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Open discussion on the factory VAC boost control.... Continued**

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I think the vac system worked better as well. My truck would hold 10-11lbs of boost under heavy throttle towing.
I bought the turbo master thinking I would gain something but never gained anything. I removed it after a bit and went back to the vac system.
I now run the ATT
 
My response really doesn't follow Great White's premise of open dialogue, so I apologize up front. My vac system was 100% operational when I removed it, but I liked fewer parts to maintain, fewer hoses under hood, and the performance of the (admitedly) archaic spring system were/are greatly improved over stock. I'm one of the towing folks and my properly functioning vac system could not touch my TM. Ran it without a chip for nearly a year- the TM was much better for my application.
 
First vacuum pump (diaphram) went bad. Northeast rust made getting the pulley off impossible, so just swapped diaphram piece (worked, but a mistake in the long run!)

Then waste gate solenoid went. Then hoses were cracked and leaking. Then the pump piece puked, locked up and ate the almost new serpentine belt

On trip, broken (and broke) I wired shut the waste gate and removed the vac pump. Then installed a homemade turbomaster ($5) Best $5 I ever spent

I think the same GM flunky who designed the PMD also had his hands into the vacuum system!! :rant:
 
TMHark said:
First vacuum pump (diaphram) went bad. Northeast rust made getting the pulley off impossible, so just swapped diaphram piece (worked, but a mistake in the long run!)

Then waste gate solenoid went. Then hoses were cracked and leaking. Then the pump piece puked, locked up and ate the almost new serpentine belt

On trip, broken (and broke) I wired shut the waste gate and removed the vac pump. Then installed a homemade turbomaster ($5) Best $5 I ever spent

I think the same GM flunky who designed the PMD also had his hands into the vacuum system!! :rant:
Click to expand...

How many miles when this failed were on it?
 
Crankme69 said:
How many of you have tried a chip / PCM that had a program that utilized the Vac "TUNED" wastegate control vs the TM?
Click to expand...

I ran that way for a while when the 1st reflashed PCMs started showing up, I was not impressed, but possibly early in the game before the tunes were "refined' I also ran with a fooler for a long time, for me the vac system even with the fooler did not meet my expectations.
 
Crankme69 said:
How many miles when this failed were on it?
Click to expand...

My truck 2 year old @ 37K when I bought it:

1st WG solenoid failed @ 40K, a MAP sensor @ 60K, a vac pump @ 110K 2nd WG solenoid, somewhere in there a baro sensor, vac canister on turbo vac actuator got a hole in it and would not allow full vac to stay on the system 2 psi max boost with my fooler @ 130K-140K ??? not sure that one but it's demise drove me to permanent install the TM I had been keeping "just in case".

The vac pump went before the WG diaphragm (bought a replacement pump) all vac system components that left me stranded but I carried spares or would plug in my TM as backup WG diaphragm was "last straw".

I ran vac system until it was no longer viable to keep it up, then with a TM until going to ATT, the permanent solution :thumbsup:.

IMO vac system had good intentions but a weak link as GM was using available tech at time of design to make an more emissions friendly electronic controlled vehicle.

For it's time it was an okay design, I don't think GM ever envisioned that the 6.5s would still be "truckin" all these years later or possibly they would have made the components more "robust".

The problem we face with our "mature" vehicles is parts are worn and aftermarket replacements are "outsource" manufacture even if in a GM box bought at the GM store; so we get a mix of good and bad parts that possibly not built to same standards when GM had some warranty skin in the game and reliable repair parts they sold was a must.

How much pain is GM feeling over an "obsolete system" in their mind not enough to worry where replacement parts come from or how long they keep the vehicle fixed, add to that folks who want least cost pricing on parts and "discounted parts" and you get discounted repairs that last how long ?

GM IMO really would rather the "OLD 6.5s" would just go away as they hurt new vehicle sales, why do you think "cash for clunkers" got so much support.

