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dayunbao
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PostPosted: Sat Feb 10, 2018 1:18 pm    Post subject: Strange engine idle Reply with quote

I've noticed that about a minute of two after starting my car, the engine begins idling in an unusual way. I recorded the car while it was idling this morning so you could hear what I'm talking about. I made a YouTube video of it since that seemed like the easiest way to share the audio. Here's the video:


Link


I don't know much about the history of this engine. The odometer is broken, so I don't know how many miles are actually on it (been meaning to look into fixing that). The previous owner didn't ask the original owner much about the engine, either. So, I don't know when, or if, the engine was ever rebuilt. As far as I know, this is the original engine with the original FI system. No carbs.

The engine was running fine when I bought it, so I haven't had any work done on the engine yet. I'm sure it needs a tune up, and I guess it's time for me to start learning how to do that. It only recently began developing this weird idle. In the last few days it also developed some minor issues when starting (a slower, lower sound when turning over, turning over for longer before the engine starts, having to pump the gas to get the engine going, sometimes dying right after the engine starts). I'm going to start looking through my Bently's, and order "How to rebuild your Volkswagen air-cooled engine." I'm hoping whatever is going on with the engine can be fixed by something relatively simple (adjusting idle, adjusting valves, etc.).

By the way, what is the deal with using fuel injector cleaner in our old cars? Can we use any of the typical off-the-shelf varieties? If those are OK to use, I'll try putting some in with my next tank of gas and see if that helps with the issues that have recently popped up.
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PostPosted: Sat Feb 10, 2018 2:11 pm    Post subject: Re: Strange engine idle Reply with quote

Sounds like a lean idle surge.

I'd start with a full tune-up, including valve adjustment, dwell, timing, and clean/gap the plugs. Eliminate all other causes before trying to "fix" the FI system.

While you are tuning it, check for leaks in any hoses, especially those to the MPS and AAR from the plenum.
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PostPosted: Sun Feb 11, 2018 11:05 am    Post subject: Re: Strange engine idle Reply with quote

If all that doesn't fix it ( what KTPhil recommended), then you'll need to bump the idle down.
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PostPosted: Sun Feb 11, 2018 4:02 pm    Post subject: Re: Strange engine idle Reply with quote

I watched some videos on how to adjust valves, but all the cars whose valves were being adjusted were Beetles. Since the engine layout is a bit different on my Fasty, I wanted to confirm a few things.

First, to turn the engine over so that the valves are in the correct position, I'll have to turn the nut on the generator, located in the lower left hand side of the picture below, right?

Image may have been reduced in size. Click image to view fullscreen.


Here's close up:

Image may have been reduced in size. Click image to view fullscreen.


Is there a way to tell top dead center from looking at that part? I noticed a small square piece of metal in one location on the wheel near that nut. Does that show you where TDC is? Or do you have to go by the position of the rotor in the distributor? Speaking of which, the part of the rotor that is "pointing" is the side with the orange mark and metal tip, right?


Image may have been reduced in size. Click image to view fullscreen.


I noticed that the metal end of the rotor was a bit scored, and there were corresponding abrasions on the contacts under the distributor cap. I took some closer pictures, but they are pretty blurry (cheap phone). Anyway, I've includes them below.

Image may have been reduced in size. Click image to view fullscreen.



Image may have been reduced in size. Click image to view fullscreen.


Is that normal? Or is that an indication of a problem?
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PostPosted: Sun Feb 11, 2018 8:01 pm    Post subject: Re: Strange engine idle Reply with quote

Any manual will show you how to set TDC. What manuals do you have?
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PostPosted: Sun Feb 11, 2018 9:58 pm    Post subject: Re: Strange engine idle Reply with quote

I have the Bentley, and read through it this morning. I guess I didn't see where it said how to set TDC. I'll look again.
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PostPosted: Mon Feb 12, 2018 12:38 pm    Post subject: Re: Strange engine idle Reply with quote

Yes, the cap and rotor are normal. That's called "carbon tracking". It's from the spark jumping the gap in the cap.

Other than the lay out being slightly different from a bug, the adjusting process is still basically the same. You bring cylinder #1 to the to (firing position), and adjust that set of valves. Rotate the engine backwards (CCW) 180* to #4 firing position, and adjust that set of valves. Repeat for #3 and #2 cylinders.

