In which our hero descends upon Renton, WA.

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Jivermo
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Re: In which our hero descends upon Renton, WA.

Post by Jivermo » Sat Aug 23, 2014 5:56 am

How is BobD running?

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Ronin10
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Re: In which our hero descends upon Renton, WA.

Post by Ronin10 » Sat Aug 23, 2014 10:53 pm

Well, like an out of reach itch, the bucking came back. But here's what I did first:

Did a fuel rail pressure test. Checked idle, 1/2 throttle, some ramp ups and downs, but came in under all circumstances between 32 and 37 psi. So good there.

I then pulled the plugs to check their condition:
Image

#1 on the left to #4 on the right. A little sooty, but that's not unexpected given the sooty smell of the exhaust.

I then checked the gaps on them and each of them was a little wide, #4 the worst of the lot. Reset the gap to 0.7mm and for curiosity's sake, checked the compression: 125-130 psi on all cylinders. Again, nice and healthy.

Reinstalled the spark plugs and then drove over to my parent's house for a family get together, about 20 minutes to get there. I let the engine warm up for a couple minutes then set off. Hadn't gotten more than a mile and half before I felt a severe buck while accelerating in second gear. Nothing for a long while after that, but then cruising on the highway about 10 minutes later, the milder bucking but more frequent bucking occurred. And then, when climbing the hill out of the valley to my parents in 3rd, considerable bucking.

The return trip home yielded some more bucking, along the lines of the trip there. Long story short, that bucking gremlin still exists.

Tomorrow, I aim to check out the #1 injector as well as spark quality, coil integrity, points vs. Pertronix, etc.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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aopisa
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Re: In which our hero descends upon Renton, WA.

Post by aopisa » Sun Aug 24, 2014 7:38 am

I had the bucking issue plague me for two years. Finally got so bad I could no longer drive the bus.

It seems that every time I read about someone with a bucking problem the solution is unique. There never seems to be two identical causes.

Mine turned out to be a very simple grounding issue. Have you checked all the FI grounds including the ones on the plenum? Connections at the coil? How about the connections at the battery? Do not just check to see if they are tight. Remove, clean and tighten. How about the negative battery connection to the body? That was my problem. Beach sand (former CA bus) and paint were not allowing good contact. Once sanded and cleaned I have not had one little buck or hesitation since. How about the transmission ground strap? Is it clean and shiny as a new penny?

Good luck. It is such vexing issue. Comes and goes and not easily produced in order to trace.
1977 Westy 2.0L F.I.

Flow with whatever may happen and let your mind be free. Stay centered by accepting whatever you are doing. This is the ultimate. - Chuang Tzu

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Amskeptic
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Re: In which our hero descends upon Renton, WA.

Post by Amskeptic » Mon Aug 25, 2014 7:06 am

aopisa wrote:I had the bucking issue plague me for two years. Finally got so bad I could no longer drive the bus.

It seems that every time I read about someone with a bucking problem the solution is unique. There never seems to be two identical causes.

Mine turned out to be a very simple grounding issue. Have you checked all the FI grounds including the ones on the plenum? Connections at the coil? How about the connections at the battery? Do not just check to see if they are tight. Remove, clean and tighten. How about the negative battery connection to the body? That was my problem. Beach sand (former CA bus) and paint were not allowing good contact. Once sanded and cleaned I have not had one little buck or hesitation since. How about the transmission ground strap? Is it clean and shiny as a new penny?

Good luck. It is such vexing issue. Comes and goes and not easily produced in order to trace.
Good God, it is an epidemic around here. I have to get on this.
Colin
(Ronin10, PM me for an intensive diagnostic)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

TrollFromDownBelow
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Re: In which our hero descends upon Renton, WA.

Post by TrollFromDownBelow » Mon Aug 25, 2014 9:04 am

Where is RandyinMaine when ya need him? :flower:

I'm not one for throwing parts at a problem, but would spend $20 to put in a new TSII. Before you do that, check that it is still tight in the head when the engine is WARM, ....the heads expand faster than the TSII does, so will seem fine when cold, but loosens up once the head warms up....and check the TSII connector - replaced mine with a simple bullet connector.

I had a TSII that once it warmed up the connection between the lead and the sensor would get sketchy, and it would also come loose from it's threaded seat in the head. Had the same bucking problem that plagued me for at least two years.... new TSII with some blue loctite and all is good now. :bounce:
1976 VW Bus aka tripod
FI ...not leaky, and not so noisy...and she runs awesome!
hambone wrote: There are those out there with no other aim but to bunch panties. It's like arguing with a pretzel.
::troll2::

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aopisa
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Re: In which our hero descends upon Renton, WA.

