Flat spot on FI automatic

[raygreenwood]

[Bobnotch]

I prefer to call them out by location myself. That way even the type 4 guys understand which sensor I'm talking about. I even call out the sensor located in the case (68-69 models) the IAT sensor, as it's a 2 terminal sensor found in the D-jet wiring diagrams, and most of the time will be found screwed into the plenum unless were dealing with a 68 or 69 system.
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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]

So....back on page 1....you showed us pictures of two of your SPARE MPS's.

But I do not recall is you showed up any pictures of the back end of the MPS you are using.

Can you post a picture or that please?

Technically there are three basic MPS designs. There is the early "B" with the slotted small diameter screw covered with epoxy. Everything you list says you should have a B system and this should be the correct MPS for your system. It's also what you showed for spares.

The next one is the "E" series that looks very similar to the B....and is parts # 311 906 051 E...but instead of a slotted screw it has an allen/hex key adjustment. Sometimes when they are grimy that "E" can look like a "B" make sure you do not have an "E".

The E has very similar guts to the B but has a hollow adjusting screw and samples atmospheric pressure through that hex screw.

The last version is the C and similar....in type 3.....or B, C, and E in 411/412 and 914 ....type 4....and is totally different and you do not need to worry about that. Ray

[t-royR]

Looks like I have the correct MPS on the car (see photo).

Troy

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T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[raygreenwood]

[t-royR]

Thanks. I have new sensors on order.
I'll get those in and then conduct the other checks mentioned earlier.
_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[t-royR]

Good day,
I have the new temp sensors in the engine. Yay!

I ran the car for a good ten minutes after starting (it was idling perfectly). I ran it slowly up to 1800 and then beyond on the rpms and hit no flat spot. Continued to return to nice idle.

When I put it into gear, it once again dropped significantly in rpms (from 1200 to 550), as was the case before changing out the sensors. And, after putting the car back into neutral, it struggled to idle as nice as it did before going into gear.

Timing is good and plugs too. Valves were adjusted in the late fall. Did a check on fuel pressure and steady at 28 psi.

I must remind that when the car ran at its best a few years back, when I went to start the car when it was cold, it would pop off within 1/2 a second of the ignition key turn. Since these issues, it takes a couple of tries to get the car to start, with having to let it crank over for a good few seconds.

BUT, earlier in our testing of things (page two of this thread I think), I pulled that hose that goes to the tranny, and plugged it. When I started the car with that hose detached and plugged, the car started right off like it did a few years ago. Thought that was worth noting as we move onto next things to test/adjust.

Thanks
_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[raygreenwood]

[t-royR]

taking it step by step here. I ramped the fuel pressure up to 31 psi. Car started fine, (actually, kicked off a bit sooner than it did before this adjustment).

RPM does still drop significantly when put in gear. I'll try reducing the pressure now and report back on that.

I've included a pic of the TB here, as I am not sure how to answer your last question on it.

Finally, I don't have a hand pump to test that modulator. any hacks I can use to test? I have a hand pump I use for sucking old gas out of my tank when I need to. could I McGiver somoething out of that?
_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[raygreenwood]

[t-royR]

Hello,
I brought the fuel line pressure down to 25 and the car did not like it. It started, but took a bit more, and idled poorly. Also, when I gave it some gas, it really complained.

I've added a photo of the TB

_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[t-royR]

Okay. few updates/observations...

1) returned the fuel pressure to 29. idles like a champ. still drops to 500 rpm when put in drive.

2) while idling nicely with 29 psi, I unplugged the case temp sensor, to test the effect I experienced last time unplugging it......which is that the idle increased 100 rpms, and when put in gear, only dropped to 800 rpm. same affect this time.

not sure if we're any closer to a resolution; if there is still a problem (I don't like how much the rpm drops when put in gear); does the effect noted in #2 above signify anything to act on? It is a new sensor

Finally, an observation.....I had the air filter removed while I was adjusting the fuel pressure (and had the car running at that time), and I wondered it there should be any suction from the AAR once the car is warm. I thought it was temp activated, and cut off air once car is warm. I had pulled that AAR earlier and tested it with a hair dryer and found it closed completely. But, wiht that said, I wouldn't expect to have suction from it. I did plug that hose and then dropped the car into gear, which had no different affect than when it is not plugged.
_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[raygreenwood]

[t-royR]

I took my backup pressure sensor apart to get acquainted and to see how dirty it might be. I didn't go deep and take out the inner parts. There was some very small amount of oil in there. So, since I had to move the car out of its winter spot to the garage, I put the backup sensor into the car. Seemed to run rather similar to the one I took out. I'm going to check on the plugs and double check timing.

QUESTION.... I put the new head temp sensor in earlier on. So, today was first test drive with that in. Of course, I park the car and find a nice new oil spot just below that sensor. Sure enough, leaking. MIght have been the source of my mystery oil leak all along. But, question is, what kind of washer goes on the end of that sensor before inserting into the head? I found a spring/wavy washer near my work area, which I think came off there, but not so sure as it is a little larger ID. Looks worn into an out-of-round ID. Can someone point me to the right washer type to put in there??

Thanks
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T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[KTPhil]

The threaded hole the sensor screws into is closed off... no chance of an oil leak.
I think the gasket is as a crush washer to help hold it in place, not a seal.
_________________
Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback

[Bobnotch]

[t-royR]

As always, thanks for the info!

Update....I checked the modulator on the transmission and it does not leak. Yay.

I'll be getting the car out for a good test drive today and assess where things are at now. What still remains for me is to accept and move on regarding the drop in rpm when put in gear. Or, keep chasing it. I think I"ll pull the AAR and clean it good, to make sure it can close all the way. Did that once months ago, so can't figure out why I now have suction on the hose feeding the AAR when the engine is all warmed up. I'll test plugging that hose and then putting the car in gear to see if the drop in rpm changes.

Any other thoughts out there with all I've been through and all I have tested? I'll add one more thing, just for the heck of it......When I had the air filter off as I was changing the fuel pressure, I ran the car and could hear a lot of air moving, seemingly through the oil breather. I could feel the air blowing out of the hose coming off of there that usually attaches to the air filter. That makes sense to me, but the amount of hissing I heard with that air filter off and the hoses to it detached, surprised me.

Thanks
_________________
T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[raygreenwood]