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Loss of power at highway speed
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Ahwahnee
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PostPosted: Wed Aug 03, 2016 5:28 pm    Post subject: Re: Loss of power at highway speed Reply with quote

IoWesty wrote:
Driving down a hill foot off the accelerator. RPMs fluctuate...


Is this a manual or automatic?
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T3 Pilot
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PostPosted: Wed Aug 03, 2016 5:30 pm    Post subject: Re: Loss of power at highway speed Reply with quote

Time to get busy in the engine Bay.

Did you print out the Manual yet?

I wasn't joking in my last post.....
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IoWesty
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PostPosted: Wed Aug 03, 2016 6:02 pm    Post subject: Re: Loss of power at highway speed Reply with quote

It's a 1991 automatic.
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Terry Kay
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PostPosted: Wed Aug 03, 2016 6:03 pm    Post subject: Re: Loss of power at highway speed Reply with quote

IoWesty wrote:
If I have the van in park or neutral and rev the engine, the RPMs appear to be at normal levels. It's only when the van is in gear and I'm actually driving that is won't rev.



After reading this post I am convinced you are going to require a bunch of hands on mechanical guidance.
There is no "normal" rpm while you're hammering on & off the throttle.

What's normal?

I detect you wanting instant gratification situation here for something you totally can't get a grasp of.

Read the manual.
Familiarize yourself with all of the components and what they do.
If not you'll wind up chasing your tail trying to figuring this out.
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Last edited by Terry Kay on Wed Aug 03, 2016 6:42 pm; edited 1 time in total
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IoWesty
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PostPosted: Wed Aug 03, 2016 6:06 pm    Post subject: Re: Loss of power at highway speed Reply with quote

This manual?

http://www.thesamba.com/vw/archives/manuals/afc_fi...Manual.pdf
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Terry Kay
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PostPosted: Wed Aug 03, 2016 6:46 pm    Post subject: Re: Loss of power at highway speed Reply with quote

As long as your trying to get your air cooled van running right , that is the correct download.
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Ahwahnee
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PostPosted: Wed Aug 03, 2016 6:47 pm    Post subject: Re: Loss of power at highway speed Reply with quote

No... this one:

Digifant ProTraining Manual
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IoWesty
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PostPosted: Sun Aug 21, 2016 7:00 am    Post subject: Re: Loss of power at highway speed Reply with quote

problem was a corroded lead off the temp2 sender.
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j_seara
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PostPosted: Tue Jun 26, 2018 6:29 am    Post subject: Re: Loss of power at highway speed Reply with quote

IoWesty wrote:
problem was a corroded lead off the temp2 sender.


I’m going through a similar issue right now too with a stock 2.1

Did you figure this out by testing the sensor values or visual inspection?
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Abscate Premium Member
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PostPosted: Tue Jun 26, 2018 9:19 am    Post subject: Re: Loss of power at highway speed Reply with quote

j_seara wrote:
IoWesty wrote:
problem was a corroded lead off the temp2 sender.


I’m going through a similar issue right now too with a stock 2.1

Did you figure this out by testing the sensor values or visual inspection?


yes.

The measurement tells you of the sensor is working

The inspection tells you if your wiring is reporting the sensor value correctly back to the ECU

You need both.
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otiswesty
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PostPosted: Wed Jun 27, 2018 9:04 am    Post subject: Re: Loss of power at highway speed Reply with quote

I have a new rebuilt engine, GW 2450. Idles and runs well but bogs down under load at 2000-2700 RPM. Tried disconnecting the O2 sensor without improvement.

I noticed this disconnected vacuum line in the engine compartment and hooked it back up and capped the open Y, but no difference. Any idea why this may have been left disconnected?

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

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riceye
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PostPosted: Wed Jun 27, 2018 9:24 am    Post subject: Re: Loss of power at highway speed Reply with quote

otiswesty wrote:
I have a new rebuilt engine, GW 2450. Idles and runs well but bogs down under load at 2000-2700 RPM. Tried disconnecting the O2 sensor without improvement.

I noticed this disconnected vacuum line in the engine compartment and hooked it back up and capped the open Y, but no difference. Any idea why this may have been left disconnected?

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.