Post by aopisa » Mon Aug 25, 2014 10:29 am

TrollFromDownBelow wrote:Where is RandyinMaine when ya need him? :flower:

I'm not one for throwing parts at a problem, but would spend $20 to put in a new TSII. Before you do that, check that it is still tight in the head when the engine is WARM, ....the heads expand faster than the TSII does, so will seem fine when cold, but loosens up once the head warms up....and check the TSII connector - replaced mine with a simple bullet connector.

I had a TSII that once it warmed up the connection between the lead and the sensor would get sketchy, and it would also come loose from it's threaded seat in the head. Had the same bucking problem that plagued me for at least two years.... new TSII with some blue loctite and all is good now. :bounce:
I was going to suggest that, but dared not to step into RandyinMaine's shoes. :blackeye:

I would still check all the grounds first before putting any new parts in. For one, it's free. I have found that these FI systems really want aconstant steady supply of free flowing electrons. Any variance seems to give them everything from hiccups to convulsions.
1977 Westy 2.0L F.I.

Flow with whatever may happen and let your mind be free. Stay centered by accepting whatever you are doing. This is the ultimate. - Chuang Tzu

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Amskeptic
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Re: In which our hero descends upon Renton, WA.

Post by Amskeptic » Mon Aug 25, 2014 12:22 pm

TrollFromDownBelow wrote:Where is RandyinMaine when ya need him? :flower:

I'm not one for throwing parts at a problem, but would spend $20 to put in a new TSII. Before you do that, check that it is still tight in the head when the engine is WARM, ....the heads expand faster than the TSII does, so will seem fine when cold, but loosens up once the head warms up....and check the TSII connector - replaced mine with a simple bullet connector.

I had a TSII that once it warmed up the connection between the lead and the sensor would get sketchy, and it would also come loose from it's threaded seat in the head. Had the same bucking problem that plagued me for at least two years.... new TSII with some blue loctite and all is good now. :bounce:

We here at Itinerant Air-Cooled strongly suggest a diagnostic path to parts replacement.
Loctite is sorely not recommended. That sensor has to ground cleanly at the engine. A little anti-seize on the threads and clean washer is all anyone needs for a reliable TS II. You used Loctite because it inadvertently loosened on you? Is there a torque spec on these little buggers? Use it.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Ronin10
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Re: In which our hero descends upon Renton, WA.

Post by Ronin10 » Mon Aug 25, 2014 1:41 pm

Thanks for all the input guys. My TSII is good, previously validated. I'm going to do a little air fuel ratio testing before moving through my ignition system.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

TrollFromDownBelow
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Re: In which our hero descends upon Renton, WA.

Post by TrollFromDownBelow » Mon Aug 25, 2014 2:29 pm

Amskeptic wrote: We here at Itinerant Air-Cooled strongly suggest a diagnostic path to parts replacement.
Loctite is sorely not recommended. That sensor has to ground cleanly at the engine. A little anti-seize on the threads and clean washer is all anyone needs for a reliable TS II. You used Loctite because it inadvertently loosened on you? Is there a torque spec on these little buggers? Use it.
Colin
Duly noted...my diagnostic suggestion is to check everything when the engine is warm; both that the TS II is, in fact tight, and also that the lead to the sensor itself is tight when warm. The TSII may very well check out as good esp. when cold, but may not reveal a poor connection between the sensor and the pigtail/lead...which, for $20 and the minimal time it takes to swap it out is negligible.

As far as me using loc-tite, ahem, Sir Colin, as you may have forgot (it's been 7 years!), my engine had a death grip on my old TS II, you either had to retap the old hole, or tapped a new one (can't remember which it's been so long), it kinda sticks out at a slightly funky angel. You told me to be extremely cautious not to cross thread (which I have been!). I have torqued to the 7 ft lbs, and probably a lb or two more (with a washer) and it simply would not stay put. Loc-tite was a last ditch effort to make the bus runnable/reliable without dropping the engine and finding a new place to drill a new hole (although if it did happen to me now, I'd think I'd steal hippiewannabe's rheostat idea! :sunny: :sunny: ).

