LS1 Swap

[BonzoHansen]

So it does have some sort of solenoid now? Huh.

GM makes it work for the e-rod, so you should be able to as well.

[LTb1ow]

I don't get it.. you are making this way to complicated.

Why don't you just run the silly EVAP and get an aftermarket fuel guage driven off the LS1 output?

[sweetbmxrider]

Originally Posted by Tru2Chevy

Is this what is throwing you off Adam?

I read this as the PCM uses the fuel level sensor input from the tank to determine the level in the tank. Then it does what it has to do with the codes based on the level in the tank, and then the PCM outputs a signal to the fuel gauge based on what it saw from the fuel level sensor in the tank.

I don't see any reason why this output from the PCM can't be used to run a stock fuel gauge in some way.

- Justin

Originally Posted by BonzoHansen

I don't see why the cluster is needed...but....that 'out' on the pcm is a serial out, so I assume it carries other info too. So I think that is no good.

yeah the pcm sends class 2 info to the cluster and i am not sure if some of that wiring in the schematics is tied into the cluster. i could be completely over-thinking it which is ususally what i do.

[BigAls87Z28]

Well, its been tried and as of right now it hasnt been done without the use of the 4th gen dash.

And an aftermarket or stock third gen gauge, it wont work. You have to use the 4th gen dash...dummy.

[NastyEllEssWon]

Originally Posted by BigAls87Z28

Well, its been tried and as of right now it hasnt been done without the use of the 4th gen dash.

And an aftermarket or stock third gen gauge, it wont work. You have to use the 4th gen dash...dummy.

so your saying they dont make aftermarket gauges that run off the stock ls1 fuel gauge signal???

[BigAls87Z28]

No, the gauge is not a problem. Moddifying the sending unit or the gauge itself isnt a problem.
The problem is evap and what to do with it. Even keeping the third gen tank, the problem is what to do about evap.

[V]

i think everyone needs to take a step back and look at this issue again. I have not read up on the issue, nor do i have any direct experience with an ls1 swap, yet there are some basics. One option would be to "utilize" a 4th gen cluster, but in a different sense. You can just remove the main board and install it behind the dash or in some area as to serve a purpose of being connected but no need to actually use it. Times like this one needs to think outside the box. You could even try to replicate maybe what that circuit wants to see, i read 15-85% before, correct, if so, whats the Ohm reading or signal voltage at say 75%? you'd need to start looking into ides like that maybe. What about tuning issues? can you change a setting in the PCM to activate the EVAP circuit fulltime regardless of any possible "feedback" from the cluster?
id think looking into these things would be more productive than going back and forth about who says it will or wont work, just my own opinion.

[BigAls87Z28]

Yeah I have thought about finding and replicating the circuit or a system to mimic it. I think some have tried but end up bailing out due to complexity and cost. Some would rather just swap the dash and do it that way. There has to be an easy way to do this then swap in that god awful dash.

[sweetbmxrider]

yeah, **** evap. stick a one way filter on the hose and good night

[LTb1ow]

Originally Posted by sweetbmxrider

yeah, **** evap. stick a one way filter on the hose and good night

And have a car that rivals mine in reaking of gas at idle, yea fun.

I would def try to get the EVAP system working, even if its just a line hooked up to the tank and a manual operated noid..

[BigAls87Z28]

I was trying to think on how I can keep the stock canister working. I dunno if the LS1 computer can be used to switch the solinoid.
Im gunna keep looking on TGO and see what some have done.

[PolarBear]

Originally Posted by BigAls87Z28

Im picking up sarcasim a bit?

I think he is being genuine as he wouldnt bother with looking stuff up if he didnt care. Scott and I see eye to eye on some of the emission related stuff, I want to put cats on my 73 because I hate the smell of the exhaust without them and with the newer technology adding them doesnt hurt the performance that much. Two high flow cats on a true dual exhaust isnt going to cost anythng but high RPM power, something which my BBC isnt going to see too often.

Originally Posted by BonzoHansen

Al, how does evap work in your car now?

In theory all the EVAP stuff is the same, controlled by the PCM at some point. The newer car is just using more input as to when and how it should be comannded. IIRC the TPI/TBI/MPFI command EVAP under light cruise after the car is in closed loop?
The physical hookup is also basically the same, except the canister is on the tank in the 99-02 cars and in the 3rd gen it was in the engine compartment. I am on the same page here as I left the canister and everything on my 4th gen tank when I put it in. In time I had planned on running the wires to the back of the car and hook the 4th gen canister to the 7730 computer, it is after all just a solenoid that controls this.

The problem Al is that if what is said is true about the cluster you are not goign to be able to get the EVAP to work with or without the 4th gen tank. If this is the case there really isnt too many cons inusing the 4th gen tank instead. If you want to screw the PCM you can swap out the resistor board on the bucket and get the correct value for the level or you can swap out the resistors in the cluster to utilize the 4th gen level and possibly get the EVAP to work later. As far as the lines go the 4th gen stuff almost bolts right in. I think you just need a few different fittings and you can use the 3rd gen hard lines and everything. You would basically just disregard the return line from the 3rd gen and use the stock feed line, and then put a short hose at the engine compartment. Alternatively you can also run a braided line all the way to the front of the car and get more volume if you decide to make big power later. Either way you can do the 4th gen tank fairly easy. If you want to come see my setup as is now you can, or I can dig all the parts up this weekend and try to set it out in mockup. The only part I dont have is the stock feed line from the filter to the engine compartment. IIRC the "T" block from the 4th gen setup screws into the stock 3rd gen filter, you just have to relocate the 3rd gen fuel filter bracket slightly.
I did this a while ago but it really sint rocket science, I think people are overthinking the whole covette filter thing too.

