Trying to understand the new EA288's behavior in a GSW

I am on my second tank of fuel, and also vent through my first regen with this car.
Regen was as usual, raised idle speed, cooling fans blasting, noticeable noisier exhaust tone at the tail pipe as well as hotter exhaust coming out of the tail pipe, MPG drops on MDF.

Two things that are new to me on this new engine behavior:
Also want to verify if others are experiencing the same thing.
1) idle speed seems to fluctuate with no good reason btw about 850 RPM and about 1000 RPM. (not during regen.)
I am thinking this may have something to do with keeping emission parts hotter for EPA reasons.
Sometimes in park at normal engine operating temps
RPM may be 1000 other times 850- minutes apart. AC on or off does not matter. In gear (D) waiting at the stop light , same thing it is either 850 or about 1000 RPM. (again not regen). it did this from day 1 with 15 miles on the car.
2) relates to regen: with the new urea injection, is the additional fuel dumped during regen to heat up DPF, is fuel directly injected after the turbo and front of the DPF?

3) head lamp output/ halogen: is it reduced power to 12V (bulb life extender) like it is on the Passats? or is it getting full alternator output/battery voltage?
Did not see anything in VCDS.

I can't answer many of the questions, but the idle speed is something many of us started noticing when it started getting hotter early in the summer.

For me, basically if the car is sitting in the sun on a hot day, the idle immediately after start will be ~1000. This seems to be insensitive to toggling the AC on/off. Usually after i drive for a while, if i then hit a stop, the idle will be back to 850. There are 1 or 2 threads on this point here, I think the consensus being it is related extra power draw/ alternator voltage requirement upon hot start.

I've been a little uncomfortable with this explanation, however, because it seems to happen with or without AC on, and I don't know what else could require higher alternator voltage in hot temperature. It for sure is related to outside temp though.

Fuel is not injected after the turbo.

2) relates to regen: with the new urea injection, is the additional fuel dumped during regen to heat up DPF, is fuel directly injected after the turbo and front of the DPF?

Click to expand...

pretty sure the extra fuel is injected with the regular injectors AFTER combustion is complete and the exhaust valves are open, and the burnt gasses are being pushed out...Thus providing extra fuel to light off the DPF and cause the regen...

SO same as on the previous model engine.
Would be nice if they would just put an extra injector after the cylinder head, like chevy does it on the duramax, if I am not mistaking it is after the turbo.. But I am sure there is a reason why VW do it this way, which is unknown to me.
I was just curious.
sounds good
thanks

charley654 said:

SO same as on the previous model engine.
Would be nice if they would just put an extra injector after the cylinder head, like chevy does it on the duramax, if I am not mistaking it is after the turbo.. But I am sure there is a reason why VW do it this way, which is unknown to me.
I was just curious.
sounds good
thanks

Click to expand...

Just read on here that is how it is being done...have not seen anything to make me believe anything else...
It's a proven Zero added cost way of doing it....
Most us HD diesels (over the road) in trucks use the same techniques... Heck, modern motors like Detroit DIESEL DD-13, AND DD-15 use the same techniques...Detroit diesel is actually euro owned now....

It would help to get a VCDS and run some logs.

these would reveal the relationship between DEF injection, DPF regeneration, and idle speed, among others.

would be interesting to see if the DPF regeneration cycle would disable DEF use.

Do over the road trucks coat the DPF with additional catalyst and react the DEF? or is the DEF injection and reaction done in a different part of the system?

the VW TDI EA288 package is a marvel of packaging and efficiency. less parts, less weight... if you need fuel in the exhaust, and can use the injector, why not? why would you want a separate system?

meerschm said:

It would help to get a VCDS and run some logs.

these would reveal the relationship between DEF injection, DPF regeneration, and idle speed, among others.

would be interesting to see if the DPF regeneration cycle would disable DEF use.

Do over the road trucks coat the DPF with additional catalyst and react the DEF? or is the DEF injection and reaction done in a different part of the system?

the VW TDI EA288 package is a marvel of packaging and efficiency. less parts, less weight... if you need fuel in the exhaust, and can use the injector, why not? why would you want a separate system?

Click to expand...

OK..I'll try to keep this simple, the DPF and DEF are to different systems.

Most Big Bore Highway trucks use post engine injection, which yes means an injector after the turbo. Usually it's the smaller engines that the base injectors to get the fuel to the after treatment.

The DPF is there to collect the soot. When soot load get high enough a regen is started to burn down the soot to harmless particles.

During a regen extra fuel is put into the exhaust and that fuel then reacts DOC to rise the temp in the DPF to 1000F to burn down the soot.

The DEF/Urea injection system is there to reduce NOx. A few years ago the emission standards were relaxed enough that NOx could be controlled with EGR alone. Now they use a combo of EGR and Urea injection to reduce NOx levels.

On highway trucks the DOC/DPF/SCR(DEF) systems take up alot of room. VW has found a way clever to pack all this into a pretty small package but it's doing the same thing.

Keep it simple all you want, but the 2015 EA288 engines sold here inject the DEF fluid between the DOC and DPF, and the fluid reacts with the exhaust in the DPF.

http://www.volkswagenag.com/content...n.html/binarystorageitem/file/VIAVISION_e.pdf

see page 7.

meerschm said:

Keep it simple all you want, but the 2015 EA288 engines sold here inject the DEF fluid between the DOC and DPF, and the fluid reacts with the exhaust in the DPF.

http://www.volkswagenag.com/content...n.html/binarystorageitem/file/VIAVISION_e.pdf

see page 7.

Click to expand...

I was referring to the question of how highway trucks do it.

FreezingInSask said:

I was referring to the question of how highway trucks do it.

Click to expand...

thanks for the clarification. my bad I lost the transition between the trucks and the car.

hello, please excuse me for my bad English, with me the problem is when I'm driving at a distance of 70 km and stop at the traffic lights and the engine shakes. in the morning strain I start it no problems. do you have any idea what it might be like?

https://www.briskoda.net/forums/topic/455699-clha-engine-16-tdi-105-hp-problem/ first video is my engine in idle . Only idle problem . No fault code , no low power . No chek engine light .

https://www.briskoda.net/forums/topic/455699-clha-engine-16-tdi-105-hp-problem/[/url] first video is my engine in idle . Only idle problem . No fault code , no low power . No chek engine light .

charley654 said:

Two things that are new to me on this new engine behavior:
Also want to verify if others are experiencing the same thing.
1) idle speed seems to fluctuate with no good reason btw about 850 RPM and about 1000 RPM. (not during regen.)
RPM may be 1000 other times 850- minutes apart. AC on or off does not matter. In gear (D) waiting at the stop light , same thing it is either 850 or about 1000 RPM. (again not regen). it did this from day 1 with 15 miles on the car.

Click to expand...

Not sure if this answers this, but something about the mk7 that I immediately noticed and hated is that the idle is at 1000rpm when at a red light if I am holding it with light pressure on the brake pedal. Press harder and it drops to 850rpm. Could that possibly be the case for OP?

Darth_Furious said:

Not sure if this answers this, but something about the mk7 that I immediately noticed and hated is that the idle is at 1000rpm when at a red light if I am holding it with light pressure on the brake pedal. Press harder and it drops to 850rpm. Could that possibly be the case for OP?

Click to expand...

i was gonna say the same exact thing, press harder on the brake when waiting on the red light and it drops, or put the lever in neutral, it is actually wearing out the clutch when you holding the brakes lightly

definitely seems to me to be DSG related.

push in on the brake, it disconnects the trans (~puts it in neutral) and the RPMs drop. release the brake slightly, it reengages the transmission and raises the idle to prepare for takeoff