I have a '91 GL wbx that would not idle down until I swapped in a spare
ECU.  Is there anyone nearby that can lend you one to try?

Larry A.

On Sat, Oct 18, 2014 at 6:16 PM, Stuart MacMillan <stuartmacm@gmail.com>
wrote:

> With the ISV connected. Unplug it and it won't idle at all, even after a
> few minutes of holding down the pedal.  Plug it in, and it's up to 3500
> rpm, 2000 with the T2 disconnected.  T2 voltage drops from 4.98 to 1 volt
> when I plug it in with the engine barely warm, measured with my Fluke meter
> by sticking the probe into the back of the connector. Bentley shows
> resistance dropping with increasing temp. There are two wires coming to the
> voltage terminal, and one ground wire from the other.
>
> With ISV plugged in and pinched off it won't idle. Adjusted throttle stop
> per Bentley.  No matter what I've tried it will not idle, or idles at 2000
> to 3500 rpm depending on whether the T2 sensor is connected.
>
> This happened literally over night after driving the well-running van 270
> miles home.  The next day all this appeared.
>
> I did find a very weak alternator, and the battery was run down to 25% the
> next day. It would crank but not start, but started with a jump.  Maybe
> that did in the ECU.
>
> Something is sending the wrong signals obviously, but this engine is
> pretty clean, unmodified, and has been professionally serviced its whole
> life, which has been in the northwest.  No cut & spliced wires, cut
> sheathing, corroded connectors, added equipment, accidents, etc., so I
> don’t think it's a wiring problem.
>
> Just for fun I popped the ECU plug and it looks fine.  Situation is the
> same plugging it back in.  At proverbial wits end.  I have the TA version
> ECU, are they know to be problematic?
>
> Van Cafe wants $225 for a rebuilt ECU.  I'm tempted to order one right now!
>
> Stuart
>
>
> -----Original Message-----
> From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> Sent: Saturday, October 18, 2014 2:04 PM
> To: 'Stuart MacMillan'; vanagon@GERRY.VANAGON.COM
> Subject: RE: Weird idle problem continues
>
> Is that idle with the stabilizer valve connected? You need both fuel and
> air . Again,  start by getting it to run/idle with the valve disconnected,
> maybe even pinch off or block the hoses. Check the voltage at that plug
> terminal with the sensor connected and disconnected. There must be a
> difference. If not you have a wiring issue or a bad input on the ECU. If
> fast idle with idle valve blocked you have a vacuum leak somewhere or the
> throttle is partly open.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Stuart MacMillan
> Sent: Saturday, October 18, 2014 4:51 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Weird idle problem continues
>
> Checked the T2 sensor, and it's 1500 ohms @ 35 C, right what the Bentley
> says it should be. Sensor in AFM is also spot on.  That T2 connector is
> clean as a whistle, contacts inside are not broken or corroded either.
>
> But remember, it idles at 2000 rpm with it unplugged!  Something is
> dumping fuel in, and it must be a bad ECU unless you can think of something
> else.
>
> Stuart
>
> -----Original Message-----
> From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> Sent: Saturday, October 18, 2014 1:23 PM
> To: 'Stuart MacMillan'; vanagon@GERRY.VANAGON.COM
> Subject: RE: Weird idle problem continues
>
> The ECU thinks the engine is really cold. Try changing the connector. It
> is the same as for the injectors except for color. A good auto parts store
> will have the connector and pigtail wires, maybe the Help or Cal-Term
> board. GM uses the same connectors.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Stuart MacMillan
> Sent: Saturday, October 18, 2014 4:20 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Weird idle problem continues
>
> I've got 4.9 volts, and 0.02 volts on the connectors.  Fuel pressure is 30
> psi and no leaking at the regulator vacuum connection.
>
> All hooked up and the same situation--hard start, won't idle, 30 seconds