So one can "band aid" their aging vac systems, and keep them viable, and even make tunes for them and get a good result.

My burb had 130K on it when I bought it and repeat pattern as soon as the WG solenoid started acting up @ 140K it got a TM and vac pump came off. I have no idea what had happen maint. wise when owned by others, I think I was 3 or 4th owners, I finally went ATT & reflash when funds became available.
 
Why didn't GM use an electric solenoid? Wouldn't that be possible? Seems a better idea to me for a few reasons... less weight, fewer components, no need to add a power robbing, belt driven accessory, quicker to react, possibilities for reprogramming, etc.
 
CONTINUED from Previous thread due to server issues.
 
Yes, can't edit the hard links so continue here.
 
Cant read the last few posts...but i will say this, I think most people opt for the turbo master for the reason of towing or cost. I dont feel that is is superior to the factory vac control other than at top end where the factory system cuts the boost pressures. In fact, i think i lost some mpg's with both my 95 and 96 after adding the tm. Dont have numbers to back this up, but it seems i lost some range on my tank. Not much at all, but enough to notice. More boost at lower rpms seemed to eat up more fuel.

I always thought of designing an in cab switch/cable in which you could limit the boost pressures when not needed so as to gain fuel economy. Much the same as a n/a engine. Obviously one would have to watch egt's, but without towing and easy highway driving, they shouldnt climb too high.

Someone before mentioned replacing his vaccum pump for $150 or spending $500 to add a tm. The turbo master if bought costs a little over $100 and one can be made for under $10. A reflash or chip(which i am assuming is where the $500 came from) is not nessasary when adding the tm. If boost numbers are kept within the factory specifications, no overboost codes should be seen. This can all be set by adjusting the spring tension.

I personally went the route of the tm for two different reasons. On both my trucks too provide more boost at higher rpms for towing, and also for the fact of fewer things to go wrong. One of the main reasons i love old vehicles is simplicity. The less electronics the better. If a $100+ vaccum pump, problematic lines and solenoids can be replaced by a spring.....I am all for it. Not that I cant diagnose or understand the factory system, I would just rather do without it. Same reason i may go to a mechanical db2 pump when my ds4 craps out again.

just my .02
 
HighSierra86 said:
I personally went the route of the tm for two different reasons. On both my trucks too provide more boost at higher rpms for towing, and also for the fact of fewer things to go wrong. One of the main reasons i love old vehicles is simplicity. The less electronics the better. If a $100+ vaccum pump, problematic lines and solenoids can be replaced by a spring.....I am all for it. Not that I cant diagnose or understand the factory system, I would just rather do without it. Same reason i may go to a mechanical db2 pump when my ds4 craps out again.QUOTE]
:iagree::thumbsup::thumbsup:

I couldn't have described it better my self, the less diagnosing I have to do, the less headache I have, the happier I am. Also another reason why my '51 is my daily driver.
Click to expand...
 
chickenhunterbob said:
Those who have replaced a faulty (for whatever reason) OE controlled waste gate with the spring, well, they think they died and gone to Heaven. They'd be equally impressed if they corrected the fault in the vac system.

However, far less moving parts with a spring, no more worry about vac pump, solenoid, etc. failing, though they are removing the factory protection the (yes, somewhat complicated, and somewhat conservative system) provides. Protection is still there, via defuel tier 2 protection actually with a fooler if the PCM is not aware of tru boost pressure there is little difference in running a TM as far as de-boost goes, both defuel on mega high boost or high IAT in some ways a fooler might be worse as PCM will never see the mega high boost depending how much fooling one has dialed in

The OE system generally provides trouble free service for ~150,000 miles, but YMMV...

