Recently purchased TDI Jetta

Hi, I am trying to fix an issue that seems to be slowing down my TDI. It runs cold and sometimes has trouble accelerating by bogging down. So it can, but not always feel like it is missing. Sometimes cant climb hills just have to go slow. I think the thermostat is either stuck open of it is the wrong one (guessing 160 degrees) Also guessing it needs a 190 degrees to run at full capacity. Already tried cleaning the EGR valve, draining the water from the fuel filter, and primed the fuel lines from air. I learned the hard way which additives not to add to the tank. Also tried spraying cleaner solvents/water into the air duct to flush out the carbons. All this worked great but still having a bogged down sensation when stepping on the gas sometimes. Any ideas?

Find someone with the VCDS tool and get it scanned. No point in just guessing when you can know. There is a list here that has the people with the tool and willing to help. Find someone near you.

Here:

http://forums.tdiclub.com/showthread.php?t=296841

Welcome!

add your transmission to your vehicle description

OH OK I almost forgot, I scanned it with the OBD and it gives a P code of P0128 which reads NO DTC which I am told it means "No Code" or running to cold.

BobnOH it is Automatic

I still can't believe people dump water down the intake of a diesel, it already has such tight tolerances due to the ultra high compression, one good gulp of water and you will have a bent rod.

Water seems to work very well at 2000 RPMs, I would only spray it in slowly if idling, rev a little and spray a little back and forth.

So I am kind of going back and forth by draining the fuel filter, priming the fuel injectors and spraying out the throttle body with water and spraying out the EGR valve with carburetor choke cleaner. I observed a few youtubes to get the experts advice on how to. I did replace the thermostat and since it is running hotter it is releasing more carbons into the EGR valve and clogging it up again. I can see fuel deposits on the block under the overflow hole on the EGR valve. And some the research tells me it has been stuck open and not stuck closed. Research points to EGR valve mostly needing to be cleaned and not replaced in most cases but I am still unsure. Tomorrow I am driving home (about 200 miles) and I will be able to tell if I fixed the issue. I dont want to start new thread to ask for help but no one has made any helpful comments yet.

Vacuum Lines,check the vacuum lines.Mine bogged down a lot. Redid all lines and runs like raped ape.
Ron
2/99 VW Jetta TDI 1.9 5 speed

New air filter and clean the snow screen? Also how about a NEW fuel filter and thermostat. It takes a good 15 miles in cool weather to get up to the 190 mark and will not get up there if only left to idle? Even at 160 though you should have plenty of power not a noticeable miss

I found a Youtube on how to spray out the EGR and I went back and did it and also primed the fuel injectors a bit better. I drove 200 miles after that without a single issue. So I suppose either air in the lines, vapor lock or EGR needed a little more cleaning, but it runs good now. I dont know if it will come back up again or not. I will have to wait and see.

Well I got a few miles down the road and her it comes again. Finally I disconnected the wires to the one fuel injector that has that wire running out of it. It ran smooth and never gave me another issue. I am now seeing that it was the faulty injector. But I learned that TDI has 2 types of injectors. 3 are pressure injectors and one is a combination pressure and electronic injector. I had to disconnect the electronic portion so it would only run from pressure and it was all good. This one injector is made to dump excessive fuel into the cylinder when the motor is cold to aide in cold starts and warm up fast.