Bucking, lurching leads to no camping and bummed out kids

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TrollFromDownBelow
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by TrollFromDownBelow » Tue Jul 31, 2012 7:14 am

IMHO - Back to the original topic, if the issue is erratic/ not predictable, I would agree with the general consensus and think it is not distributor related .. the only caveat would be the Petronix unit.... that could give you some wonkiness.

Have you replaced the cap/rotor/wires yet? I skimmed through the responses, but don't recall. I would do this to set a baseline.

I would focus on TS II (i know you checked resistance, but is it securely fastened to the head? If it is loose, it will act like it is dead ... you mentioned issues with getting it screwed in), electric grounds, esp @ double relay, and the AFM wiper ... I would post a pic of this if you could.
:sunny:
1976 VW Bus aka tripod
FI ...8 completely solid lifters.... now it's both kinda noisy and leaky, but she sure runs good!
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aopisa
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by aopisa » Tue Jul 31, 2012 7:35 am

TrollFromDownBelow wrote:IMHO - Back to the original topic, if the issue is erratic/ not predictable, I would agree with the general consensus and think it is not distributor related .. the only caveat would be the Petronix unit.... that could give you some wonkiness.

Have you replaced the cap/rotor/wires yet? I skimmed through the responses, but don't recall. I would do this to set a baseline.

I would focus on TS II (i know you checked resistance, but is it securely fastened to the head? If it is loose, it will act like it is dead ... you mentioned issues with getting it screwed in), electric grounds, esp @ double relay, and the AFM wiper ... I would post a pic of this if you could.
:sunny:
Thanks for bringing this back into focus. I have replaced the plug wires. I have a new cap and rotor ordered. It should be delivered in the next few days.

I will recheck the temp sensor ll, but as I stated I have unhooked it and it kills the engine. When I disconnect the sensor and ground the wire that leads to the ECU, the problem persists.

I have also checked, cleaned and rechecked the double relay grounds as well as the FI grounds located on the underside of the air intake plenum. The left wiring block of the double relay looks pretty gunked up with oil, and dirt. I have tried to clean the contacts.

Here is a picture of my AFM. The junk in the bottom right is a PO hack and Colin has seen it.

Image
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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56ovalbug
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by 56ovalbug » Tue Jul 31, 2012 8:42 am

The tracks in your AFM looks good.

Come to think of it... I have a friend that had a Pertronics ignition that would start to cut out at high RMS once warmed up so I wouldn't rule out the distributor just yet.
Joey

'56 Beetle|'65 Beetle|'74 Bus|'79 Panel

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aopisa
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by aopisa » Tue Jul 31, 2012 8:55 am

56ovalbug wrote:The tracks in your AFM looks good.

Come to think of it... I have a friend that had a Pertronics ignition that would start to cut out at high RMS once warmed up so I wouldn't rule out the distributor just yet.
I don't think there is a way to test a Pertronix unit?
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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56ovalbug
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by 56ovalbug » Tue Jul 31, 2012 1:45 pm

Joey

'56 Beetle|'65 Beetle|'74 Bus|'79 Panel

luftvagon
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by luftvagon » Tue Jul 31, 2012 5:47 pm

did you test the voltage on the AFM with ignition on, and motor not running?
check voltage as the flap moves -- it should be a logarithmic curve from anywhere around 1.5-1.8v closed to 7.5v fully open... dont check resistance on AFM -- its meaningless without voltage.
check reference voltage?
check temp sensor I?
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

luftvagon
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by luftvagon » Tue Jul 31, 2012 5:48 pm

btw.. spec of dust will screw up AFM in a heart beat.... get a contact cleaner and clean it.. make sure there is no junk under the needle such as q-tip fibers, etc...
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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56ovalbug
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by 56ovalbug » Tue Jul 31, 2012 6:51 pm

luftvagon wrote:btw.. spec of dust will screw up AFM in a heart beat.... get a contact cleaner and clean it.. make sure there is no junk under the needle such as q-tip fibers, etc...
Good point. I just looked at your pic of the AFM full sized and there's a lot of crap in there. I would carefully clean it out with compressed air or vacuum it out. Also, when replacing the cover use some type of sealant. It'll keep out the crap and eliminate a vacuum leak.

How about posting a pic of your engine looking through both the top and rear hatch. Maybe it'll show something we're all missing.

