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Date:         Mon, 27 Jun 2005 22:11:05 -0400
Reply-To:     Marc Perdue <marcperdue@ADELPHIA.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Marc Perdue <marcperdue@ADELPHIA.NET>
Subject:      Bob Donalds big valve engine--yet another update (WAY LONG)
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi y'all,

It's been a long time since I posted or was able to do any further troubleshooting on my van's losing power problem. But I did finally get to some of it, mainly checking the ECU, and here are the results: Pins 2 and 13, Oxygen Sensor: Well, I had it disconnected, so of course it read infinite ohms. I didn't ground it and check it that way. Pins 6 and 9, Temp. Sensor I: 1950 ohms--This checks out with the graph I have as being okay (outside temp was in the low- to mid-70s). Pins 6 and 10, Temp. Sensor II: 1942 ohms--This one didn't make any sense to me at all. Any ideas? Pins 6 and 11, Throttle Switch: 6.2 ohms--I didn't check it at idle or full throttle because my arms aren't long enough. I had previously checked it at the switch itself and it checked out there as being okay.* Pins 6 and 17, Air Flow Sensor: 562 ohms--This is within normal range of 500 to 1000. Pins 17 and 21, Air Flow Sensor: 585--You're supposed to check this one as the sensor plate is opened, but I didn't know how to do that. Did not check pin 12 at the ECU and 87 at the Fuel Pump Relay--Again, didn't know how to do this (or where pin 87 is to be more exact) Fuel Injectors: 16.3 (passenger rear), 16.4 (passenger front), 16.5 (driver front and rear)--Spec is 14 to 18 ohms. Pin 13 and Ground, Control Unit Ground Connection: 0

Okay, boring stuff out of the way. While I had the air box out to check the passenger side injectors, I decided to swap out the AFM with a presumed-good spare that I had. All I have to say is: WOW!!!!! Now, I only just did this yesterday and haven't had much time to test it, but here's the real-world test thus far: My problem presented itself most often during warmer weather. It was really hot today. I did not experience the funky idle, low-power symptoms at all today. What I did experience is a van that has a great deal of kick to it! It idles a bit rough at low RPMs, but when you put your foot into it, it takes off like a bat out of hell . . . well, like a really heavy, underpowered bat out of hell, but way more power than it's had ever since the new engine was put in! One thing the engine was doing was seeming to lose some of its power when it shifted from second to third gear. This is gone. The transition is much smoother now. My initial thinking is that the "new" AFM has fixed PART of the problem I was having.

The reason I say PART of the problem is this: After I put in the AFM, I was testing the throttle because it was idling rough. I'd give it some throttle by hand and hold it steady but the speed of the engine would drop instead of staying steady. So I'm trying to think of what keeps the speed steady when you're holding the throttle. Vacuum advance? Hall sender?

Anyway, this is just some quick testing I'm doing now to see what effect the AFM would have. I've also got a new fuel pressure regulator to go in and, while I'm working on the fuel system, I'm going to replace all the fuel lines in the engine compartment, the lines and seals going into the gas tank, and the fuel filter. None of these have been changed in the 40k miles that I've had the van, nor have they likely EVER been changed.

*I'm also going to pull the throttle switch and physically check it out. It performs to specs, but I don't think it's set exactly right and I'm not so sure the plastic cam part isn't worn.

I think I'm seeing light at the end of this tunnel and I don't think it's an on-coming train. If my further parts testing, adjusting, replacing gives results in the right direction, I think I'm going to really like what Bob's engine is capable of. So far, today that is, it's been a blast!

That's the news for the moment . . . Marc Perdue '87 Westy, AT, BBBVE (Boston Bob Big-Valve Engine!)


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