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sixer
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Joined: March 23, 2014
Posts: 88
Location: Charleston, SC
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 Posted: Mon Feb 23, 2015 7:13 pm Post subject: |
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Updating this thread so if anyone finds it in the future while searching, the answer is here.
Symptoms: '76 2.0L FI engine starts fine and idles fine until warmed up, then dies and won't stay running. Unplugging the AFM allows the engine to idle quite well even when warmed up.
Notable things found and resolved to fix symptoms:
1) Injector seal fell off during installation. Replaced seal.
2) Vacuum leak under oil breather can. Cut and installed cork gasket.
3) Vacuum leak where intake manifold boot folded into itself when the intake tubes were installed on to the air plenum. It was of course on the bottom side, so it wasn't noticeable until smoke came out. Just rotated it around to the top, then fixed it.
4) Some idiot forgot to hook up the alternator. Hooked up alternator, reprimanded idiot.
Tools bought/made to find problems: Vacuum system smoke generator thing.
Relevant pics below. My wife did a write-up over on our blog as well, if you'd like a bit more of the story: http://ofwindsandwater.blogspot.com/2015/02/the-seventh-circle-of-vacuum-leak-hell.html
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1976 Transporter, Stock 2.0L
http://instagram.com/sixer.bus/ |
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Wasted youth
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Joined: July 06, 2012
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Location: California's Hot and Smoggy Central Valley
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| Posted: Thu Feb 19, 2015 12:06 am Post subject: |
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| sixer wrote: |
Did a little more checking during lunch. Smoking the lines again revealed a leak from the bottom of one of the intake manifold sleeves. It had folded over into itself during installation. Fixed that, and the engine now idles quite well!
Now that it's idling again, I'll re-check timing. There is a slight hesitation when increasing RPM's and some mild popping when coming back down - another small vacuum leak? |
Did you previousl set the timing with those last two vacuum leaks undetected? Said another way, could the timing have been set up with those unkown vacuum leaks? If so, then now your timing would be off, I would guess. Now that you have the vacuum leaks fixed, reset your timing before being concerned about the popping. |
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sixer
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Joined: March 23, 2014
Posts: 88
Location: Charleston, SC
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| Posted: Wed Feb 18, 2015 11:16 am Post subject: |
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Did a little more checking during lunch. Smoking the lines again revealed a leak from the bottom of one of the intake manifold sleeves. It had folded over into itself during installation. Fixed that, and the engine now idles quite well!
Now that it's idling again, I'll re-check timing. There is a slight hesitation when increasing RPM's and some mild popping when coming back down - another small vacuum leak?
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1976 Transporter, Stock 2.0L
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busdaddy
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Joined: February 12, 2004
Posts: 52918
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Feb 17, 2015 7:20 pm Post subject: |
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| sixer wrote: |
| ........ The vast majority of vacuum lines seemed to be original or at least REALLY old (as well as a few of the fuel lines)......... |
I hope you replaced them, if not better keep a bag of marshmallows in the glove box 
The bypass doesn't have a standard setting, each engine is different, to set it correctly you'll need a Co meter but if one or both are currently near maximum adjustment odds are you can improve things with some driveway fiddling.
As for the timing here's some tips that only require a timing light (don't F with that until you get it idling).
| busdaddy wrote: |
First you need to determine exactly where TDC is on your pulley and then set the timing at speed like this: Here's my timing for noobs rundown (keep in mind this assumes you have a degree wheel, timing scale or dial advance timing light and know where TDC really is, if you don't understand the marks on your type 1 pulley read this: http://www.thesamba.com/vw/forum/viewtopic.php?t=251672&highlight=stock+pulley+marks ). Or if type 4 see this: http://www.ratwell.com/technical/FindTimingMark.html
If you only have one hose attached to your distributor pull it off, you don't need to cap it (no need on single hose systems), if you have 2 pull them both off but plug the one that was connected to the nipple facing the distributor (retard). Now connect the timing light to the battery and the #1 plug wire according to the timing light instructions (and set it to zero if it's the type with adjustments). Now start the engine and shoot the timing light at the scale and pulley (hold the light in your right hand), see the mark on the pulley?, good. Now using your left hand slowly open the throttle on the side of the carb or throttle body (move it the same way the cable pulls it) and watch the timing mark VS: the scale, the mark on the pulley should start to move to the left, open the throttle a little more and continue until the mark no longer moves to the left any more (yes it's loud, isn't it?), give it a bit more throttle just to confirm the mark is staying put at wherever it stopped (hopefully 28 degrees) and then release the throttle. If it stopped at 28 move on to carb/FI adjustment, if it went past or didn't make it all the way loosen the distributor clamp a little and turn the distributor a few degrees one way or the other (you pick, if it's worse go the other way), repeat until you find the happy spot and don't forget to tighten the clamp when you are done (make sure the distributor is pushed down all the way into the case too). Avoid loose fitting clothing and long hair near spinning fans and belts too, no need for a trip to emergency. Now put the hose back on, pack up the timing light and move on to carb or FI adjustment. |
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sixer
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Joined: March 23, 2014
Posts: 88
Location: Charleston, SC
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| Posted: Tue Feb 17, 2015 6:58 pm Post subject: |
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I replaced the injector seals a few months ago, and re-used them this time. To be honest, one fell off while installing and I didn't catch it, so that was the first thing I had to fix after reinstalling the engine. I sent the injectors to Cruzin' Performance for cleaning and testing, and they sent them back with all new seals.
