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Date:         Mon, 9 Feb 2009 20:45:55 -0600
Reply-To:     Jerry <jbvelo@BELLSOUTH.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jerry <jbvelo@BELLSOUTH.NET>
Subject:      Re: Bucking, hesitation between 1500 and 2500 RPM when hot
Comments: To: Mike Collum <collum@myfairpoint.net>
In-Reply-To:  <4990C9FA.6040801@myfairpoint.net>
Content-type: text/plain; charset="US-ASCII"

Mike, This is interesting information. I have examined the green wire which goes back to the ECU. The green wire on my Vanagon does not have a braided shield around the wire. I have performed all of the pin to pin continuity tests as per the Bentley for the 02 circuit and all tests meet specification.

What effect does not having a shielded green signal wire have on the system??

Thanks

JB

On 2/9/09 6:27 PM, "Mike Collum" <collum@myfairpoint.net> wrote:

> The "Green" wire in the 02 sensor circuit is the "Signal" wire and it > resides within a shield. The green wire and the shield must not short > together. > > For the shield to work as a shield it must only be grounded at one end > (the ECU end). If it makes ground anywhere else it's no longer > providing shielding. > > The wire from the 02 sensor itself, up to where it connects to the green > wire, isn't shielded. > > Mike > > > > Jerry wrote: >> I hope for some much needed advice on this problem. >> >> I have an 88GL which actually meets the electrical >> specs of an 87 by looking at the Bentley wiring diagram. >> >> My problem is this: >> When the engine is cold it seems to run fine. >> At highway speeds all is well until the engine >> reaches operating temperature. After the engine >> reaches operating temperature it begins bucking >> during upshifts and throttle speed increase. When >> I push on the throttle to increase speed there is >> a significant hesitation. The engine speed will >> finally increase to meet the fuel demand and throttle >> response. Engine speed above 2500 seems ok. Throttle >> increase above 2800 RPM seems normal(no hesitation). >> >> I am thinking this is an Oxygen Sensor GROUND problem >> but am not sure. I have read all the posts concerning >> oxygen sensor grounds and I have questions. >> >> Where does the oxygen sensor ground(green wire)? >> Does it go to ground at the #29 chassis ground by the ECU? >> >> I have a three wire oxygen sensor. Where does the brown >> wire ground from the oxygen sensor(chassis harness). The Bentley indicates >> a ground at #12 ground in engine compartment(left). The brown wire >> on my 2.1 02 sensor goes into the engine compartment harness which >> runs along the front of the engine deck. I cant tell >> that the brown wire goes to ground from the 02 sensor. >> >> I have cleaned and reinstalled all grounds, however >> I combined some of the grounds at two locations on >> the left engine firewall. >> >> I have a 2.1 Boston Engine installed in MAR 2008 >> New AFM >> New Idle Control Unit >> New 02 sensor >> New Distributor and Hall sensor >> New ECU >> New Evaporative control canister >> >> This problem has got me down! >> As you can tell I've replaced just about all components. >> I also have the harness installed between the AFM >> and original chassis harness. >> >> Thanks for any advice. >> >> JB 88 GL Guido >> New spark plugs, cap, rotor and wires >> New fuel injectors and fuel lines >> New fuel pressure regulator >> >> >> >


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