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Date:         Sun, 19 Oct 2014 08:59:06 -0400
Reply-To:     Larry Alofs <lalofs@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Larry Alofs <lalofs@GMAIL.COM>
Subject:      Re: Weird idle problem continues
Comments: To: Stuart MacMillan <stuartmacm@gmail.com>
In-Reply-To:  <004701cfeb21$2c851100$858f3300$@gmail.com>
Content-Type: text/plain; charset=UTF-8

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 > > >


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