I inspected all hoses then replaced/repaired them as needed. Same with the little elbow into the AAR and other bits and pieces. All of them seem to be tight on their fittings. The vast majority of vacuum lines seemed to be original or at least REALLY old (as well as a few of the fuel lines). Seriously wondering how the engine ran as well as it did. Come to think of it, when I did the first tune-up, it was timed way advanced (like 20° BTDC at idle), and that was covering some vacuum leak symptoms. Timing is 7.5° BTDC now at idle, although I can't confirm the RPM as I have no tach.
I will check the bypass screw position first thing once I get out there tomorrow. I assume the Bentley has adjustment procedures to follow?
Thanks again for the help!
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1976 Transporter, Stock 2.0L
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Feb 17, 2015 6:37 pm Post subject: |
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The breather box would definitely be a vacuum leak as well as valve covers and oil filler caps.
Assuming you replaced all the injector base seals and confirmed all the hoses were in good condition and fully connected when reassembling after the cleanup I wonder if you fixed a previous vacuum leak that the bypass and idle mixture had been adjusted to compensate for? Now that it's sealed up properly it may be too lean and low, is the bypass screw on the throttle body screwed in almost all the way?
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sixer
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Location: Charleston, SC
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| Posted: Tue Feb 17, 2015 6:29 pm Post subject: |
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Just an update after a few hours in the garage this evening. Built a smoke generator and pumped some smoke into the vacuum system. By doing this, found out the gasket was missing under the oil breather box. That was the only source of smoke noticed so far. Installed a new cork gasket under there, and started the bus. That was not the problem, it once again ran great until it was warmed up, then started stumbling and died. Will smoke it again tomorrow to see if there are more vacuum leaks.
Any other ideas? Could it still be the intake manifold gaskets, even if there is no smoke coming out?
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Feb 17, 2015 8:53 am Post subject: |
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| Wasted youth wrote: |
| Why phenolic blocks on fuel injection? Could the conductive heat from the heads be that influential? |
Keeps the injectors happy, especially after shutdown.
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Wasted youth
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Joined: July 06, 2012
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Location: California's Hot and Smoggy Central Valley
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| Posted: Tue Feb 17, 2015 8:31 am Post subject: |
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| busdaddy wrote: |
| Metal gaskets and no block for carbs, paper each side of the phenolic block for FI. |
The 1700 I did that on had them.... but (!) it also has a Progressive carb set-up, with their intake runners. Don't know why they installed them on it, and at the time, I was pretty ignorant to the whole mess. Now I know... just a little bit more. 
Why phenolic blocks on fuel injection? Could the conductive heat from the heads be that influential? |
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busdaddy
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| Posted: Tue Feb 17, 2015 7:24 am Post subject: |
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Metal gaskets and no block for carbs, paper each side of the phenolic block for FI.
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sixer
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Location: Charleston, SC
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| Posted: Tue Feb 17, 2015 5:32 am Post subject: |
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I'll definitely have a look at the intakes tonight. We did not replace the gasket material there (nor did we see any existing). Is there supposed to be a paper gasket on each side of the thick block, or a metal gasket, or a very thin smear of some gas-resistant RTV? Some reading and searching has told me that metal gaskets are recommended, but Copper Ultra RTV may work to get us on the road, and a few people mention paper.
