Surging follow-up, need part, electromagnetic valve

adamharo

Following up on my other post, according to the shop I have a bad idle up valve, or they said it might be called an electromagnetic valve. Are either of these the proper names for the part? Any idea on who would carry one or is there is a part off a newer vehicle that would work?

Thanks
Adam

raygreenwood · Posted: Sun Nov 04, 2012 8:52 am Post subject:

Are they speaking of the electric deceleration valve? The one that is triggered by a presure switch from the automatic transmission? Confused

Uh...no...Im not buying that. If its causing surging...just disconnect it and plug the line to the manifold. Comparatively few cars came with that valve (California mainly). Plenty of automatics including my first 411 came with the pneumatic version of that valve and worked fine. Even without it out all you get is sime mild popping on deceleration from high speed.

Yes...it could be kicking in and out at the wrong time causing intermittent enrichment, but more often its the control relay or the pressure switch that is at falt. Unlesss you are in Californis or really want to save it....remove it and go to a vacuum version of the valve which is also easier to adjust.

Also...long before you suspect that part...have you checked the other items I listed? Ray

adamharo · Posted: Sun Nov 04, 2012 11:56 am Post subject:

Thanks Ray. They did check fuel pressure. Supposedly they were also checking temp sensors too. I'm not sure they were suspecting tthis valve as causing surging as much as throwing off fuel mixture. So you are saying this valve can be bypassed without issue?

Tram · Posted: Sun Nov 04, 2012 1:08 pm Post subject:

Are they talking about the vacuum dash pot?
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 50360

Pictures?

adamharo · Posted: Sun Nov 04, 2012 9:38 pm Post subject:

I'm going to run by the shop tomorrow I will grab a picture of the valve. According to them it is specific to automatics.

raygreenwood · Posted: Tue Nov 06, 2012 7:47 pm Post subject:

Yes...good question Tram. The vacuum dashpot on the 411/412 with D-jet is an automatic transmission part. Its hard to do without and it can be problematic. its not really hard to adjust.....but with age it can leak causing slight problems.
Also if the egnine has low compression because of age....it usually also corresponds to erratic vacuum signature which can cause the valve to be difficult to adjust correctly.
If you also have a deceleration valve that is malfunctioning or adjusted incorrectly...whether its pneumatic or electric...it can cause issues with the dashpot. All of this can be compounded....even with a properly working dashpot.....if your automatic transmission modulator is not properly adjusted.

What this dashpot does is to prop the throttl very slightly open as you gear down or come to a stop until the torque converter decouples and take the load off the engine. The dashpot is to keep the engine from stalling as you come to a stop.
You can get along without it with some careful adjustment of ignition timing and idle speed. Slightly higher than stock idle can keep teh car from stalling. It can also make the transmission slightly jumpier off the line.

The deceleration valve I was speaking of is helpful. It is actually slightly redundent in most later cars. Its purpose is to bleed a little air into the mixture...which actually slightly richens the mixture because it affects the MPS.....when you come off the gas at high rpm. When the throttle snaps shut at high rpm.....the vacuum spikes to its highest point. That causes the MPS to trigger full lean, but your ignition advance is still at maximum. To keep from getting popping in the exhaust or pinging....the decleration valve pops open and bleeds in some air right next to the MPS vacuum line triggering slight enrichment.

The redundent issue is that on later models of D-jet with fuel cut-off on the TPS....if the throttle snaps shut...fuel should be shut off. I "think" I had heard maybe from Brad Anders that the rpm signal keeps a certain amount of fuel running. I do not know that for certain.

Either way....I have found you will get better running when going without the decel valve at most throttle settings by pulling the wire that signals fuel shut off out of the plug for the TPS at least temporarily. Ray

adamharo · Posted: Mon Dec 17, 2012 10:20 pm Post subject:

Just got my car back from the shop and it runs like a new car. They yanked out the fuel injection and put in a carb. Downside is I have a square box in the middle of the back cargo area but with the way it is running I could care less.

I have a bunch of injection parts if anyone is looking.

Next thing to consider is the tranny. It is pretty tired. After talking to the shop I think we'll be doing a swap to a manual tranny in the spring.

Lahti411 · Posted: Mon Dec 17, 2012 11:38 pm Post subject:

NOOOooooooo!

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Wildthings · Samba Member Joined: March 13, 2005 Posts: 50360

If a center mount progressive runs well out of the box it is probably running way too rich. There were a lot of better options out there your shop could have chosen that didn't involve butchering your car; a variety of dual carbs and several styles of FI.

raygreenwood · Posted: Tue Dec 18, 2012 4:42 pm Post subject:

Tram · Posted: Tue Dec 18, 2012 5:21 pm Post subject:

Mike Fisher · Posted: Tue Dec 18, 2012 5:28 pm Post subject:

A VW garage in Eugene wanted to do that to my '69 FI/AT squareback! It just had a plugged up fuel return line, I found out when I towed it to a different mechanic.
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adamharo · Posted: Tue Dec 18, 2012 11:43 pm Post subject:

Honestly the carb swap made sense. The shop is very reputable in my area, the parts needed to get the FI were not available. Ray, I would be interested in a link to the rebuild kit for the AT. This isn't something I plan on dealing with till spring when I have the money. The AT currently works but shifts from 1st to 2nd very early and slips when shifting from 2nd to 3rd.

Tram · Posted: Tue Dec 18, 2012 11:53 pm Post subject:

Bobnotch · Posted: Sat Dec 22, 2012 1:24 pm Post subject:

KTPhil · Posted: Fri Dec 28, 2012 3:48 pm Post subject:

Lahti411 · Posted: Mon Dec 31, 2012 3:26 am Post subject:

By the way, as you now have taken all the FI parts out, you'd have a perfect opportunity to clean the parts and electrics, change the injector seals, change the fuel lines and vacuum pipes. Then, when you have the time, just put everything back to your car and enjoy driving! Infact changing to carburettor might have been a great idea: now you have a driveable car which you can enjoy, and you can repair the FI without any hurry!
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adamharo · Posted: Mon Dec 31, 2012 10:34 am Post subject:

Alright, I get the carb switch appears to be a mistake. Pardon my ignorance and I mean this in all seriousness but can someone explain why? Aside from modifying the engine cover I don't get it. It seems the FI parts are hard to find whereas a carb can be easily replaced. Maybe the FI system gives you more power but it's not a race car anyway and it moves out pretty well.
Is everyone just a VW purist?

KTPhil · Posted: Mon Dec 31, 2012 2:33 pm Post subject:

FI gives better starting, smoother idling, better mileage, and lower emissions. It actually does not do much for power. It just gets you that power in a more efficient way.

And once you get the wiring fixed, and your gas filler water entry problems, it will be more reliable. Parts are easily found here on the Samba, or on ebay.

Take the advice, good though perhaps said tongue in cheek, to clean, rebuild, and rewire the FI, and put it back on next time you have a couple of days and are sick of the constant fiddling carbs bring you.

And yes, some of us are purists! But VW got it right with the simple FI they introduced on these cars.


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Surging follow-up, need part, electromagnetic valve
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