WILL A BAD HALL SENSOR MAKE MY TT NOT START???
Thread Starter
New Member
Joined: Oct 2005
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because no one is giving me any useful information on my emergency situation.
I have to get it running tonight. I was getting a code for the hall sensor, but the car was running fine right up until the TB failure.
So I don't know how the Hall sensor could have gone bad while sitting, and I don't know whether to keep screwing with the timing trying to get it to run, or try to get a Hall sensor from PAP in the morning.
So I don't know how the Hall sensor could have gone bad while sitting, and I don't know whether to keep screwing with the timing trying to get it to run, or try to get a Hall sensor from PAP in the morning.
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Joined: Mar 2005
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I have no idea what you are talking about your TB failure
we need WAY more info to even begin helping you.
1. specific fault code numbers
2. are you getting fuel pressure
3. is there engine damage from your TB failure
4. was your new TB installed correctly
5. are your fuses and relays ok
...and much more. Any specifics you can provide would help your situation. Getting mad and yelling at people here will not help your situation.
1. specific fault code numbers
2. are you getting fuel pressure
3. is there engine damage from your TB failure
4. was your new TB installed correctly
5. are your fuses and relays ok
...and much more. Any specifics you can provide would help your situation. Getting mad and yelling at people here will not help your situation.
Thread Starter
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Joined: Oct 2005
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I asked a specific question and got a less than helpful answer. All my info has been posted in
the last 24 hours. As it turns out, now there is no fault codes showing and still it won't start.
There was damage from TB failure, and the head was rebuilt with new valves, new timing gear, installed per Bentley procedure.
I couldn't index the old belt, as it had taken a dump and wasn't worth a crap. So I'm setting the timing solely by the timing marks on the crank pulley and the cam pulley. Which is a PITA!
I needed to know if a Hall sensor could just go bad in storage, and if that would keep a correctly timed engine from starting, or if there is still something amiss with the timing.
The motor chugs while turning over, and I can smell some sort of combustion residue, but it won't fire.
Any helpful input is graciously appreciated. I'm an experienced mechanic, and a Mechanical Engineer. Comments like "bring it to a mechanic" can be kept to yourself!
There was damage from TB failure, and the head was rebuilt with new valves, new timing gear, installed per Bentley procedure.
I couldn't index the old belt, as it had taken a dump and wasn't worth a crap. So I'm setting the timing solely by the timing marks on the crank pulley and the cam pulley. Which is a PITA!
I needed to know if a Hall sensor could just go bad in storage, and if that would keep a correctly timed engine from starting, or if there is still something amiss with the timing.
The motor chugs while turning over, and I can smell some sort of combustion residue, but it won't fire.
Any helpful input is graciously appreciated. I'm an experienced mechanic, and a Mechanical Engineer. Comments like "bring it to a mechanic" can be kept to yourself!
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AudiWorld Super User
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Go back to basics...
There's fuel, spark and timing. You only have control over valve timing. Fuel, spark and spark timing are go/no go.
Since the TB was replaced, be very suspicious of valve timing. Did you move the crank to TDC (check for the mark on the flywheel through the hole provided in the crankcase). Where's the mark on the cam sprocket?
Pull a plug - is it wet with fuel?
Put the plug back in, but not the coilpack. Connect the coilpack, make sure the metal bushing in one of the mounting holes is grounded, then figure out a way to have a screwdriver or a spare plug or ??? pushed into the coilpack and also held close to the valve cover while someone cranks it over - is there spark? (it was so much easier when there were plug wires)
What codes does VAG-Com pull?
Since the TB was replaced, be very suspicious of valve timing. Did you move the crank to TDC (check for the mark on the flywheel through the hole provided in the crankcase). Where's the mark on the cam sprocket?
Pull a plug - is it wet with fuel?
Put the plug back in, but not the coilpack. Connect the coilpack, make sure the metal bushing in one of the mounting holes is grounded, then figure out a way to have a screwdriver or a spare plug or ??? pushed into the coilpack and also held close to the valve cover while someone cranks it over - is there spark? (it was so much easier when there were plug wires)
What codes does VAG-Com pull?
AudiWorld Super User
Joined: Mar 2005
Posts: 11,616
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cam sensor fault can indicate timing is off
seen it before. when the crank pulley is lined up to its mark the cam gear mark can look a tooth off from the mark on the valve cover. It doesn't seem to line up exactly, but it is in time.
If your timing is off and the engine does run the ECM will throw a cam sensor fault code about a half mile down the road, and CEL comes on.
If you have a cylinder compression gauge I would see if all 4 cylinders are within spec. In the meantime verify the engine is in time using the marks.
It is possible the cam sensor got damaged somehow during the TB fiasco, although that is pretty rare. but I believe the ECM will use the crank sensor to get the engine running if it can't see the cam sensor. Make sure it is plugged in first of all.
If your timing is off and the engine does run the ECM will throw a cam sensor fault code about a half mile down the road, and CEL comes on.
If you have a cylinder compression gauge I would see if all 4 cylinders are within spec. In the meantime verify the engine is in time using the marks.
It is possible the cam sensor got damaged somehow during the TB fiasco, although that is pretty rare. but I believe the ECM will use the crank sensor to get the engine running if it can't see the cam sensor. Make sure it is plugged in first of all.