Hard starts when car sits overnight/RPM gauge slow to read

Hello everyone, ever since my runaway I had a swap put in my a local TDI guru.

My MK4 ALH has been running great so far *knock on wood* but there are a few things I did notice with this engine.

1) When the car sits overnight and I try to start it in the morning, it starts but it doesn't start on the first crank. I think it's 2-3 cranks for it to fire up.

When the car is driven around for a bit and I try to start it, it obviously fires up great.

2) When I do start the car, I notice a delay from when the engine starts and the RPM guage starts to read.


With my car, I have a new GP harness and the GP system works. The only thing I haven't done with this engine is replace the glow plugs as they are the ones the previous owner had in there.


Any suggestions on what I could do to help the car start up better?

Assuming you are correct about your glow plugs (they don't operate above 9 deg C anyway despite what the light shows. Clutching at straws, pull out your crank sensor and clean off the accumulated metal filings on the magnetic tip. Costs nothing. Of course your fuel lines are bubble free?.

Is it common for the crank sensor to be cleaned? I've searched this forum and haven't found much at all on this.

Crank sensors are fairly low price (25.00 IIRC) but I am not certain if it would help with the starting.

Has anybody cleaned the crankshaft sensor? does it make a noticeable improvement in starting?

I have already tackled my starter/alternator which are problem free and both rebuilt.

I've cleaned mine with sucess after reading about it on myturbodiesel.com
You don't need to change it. Your motor won't start if the sensor is bad. I mentioned it as it's a remote possibility for you and it happened to me. If it is the problem you will find it has grown a bears of iron filings.

You could check that your timing is at the advanced end of spec (with VCDS). That may help. Increasing the cranking speed would help too. Maybe your battery is a bit weak. When the ambient temperatures start getting high enough that the glow plugs aren't used, the car might appear to have a harder time starting than you would expect at that temp.

To be explicit, you're probably experiencing longer crank times after the car has been sitting for a while because the temperatures inside the cylinder when the diesel is injected is low. Crank speed, timing, glow plugs and ambient temperature all play a role.