AFB Carburetor: Cold Start Problems & Solutions

Hello everyone!

Okay, now that it's getting colder at night again, I'm having a problem with cold starts in the mornings or after being stationary for a long time. It usually only works on the second or third attempt. The preheating indicator light only comes on for a maximum of half a second when the ignition is turned on. I assume that, according to the engine control unit, preheating is not necessary at the current temperatures?
I've already tried using the VAG-COM software to increase the starting fuel quantity, but it doesn't work because I can't access the necessary adjustment settings with the standard login.
'However, I find it hard to believe that this is solely due to the starting amount, so I'm asking if anyone has any ideas or experiences regarding this strange behavior? He now has 158,000 km on the odometer and otherwise functions perfectly... he easily reaches his top speed...'

At what outdoor temperatures does it typically start to overheat?
If it doesn't need to be red hot to work, why does it start up so poorly?

It would be great if someone had an idea...

Best regards.

DENNIS

Hey,
Generally, preheating starts at around 5 degrees Celsius. How long does it take you?
He starts up? / Does it start up?

Best regards from Bielefeld.

Peter.

Hello!

It's actually quite different. Sometimes it comes on after 1-2 seconds and then turns off again. Usually, it starts working after the second or third attempt. This afternoon, it took 3-4 seconds before I felt any sign of life, but then it stayed running.
'There's nothing in the error memory. Also, it doesn't produce excessive black smoke after starting, and I haven't really seen any blue smoke either. At least, I haven't noticed anything so far. I'll keep an eye on that next time I start it.'

Regards,

DENNIS



Hey,
Generally, preheating starts at around 5 degrees Celsius. How long does it take for you?
He starts up? / Does it start up?

Best regards from Bielefeld.

Peter.

Hey,
'My Volvo does something similar from time to time. I've managed to get it started by giving it a little gas during the start-up process. How good is your battery? Maybe the starter motor is already struggling a bit, and that's why it's not getting enough power.'

Best regards from Bielefeld.

Peter Schwarck.

Hello Peter!

The battery is 6 months old and has a voltage of 12V and a capacity of 100Ah. The voltage indicator and the battery's performance are normal.
I didn't experience these problems to this extent last winter, and now I'm encountering them even with relatively mild nighttime temperatures.
Even with my previous 4-cylinder TDI models, it usually only took about a second for them to start.
I would say there's a 99.99% chance that the battery is the problem.

DENNIS


Hey,
'My Volvo does something similar from time to time. I've managed to get it started by giving it a little gas during the start-up process. How good is your battery? Maybe the starter motor is already struggling a bit, and that's why it's not getting enough power.'

Best regards from Bielefeld.

Peter Schwarck

Hi.

Are all the glow plugs and the fuse for the preheating system working properly?

Have you ever measured the voltage at the spark plugs during afterglow (after a cold start)?

Hello Ulf!

During the last inspection (approximately 18,000 km ago in February), all six glow plugs were replaced. I haven't checked the fuse or voltage yet. But as mentioned above, it doesn't actually start to glow until 5°C? So, the problem shouldn't be related to a lack of glowing or a faulty fuse, right?

Regards,
DENNIS


Hi

Are all the glow plugs and the fuse for the preheating system working properly?

Have you ever measured the voltage at the spark plugs during afterglow (after a cold start)?

GarfieldMZ wrote:

During the last inspection (approximately 18,000 km ago in February), all six glow plugs were replaced. I haven't checked the fuse or voltage yet. But as mentioned above, it doesn't actually start to glow until 5°C, right? So, the cause shouldn't be related to a lack of glowing or a faulty fuse!?

Hi Dennis,

Yes, that might be true.

I don't know the 6-cylinder engine well, but I think that even with the current outdoor temperatures, it definitely glows in the morning.

If that doesn't work, it might be a reason why it keeps turning off again, in my opinion.

Hi Ulf!

Tomorrow I'll try to check the fuse and see if there's any voltage reaching the glow plugs. Normally, you should be able to get the glow plugs to heat up using the 'actuator test' function in the VAG-COM software, even without it being cold.

I'll get back to you by then at the latest!

Group 0.

DENNIS



Hi Dennis,

Yes, that might be true.

I don't know the 6-cylinder engine well, but I think that even with the current outdoor temperatures, it definitely glows in the morning.

If that doesn't work, it could, in my opinion, possibly be a reason why it turns off again.