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Wasted youth
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Location: California's Hot and Smoggy Central Valley
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| Posted: Mon Feb 16, 2015 7:54 pm Post subject: |
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| I have inadvertently cracked one of the phenolic blocks that go between the intake runner and the head on my 1700 a year or so ago. Developed a significant vacuum leak but didn't realize that's where it was coming from. Very easy to crack, I guess, but haven't had any troubles ever since. Worth a look. Once you take those runners off, you will need to replace the gasket material on those blocks before a carefully torqued re-installation. |
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sixer
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Location: Charleston, SC
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| Posted: Mon Feb 16, 2015 5:09 pm Post subject: |
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We did pull the (intake) manifolds. I will double check the tin isn't under one. Do you happen to have a picture of the likely culprit area handy so I know what I'm looking for? I did not replace the full brake booster line yet. I did double check the connection right behind the front tin. Actually, I plugged off the tee where it goes to the booster to eliminate that run as a possibility when I was hunting for vacuum leaks.
A large vacuum leak is exactly what we have been thinking as well, just can't find it.
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busdaddy
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| Posted: Mon Feb 16, 2015 4:59 pm Post subject: |
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It sure sounds like it's got a big vacuum leak, when you had the engine off did you remove the manifolds?, if you did are you sure a corner of the cylinder tin isn't pinched under one?, how about the brake booster hose?, didn't forget that one under the bus did you?
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sixer
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Location: Charleston, SC
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| Posted: Mon Feb 16, 2015 4:24 pm Post subject: |
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Unplugging TS2 with the engine warm results in a very rough, surging idle, followed by the engine stopping. That is with the AFM unplugged, the only way it runs when warm. I tried to get it to run with the AFM plugged in and TS2 unplugged, but it refused.
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busdaddy
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| Posted: Mon Feb 16, 2015 4:00 pm Post subject: |
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What happens if you unplug the TS2 when it's warm?
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Rust NEVER sleeps and stock never goes out of style.
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sixer
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Joined: March 23, 2014
Posts: 88
Location: Charleston, SC
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| Posted: Mon Feb 16, 2015 2:46 pm Post subject: |
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So, tonight's troubleshooting session started with:
1) Connected fuel pressure gauge, reading 38 psi with ignition on and AFM open, engine not running. Started engine, gauge bounces between 20-30psi wildly. As the engine warms up, it starts to stumble, and eventually stumbles more and more until it dies. Holds about 28psi of fuel pressure with engine off.
2) Applied power to cold start valve, fuel pressure dropped as it should.
3) Tested TSII again, read ~500ohms and steadily climbing on a warm engine.
4) Verified 20-30 ohms between contacts in AAR.
5) Verified double relay ground is connected.
Now what? Any suggestions? I am out of ideas. What would you check next?
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Mon Feb 16, 2015 7:27 am Post subject: |
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| sixer wrote: |
| Busdaddy- Not sure what you mean, sorry. Incendiary time bomb filter? I have the standard square fuel injection filter plumbed in prior to the fuel pump under the bus. Are you saying the fuel pump should not run with the AFM unplugged, unless the starter is engaged? That is interesting. The engine would run as long as I asked it to with the AFM unplugged. . |
Whoops, I've confused you with another poster here who had one of those dismantleable glass filters in thier system, the square plastic one is just fine.
A bus will idle fine with the AFM unplugged but crap out when you give it throttle, there's enough gravity feed from the tank that the pump isn't needed for idle.
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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sixer
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Posts: 88
Location: Charleston, SC
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| Posted: Mon Feb 16, 2015 5:37 am Post subject: |
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Busdaddy- Not sure what you mean, sorry. Incendiary time bomb filter? I have the standard square fuel injection filter plumbed in prior to the fuel pump under the bus. Are you saying the fuel pump should not run with the AFM unplugged, unless the starter is engaged? That is interesting. The engine would run as long as I asked it to with the AFM unplugged.
Wildthings- I've checked TSII sensor, it seems to fall within the specs listed in the AFC fuel injection guide. It registers around 5k ohms which is high according to the Bentley, (which seems to only give the value for room temperature) but falls right in line with the resistance vs. temperature chart listed in the AFC troubleshooting guide. It was ~30°F out the morning I checked it. I checked the sensor both with the pigtail and through the ECU plug to eliminate any wiring issues. Unplugging the TSII sensor causes the engine to run very rough and die faster.
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Wildthings
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| Posted: Sun Feb 15, 2015 11:20 pm Post subject: |
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| Check to see that your TSII sensor is hooked up. This is how the ECU determines how hot your engine is. If the wire to the sensor is not connected the ECU will think the engine is stone cold and dump in way to much fuel as the engine warms. |
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