There's also a short cut version, but you'd have to look it up (it's in the type 3 forum).
I hope this helps.
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PostPosted: Mon Feb 12, 2018 2:46 pm    Post subject: Re: Strange engine idle Reply with quote

Thanks, Bob!

I guess what my original question was this: Given that the crank pulley isn't accessible on our Type 3s like it is on a Beetle, then do we only have the position of the rotor to indicate TDC? On the JBugs site (http://www.jbugs.com/vw-auto.html), it says this (emphasis mine):

Quote:
Pull off the distributor cap and locate the small notch on the rim. This notch indicates cylinder #1. Rotate the engine by either turning the generator or alternator pulley with a 19mm wrench or by turning the crank pulley with a large adjustable wrench until the rotor is pointing towards the small notch on the distributor. Then and most importantly line the large notch on the crank pulley or the markings on your degreed pulley up with the centerline of the case. This is top dead center (TDC) for cylinder #1.


The notch on the crank pulley (http://www.jbugs.com/store/graphics/00000001/Small%20notch%20on%20rim.jpg) seems like a really easy way to know how everything is lining up.

I haven't had a chance to double check my Bentley's yet, but will tonight. I just wanted to clarify my question.
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PostPosted: Mon Feb 12, 2018 3:09 pm    Post subject: Re: Strange engine idle Reply with quote

The crank pulley is easily seen through the round hole on the rear belt shroud. It should normally be plugged with a rubber plug when done. People often bugger up the hole by prying on the pulley with a screwdriver to rotate the engine. You may have to flatten it back out before a plug will fit.

Check Bentley and your year/engine code and make sure the pulley marks are what they should be-- sometimes people change out the pulleys. Below are two variations. Also check this link:
https://www.thesamba.com/vw/forum/viewtopic.php?p=8409670

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


Also see:
Image may have been reduced in size. Click image to view fullscreen.


See how there is a "bridge" between the lobes? At 180 degrees, you will see three lobes similarly bridged. The center lobe is exactly 180 degrees... or close enough for valve setting.
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PostPosted: Wed Feb 14, 2018 9:44 pm    Post subject: Re: Strange engine idle Reply with quote

KTPhil wrote:
The crank pulley is easily seen through the round hole on the rear belt shroud. It should normally be plugged with a rubber plug when done. People often bugger up the hole by prying on the pulley with a screwdriver to rotate the engine. You may have to flatten it back out before a plug will fit.

Check Bentley and your year/engine code and make sure the pulley marks are what they should be-- sometimes people change out the pulleys. Below are two variations. Also check this link:
https://www.thesamba.com/vw/forum/viewtopic.php?p=8409670

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


Also see:
Image may have been reduced in size. Click image to view fullscreen.


See how there is a "bridge" between the lobes? At 180 degrees, you will see three lobes similarly bridged. The center lobe is exactly 180 degrees... or close enough for valve setting.


Wow, thank you so much for all the info! I'm in the process of getting the parts and tools I'll need to adjust the valves, replace the points, and replace the spark plugs. I won't have time to do any of that until the weekend, though. Hopefully my engine will be happier after I get all of that work done. Thanks again!
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PostPosted: Sat Feb 17, 2018 6:50 pm    Post subject: Re: Strange engine idle Reply with quote

Adjusted my valves today. Most were too tight. Unfortunately, the problem I was having didn't go away. In fact, it got worse. So, I either botched the adjustment, or the valves being in the right place exacerbated the problem. Once I got the car started (it took a few tries), the idle sounded fine for about 2 minutes, then it began sounding like the audio clip I posted (but worse). One thing I noticed while cycling through the cylinders was that I didn't hear any hissing sounds like I did in the YouTube videos I watched of people adjusting valves. In one video, the guy doing the adjustment mentioned how that's a good sound and shows that the engine doesn't have any compression issues. Related?

