Vacuum Hoses and the Idle

[HMeeder]

I have read many times in some of the old posts about the mysterious Missing vacuum hose. My '74 is missing the second nipple from the throttle body and therefore just has the hose that runs from the retard side (this also caused the car to fail CA smog, tech wouldn't listen to my pleas of "it's supposed to be that way!" connected a hose and snaked into oblivion) Any rate, dwell and all ignition is good and timing is dead on with the vac disconnected. The moment I connect the vac back up, the car dies and I cannot get it to run well at speed or at idle. My idle screw only goes in about 1/2 way and then stops. Now if I connect the advance side to the nipple, the car runs great. What's up with that? I'm banging my head against the wall here.

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Herb

[John Rogers]

Well you appear to have the hoses hooked up wrong, I.E. the single vacuum connection does in fact go to the retard side of the distributor. Having it hooked up to the advance side will cause the advance to kick in at idle which is wrong. If your idle adjustment screw does not get full travel there may be dirt of goop from the gas in the port. If you take off the air cleaner and then remove the screw and spray some carb cleaner through the hole, you should see it come out inside the throttle body. If not, then a through cleaning is in order. Good luck.

[HMeeder]

Yes, exactly my problem. When I hook up the retard side, the car won't run right (at idle or speed) I performed dwell and timing adjustments without vac attached, then I hook up the retard hose and the car dies. If I try running down the street that way, the car stutters and surges and runs lousy. If after that I hook up the hose to advance, the car runs fine. Stranger and stranger. I'll go back in and try to blast Berryman's through the idle screw hole. Maybe that'll allow me to get and idle and I can start working on my other prob. Thanks.

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Herb

[John Rogers]

Also pull the distributor cap and check the advance springs/plate. Once the engine starts to come up in RPM the vac drops and the retard on the distributor disappears and the mechanical advance should kick in to give correct timming. Sounds like a rusted advance weights problem? Good luck.

[HMeeder]

Thanks John:
I will check the weights, but I'm afraid the solution was simpler than that. Afraid, because it was at least partly my fault. The car failed smog and I was in a huge hurry. I took it to a local "VW/Porsche" shop to get some quick action. Well, the clown attached the advance side to the TB and then leaned the car out so he could get the car to fall into specs. By attaching the retard back up and richening the mixture, car started and now runs very good (not great, still a touch of surging, but the sputtering and popping is gone. I still need to fiddle a bit to get things where I want them) Car still hunts a bit and I'll methodically begin to replace all the hoses and boots and seals until it goes away. Expensive and irritating lesson learned. I think I'm going to go stalk that mechanic (OK, no I won't but I am going to get some money back)

Herb

[rich]

Just goes to show ya! If you want something done right you have to do it yourself!! I hate that!! Man,!! Geeezzz! Fix it right! A good friend of mine once said, "you get what you pay for if your lucky" Sorry I'll stop going off now...

[Steve M]

You may still want to investigate why the idle screw doesnt come out all the way. It may not be a good idea to spray it directly down into the manifold. You could get whatever dirt is stuck in there into your intake.
Not to insult your choice in method of repair, but I would never trust a grease monkey to work on my car(s). Not even a dealership, very rarely do they know what they are doing. I can say this because I used to work in a body shop and saw the quality of personel at these 'mechanics' rodeo's.

[HMeeder]

No insult. I question it myself. This shop was supposed to be a "specialist" on the car. I haven't gone back to discuss the job with the guy yet (I'm on my way there now). While I am no expert myself, at least I know what I've done and can either undo it or blame no one but myself for not doing the research to ensure the work is correct. :mad

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Herb

[HMeeder]

Ok, so here's the deal. The guy at the the shop insists that the advance side is the one that should be hooked up to the TB. Says that since I monkeyed with the hoses myself, he won't honor a refund but wants to find out the truth. Doesn't trust DD's diagram because it's not "The Manual" (you hear that Dave?) and the miscellaneous ramblings of a couple dozen guys on-line count for even less (despite that fact that they work on and play with the things daily). The diagram in the Haynes manual is useless. Of course his guy says he's been working on aircooleds for 25 years and has never heard of such a thing. He claims that he is going to check the factory manual (strangely doesn't happen to have one on hand) and wants to make good on the repair. The guy seems earnest enough, so I'm going to try and prove it to him. Does anyone out there have access to the manual to back up our claim (see how I got you guys involved in this?) or is there a factory machanic who can throw some weight behind this? Help! I hate being screwed?


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Herb

[John Rogers]

I'd forget it and find another mechanic. Then I would file a complaint with the Better Business folks. Because he said he worked on aircooled engines doesn't mean Porsche type IV's. The vacuum still goes to the retard side of the vac pot. Good luck.

[JP Noonan]

The two ports on the TB and the dizzy are different sizes if you look closly. One is 4mm the other 5mm. The 4mm from the TB goes to the 4mm on the dizzy and so on.

[John Rogers]

I happened to remember that in Panarama a couple of years ago there was an explanation of the d-jet system, distributors, etc and a comment was made about the distributor with two ports but only one port on the throttle body and how to hook it up. You might want to check them to see if you can find it. Good luck.

[Dave at Pelican Parts]

Sadly, the factory manual is of no help at all. The diagrams in it are from some VW application, and don't even mention throttle bodies with only one fitting. I think the diagram in Haynes is the same one from the factory book.

There is a diagram in the 9/93 (I think) issue of Panorama, where Allan Caldwell published a diagram of the vaccuum hoses for a 73 2.0. That does have the two fittings on the throttle body, but it shows which one goes to which side of the distributor dashpot. Yes, it matches my diagram. Would your mechanic trust the PCA National 914 Tech guy?

--DD

[HMeeder]

Thanks for the help and constructive? criticism. I have no intention of ever letting those guys near the car again. I plan on looking my mechanic in the eye every morning as I brush my teeth. The car is running very well now and I've got a few small problems on the motor to fix (managed to accidentally yank the CHT lead off, $20.00 later that's fixed, also rebuilt the distributor and cleaned up the injector points while I was checking the weights out.) I'm not a PCA member so I really don't have access to old copies of Panorama(or know anyone who does.) I suppose there may be something in their "Fixin Up Der Porsche" series as well. Again, not accessible to me at this time. Chalking it up to experience and cursing their ignorance and my trusting nature (I'm usually cynical and suspicious by nature.)

Herb