I recall early on gmctd had a concern about wastegate component wear with the spring, as it is constantly flapping to relieve boost, that's the chatter you may hear buzzing under hood, he stuck with the boost fooled, vac actuated system... That is not way I remember it, I'll call later tonight to reconfirm

We're starting to see a few examples of that now on these forums, though very few, so probably not of great concern. I've seen more worn WGs over the years of being on the forums with vac controlled systems than any with a TM, what is not being captured in your assertion is how many TMs were installed after the fact of a bad vac system that may have had wear prior to the TM being installed? And an incorrect assumption made that really is a coincidence to the timing of the TM install

When the 6.5 first hit the road, those using for towing were quickly looking for more boost than GM programmed, and a boost fooler was invented over at the Page, John Kennedy sells a variable plug and play version, which works fine to this day.

Agreed I had one of those and ran it for years until I reflashed and I no longer needed it.
A fooler is a good stop-gap to aid in better performance from stock but a reflash is the cure and if folks gripe about the cost of a TM see what Kennedy's fooler costs for $5 worth of electronics and $10 worth of connectors for plug & play I'm not knocking his fooler at all free market sytem one can charge what they want for their widget, but when I got it I was disappointed to see what it was vs. what I paid for it

The pre-94 6.5 turbo diesel had a similar arrangement to the Heath spring, except was dampened so as to not chatter. Not exactly similar yes but that spring was for boost regulation at same wussiliy boost curves as what GM provided with the PWM boost control, the TM does a far better job on those as well, now one can modify a early style to work like a TM and be as well served with that as a TM, you just need boost monitoring capability to set it properly FYI Kennedy at one time sold TMs from Heath I don't know if he still does so it was a viable solution for him as well at one time

A spring is a good solution for those without the wherewithal to diagnose and maintain a GM designed digitally controlled waste gate.

Only my observations, but I'm sticking with my vac system, quite happy with it, and so far it seems have competent enough to maintain it.
Click to expand...

Well CHB I see you haven't changed much in your attitudes as being cock sure on certain positions, I and a number of others are plenty capable of to diagnosing/maintaining them yet we chose to delete the vac system as you see in post 27 I got tired of repairing an aging system that left me stranded on more than one occasion, and on my burb I wanted the reliability of the TM on the family people mover, nothing worse than being on vacation than having a boost issue, minor or major or have the wife out getting groceries and vehicle won't get out of it's own way once you get used to it being able to quickly accelerate.

Im glad vac system works for you, and hope you live long & prosper with your endeavours with it, but not really a fair assesment to make the claim that those that choose to delete it are inept at maintaining it.

Oh JD (GMCTD) has no special affinitiy to the vac system, if it's more cost effective to repair it, do so, but when it gets to point ofbeing beyond economical repair he's in same camp as many of us, buy/make a TM setup.

What scenarios would constitute that IMO if the WG actuator bushing were shot and WG flapper can't seal, the WH actuator diaphragm was bad, or the vac pump itself were dead, all can be repplaced with new $$$ or used with same age issues potentially as what caused the initial failure.

All of this is moot once you go with ATT well discussed elsewhere so no need to go into that again.
 
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Man are we ever passionate about this mercy sakes it just a spring vs a vac operator right???

I think the entire reason for this post was so we could listing the pro & cons of each control system so an individual can make a choice based on facts & experiences period.

Here is one point that I'm sure we also with have some pasion with, there is NO way you are gonna adjust a SPRING with the same accuracy as you can gain with a vac controlled wastegate. it just ain't gonna happen.

Boost requires FUEL and if the end result is you end up running more boost at cruise it's gonna cost ya some MPG...how can you argue that?

There is my story & I'm sticken too it LOL!

Ok now be NICE!
 
Agreed on all points, vac system has "precision control" until it decides to give up the ghost, the degree of precision with some of the reflashes I've seen have not been a big deal, spring or vac work equally well for 99% of the 6.5 population my opinion for what it's worth; the spring is the better of the 2 in longevity, & my apologies for the passion but some inaccurate assumptions were put out that needed an opposing viewpoint.
 
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