I got new spark plugs, but still need to get a few tools before I change them. I also didn't touch the points. I bought new points, but doesn't an adjustment, or installing new points, require a timing adjustment? And you need a special tool to change the timing, right?
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PostPosted: Sun Feb 18, 2018 1:40 pm    Post subject: Re: Strange engine idle Reply with quote

New points ALWAYS have to be adjusted. Use a feeler blade and work carefully. Same requirement as valve adjusting to feel for the SLIGHT drag on the blade. Make sure it's aligned and not cocked.

THEN adjust the timing. You can do it with a stroller moving, or at rest using a bulb/test light.
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PostPosted: Sun Feb 18, 2018 2:42 pm    Post subject: Re: Strange engine idle Reply with quote

KTPhil wrote:
New points ALWAYS have to be adjusted. Use a feeler blade and work carefully. Same requirement as valve adjusting to feel for the SLIGHT drag on the blade. Make sure it's aligned and not cocked.

THEN adjust the timing. You can do it with a stroller moving, or at rest using a bulb/test light.


Awesome, thanks. I'll have to do a lot more research about setting timing before attempting anything.

Last night I found a YouTube video of someone with a 70's FI Beetle that has the exact same problem as my Fasty. In the comments, a few people said they had had the same problem. They fixed that problem by replacing the fuel filter, fuel pump, and fuel lines. After hearing that, and revisiting KTPhil's earlier suggestion:

Quote:
While you are tuning it, check for leaks in any hoses, especially those to the MPS and AAR from the plenum.


I spent this morning going through the Bentley's and reading about the fuel/air system, then poked around in the engine bay to find the AAR, MPS, and look at some of the hoses. The picture below is the MPS, right?

Image may have been reduced in size. Click image to view fullscreen.


What is that black thing on the left end? The pictures of the MPS in the Bentley's don't have that.

I checked the hoses from the AAR and the MPS to the IAD, and there weren't any visible holes or cracks. The only thing I saw was that some of the hoses had cracks at the ends (just in front of where the hose clamps are), like this:

Image may have been reduced in size. Click image to view fullscreen.


Not sure if that would cause a leak, though.

After putting everything back together, I started up the car, let it idle for 5 minutes, and it idled perfectly! I drove it around the block a few times, stopped once to let it idle, drove it some more, parked it and left it running, and it still sounded fine. I turned the car off, restarted it, and it still sounded fine. It seemed like I could just barely hear a slight variation in the idle, but nothing like after adjusting the valves. After letting it idle some more, I gave it some gas, then let it drop back to an idle. That was when it started surging, but after a short time it settled down to a normal idle. I made a recording, but the audio got screwed up, otherwise I'd post it.

Are the ECUs in these old cars sophisticated enough to "learn"? I ask because when I had to change out a solenoid that was part of the turbo system on my daily driver (2000 TDI Beetle), it took a minute for the ECU to adapt to the new, properly working solenoid. So, I'm wondering if the ECU in my Fasty needs time getting used to the adjusted valves? What are the chances that it could just be a fuel pump that is starting to fail, and so only causes problems intermittently?
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PostPosted: Sun Feb 18, 2018 4:31 pm    Post subject: Re: Strange engine idle Reply with quote

Yes, that's the MPS.

That cracked hose is just what you want to replace! Yes, that will cause a leak that will confuse the FI. Same with any hose to the IAD (plenum) and the AAR. The system has ZERO tolerance for vacuum leaks. It's hard to get to the connections on the underside of the IAD, so it's best to just replace them and be sure. At least on your late model, the MPS hose is on top-- easier to get at.

The ECU has no "learning." This FI system is fundamentally different than anything built today (or for the last 20+ years): it is analog, not digital. It has no software. In fact, other than in an old ad or two, VW/Bosch never called it a "computer." Instead, they called it an "electronic control unit," or ECU.
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PostPosted: Sun Feb 18, 2018 11:26 pm    Post subject: Re: Strange engine idle Reply with quote

Quote:
That cracked hose is just what you want to replace! Yes, that will cause a leak that will confuse the FI. Same with any hose to the IAD (plenum) and the AAR. The system has ZERO tolerance for vacuum leaks. It's hard to get to the connections on the underside of the IAD, so it's best to just replace them and be sure. At least on your late model, the MPS hose is on top-- easier to get at.


Oh, that's good news. Replacing hoses is pretty easy. Should every vacuum hose have a hose clamp on it? There are some that currently don't have clamps.

