Date: Thu, 10 Oct 2013 14:03:17 -0700
Reply-To: Scott Daniel <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel <scottdaniel@TURBOVANS.COM>
Organization: Cosmic Reminders
Subject: Re: Runaway Engine RPMs
In-Reply-To: <CAMuoOU7jNzHStXGAmUEdXFssda3Hs+ufttEqegiGac0QSQj=DA@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi John..
yes, it should hum with the key on- a good sign.
It never hurts to inspect contacts or solder joints at and in the ecu .
Personally I don't suspect your ecu very much for this event.
I have for sure seen the ISV system do it though.
I suggest remove your right tail light..
and take the ISV control unit there out ..
usually they have never been looked at or touched in the life of the van ..
or at least I find that to be the case often.
Sometimes they are not even there ( like missing ) or are rattling
around loose and not mounted propertly, or badly corroded at the
connector contacts.
Doesn't sound like a throttle cable problem ..
I do find that 'most vanagons' need their white plastic tube in the
front half of the van, for the throttle cable cleaned out with
compressed air ..and cable re-insterted with lots of nice lube .
Also ..that white tube tends to slide forward..exposing the inner cable
at that junction right in the middle of the van underneath.
a little hose clamp at the forward end fixes that though.
Scott
On 10/10/2013 1:54 PM, John Meeks wrote:
> Thanks Scott -
>
> I'll try unplugging the ISV next time it does this. I think that's a good
> troubleshooting first step. Not sure yet what it will tell me. I think that
> valve just add more more less air to the mix. You can hear the little motor
> running in there with the key on.
>
> It's probably worth inspecting the ECU solder joints with a strong
> magnifying glass too. I'll be able to do that this weekend.
>
> John
>
>
>
> On Thu, Oct 10, 2013 at 3:28 PM, Scott Daniel <scottdaniel@turbovans.com>wrote:
>
>> I sure wouldn't call 3K rpm 'runnaway' ..though it does sound really
>> dramtic to discribe it that way.
>> if it was really runnaway ..
>> it would be screaming at 6,000 rpm or so.
>>
>> I wouldn't think that the TPS telling the ecu that your at full throttle
>> would do this.
>> I believe all that does is bypass 02 input at WOT.
>>
>> And ..I have seen the electronic control unit and/or idle air valve cause
>> this.
>> I've had a vanagon sitting in a bay of my shop idling ..
>> suddenly jump to very high rpm all by itself.
>>
>> Unplug the Idle Air Valve right there on top of the engine.
>> ISV valve sometimes called too. Idle Stabilizer Valve.
>>
>> Scott
>>
>>
>>
>> On 10/10/2013 9:44 AM, John Meeks wrote:
>>
>> Yesterday I was in a 2 mile stop and go traffic jam. About 3/4 of the way
>> the low speed fan came on as expected. A minute later the engine revved up
>> tp 3K rpm and stayed there. The gas pedal was all the way up. Couldn't get
>> off the road so I turned off the engine when there was a stop situation.
>> Turning it back on the engine revved right up to 3K again.
>>
>> Finally pulled into a parking lot and waited about 15 minutes. Started
>> normally with no recurrence the rest of the way home.
>>
>> I had this same problem about a year ago (intermittant) and 'fixed' it with
>> a new throttle cable and cleaning out the rust and dirt from the pedal to
>> cable housing. Now it's back!
>>
>> Side note just put the engine in after head gaskets and ring replacment
>> and It was running great for the past week.
>>
>> Could the TPS be the culprit if it made the ECU see full throttle and ECU
>> then enriched the mixture?
>>
>> Any ideas are welcome.
>>
>> John Meeks
>> '91 Vanagon MV Phoenix
>> Stock 2.1 250K miles
>> Northern Michigan
>>
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>>
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>>
>>
>>
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