disasterman

I have a new return rail if anybody is interested in it. $125.

admiralkhole

Hey guys, just wanted to check in after finding this thread...I usually frequent the 24/44/51/68 forum.

I have an '83 with an lt1 swap. It's got a few goodies on it, and I've upgraded the suspension. The engine is in, it's all wired up (need to put in loom and tuck), almost ready to fire. I still have a few things left to get like a vss kit, tach converter, fuel pump,etc. I'm stuck cleaning the varnish tar in the gas tank at the moment, the po left gas in there and it sat for a while...it also froze up the pump.

I am just slowly plugging away, I don't have enough time and money to do it as fast as I'd like, I work and go to school and have a family to support.

Anyone with some advice on anything would be greatly appreciated.

TonyG

I'll preface this with just saying that I don't have any direct experience with what I'm about to say (or paraphrase rather...). But it does seem to make sense.

The first is that Dead Head fuel systems were replacing return lines for evaporative emission reasons starting in the late 90's. And from that stand point, it does seem to make sense.

The second, from Kinsler (as well as Vision and a slew of other big name engine builders and big name injection manufactures)... is that the main problem with dead head system is that you 1) don't get even fuel pressure across all of the injectors, and 2) the fuel heats up in the rail since it's sitting there rather than being constantly recycled.

The GM computers do not have a map for fuel temp, thus can't compensate for fuel temp. Likewise, unless you have an EGT on each exhaust primary, you can't compensate for slight differences in fuel pressure at each injector. Again... this also makes sense.

That said... it seems that no injection manufacturer recommends dead head systems. In fact, none recommend even a series setup (in one fuel rail, out to the next fuel rail, then returned from the second fuel rail).

So like I said, I have never tested what has been written and told to me. But it does make sense.


TonyG

Lemming

I'm headed to the dyno on Tuesday to deal with recent changes. In texting with my tuner he said "Cool, I'll have 3 944 LSX's that night to tune". And yes Tony, I"m pretty sure that one of them is your old car.

zeusrotty

I bought a car he built and ran into the same thing. Not very well built for sure. I called him a few times and he was absolutely no help.

OEMTim

So, I just got to trying to install the VSS but I guess I'm missing something. I have the pieces from TPC, but it looks like I need a pigtail or something to plug into the harness. I thought it was made to work with the Porsche plug.

OEMTim

Wow. Nice and clean under there.
I don't see it on my wiring harness. May have been cut off because I do see where a few wires were snipped.
I thought the 951 had a speed sensor. I see something plugged in right above the mounting spot for the VSS.

TonyG

Excuse my ignorance, but why are you guys using the VSS? Traction control?

TonyG

TonyG

hmm

I never paid much attention to the mappings of the VSS. My last car was perfectly tuned for the street (on two drastically different cams) no VSS at all.

TonyG

rlets

Adding a VSS cured the CEL I kept getting for "improbable idle speed." The return to idle is slower and smoother now and its occasional stall is gone.

Rich

TonyG

When you say, "return to idle", hints that the map for the decel fuel cut off is probably a little off. If you tweak it so that it comes out of fuel cut off at a lower map pressure (meaning it will come out sooner) it will fix that problem. From recollection it's the DFCO map.

Anyway... what I'm trying to say is that the cel lights are controllable and you don't need the vss for driveability.

That's why I was confused as to why people were installing the vss in the first place. I thought people were using it for a speedo or for traction control.

TonyG

PorscheDoc

No vss here either, no issues.

Lemming

Nor do I.

OEMTim

Almost done.......

LS1Porch

The VSS is so easy, there's no reason NOT to do it.