will certainly cause limp mode or serious driveability issues first. Thanks in advance! :wave:
 

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2003 GTI 1.8T
Joined
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1,004 Posts
Hey gang,

Finally got the Mk2 1.8T back on the road. First light test drive went OK. On the second drive, I had issues after getting into moderately heavy boost. A couple miles into my drive, the car started to lose throttle input after I got into boost pretty good (75% throttle). I would push the pedal 3-4 times before it registered the input, and in order to keep it moving/running, I basically had to give it 80% throttle and slip into the clutch to leave stoplights (read: I looked like a complete goober). I limped it home, fighting the throttle input and near stall issues. There's a serious delay/hesitation upon pressing the throttle, sometimes not registering at all. *the car has a cable throttle, not DBW*.

I scanned it with Torque (no VAGCOM), and this is what I came up with:

P0122 - TPS low input
P1338 - Cam sensor (I found the issue and corrected this)
P1426 - Fuel tank vent valve (I noticed the tank is wet on the pass side below the filler; doubt this would cause limp though)
P1473 - EVAP control open circuit (all the EVAP **** is deleted; again, I don't think this would cause a limp mode)
P1543 - Throttle actuation potentiometer (another TB/TPS code...)
P0107 - *pending fault* MAP/barometric pressure sensor (I need to verify that the person who swapped this carried the barometric sensor over)

The car uses an AEB wire harness and ECU, and I don't care about check engine lights (I don't have one wired up, and there's no smog here). Just want to focus on the trouble codes that will certainly cause limp mode or serious driveability issues first. Thanks in advance! :wave:
The two I bolded will cause limp mode.
 

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Discussion Starter #3
The two I bolded will cause limp mode.
Thanks much, bud! I figured the same.

I'm on my way to go find a replacement TB...I've read a lot about using various OBD2 2.0L TB's on the 1,8T and vice/versa. Can anyone confirm that those other TB's will work?

And/or, is there a known DIY repair for faulty TB's? I hate that the TPS is no longer a separate (cheaper) part. :wave:
 

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2003 GTI 1.8T
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Have you tried cleaning the throttle plate and cleaned the motor area as well? It's rare for throttle body's to actually fail unless it's the plastic gearing or the motor. The other thing I would look at is your O2 wiring, make sure that's all good, because any short in those wires can kill the throttle circuit in the ECU and trigger false throttle/pedal/epc codes.
 

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Discussion Starter #5
I got it sorted out. Local yard had an untouched '99 A4 1.8T. I replaced the TB, and I had a code for the cam sensor as well...

...good thing I found that Audi. The bolt backed out of the camshaft, and bored a hole through the wires in the cam sensor. :what: It's got Loctite on it this time. haha! :wave:
 
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