Cylinder pressure sensor Adaption ground signal runtime

[jj20_09]

I have an 2011 Jetta sportwagen. Do not know if I am having an issue or not. The VCDS says everything is fine. No issues. Sometimes, especially when it is cold, it will seem to have a miss or hesitation. When you let your foot off the breakbyou will feel a kind of jerking. You press the gas and it goes away. You can bring the RPMs uo slightly and its fine. By slightly I mean just above idle. Sometimes it will run quite and after it a few seconds makes like the old school diesel knock sound. Got to looking at everything in the live stream data and found that in channel 146. Cylinder pressure adaption ground singal runtime for cylinder 1 is negative 7ms. Cylinder 2 and 4 are about 10.5ms and cylinder 3 is 14 5ms. I can see 3 being higher if it is making up for 1. Just do not know what it is taking about. Is that normal? Do I have a problem with clinder 1 injector? I have already swapped 1 and 2 glow plug since the sensor is in the glow plug and it stayed with cylinder 1. Does that mean I have an bad ground in the harness? Sorry for being ramdon. Just trying to figure out what this means. Any help would be awesome.

 

[oilhammer]

Go to MVB 141, this is the data for each cylinder pressure sensor.

Have that up on a cold start, and swing your PC around so you can see it from under the hood. While it is acting up, gently wiggle around on the plug connector(s) and see if anything changes.

Your description sounds like you may have a spotty injector spray pattern on #1. And the nailing sound you are hearing would suggest that as well.

If it goes away once warm, I'd probably try the easiest stuff first. Injector cleaner in the tank (BG245 works pretty good, LiquiMoly has some even better stuff). Run a few tanks treated with that and see if anything changes. Next step would be trying some diesel "purge" but that is a little tricky to set up and use on a CR engine (although it can be done). This involves making the engine run exclusively on a strong cleaning agent for a few minutes, bypassing the car's own fuel supply.

I've not run across much of any issues like this with the CJAA's piezo injectors. But it is VERY common on the CKRA engine's solenoid injectors. Luckily on the CKRAs, the injectors are relatively inexpensive. The CJAAs, no so much. So I'd at least try the cleaning first.

 

[jj20_09]

Ok thanks. Ill have to get some. Ill try and find some LiquiMoly stuff. It does it more when it cold and at idle. I don't notice it when you have the RPMs up. The injectors were replaced probably over a year ago by what I thought was a good German auto shop but when I started the car up go home apparently numbe 3 injector was not seated well and popped out. So I have little faith in them putting quality injectors back in it.

 

[oilhammer]

You may want to check to see if they even input the injector calibration numbers properly then.

2.0L CR TDI - Ross-Tech Wiki