ALH Turbo VNT actuator doesn't move until 8"HG. Is this ok?

wonneber

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Well, uh, no. If you make the actuator arm longer you are setting the turbo to boost even later then it is now.
When I replaced my actuator I had it adjusted to the 3 and 18 (iIrc) inches of vacuum.
I was easily getting 25 LB boost taking off.
I lengthened the arm about 1.5 turns and still can get limp mode on hills on the highway.
For me it seemed like the initial adjustments were ball park setting that needed real world adjusting.
Just my 2 cents (US)
 

wonneber

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I'd read that if I'm getting Overboost, I need to lengthen the actuator rod on an ALH... no?
Correct.
I went 3/4 turn (or so) the first adjustment, then 1/2 turn twice more now.
I can still get 20 LB on take off but it seem to back down easier now.
 

Nevada_TDI

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My apologies to one and all here... I somehow lost lost the fact that even with the actuator "too slow" it was still over boosting. Yes, the correct thing to do when over boosting is common is to lengthen the actuator bolt.

wonneber, you are absolutely right; real world vs. factory suggested can be two very different things. A couple of factors can also come into play here: do you have a tune, and how aggressive is the N75 set up? If there is a third thing, I guess the third thing would be what is the output of your vacuum pump? This of course would apply more to lack of boost than generally to over boost, but I wanted to discuss both sides of this particular coin, as they say.
 
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AndyBees

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I'll throw this question in...

Down stream from the check valve (where all things operated by vacuum are located), how long after engine shut-down should that part of the system hold vacuum?
 
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wonneber

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My apologies to one and all here... I somehow lost lost the fact that even with the actuator "too slow" it was still over boosting. Yes, the correct thing to do when over boosting is common is to lengthen the actuator bolt.

wonneber, you are absolutely right; real world vs. factory suggested can be two very different things. A couple of factors can also come into play here: do you have a tune, and how aggressive is the N75 set up? If there is a third thing, I guess the third thing would be what is the output of your vacuum pump? This of course would apply more to lack of boost than generally to over boost, but I wanted to discuss both sides of this particular coin, as they say.
Mine is stock, no tune or mods.
N75 is new (ID Parts).
Actuator was replaced a few years ago, OEM
Vacuum hoses replaced with the high mileage belt kit last year.
After packing the vacuum pump nozzle with silicone it gets over then 20 inches.
 

wonneber

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I'll through this question in...

Down stream from the check valve (where all things operated by vacuum are located), how long after engine shut-down should that part of the system hold vacuum?
I would think the ASV would take some vacuum from the reservoir.
My old N75 did not hold vacuum with 2 ports looped together.
Only took a few seconds.
Should have tested the new one before I installed it.
 

AndyBees

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Yeah, I have a below dash vacuum gauge connected to the vacuum system on my ALH in the Vanagon. After shutting down the engine, vacuum drops off really fast. And, although my EGR is modified, the ASV is still functional.
 

turbocharged798

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Overboost codes are almost always a sticky VNT. Pull the actuator off and move the lever back and forth. If it sticks at all you have a problem.
 

Nevada_TDI

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Off topic, I have the vent-mod done on my Jetta and last night she took 14.695 gallons of D2, I wonder how close to actual empty I was; the low fuel light light had been on for ten miles or so.
 

Judson

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I put in 15.5 gallons once (approximatly). I thought it was commonly assumed that post-ventectomy the max was 16.5. I've put in 14.5 gallons a lot of times.
 

Nevada_TDI

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Judson, thank you. I was trying to remember if if post-ventectomy tank volume was 16.5 gallons or so. I just did the fuel tank level mod so the first half of my tank doesn't last 300 miles and the second half lasts 150 miles. I am sure this will affect my low fuel warning light now, so I will have to wait until it comes on again and see just how thirsty she is at that point.
 

UhOh

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Judson, thank you. I was trying to remember if if post-ventectomy tank volume was 16.5 gallons or so. I just did the fuel tank level mod so the first half of my tank doesn't last 300 miles and the second half lasts 150 miles. I am sure this will affect my low fuel warning light now, so I will have to wait until it comes on again and see just how thirsty she is at that point.
I recall reading that the average amount of fuel available just when the light comes on is 1.7 gal. I know that I've gone over 60 miles after the light has come on, but I try to keep it to no more than 40 miles because you don't know if you're going to get caught in traffic or not (I generally don't worry about this, but it seems that stuff will happen out of the blue in the worst possible times).

Looking at my records 15.375 gal is the most I've put in my car.
 
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