Mk1 tdi starting problems

[Mihkel Ader]

My 1.9tdi AFN cranks for 4-5 seconds before it starts, hot or cold its  the same, tried new coolant temp sensor, but still cranking 4-5 secs before starting. When i disconnect the coolant temp sensor it starts right away? Is this something with the ecu?

[johnnyroper]

Have you tested the glow plugs? Unplugging coolant temp sensor will cause them to glow longer if they are slow heating then they could possibly be the cause as light will go out before they reach operating temp.

Mark 1 TDI is the VE engine I think so glow plugs more critical than the later PD lumps.

[Mihkel Ader]

The glow plugs are good, i checked them. Can the maf be causing this? if i unplug the maf while the car is running nothing changes

[brianh]

How have you checked them? Its unlikely to be the maf, but try starting it in that state.

Is it any better if you try restarting it within a minute of stopping, or is it the same sort of delay?

[Chrispb]

Have you had a cam belt fitted/changed recently or anything else done where the timing may have been altered.

[Mihkel Ader]

I checked the resistance and i tested them by taking out all and seeing if they work correctly and heat up fast. I replaced the injection pump with a new one, the timing should be spot on and pump adjusted.

[Mihkel Ader]

I will test the maf tommorow, i have another one i can put on.

[Chrispb]

Re check timing with VCDS and for any codes, assuming starter is cranking engine over fast enough as i'm sure there can be a problem if the cranking speed is too slow.

[Mihkel Ader]

There are no codes, timing is set and cranking speed is high enough im sure because when i disconnect the coolant temp sensor it starts instantly .

[Chrispb]

I still think you may have a timing issue, these engines also suffered from a worn crankshaft sprocket which could allow the timing to alter a few degrees.
You should be able to see the timing dynamically if you have VCDS

[Mihkel Ader]

The timing is spot on, injection pump timing is set also perfectly.

[christiant]

Making the glow plugs glow longer makes it easier to start but could be masking issues. It is very possible the Bosch VE pump has something to do with this issue. Normally if the plunger is starting to wear out on rotary pumps it gets harder to start when hot. It is also very possible it is slow cranking speed even if it seems to be cranking fine. How are you checking the timing? You can try to advance it slightly.

[Mihkel Ader]

I checked the timing with vag-com, it was almost at the most advanced part of the timing with it starting still like that, but when i set the timing to the middle it still does it.

[christiant]

It is very possible your cranking speed is low. Check your starter motor for bushes on the shaft etc. it is very common for these engines with high mileage. It is worth mentioning the battery must be good too. I have come across this issue before.

[Mihkel Ader]

I dont think it has anything to do with the starter/battery since when i unplug the coolant temp sensor it starts perfectly

[johnnyroper]

Sounds fuel/engine related to me unplugging coolant temp is allowing glow plugs to run for longer and mask it.
Did you replace the VE pump for this fault or did fault start after pump change? Also was the pump new,recon or used?

Assuming pump is all ok I would get injectors checked and do a compression test if the timing is definitely spot on.

[Mihkel Ader]

The car was not wanting to start , so i got the pump restored by a local. And after that it didnt do it at first but over some time it started doing the long starting.

[christiant]

If so, that seems like a very likely pump issue. Try to crank it for 2 seconds and then try to start again. If it starts better most likely the pump has an issue.

[Chrispb]

Is the stop solenoid on the pump receiving voltage when first cranking engine with coolant sensor connected.