I am also assuming "Pocket" is going to do you r harness now?

[BonzoHansen]

Originally Posted by BigAls87Z28

Im picking up sarcasim a bit?

Bear is correct, 0% zero sarcasm, 100% props.

[PolarBear]

Originally Posted by crainholio

Nice guy and very helpful, but extending the PCM connection by soldering extra wire to all the pins is (IMHO) a bad approach.

Care to elaborate? IMO I would have no problem doing that, as long as one is a competent solderer

[BonzoHansen]

Originally Posted by crainholio

As for the evap can, I just put in an '85 or whatever Monte Carlo evap can that had no solenoid as designed. Just an inlet from the tank, and an outlet to the engine. I connected that to the LS1 evap solenoid, even though the PCM is not likely to switch it.

No gassy smell under-hood since 2004. Fuel tank holds pressure and hisses when the filler cap is unscrewed.

I was thinking along those lines, like the one in my 77. That is why I asked about the stock canister

[BonzoHansen]

Originally Posted by crainholio

Speartech worked for Delphi and knows his shiite. If I was doing major harness surgery, I'd pay him to do it.

his rep is very good.

[BigAls87Z28]

Originally Posted by crainholio

Careful with that Pocket guy, he's on LS1Tech begging for help figuring out why his swap car won't run right...

http://www.ls1tech.com/forums/pcm-di...-problems.html

Nice guy and very helpful, but extending the PCM connection by soldering extra wire to all the pins is (IMHO) a bad approach.

As for the evap can, I just put in an '85 or whatever Monte Carlo evap can that had no solenoid as designed. Just an inlet from the tank, and an outlet to the engine. I connected that to the LS1 evap solenoid, even though the PCM is not likely to switch it.

No gassy smell under-hood since 2004. Fuel tank holds pressure and hisses when the filler cap is unscrewed.

Originally Posted by crainholio

Even a slight amount of additional resistance on many of the sensor input circuits will throw off the PCM and cause all manner of chaos. Going to town w/ your soldering iron to extend the PCM leads for relocation like Pocket did is therefore a bad idea.

He may have fixed it by now but he's keeping quiet about it.

Speartech worked for Delphi and knows his shiite. If I was doing major harness surgery, I'd pay him to do it.

I cant imagine solder giving that much resistance, or any more then what you would see from extending the harness an extra 3ft to sit inside the car, no?

Ive tossed around the idea of going with a Speartech harness...but thats a large chunk of change to drop. If I could sell more of my stuff, I could free up a bit more money for the budget, but...its another 350 bucks!
Ill toss it around.

Back to the tank.
I still like all the advantages of teh 4th gen tank. Reading on TGO, it seems that the fumes are vented through the onboard charcol canister, with or without evap, so I guess that can do a good enough job scrubbing the fuel smell. I gotta look at that picture of the top of the 4th gen tank again.

[BonzoHansen]

when voltages are read in the tenths of volts and less it matters.

[BigAls87Z28]

I guess so, but again wouldnt that also be effected in lengthened harness? I guess the two of them combined cause problems.

[Frosty]

Originally Posted by crainholio

Speartech worked for Delphi and knows his shiite. If I was doing major harness surgery, I'd pay him to do it.

Absolutely no question about that....Speartech FTW, if I was doing a late model motor transplant I'd buck up and the harness from him or have him modify mine.

He knows his stuff and he stands by his work.

[LTb1ow]

Can't you tune out the EVAP and pressure sensor stuff, then run the third gen tank with the charcoal canister mentioned above?

[PolarBear]

Originally Posted by BigAls87Z28

I cant imagine solder giving that much resistance,

This is aimed more toward crainholio but solder SHOULDNT add ANY resistance to a circuit, again that is why I stated when someone is competent soldering. I will agree, however that you should use the proper gauge wire, going smaller is NEVER a good idea. Going a wire size up will decrease resistance.

Originally Posted by BigAls87Z28

Ive tossed around the idea of going with a Speartech harness...but thats a large chunk of change to drop. If I could sell more of my stuff, I could free up a bit more money for the budget, but...its another 350 bucks!
Ill toss it around.

More like $450 for a re-work and $750 for new, no thanks. I may just leave the computer in the engine compartment on mine.....

[BigAls87Z28]

450 to redo a harness I send them or 750 to have them just send me a new one?
I think Im gunna pull the trigger on the Speartech...gotta sell these damn heads!

[BonzoHansen]

Originally Posted by BigAls87Z28

450 to redo a harness I send them or 750 to have them just send me a new one?
I think Im gunna pull the trigger on the Speartech...gotta sell these damn heads!

I'd call him and pick his brain about your fuel & evap questions. You have to take advantage of experienced knowledge like that.

[PolarBear]

Originally Posted by crainholio

Yup, properly applied solder has negligible effect on net resistance. The guy's use of non-same wire gauge was my point. And who knows how good/bad he is at soldering. The thing looks like a hack job, the engine won't run properly, and he can't figure out why.

I only, kind of, disagree only because he does quite a few according to others on TGO but I am not discounting that his problem in that thread isnt related to the harness somehow. In one of the other threads he put a hole in the FW so he didnt have to lengthen the harness? Are these the same cars?

I was wondering around on Waytech's site a while ago and they used to sell ALL the proper color coded wire and insulation type like GM uses but now I cant find anything but the solid colors. I was kicking around the idea of buying spools of wire and making my own harness, the connectors get expensive quickly though. If successful I would have all the wire needed to make more harnesess......