Thanks for the reply Scott.

I have replaced and tested the Temp II sensor.
I have also adjusted the TPS per the Bentley.

My green wire to the ECU is not shielded.
How does the shield connect to the ECU?
What effect does not having a shielded green wire
have??

I installed the Boston engine.
I cleaned and replaced all the grounds
during installation.  I know that the
brown ground wire to the left head is good.
I also installed a new ground cable from
the left head to the left side under the coil.

Could this new ground be causing a problem
with my 02 ground circuit? They are grounded
at the same point on the left head.

At this point I'm just guessing.

JB 88 GL

On 2/9/09 6:56 PM, "Scott Daniel  - Turbovans" <scottdaniel@turbovans.com>
wrote:

> some of my thoughts.......
> you might be getting a slew of emails suggesting your temp sensor
> ........Temp Sensor II ........the one at the thermostat housing.......it's
> a critical input to the ECU.
>
> throttle switches are often off........you should at least check that.
> Pretty easy to do.
>
> on your oxygen sensor comments.....
> the green wire goes to the ecu, and is the input to the ecu.
> it's shielded.......and that shield connects to the ECU.........and to a
> ground wire there........that goes back  to the engine block.
> The body of the oxygen sensor is grounded to the exhaust system
> ...........as shown by current track 25.
> you should be looking at page 97.89.
>
> looking at my 86 I see the brown ground wire disappears into the main
> harness and it's not easy to tell where it grounds.
> you could just unplug the connector plug and use an ohmmeter to check
> continuity and resistance to ground.
> if it tests OK that way, it probably is all right.
> you could also just add your own ground for that wire if you needed to.
>
> the white wire is power, for oxygen sensor heat, from the main relay.
> that wire should have power on it any time the key is on I think.........and
> certainly any time the engine running.
>
> oxygen sensor heat is not absolutely critical to making the engine run, or
> run right. Of course you want that system working.......
> but not likely that lack of oxygen sensor heat is keeping your van from
> running properly.
>
> I do read of, from time to time,  a shorted out oxygen signal in the oxygen
> sensor sometimes, but have never seen that myself......and sort of 'don't
> believe in it.'
>
> oh.....in general..........you should just undo, clean, and tighten all the
> Ground Wires by the coil, on the left side of the engine compartment, and on
> the engine block, left side, especially that one - I see them quite corroded
> all the time.  I recommend a general WD-40 spray down , moderately, of any
> engine that's showing signs of corrosion.  Just don't spray it inside the
> alternator......but everywhere else is good.
>
> that many new parts makes me nervous.
> a part being new is not an automatic guarantee that it's good........or that
> it was installed correctly either.
>
> I don't know who installed your new engine .......
> but I commonly find a few workmanship errors on waterboxer engine
> installations.  You'd think anything related this way would do it from the
> beginning though.
> Scott
> www.turbovans.com
>
>
>
>
>
>
>
> ----- Original Message -----
> From: "Jerry" <jbvelo@BELLSOUTH.NET>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, February 09, 2009 3:49 PM
> Subject: Bucking, hesitation between 1500 and 2500 RPM when hot
>
>
>> 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
>