So I should have clarified, that the TrollLocTiteHippyFix should only be used if it is constantly coming loose, and has been found to be loose esp when the engine is warm despite valiant efforts to make it tight. :geek:

I should also note, that I am on a bit of a mission to see how long I can get my helicoiled, 20k mile-seized-spark plug, with two-stripped studs-heads to last, Ergo, may employ other hippy fixes, therefore all of my mechanical advise should be taken with at least two grains of salt and a goo IPA. :drunken:
1976 VW Bus aka tripod
FI ...not leaky, and not so noisy...and she runs awesome!
hambone wrote: There are those out there with no other aim but to bunch panties. It's like arguing with a pretzel.
::troll2::

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drober23
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Re: In which our hero descends upon Renton, WA.

Post by drober23 » Mon Aug 25, 2014 4:34 pm

You're giving us hippies a bad name! You fix things like the farmer that owned my property before I moved in :-)
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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Ronin10
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Re: In which our hero descends upon Renton, WA.

Post by Ronin10 » Mon Aug 25, 2014 9:07 pm

Had to purchase a new O2 sensor, but did get some baseline readings tonight...

Cold start, but not cold-cold start: 21-22.
50% throttle: 19.6
75% throttle: 19.8
WOT: 19.8

O.O

Even after warmup, things only dropped to about 18.5 to 18.6. So a way lean/lean setup. Going to read through the AFM tuning guide again as a refresher and then set about get my AFM to reasonable levels.

On the Samba, I came across a post from Ratwell with these settings:
Idle: 14.2:1
Light Throttle: 14.7:1
50% Throttle: 13.5:1
WOT: 12.6:1

Thoughts on those values as approximate targets?
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Amskeptic
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Re: In which our hero descends upon Renton, WA.

Post by Amskeptic » Tue Aug 26, 2014 6:49 am

Ronin10 wrote:Had to purchase a new O2 sensor, but did get some baseline readings tonight...
Make sure you are not getting oxygen dilution due to a probe that is not sufficiently inserted. Your numbers are lean.

Ratwell is pretty by the book numbers oriented, but out in the countryside, I have found that a richer mixture is required for a happy engine.
11.3 full throttle at 50 mph 4th gear up to 12.3 at 70.
Idle can be whatever.
Part throttle can vary all over the place depending on rpm, but generally mid 13s with quick dips to 12.5 under application of accelerator.

Get out from under the numbers your test equipment is giving you. You NEED a sensory baseline.
Sensorily, you can HEAR the engine respond to manual ministrations of the wiper in the AFM.
When you get the happiest mixture (the engine runs the fastest for that position of the wiper), you should see 12.3-12.6 on tester. You should also see 20.9 with the probe swinging in free air.
ColinThisHasGotToGetPutElsewhereOnForum
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Ronin10
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Re: In which our hero descends upon Renton, WA.

Post by Ronin10 » Tue Aug 26, 2014 10:29 pm

I did some adjusting today, moving the wiper to the limit of it's travel range (there wasn't much adjustment room anyway) to enrich the full fuel map and tweaking the black cog some. Ended up dialing in based on 50% throttle since idle and light throttle were giving erratic numbers. I had the probe as deep in the tailpipe as possible, but that bend comes up pretty quick and it's not deep enough it seems. I may have to get the bung welded in just after the instead of using the probe. A project for another time.

Long story short, based on 50% throttle readings, I was able to adjust to 13.2 and my seat of the pants-meter liked it too, although the bucking still exists. Tomorrow, my son and I are driving Greta about 4 hours from home to camp on the Olympic peninsula. I intend to do some work one Greta while we're out, but nothing to risky. Some little jobs unrelated to the bucking issue, but I may swap out the injector as well put in my points and see what happens. As Colin knows, a good road trip is a great test arena.

I'll start a new thread on the bucking issue after I return on Friday.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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cheesehead
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Re: In which our hero descends upon Renton, WA.

Post by cheesehead » Wed Aug 27, 2014 7:23 am

I will chime in with just an idea...I know you said you thought there were no vacuum leaks but I wanted to ask... Do you have a good block off plate for the EGR at the plenum German Supply has a perfect one for your bus? And a solid quality seal for the throttle body to plenum?

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Ronin10
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Re: In which our hero descends upon Renton, WA.

Post by Ronin10 » Wed Aug 27, 2014 8:41 am

Thanks for the suggestions. The EGR has a complete seal made with fresh gasket material and the throttle body seal is new as well. Neither show any sign of leaking.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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