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V10 no start when hot

2979 Views 65 Replies 8 Participants Last post by  Professor Eggman
So I'm almost able to drive my 2006 V10 after a year, but I cannot get the engine to start after the coolant gets up to temp. When the engine is cold, or slightly warm, I can kill it and it will start right back up. When it's up to temp, if I kill it and immediately try to restart, it just cranks. I'm reaching the end of my ideas to figure this out. Here is what I've done so far to try to change this:

Fresh fuel
Removed and cleaned fuel pumps/filters, new fuel filter
Hardwired fuel pump to run continuously
Added jumper cables to another running engine to add starting power
Released pressure in coolant system
Opened PCV to atmosphere
Removed coolant temp connector
Removed coolant return temp connector
Opened ECU to check for corrosion: appears all intact, no areas of damage or corrosion
Checked all fuses and relays

Currently, cam position sensor is still reading "signal out of range", so signal return wire has been removed from ECU wire harness. This leaves "no signal" fault.
Also, Steering Angle sensor is not working despite all wires being intact and voltages present, leading to steering and steering wheel electronics faults.
Batteries and related grounds are in good condition, with batteries being kept on a charger/tender.
I'm also posting before and after scans of the hot no-start, as well as video of it cranking while hot.
If I can solve this, I'll finally be able to drive this beast on a regular basis.
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That sounds like the classic Crankshaft position sensor failure that is common over multiple vehicles and manufacturers and often does not throw a code.

When the sender gets hot the resistance changes and the vehicle won't start.

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If it was the ground....why does it start with cold engine without issue?

Remember he said it only fails to start once the engine warms up.
One last Rando thought. You were messing around with the ECUs if I understand correctly. I think behind #1, there's a critical ground to the body that is often not properly reattached or damaged during work. Without that ground, your injectors won't fire. Might be worth checking it and cleaning it.

Do you smell fuel when cranking?
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I just went through this whole thread again as there's a lot of flaky info in it.
I don't even know how both you and the OP have gone to the Crank sensor, when the codes are for the CAMSHAFT

What am I missing?
You should work on your reading comprehension then.

I mentioned that Crankshaft sensors often fail when hot without throwing a code.

This is not just a VAG problem. I have read about the same issue with Ford, Chrysler, GMC, Honda, etc etc.

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So what's he getting his hot rpm readings from? The same failed hot sensor?
So I postulated about a possible issue right near the beginning of this whole thread, well before the OP had even tried to log his RPM. All the information that was available from a VCDS scan with time stamped codes.

You then play Captain 20/20 hindsight and dredge my post up way down the thread, well after the OP has now provided logged RPM values and claim I am throwing out misinformation.

So once again, you need to work on your reading comprehension and context. If I had a crystal ball back at the start, he would have it fixed now.

At no point later in the thread did I say it was a crankshaft sensor there Turbo.

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