Wow! Twice in a week. Whooda thunk?

That looks to be an abandoned cruise control hose. It should not be connected to your intake/vacuum if it's not in service. Scan through this thread.
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otiswesty
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PostPosted: Wed Jun 27, 2018 9:32 am    Post subject: Re: Loss of power at highway speed Reply with quote

The upper hose that goes to the CC is connected. I haven't tried to use the CC lately, but I think it worked last I tried.

The disconnected hose is a different one
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riceye
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PostPosted: Wed Jun 27, 2018 9:38 am    Post subject: Re: Loss of power at highway speed Reply with quote

otiswesty wrote:
The upper hose that goes to the CC is connected. I haven't tried to use the CC lately, but I think it worked last I tried.

The disconnected hose is a different one


The other hose is for storing your drill bits. Wink
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'87 Westy Weekender - daily driver on salt-free roads

There's gonna be some changes made.

“I find that things usually go well right up until the moment they don't.” - Ahwahnee

"Quality isn't method. It's the goal toward which the method is aimed." - Socrates, later quoted by R.M. Pirsig
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riceye
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PostPosted: Wed Jun 27, 2018 10:27 am    Post subject: Re: Loss of power at highway speed Reply with quote

Following up with a less snarky remark, refer to the diagram from Bentley, below:
Image may have been reduced in size. Click image to view fullscreen.


Looks like the cruise hoses are connected improperly, though this should not affect your hesitation. If it happens at a specific rpm, I would be suspicious of the wiper under the cover of your air flow meter. You may want to start your own thread for this.
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'87 Westy Weekender - daily driver on salt-free roads

There's gonna be some changes made.

“I find that things usually go well right up until the moment they don't.” - Ahwahnee

"Quality isn't method. It's the goal toward which the method is aimed." - Socrates, later quoted by R.M. Pirsig
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otiswesty
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PostPosted: Wed Jun 27, 2018 11:15 pm    Post subject: Re: Loss of power at highway speed Reply with quote

Thanks for that
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Abscate Premium Member
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PostPosted: Thu Jun 28, 2018 12:51 am    Post subject: Re: Loss of power at highway speed Reply with quote

riceye wrote:
otiswesty wrote:
The upper hose that goes to the CC is connected. I haven't tried to use the CC lately, but I think it worked last I tried.

The disconnected hose is a different one


The other hose is for storing your drill bits. Wink


Good for a chuckle
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otiswesty
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PostPosted: Thu Jun 28, 2018 11:03 am    Post subject: Re: Loss of power at highway speed Reply with quote

Looks like the disconnected hose went to the vents on the brake and clutch circuits. These are triggers for the CC when clutch or brake pedals are depressed, to break vacuum to the CC diaphragm.

They are redundant as those switches also send electrical signal to the CC to interrupt function. The reason the tubes were disconnected are that they tend to weaken the vacuum to the CC module and can cause the CC to become less reliable.

So unfortunately, not the cause of my engine flat spot and bogging
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vw66bus
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PostPosted: Sun Dec 03, 2023 9:44 pm    Post subject: Re: Loss of power at highway speed Reply with quote

Reviving an old thread here.
The contents got me to my solution.
I have an 81 air cooled vanagon with automatic transmission.
I rebuilt the automatic side of the transmission this past winter/spring shortly after buying it.
I didn’t do anything to the differential side.
I swear I checked the fluid level and topped it off, but maybe that was another one of my VWs.
I had the same issue where I could not get high speeds past 55.
I did a lot of tuneup stuff with the throttle linkage and timing, points and coil.
This all made it run great. With more power in general. But still couldn’t get past 55 miles an hour.
ATF fluid was full.
So I went to check the differential fluid. I feared that I had ATF dumping into the differential.
It seemed that the differential was empty. It took over a quart of gear oil to fill it.
I’m not sure if the gear oil level affects the governor.
But after filling it, I was able to reach 74 mph.
I have not noticed a leak when parking it.
So my fix was adding more gear oil.
Hope that helps some of you guys

Update 2/5/24 -
Seems my trans is leaking diff gear oil from one of the two "back to back" seals. I have pulled the tranny and about to investigate further.

Peace,
Vw66bus
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