BEW misses on cold start

[buyingconstant7]

No matter what the ambient temp, I turn the key, wait for the glowplug light to go out, crank over, and it stumbles a bit and misfires for the first couple seconds. Do BEW's show codes for a bad glowplug? What should I check?

 

[OlyTDI]

Try leaving the key on for another 5 - 10 full seconds after the GP light goes out then start. The glow plugs will continue heating after the light goes out.

My BEW always will "stumble" start if I just wait the few seconds for the light to go out. If I wait a few more seconds, it starts without the stumble.

I use a coolant heater which eliminates needing to do the above when I get in the car in for the morning commute as the car already is at operating temp.

 

[Vince Waldon]

Do BEW's show codes for a bad glowplug?

In answer to your question, yes, they do.

 

[JB05]

I follow Oly's advice. After the GP light goes out the pre glow continues for another 15 seconds or so. I'll still get a minor stumble when the ambient temp. is in the teens.

 

[JETaah]

Make sure that you have glow plugs rated for the voltage that the ECU is programmed to provide. If at some point someone put 11 volt glow plugs in there then you might get those symptoms. It is usually marked on the glow plugs that I have seen. I have seen the same glow plugs being spec'd for the BEW as the ALH and earlier TDIs on Ebay and other auto part stores which they are not.
The BEW glow plugs should be the 5 volt or 7 volt plugs depending on the ECU update.
A 5 volt BEW glow plug that is matched with a 7 volt ECU program will cause a problem to a lesser degree.

A faulty coolant temp sensor may also be an issue here. It does not always register a fault code unless the reading is way off.

 

[PGM jetta]

No, you should not have any stumble. With ambient temperature above freezing, I can start my BEW with a cold engine easily without waiting on glow plugs.

Have you checked or tested any of the glow plugs?

If you remove them all, it would be a good time to do a compression test as well

 

[Vince Waldon]

The "PD worn cam" issue can sometimes start to show itself as cold idle stumble... that eventually becomes warm idle stumble.

A long shot... but if you eliminate glow plugs etc it might be worth the 5 minutes to pull the valve cover and have a peek.

 

[buyingconstant7]

Well, I think I'll just replace all 4 glow plugs. I read through it's previous owners paperwork and it did have a software update to the glowplugs and they all got replaced, but that was a while ago. How do I know which ones to buy? Should I just order them through the dealer?

 

[jasonTDI]

More likely worn injectors far part their service life.

 

[buyingconstant7]

Yeah, the more I think about it, I'll do a resistance test on the glowplugs and see where that lands me. If the resistance is very low like 1-2 ohms, I know they're fine. I'm guessing they will be because theres no codes. Then I'll pop the valve cover and see the cam.

 

[buyingconstant7]

More likely worn injectors far part their service life.

But wouldn't injectors be hard starting? The car starts great, it just stumbles for a few seconds. Fires up fine. The smoke I'm getting is blue, from the turbo replacement I did, there was oil everywhere in the exhaust so every time I start the car there's less and less smoke, but I'll look at injectors if I can't find anything else.