73 PCV Valve Failure

[JoMoSqBk]

Searching the forums I have not really found a good solution for this. In 2003 I found Ray talking about it on another site where he recommends using a plastic marble with a 3 mm hole drilled into it. in place of the flap and spring. Is this still the best solution?

Here is a video of plugging this port at idle which I think idicates failure

Link

[raygreenwood]

[JoMoSqBk]

Perfect I'll go dowl shopping today! I have a friend who is going to try his hand at 3D printing a replacement for me so I'll let you know how that turns out.

Is there a video of someone adjusting the MPS? I'd like to see it happen before I go in there. I am very afraid of this part. I know it shouldn't be that hard but the idea of ruining it makes me sick.

To adjust fuel pressure is there a trick to this? I have a newer Airtex 2 port pump. is there an adjustment on the regulator or do I swap it out with a different one?

When you say idle adjustment you are referring to the idle air screw and checking the timing correct?

[Bobnotch]

[raygreenwood]

[JoMoSqBk]

Thanks for all the help!

Alright, so I drilled a 2mm hole in a 1/2" aluminum rod and installed it. This fits perfectly and has removed the vacuum leak. As you suspected my fuel pressure was too high at about 32 PSI I backed this down to 28 but I am still rich (or maybe lean?). I have limited power until I get into higher RPM also there is almost no power difference between half throttle and full throttle. Hopefully not TVS too (which is the 10 wire)?

Below are the images of the installed dowel as well as my MPS. That black cap on the back does not remove easily so I am guessing the next step would be to pull it off the mounting bracket so I can fully see what I am doing?

[raygreenwood]

Ok....good stuff.

I would make that aluminum dowel easily removeable so you can tune its opening diameter if needed. It needs to be large enough to flow some air.....but small enough to moderate the vacuum leak it really is....in a stable manner. But it's there...thats good so far.

Also understand about the fuel pressure issue. As noted....every +/- 1 psi is a a +/- 3.57%.....so the actual pressure is critical.

But also.....these injectors are low impedance....so they have low internal spring pressure ....and have a large pintle with a narrow angle. They have issues when they get up around 35 psi or higher. They have problems re-seating/re-ssaling the pintle ahove 2000 rpm. Tbeh have a tendency to keep flowing and revert to a stream instead of a spray.

So.....if you are above 30 psi.....and are not using a gauge that is KNOWN to be accurate.....you could be enough higher in pressure to cause issues. So its good to keep it at 28.....normal.....with the possibility that you can go up to 32 psi if you need a little.

I think you MPS is a "B" unit.....have to check my cheat sheet. Read the parg number to us please.

You need to check the resistance of the outer pair of connectors on it and then the inner pair. You need to check that it holds vacuum indefinitely. If you have a hand pump....great. if not just pull off the hose, suck on it and hold your toungue over the end. 10 seconds will tell you.

Thats probably a four wire TVS....right? If your system does NOT have a vacuum pressure switch under and bolted to the underside of one of the runners.....then your WOT enrichment is part of the runing of the MPS and the circuitry in the ECU and probably one WOT contact in the TVS....so TVS has to have the correct part number.

That black cover on the back of the MPS is an anti tamper cover. It does not,come off without breaking it.....which ro me means nothing. If the MPS needs to be adjusted it needs to be adjusted.

More when you tell us what you have. Ray

[JoMoSqBk]

Thanks for the quick clear feedback!

Just to be clear the PO swapped my injectors so they are no longer needles but have three holes. These have worked well for quite a while so I do not suspect them.

I trust the pressure gauge is accurate. It is brand new and when I made changes it reacted as it should.

My MPS Part number has a Bosch number and a VW number:
0280100116
311 906 051 E

Checking resistance at 2k I get the below readings if this should be a different multiplier I can give those as well:
Outside 93 ohms
Inside 343 ohms

My TVS actually has 5 wires running to it it is part number 311 906 111 E. I am not sure about the pressure switch or WOT so if you need more details about these please let me know and I can do a little research.

I am good with cutting the cover off just say the word

[JoMoSqBk]

Also, I am not sure if it is relevant but my plugs are longer than the standard so I am wondering if somewhere along the line there was an adjustment to add HP and that would explain the higher fuel pressure?

[raygreenwood]

[KTPhil]

[raygreenwood]

[Bobnotch]

Ray, what you're calling the "B" MPS (for a t-4), is the C-D MPS (70-71for a t-3). The T-3 got the "E" MPS for 72-73, and it is different from the t-4 "E" MPS.
The "A-B" t-3 MPS is the simple set up with a divorced pressure switch, and a 2 wire MPS unit. Don't know if this helps clear up things, or makes it more complicated.
What jomosqbk (the OP) has is a 70, that uses the copper plate inside the MPS, or the "C-D" system.-
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120

[raygreenwood]

[JoMoSqBk]

Yep I am all 73 and matching E's across the board.

I took the TVS out and cleaned/oiled it well last night. Thanks for the step by step guide! Two quick questions before installation.

In your guide you also remove the throttle body, this looks a little more involved on the T3 than the T4 is this necessary or can I run the tests with the TVS mounted back on the car?

Also, I have lost a considerable amount of brass over the years is this a concern? Is there a repair I can do? I scooted the contact over a MM or two to make better contact.

[raygreenwood]

[JoMoSqBk]

I adjusted the best I could but no matter what I do there is too much play in the plastic piece. After opening the throttle it will always return to the off pole even when turned all the way out.

I adjusted the pressure plate that sits against the throttle return but that did not correct the issue either.

Should I go ahead and begin adjusting the MPS with the TVS as close as it can be to being set? Right now it is driving like it is out of time (it isn't) there is very limited power and I can barely accelerate up even the smallest incline.

*Edit for clarity the power issue is worse at higher speeds and higher gears but can be felt immediately.

[KTPhil]

[raygreenwood]

[raygreenwood]