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Date:         Fri, 24 Jul 2009 18:41:25 -0700
Reply-To:     Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject:      Re: Need help with a 78 Bus
Comments: To: Ken Wilford <kenwilfy@COMCAST.NET>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=response

I try not to get involved in those Type IV fuel injected engines..... but... I have noticed that they have fuel injection ground wires on spade connectors, under the intake manifold I think. Very weak. I convert those to screw and eye terminal. There should be a trans to body ground strap. That's usually thought of as being important for starter operation ..... it could be VW thought it was sufficient for the fuel injection.

and perhaps it's not, since all waterboxers have that dedicated little ground strap on the left side of the engine. I would just add one myself. there is much to be learned noticing what VW changes from year to year.

for example.....on the Type IV air-cooled engine, the temp sensor in the left head has one wire, that goes to the ecu. The 'return path' is the sensor screwed into the head. So you get a little road salt there, or just age........resistance builds up, messing up the signal to the ecu perhaps. So what does VW do ........on waterboxers, there is a dedicated wire for return path on that circuit, and they are not depending on contact where it was screwed into the head on the earlier designs.

many possibilities come to mind - vacuum leaks. muffler or cat problem does it have EFI points in the bottom of the distributor ? ........not sure if a 78 does ......earlier Bosch EFI did, those could be worn. is it points ignition or electronic ? if points..........worn distributor comes to mind. air flow meter comes to mind. fuel pressure ? likely that is all right since it runs right once it's 'on the pipe' so to speak, if you know about two stroke power curves regarding what 'on the pipe mean' .......same as 'on the cam' .

what do the spark plugs look like ? oh here's one .........timing, and timing curve. is the timing advancing correctly ? Vacuum diaphragm on the distributor ? you know that felt pad under the rotor in many distributors ( including 1.9 waterboxers ) ..........? I'm pretty sure that most of the world doesn't realize that's there, or know what it's for, based on cars and vanagons that I see. that's to lube the centrifugal advance mechanism. that mechanism could be wondering around, or stuck. Improper timing curve does fit your symptom.

EFI temp sensor ? I forget if those have a throttle switch, but always check those when there's one there.

Does that system have a pressure sensor gizmo ? if so, I read bad things about those..........like what they have on 914 Porsches ...though that might be an earlier system than what a 78 Bus uses. plug wires ? unlikely, but I've had them 'in the end' be one of the main things causing problems. I consider them 'nebulous' . I have several tricks for testing and checking those. Not just ohm reading either. I feel better after I've made sure the fuel filter is ok....... or checked in it for water. Water in the fuel also fits your symptom, but it's not very likely, but always consider the fuel itself. People, even pros, often never consider the fuel itself. Once in a great while it is the fuel itself that is the problem. Pretty rare though. It sounds like grounds could be an issue ..... gotta check those for sure. also.........'double relay' on that beast. Would be awfully weird if that part was the cause, doesn't seem likely, but ........you never know. The van is 31 years old after all. Anything could be corroded, clogged, worn out, stuck ......etc. etc. etc. Good luck ! Would be very nice to have another known-good Air Flow Meter to try too.

that's a start. Hopefully some Type IV engine wiz will contribute ! Scott www.turbovans.com ----- Original Message ----- From: "Ken Wilford" <kenwilfy@COMCAST.NET> To: <vanagon@GERRY.VANAGON.COM> Sent: Friday, July 24, 2009 5:00 PM Subject: Need help with a 78 Bus

> Hey guys I have been struggling with a 78 Bus that came in here on > Tuesday. He has been having a bucking and hesitation problem for his > entire trip across the US but lately it is getting worse and he wanted > me to look at it. I found one cylinder (number 3) with low compression > (60 psi) and thought I had found the problem. So we repaired that but > it still does it. If you go to take off, the bus will start to > accelerate and then start hesitating until you get above a certain rpm > then it feels like a turbo boost and you have your power back and no > hesitation. Once you get up to speed it drives smoothly with no > hesitation. Has any one experienced this with a Bus before. They are a > bit different than a Vanagon so I thought I would seek advice from folks > that have worked more on aircooled vans. One other thing I am wondering > about is where the ground connection for this engine is supposed to be? > I know in the Vanagon that if you don't have a good ground to the engine > it can cause all kinds of problems. Where does the air cooled Bus > ground to the motor? Right now there is a place on the motor with spade > connectors on it and ground connections go there, but there is one that > nothing is on (there are three together). There is no other ground > cable going to the motor that I can see. I didn't take one off. If > anyone can throw me a thought out there it would be appreciated. > > For those of you who may have been wondering why you were having a hard > time reaching me this week this is why. These folks are stuck here > until I figure this out so I have been working on it all day long for > the last several days. Hopefully I can figure this out tomorrow and get > them back on the road and get my life back as well. > > Thanks, > Ken Wilford > John 3:16 > www.vanagain.com


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