> later revs up to 3500 rpm and stays there.
>
> I give up.  At least I have a good shop close by.
>
> Stuart
>
> -----Original Message-----
> From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> Sent: Saturday, October 18, 2014 1:05 PM
> To: 'Stuart MacMillan'; vanagon@GERRY.VANAGON.COM
> Subject: RE: Weird idle problem continues
>
> High idle and timing defaulted is normal when temps is disconnected after
> engine running. That is part of the procedure to set the timing. Reconnect
> the snsor to then set the idle speed.
>
> Dennis
>
>
>
>
> -----Original Message-----
> From: Stuart MacMillan [mailto:stuartmacm@gmail.com]
> Sent: Saturday, October 18, 2014 4:03 PM
> To: 'Dennis Haynes'; vanagon@GERRY.VANAGON.COM
> Subject: RE: Weird idle problem continues
>
> Thanks Dennis, that might actually be cheaper than taking it to a shop!
>
> I'll go check that now, but it still idles at 2000 rpm with temp 2
> disconnected.
>
> Stuart
>
> -----Original Message-----
> From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> Sent: Saturday, October 18, 2014 12:51 PM
> To: 'Stuart MacMillan'; vanagon@GERRY.VANAGON.COM
> Subject: RE: Weird idle problem continues
>
> Where are you located again? Do you need me to fly there to fix it? Only
> kidding.
> The hard start and idle problem is probably related. If it is flooding
> look at the Temp 2 sensor. The original sensors rarely go bad. What does go
> bad is the connector and the wiring to it. And then there is the ground
> connection for it.  This sensor is used for both the ECU to control
> starting mixture, warm up mixture, when to go into O2 sensor operation and
> some ignition timing trim. It is also used by the idle stabilizer to modify
> idle speed for starting and warm up operation. There are also inputs for
> the AC and power steering.
>
> The temps sensor gets a signal off of the ECU and sinks it to the chassis.
> As the sensor warms up the resistance goes down increasing current flow
> which reduces the voltage at the ECU. Any high resistance in this path
> leaves a high voltage making the ECU and idle control unit think it is like
> 40 below. Yes it will run rich and if it does run idle high.
>
> Key on engine not running you can use a voltmeter to test the connections.
> On the ECU side of the sensor you need to see less than 5 volts connected,
> between the connector and chassis). On the ground side needs to be real
> close to "0" If you have voltage on both sides or much above "0" on the
> ground side you have a bad ground path. If 5 volts on one side then you
> have a bad connection to the sensor.
>
> Hope this helps.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Stuart MacMillan
> Sent: Saturday, October 18, 2014 3:13 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Weird idle problem continues
>
> I would, but son is tapped out for now.  Need to get a year or two out of
> this one!
>
>
>
> From: Don Hanson [mailto:dhanson928@gmail.com]
> Sent: Saturday, October 18, 2014 12:05 PM
> To: Stuart MacMillan
> Cc: vanagon@GERRY.VANAGON.COM
> Subject: Re: Weird idle problem continues
>
>
>
> Give in, Stuart....You know you are wanting a different motor...Do it now.
>
>
>
> On Sat, Oct 18, 2014 at 12:02 PM, Stuart MacMillan <stuartmacm@gmail.com>
> wrote:
>
> Okay,
>
>
>
> Today it was very hard to start, much cranking with foot to floor to
> minimized flooding.  Started, barely  ran but 30 seconds later runs up to
> 3000 rpm and stays there.  Warmed it up for a couple of minutes.
>
>
>
> Unplugged O2, Temp2, and idle control power plug.  Same hard to start
> condition, but it went to 2000 and stayed there.  Checked the timing and it
> was a bit advanced but steady, so I adjusted that.
>
>
>
> Hooked everything back up and still hard starting, but went right up to
> 3500 rpm. Gave up.
>
>
>
> This is not a problem with the idle control circuit.  What's left?  AFM?
> ECU? Other?
>
>
>
> About ready to have it towed to a shop where they can substitute parts
> they have lying around, but that would be painful in so many ways.
>
>
>
> Stuart
>
>
>