I'm trying to find the right kind of hose to buy, and the best place to buy it from. I'm guessing the German braided cloth stuff is the best? Where's the best place to buy them? I checked JBugs, and they offer a few different kinds of hose in a few different sizes. German Supply seems to have a wider selection than JBugs. Many of the hoses on German Supply are listed as "vacuum/fuel," so they can be used for both?
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PostPosted: Mon Feb 19, 2018 12:28 pm    Post subject: Re: Strange engine idle Reply with quote

Braided lines are not the best for fuel, but they should suffice elsewhere. Clamps are not necessary. Just cut them a few inches long, then clip off 1/2" every year to get a tight, unchecked end.
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PostPosted: Mon Feb 19, 2018 12:47 pm    Post subject: Re: Strange engine idle Reply with quote

I went through the Type 3 Parts Book - Group 1 (Engine) trying to find the part numbers for the vacuum hoses I need. In the Parts Book they seem to refer to vacuum hoses as "connecting hoses." There's only one part listed as a "vacuum hose," and it's a carburetor-related part:

    Illustration 8, Supplement 9: Key 44, Part Number 311129422 - jet 0.7 - Vacuum hose (spark retard) for carburetor 33 - 36


I can't find the corresponding illustration, though. Anyway, I'm pretty sure that isn't a part I need.

Doing a search for "connecting hose" turned these up:

    Illustration 9 : Key 12, Part Number N203741 - Connecting hose for oiI breather 12 x 3.3

    Illustration 10 : Key 29, Part Number N203741 - Connecting hose for oiI breather 12 x 3.3

    Illustration 11, Supplement 10: Key 26, Part Number 311133241 - Connecting hose 31 x 4 x 45 (there seems to be something wrong with this one since the key numbers and what they point to in the illustration don't match)


I'm obviously missing something, as two of the three above hoses are the same hose, and I'm pretty sure there are a few different size vacuum hoses in the engine bay.

Since "vacuum hose" and "fuel hose" seem to be interchangeable, I also did a search for "fuel hose," but those results were definitely for hoses that were part of the fuel system (and so don't carry air).

Doing a search through the Type 3 forum, I found this thread where hose sizes are discussed: https://www.thesamba.com/vw/forum/viewtopic.php?t=612904. I'm no sure if all the vacuum hose sizes are included in that thread, though. Since there doesn't seem to be one thread where all this info can be found, I'd be willing to put something together for a sticked thread. If I can all get the info for the hose sizes all in one place, I could take a diagram like this - https://www.thesamba.com/vw/gallery/pix/770395.jpg - import it into an image editing tool, and add captions that say what diameter the hoses are, along with their part numbers. Anyone want to help?
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PostPosted: Wed Feb 21, 2018 7:47 pm    Post subject: Re: Strange engine idle Reply with quote

So this is what I'm thinking about doing:

Image may have been reduced in size. Click image to view fullscreen.


I took the hose sizes mentioned in this post - https://www.thesamba.com/vw/forum/viewtopic.php?t=612904 - and put them in the image. I wasn't always 100% sure on which hose was being referred to in the post, though. Does anyone want to help? I'm willing to do this for engines of other years, too (if they are different and if someone gives me the info). If someone is willing to help, it might be easiest for me if the hoses are referred to by what number they go from and to (for example, the hose from number 6 to number 1).

By the way, I can also clean up the image a lot so it looks better.
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PostPosted: Thu Feb 22, 2018 11:38 am    Post subject: Re: Strange engine idle Reply with quote

dayunbao wrote:
So this is what I'm thinking about doing:

Image may have been reduced in size. Click image to view fullscreen.


I took the hose sizes mentioned in this post - https://www.thesamba.com/vw/forum/viewtopic.php?t=612904 - and put them in the image. I wasn't always 100% sure on which hose was being referred to in the post, though. Does anyone want to help? I'm willing to do this for engines of other years, too (if they are different and if someone gives me the info). If someone is willing to help, it might be easiest for me if the hoses are referred to by what number they go from and to (for example, the hose from number 6 to number 1).

By the way, I can also clean up the image a lot so it looks better.


Keep in mind not all FI cars don't use all of those hoses.
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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
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