2002 VW Jetta 1.9L TDI internal IP pressure questions...

[Josh8Loop]

Fellas,

Just the other day I was reading a post by Hagar I believe about adjusting the internal IP pressure to about 76 at 1000 RPM. I rigged up a pressure guage that measures the internal IP pressure from the vent bot on the back of the IP. I am measuring 100 psi at idle for the pressure....Is that a little too high? It also takes probably 25 or so seconds to reach this pressure. Any thoughts?

[Josh8Loop]

Guys,


Just wanted to give some background and a little info on my IP pressure dealings. Probably 3 weeks ago I read a thread about adjusting the IP internal pressure back to specs on VW diesels. Since I get a little gung ho on things I decided to go ahead and tap a little bit on the IP fuel pressure adjusting fitting on the top of the IP. At that time I had no way of measuring the pressure it started out at, and hence no way of testing the pressure after the adjustment. Not having a way to test the pressure during modification was a big no-no I know, but I did it any way. After this mod I knew I needed an easy and unobtrusive way to measure the IP internal pressure. Here is what I did to create a fuel pressure test port:

I went to the junk yard and obtained a stainless steel fuel rail fuel pressure test port from a chevy or chrysler vehicle(for free). These are the pressure test ports that are on gas vehicles, and they have a schraeder valve in them, and a black plastic cap that keeps dirt from the test port internals. I cut the test port out of the vehicle with tubing cutters, and left about 2 inches on either side of the test port. After some injection pump research, I located a direct path to the inside of the IP that I could hook my pressure test port to in a pretty straightforward fashion. I took out the bolt/vent plug on the back of the injection pump(the side facing the engine), and drilled a .080 hole straight through it. Once the hole was drilled, I cleaned the bolt/vent plug and got it ready for brazing. I also prepared the pressure test port by first removing the schreader valve(so it wouldn't burn while brazing), and cutting it down a bit so it would fit directly on top of the bolt/vent plug. I went ahead and brazed things up, cleaned the assembly, and checked for braze continuity.

Everything looked good, so I placed the schraeder valve back in and torqued it back onto the injection pump. By the way, without the black cap the new pressure test port doesn't interfere with tightening the bolt/test port if you use a socket. This gave me a nice handy test port, and I could use my current fuel pressure test guage that I use on my wifes gasser. The best part about this mod is that I can place the black cap on the test port, and since it is on the back of the IP, you would never know it was there!

[Fatmobile]

Got any pics?

[Josh8Loop]

I am not set up for photosharing, but I will see if I can snap a few photos.

[CoolAirVw]

You did this on a tdi?


.

[Josh8Loop]

CoolAirVW,

Yes, this was done on a TDI. I finally got arounf to posting photos with PhotoBucket:





http://s877.photobucket.com/albums/ab334/jamsue4him/


We will see if it works!

[MayorDJQ]

Why did you want to adjust the internal pump pressure? The IP has a pressure relief valve, aka Case Pressure Relief Valve. Plus, any excess fuel is sent back to the tank.

Were you having problems of some sort?

[Josh8Loop]

Mayor,

No problems neccessarily. I read a post one time about increasing mileage on some older(80's)diesel engines by readjusting the internal fuel pump pressure on some injection pumps that were worn. Some of the guys were able to get their mileages up to where they were when the car was newer by simply setting the pressure back to factory specs. I had played with(adjusted) my pump pressure without having a guage on it, so I thought I would install a test port and see if it was acceptable. I have gotten no gains, which isn't surprising since my pump is fairly(118K miles) new, but at least I know where it is set.

[CoolAirVw]

Hmmmm....

On the IDI IP, raising or lowering the internal pressure adjusts the "injection timing curve"

On Tdi the timing is controlled electronically. You probably shouldn't mess with it.

You now need to look to see if you've messed something up. Scan with vag-com to check the injection timing. Hopefully the computer is able to compensate for the adjustment you made.

Then "cloud" the graph as you drive to see if the computer can control the timing under most driving situations.