Computers/ LT1 vs LT4

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Nov 26, 2009 | 11:58 AM

Klondike

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Computers/ LT1 vs LT4

I know the LT4 has a plug-in chip that is for different (LT4) knock sensors, and it has the rpm limit raised to about 6300rpm. My question is, are the computers really different or is it just a programming procedure that you can apply to any LTx computer? Should I pick up an LT1 computer as a spare, or would it not be compatible with my LT4?

Nov 26, 2009 | 12:45 PM

96GS#007

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Same computer. Just need the right program flashed.

Nov 26, 2009 | 03:02 PM

A95Y

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From: St. Louis Missouri

1996 and newer are OBDII, my 1995 LT1 is not OBDII.

Nov 26, 2009 | 10:14 PM

Klondike

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Thanks. Good to know. There's an LT1 computer near here for cheap, so I'll check out the year. Did the 97 Camaro & Firebird that had LTx engines have the same computer as the Vette?

Nov 26, 2009 | 11:02 PM

pcolt94

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Quote:

Originally Posted by Klondike

Did the 97 Camaro & Firebird that had LTx engines have the same computer as the Vette?

I think there were some differences however my main point is to consider if they had the electronic 60E transmission. (If your looking at PCMs that work with automatic trans).

Nov 26, 2009 | 11:24 PM

96GS#007

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Quote:

Originally Posted by ckp

1996 and newer are OBDII, my 1995 LT1 is not OBDII.

'94/'95 OBD I computer will run an LT4 just fine. Simply needs to have the flash file updated. Frankly, an otherwise stock LT4 will run fine on the LT1 tune albeit down a tiny bit on power since the timing and PE tables are a little different. You'll probably see an EGR code or two as well since the LT4 doesn't have the EGR system.

There are two things that will not work if you use an OBD I PCM in a '96...the gas mileage info and the ability to pass an emissions test by plugging in. You'd have to have a sniffer test instead. Otherwise...plugs right in.

Nov 27, 2009 | 01:35 AM

A95Y

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I've heard there are communication problems with the CCM using an F-Body PCM in a Corvette in the year ranges we are discussing. That may be why some functions are inoperative, as GS says. I do not know if this is a fact. I would check and see if the part numbers are different between common engine configurations.

Nov 28, 2009 | 09:30 PM

Klondike

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Well, mine seems to do everything just fine so far. But an LT4 is already 13 years old, and being a one year exclusive model, I'm starting to look for spare parts, just in case.