Hey guys, i picked up a '94 z28 for $300! T56 and lt1. Bad head gaskets though (always a catch). Replaced them and she ran like a dream. Then the title issues came, 6 months later still no title and I'm sick of looking at this car in my driveway. So I'm pulling the engine, trans, and rear axle (maybe other things if I can use them on my '90) I'm no greenhorn on swapping engines, I've done a few cool ones, but this lt1 seems like it's more difficult then any I've done before.

so I've got a few questions for you lt1 swap experts, so It seems to me, there's no way around the vats system? I've read that two wires can be spliced together to completely eliminate it, is that true?

I've read the wiring pages inside and out over and over, but I can't figure why I need to cut both harnesses up and splice so much of them together. I understand the 90 harness because I need the gauge wiring, but why can't I just tuck them into the loom of the lt1 wiring? I must be missing something lol. Can I remove the wiring from the 94, use the pcm and everything, (ground straps fuse/relay box) and wire the gauge wiring on top back into the car


Can I use the gauge cluster from the 94 into the 90? I've done (some) research and can't seem to find an answer.


Thanks for any information guys, I'd like to have this car back onto the road in a matter of days, not three+ years like I've seen a few times on here doing this swap

Pocket has the most information on building wire harnesses. He would be the one to ask those the harness questions to. You should be able to use your stock cluster because it's electronic speedo. I think it'll need a translator for the pulse differences.

Take EVERYTHING related to the powertrain and harness.

You can use the AC if you notch the K-member. There are pictures on these forums of where to cut. But it requires some work. More than an LS1 swap as the compressor seems to reach further back.

I am coincidently converting my accessories to the Corvette setup and will be getting rid of my motor mount that I modified for that A/C. PM me if you're interested in it. You can also check my build thread to see where you need to box out the K-Member.

Yeah, I've gotten good info from pocket, right now I've pulled the engine and trans, pulled the pcm and harness on both engines. Now I'm just figuring what to wire into where, I'll be taking the "easy" swap route, but I'm wondering how the hell I bypass the vats. And if I can get this lt1 started without the gauges being hooked up

VATS is a tune in the PCM.

Not many people can tune a OBD1 setup, so you might as well invest in the tools needed to tune it yourself.

Cheapo laptop + cable + software. The software you can use in trial mode for a bit if you are just making small changes.

For my car all I did to disable VATS was uncheck the switch in the tune.




Disable VATS on LT1 Tune in TunerCAT<br/>

Simple enough, so in the lt1pcmits self contained?

Or do I need the little vats pass key II thing

If its in a thirdgen then you don't need anything. I don't have my VATS bypassed in the harness on my GTA. In fact, it doesn't matter at all, because all that happens when my key goes to the run position is that the PCM is provided with 12v power. After that, as long as the engine rotates, it will inject fuel and spark the plugs. It doesn't care one iota about the key. The PCM only cares that it got its 12 volts.

The LT1 PCM's and later PCM's are pretty darn self contained. As long as VATS is disabled in the tune the PCM will run the engine anytime it has 12v for the most part.

I'll probably get this https://m.summitracing.com/parts/prf-64024?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-painless-performance&gclid=CJGp3YSnlc4CFQyRaQod60oGvA anyone use one before?

You won't need it. Spend that much on a cable and you can do it for free. Then you can change rear-end ratio's, tire sizes...etc....

Its not even really tuning per say. Its just turning features on-off with checkboxes.

I guess I already have a tuning laptop for the turbo ranger and he supercharged bronco. What cable and program do you use?

If you want the super easy to obtain method: http://www.tunercat.com/cables/lt1kit.html

If you want cheaper you can build your own cable and buy the software separately. or just use the trial version of the software.

Basically, the only thing you really have to buy is the EE definitions file. But once you have it, you can completely tune the car, or just change little things.

Cheaper is (hardly ever) better, but not having to spend $200 for it is better, the byo cable and software route, where would I start making my own cable? 12 pin aldl connector that goes to something?

All covered in huge detail elsewhere. And OBD1 ALDL cable is pretty much an OBD1 ALDL cable.

Alright, I'll be stabbing the engine into the engine bay this weekend as long as my clutch shows up. Get it wired hopefully enough to start, and I'll let you know if I need more help

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Made my $10 tuning cable, going to remove the vats as soon as I have power to the pcm. Still waiting on he clutch and have to install a bung into the other header for the passenger side for the 02 sensor. I have some pictures and info, hope i can help someone lol