switchblade327

Hey everyone,

I'm just about to get my LT1-equipped 1966 Chevelle back out of the restoration shop and on the road! The LT1 is a mostly stock bottom end but with dished pistons, ARP fasteners and a stage 2 heads and cam package from http://elliottsportworks.com/

Trouble is, the previous shop (who is now out of business) seems to have messed up some things. The engine is a '96 but the PCM might actually be an OBD1 unit from a '95. It's getting just a few MPG and the plugs are pretty wet with gas so something is obviously wrong and I knew the tuning and wiring might be suspect.

My question is this: with an LT1 that doesn't need to take emissions inspections, should I go down the road of trying to figure out what crazy stuff the previous shop did or I should I just bin it all and get a Megasquirt or some other later model or aftermarket engine management?

My engine isn't too crazy; I just want it to run right and get reasonable mileage for what it is and I'd like to do that in the most cost-efficient way possible.

And maybe leave the door open to supercharge it later

I'm aware of the 24x coil pack conversion but I'm hoping to not spend that much.

HellTeeOne

The stock OBD1 or OBD2 PCM is plenty capable at that level. Just need a competent tuner, some will tell you the OBD1 is easier to work with.

Whoever put dish pistons in a n/a LT1 pretty much screwed the pooch from the start anyway.

TravisMcGill2000

iTrader: (2)

Did you install bigger injectors? Does it have any kind of tune for the mods you have done? Also you shouldve went with flat top pistons. Your gona be loosing little power with the dish.

sweetbmxrider

iTrader: (13)

If he is going to supercharge it down the road, why would he want high compression?

I'd do a mail order tune from pcmforless.com if you know exactly what you have mod wise.

TravisMcGill2000

iTrader: (2)

Oops just seen the supercharger later.

switchblade327

Thanks for the replies.

The pistons are only meant to lower compression by half a point and are forged, with the intention of leaving the option to supercharge at the expense of some power.

I know the OBD1/2 systems are capable for my car. What I'm worried about is the potential mess of doing forensics on someone else's wiring/programming job. The tune it has now should be from PCMforless but I don't know if it actually is. I'm concerned that I'd buy a new tune, load it up and not resolve the issue. Hence my curiosity for something that can do live diagnostics.

The injectors are 30lb, I believe. Though that may actually be part of the problem. I think the old shop tried a few different sizes of injectors and maybe the tune doesn't reflect the final size.

KyleW707

30lb injectors will be fine for your setup. Check the fuel pressure regulator, make sure there's no fuel in the line. Also, make sure the line is on the correct intake port. Then I'd go about checking for leaking injectors if they're not new

sweetbmxrider

iTrader: (13)

Pull the tune and see if its been changed. Plenty of guys here to help you with that but I'm not one of them. I can barely drive.

Jazz-LT1

iTrader: (2)

I got a mail order tune from PCM4Less and I've got no complaints. Car made 366 rwhp. It's currently getting reworked due to a minor bottom end issue and I'm hoping to bump the compression and some other mild changes to get me to 380 rwhp which is 420+ at the crank.

switchblade327

Okay, I got some pictures of the PCM and the connector. Pretty sure this is an OBD1 even though the engine is OBD2.

https://plus.google.com/u/0/photos/1...64434073616929

Can anyone verify? Once I identify that, I can start looking into how to check and fix the tune.

Alex94TAGT

The serial number on the PCM in the photo (16188051) is correct for a 1994-1995 OBD1 LT1.

12-pin DLC port is also OBD1.

switchblade327

Thanks Alex. I'll pick up a cable for this and look into how to troubleshoot!