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Idle Surges While In Gear - Automatic Transmission
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I just finished my first conversion in my '91 Westy with an automatic transmission. After the engine warms up I have a VERY SLIGHT surge in RPM at idle. When I start sliding the shifter toward reverse I hear a "click" under the dash and the RPM take a big jump up and then settle down once in gear. Then while sitting there in gear at an idle the van lurches as now the RPM surge is even greater. While I sit at stop lights the van lunges back and forth as the RPMs surge up and down. On my OBDII reader I get 2 codes. One is a P1116 - Torque down prohibition output (low) and the other code is P1722 - Automatic transmission Diagnosis Circuit High Input. I assume both of these have to do with the Subaru Automatic Transmission? Do I ignore these because I am not running the suby tranny? Could these codes and surge issue have anything to do with my speed sensor? I have a rocky mountain westy speed sensor installed. Thanks in advance for any help.
~Chad in Bellingham Washington |
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It would be helpful if you would state all info available about the type of Subie engine you installed. From the codes you mentioned, it seems to be a fairly late model that I am not familiar with, but others may have some insight.
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It seems to me you need to track down the "click" under the dash. Does it happen only with the engine running or can it be heard with just the ignition turned on? Did you install any type of switch at the shift lever? --- In subaruvanagon@..., "CHAD" <ctdmx718@...> wrote:
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Based on your codes you're running an obd2 subaru engine.
Idle surging/cycling is often caused by intake vacuum leaks and/or a dirty Idle Air Control Valve. My suggestion would be to test your engine for idle leaks (use google search for help in determining the best method for you) and to remove, clean, lubricate, and reinstall your idle air control valve. There are articles in the archives on best methods for this or you can visit my site at and browse to Suby Engine-3 > IAC Servicing Then you can advance your diagnosis to validation of the wiring harness connectivity. It's not likely that the click you're hearing is related to your subaru conversion as the vanagon automatic transmission operates almost completely independant of the subaru engine. The only real interface is the throttle linkage (kickdown). That is unless you've installed some other interface that is not mentioned. All the best, Brent -- Brent Weide Portland, Oregon www.weidefamily.net/vanagon/ |
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Hey sorry for the lack of info guys. I am running a block from a 2000 2.5RS and an intake and wiring harness from a 99 Legacy 2.2L. I paid more attention to the click today as I drove it. The click must be my aftermarket battery isolater that is under my driver seat. That is where the sound is coming from. The click has nothing to do with the RPMs. Now that I am paying more attention to my issue, the van idles really well while in neutral or park. As soon as I even start sliding my shifter toward a gear selection (even before it fully clicks into gear) the motor rpms start surging. Because the fact that while out of gear, the motor runs fine, it really seems to be a trans problem. Before I posted this issue, I realized that the trans was about half a quart over filled and thought maybe that was the issue. However after I drained the trans level down to the full mark the issue still occurred. If it were a vacuum issue, wouldnt it surge all the time? Anyways... maybe I will try to make a video of the issue actually occurring, maybe that will help explain.
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--- In subaruvanagon@..., "CHAD" <ctdmx718@...> wrote:
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Hi Chad,
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We need more info re your installation: a) What year is your Vanagon, b) Does it have cruise control? c) Check your Start signal going to the Subaru ECU. Does that wire return to 0 volts when the engine is running or is it sitting above 0 volts? Also check it when you shift into Drive. I have run into this problem when I installed Cruise control in an automatic tranny Vanagon. Tom Burlington ON --- In subaruvanagon@..., "CHAD" <ctdmx718@...> wrote:
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Hey Tom,
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My Vanagon is a 1991 Westfalia. My subaru motor did not have any of its cruise control so I used the stock VW cruise control all the way to the vw vacuum diaphragm that sucks the throttle open and closed. This is the same van that you just did the wiring harness for Chad DeRosa on. I created a video of my issue so that people can get a visual of what is happening: Click Here: Can you give me some tips on how and where to check this start signal voltage Tom? Thank you. --- In subaruvanagon@..., "Tom Shiels" <tom@...> wrote:
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I created a video of my issue and posted on youtube. This will give you a good visual of my issue that I am having:
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--- In subaruvanagon@..., "CHAD" <ctdmx718@...> wrote:
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Good morning Chad,
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That sounds very similar to the issue I had with a 85 automatic Westy. The START wire is the wire that comes from your Ignition Switch and goes to the starter solenoid and also connects to Pin 6 of the Round WHITE connector in the Black Box (T7a-6). On the Vanagon side this wire will be Rd/Bk. Check to see what voltage this wire is at in PARK then measure what it goes to when you shift into gear. You will have to probe in the wire side of the connector to make this measurement. Let us know what you find. Tom --- In subaruvanagon@..., "CHAD" <ctdmx718@...> wrote:
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Brent Weide
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