LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Stock tune vs Mailorder OBD1 conversion vs Dyno tune

Old Apr 11, 2006 | 03:02 PM
  #1  
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Stock tune vs Mailorder OBD1 conversion vs Dyno tune



The first run (5) is the stock tune with the original computer.

The second run (1) is with the mailorder OBD1 conversion.

And the third run (9) is the stock computer with some dyno tuneing.

These are all with the mods in my sig from about 4-5 months ago.

Let me know if everything looks alright. Im still trying to figure out some knock problems, which i think are false.
Old Apr 11, 2006 | 03:42 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

It was pulling nicely until 5 k rpms. One thing I would look at is fuel, put a pressure guage on it, run it on the dyno and see if its dropping. I know the A/F looks good.
Old Apr 11, 2006 | 04:13 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

Will do. But where can i get one. I would also like to mount one inside the cabin so electrical preferably.

Do most stock valvetrains keep pulling past 5000 rpm.
Old Apr 11, 2006 | 04:19 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

You shouldnt have any problems with a healthy stock valvetrain up to around 58 to 6000 rpms on a regular basis.

Summit and Jegs both sell an electical FP gauge and sender.
Old Apr 11, 2006 | 04:19 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

It will level off but should pull strong until about 5400 rpm then begin to decrease rapidly. How many miles on this motor? I'm thinking you might have some bad valve springs.
Old Apr 11, 2006 | 04:20 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

just for now you cang et a guage from auto zone thathooks up to the fuel rail, just for now, and you can use it on all cars
Old Apr 11, 2006 | 04:27 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

Shes got about 77,000 miles on her. Mostly highway though. In her former life she was daily driven about 100 miles a day to and from work.

And that fuel pressure guage just mounts to the schrader valve right?
Old Apr 11, 2006 | 04:59 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

Your graphs arent showing up for me. Can you email them to me? Maybe post a link?
Old Apr 11, 2006 | 05:10 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

yea, mounts to the valve, with the hood open you can tape it to the windshield.

HOw do your plugs look, any of them rich/lean??
Old Apr 11, 2006 | 05:15 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

I havent pulled the plugs to look, not sure what rich/lean plugs would look like anyway.
Here is a link that might work fo you.
http://www.gmmodernmuscle.com/fileup...ited_copy1.jpg
Old Apr 11, 2006 | 05:20 PM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

Im calling valve float.... worn valve springs. There is no consistant decline to the hp above 5000rpm. There may be something else amiss but the valve springs are definately not helping.
Old Apr 14, 2006 | 02:39 AM
  #12  
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

So what should my fuel pressure be at idel/cruiseing/and WOT.
Old Apr 14, 2006 | 02:51 AM
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Re: Stock tune vs Mailorder OBD1 conversion vs Dyno tune

My fuel pressure at idle is ~34-36. Cruising it is around 42, and WOT it is at 42-45. I dunno bout the WOT, my eyes are usually on the road.

Lean plugs are white.
Rich plugs are black.
Stoich plugs are tan. (.....right??)
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