Lots of good tips given so far.. I'm sure you'll find the problem soon. Don't give up.
Joey

'56 Beetle|'65 Beetle|'74 Bus|'79 Panel

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aopisa
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by aopisa » Wed Aug 01, 2012 9:26 am

56ovalbug wrote:
luftvagon wrote:btw.. spec of dust will screw up AFM in a heart beat.... get a contact cleaner and clean it.. make sure there is no junk under the needle such as q-tip fibers, etc...
Good point. I just looked at your pic of the AFM full sized and there's a lot of crap in there. I would carefully clean it out with compressed air or vacuum it out. Also, when replacing the cover use some type of sealant. It'll keep out the crap and eliminate a vacuum leak.

How about posting a pic of your engine looking through both the top and rear hatch. Maybe it'll show something we're all missing.

Lots of good tips given so far.. I'm sure you'll find the problem soon. Don't give up.
I needed to take a break from it for a little while. I'm back at it again.

I blew the heck out of the AFM with a can of Dust-Off. A lot of stuff came flying out of there. I then cleaned the wiper surface with contact cleaner. The Q-tip was actually quite black. I cleaned under the wiper contacts with some photographer's lens tissue which is lint free by nature. Blew more compressed air into it again for good measure.

The only other thing I did today was add a bottle of dry gas to the tank.

It started right up and idled fine. I let it warm up and advanced the throttle while I watched the wiper move smoothly. Put the cover on and held it down securely with some duct tape. I wanted to wait to seal it in case I need to go back in again soon.

Took it for a test drive. Usually it will hesitate and lurch the moment I get it out of the driveway. Not one hiccup. Drove it pretty hard trying to get the engine warm and to get it to produce the symptoms that has plagued it (me) for more two weeks now. I could not make it do it no matter how hard I tried.

I am very reluctant to call it solved. Often the first drive of the day is not sufficient enough to reproduce the issue. I am slightly optimistic, but I am in no way going to get my hopes up at this point. I tend to be pessimistic when it comes to these types of things and have a gut feeling that the problem will return sometime later today when I take it out to really put it through its paces.

Still, thanks to all for sticking with me. At least my bus is getting a much needed tune-up.
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

luftvagon
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by luftvagon » Wed Aug 01, 2012 1:01 pm

For a good measure, crack open your ECU, take a few pictures .. make sure there is no moisture in there..

While it is highly unlikely you are experiencing the same issue as I was, it does not hurt to check it; crack open the ECU, see if there is any moisture; reseal.

My Vanagon started having intermittent problems, and it eventually died -- in the mean time, I have done everything and anything to find the problem. I ended up ripping L-Jet out, and while fiddling with the ECU on my desk I found this:

Image

Image

Image

Image

Image
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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aopisa
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by aopisa » Wed Aug 01, 2012 1:15 pm

That's pretty frightening. I will take a look even if it's only preventative. Did you find the source of the moisture?

I took a third, much longer test drive. Not one hesitation, burp, hiccup, lurch, anything, zero. I ran the bus pretty hard while defying it to stall out and leave me stranded. I even pulled some fairly decent hills. Still no sign of the problem. The engine seems to run very smoothly, even at idle and has plenty of power. I am not calling this case closed yet, but it's looking up. I will start driving the bus again as much as possible to hopefully put the statistics on my side that the issue is resolved.

So where do you put your money? Dirty AFM or a lot of H2O in the tank?
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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56ovalbug
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by 56ovalbug » Wed Aug 01, 2012 1:27 pm

The dirty AFM could very well of been the problem. If the cover wasn't sealed air would of been getting sucked in through the cover possibly stirring up the debris and all it would take is one small piece of whatever to get caught under the wiper arm contact. I removed the cover off my AFM on my '79 to do some adjustments and found it had a light oil film over everything. Before I adjusted anything I blasted it with brake clean and it made a huge difference in how the engine ran.
Joey

'56 Beetle|'65 Beetle|'74 Bus|'79 Panel

luftvagon
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by luftvagon » Wed Aug 01, 2012 1:30 pm

aopisa wrote:That's pretty frightening. I will take a look even if it's only preventative. Did you find the source of the moisture?
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1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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aopisa
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by aopisa » Wed Aug 01, 2012 1:33 pm

56ovalbug wrote:The dirty AFM could very well of been the problem. If the cover wasn't sealed air would of been getting sucked in through the cover possibly stirring up the debris and all it would take is one small piece of whatever to get caught under the wiper arm contact. I removed thed cover off my AFM on my '79 to do some adjustments and found it had a light oil film over everything. Before I adjusted anything I blasted it with brake clean and it made a huge difference in how the engine ran.
What should I seal it up with? The PO had it glued shut with gobs of black RTV which made Colin not too happy when we went to adjust it.
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

luftvagon
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Re: Bucking, lurching leads to no camping and bummed out kid

Post by luftvagon » Wed Aug 01, 2012 1:34 pm

Electrical tape.
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI with wasted spark ignition)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI

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