Howdy,

I've just wired up an SGI-5 box between my T56 and my stock 87 dash cluster (green wire, chunked the yellow box). Seems to work fine.

My question is regarding the lack of VSS into a 730 box running the Super_8D3 code. What role does VSS play in the actions? Can I run without the input, and if so, what is the impact? I know of a couple things, just curious if anyone has been through it already.

Guess I could just wire it up in parallel to the green dash wire coming off the SGI-5 box, right? Gotta look back and see which pin it would need to come in on...

-Craig

 

Obvious are EGR, CCP and TCC. Originally I did not have it hooked up because my stock PCM controls the Suburban's 4L60E.

I believe the VSS helps control idle to some extent. I am not sure how it works, but when I was not running a VSS signal to my 727, the engine would stall very frequently. As I would come to a rapid deceleration, like braking when coming off an interstate, it would surge then stall. I noticed the BLMs going to 116 or lower. If figured the lack of VSS must be affecting the DFCO and/or decel enleanment. I do not know how it all works, but since installing my SGI-5 box and running a lead to the ECM, my problem is solved.

http://www.edgesz28.com/edgesZ28/sub...tuning.htm#vss

Personally, I would not run without a VSS under any circumstance. Ed www.edgesz28.com

 

Easiest way of finding what effects what is to use TunerPro's built in "item finder". It's located under Tools... or Ctrl - F
The IAC throttle follower needs the vss.
Canister purge, EGR, Fans, Highway mode, Idle stuff, Speed limiter, TCC, and most importantly, Knock!
There is a Knock min speed that is set to a value above 0 on ever bin from GM. Put that down to 0 or you won't get any knock retard. It'll store the counts, but not retard until you're above that speed. I like it set at 5 mph for the majority of people that I help tune. I tell them to keep adding 4 degrees to the idle to show them what happens when you have too much timing. It's a great way to learn what too much timing feels like without pounding the engine too much.
Good luck with that tree puller power plant.

 

That makes sense. Confirms what I was thinking when it wanted to dip in RPMs today driving it around. Come off the gas on decel at about 10 mph, and it wants to dip and die rather than 'follow'. It does feel like it'll pull a few trees right out of the ground! Starting to second-guess the manual brake conversion, it just gets up to speed so quick, it's almost confusing ;^).

I'll wire up the SGI-5 box output in parallel with the dash cluster going out to the ECM tomorrow and see how that does.

 

Hydroboost will get the brakepower back.

 

Yes, I've read a good bit in that regard. Is there a setup that'll get me running for Hydroboost? I seem to recall a factory-type pump that was available without all the tie-ins. Wasn't real expensive either. I'd be hard-pressed to give up all that spare space where the vacuum booster used to be...

 

I think you can tie into the pressure line.
Just have to change the valve in your pump.
Been a while. I can dig up an shop in CA if you want.
Cost was too much for me to replace my new vac setup.


You trade diameter for length when going to a hydro system.
The mechanism itself is slightly smaller in dia than a std iron master cylinder. And a couple more PS lines, and more power.

 

Hmm.. Bit off topic, but interesting... Cardone 529700 Powermaster unit. Any GN guys with opinions?

 

Never seen that before.
I was thinking of this-http://home.comcast.net/~procharged6...ydroboost1.jpg

 

Craig,

There is a reason all the GN guys dumped it for a regular factory vacuum assisted setup and the Turbo Trans AM never had it in the first place :-)

Reliability was never one of its strong suites.

later
Jeremy

 

OT
I used the astrovan set up.
You may have to adjust the push rod length .
Hydro-boost

 

Thanks Bill

I saw a nice clean 3/4t gm truck unit in the JY this week.
I'll have to go get it.

 

I just got back from checking out our local yard and lucky me I found 2 of them complete.
Anybody need/want one let me know tonight because I'm going back tomorrow during lunch.
I also found a $200 32v Northstar engine complete... oh what fun that would be for a transplant of some sort .
Craig, really, let me know by tonight and I'll grab it. Both appear to be in excellent condition and low miles. I've never seen them in the yard before so I don't know if they'll last.

 

Yes, that'd be great. I'm looking to try something different, and that would be the ticket. Worst case is it doesn't work out, and I have some extra plumbing ready for the next attempt. Thanks!

 

I think you will find that all the boosters are the same (except the reserve cyl) and it's just the piston in the master cylinder that is different on the different models.

The Astro unit was very plentiful and cheap($40) in the JY compared to a 3/4-1 ton unit.
I run the whole thing including the proportioning valve.
It was a disc/drum set up but i now have disc/disc and it works great!!
I'm 5,000 lbs and 33" tires!