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post #1 of 4 (permalink) Old 06-11-2019, 12:29 PM Thread Starter
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Join Date: Jun 2019
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Just joined, saying hello and have an issue.

Hello, I have a 1996 Camaro SS bought it new and she was the love of my life, named her Miztress. I spent a small fortune making it the perfect car for me. It did not work out so well so nowadays I just call her the bitch. LOL Long story but to date there is less than 7000 miles on her. But she is gorgeous. I'd post a photo but I cant figure out how on this site, I tried by clicking insert image but then it asks for URL. I have no idea, the photos are on my computer so not being that techy I'm lost.
After years of heartache building and rebuilding and many shops that took me for bad ride I finally got the car looking and running the way I wanted it back in 1996 when I was have my midlife thing. LOL

Took it out of winter storage, ran great. Parked it for a week then I took her for a little spin, pulled out of my drive way and as soon as I hit 1900 RPM she started missing and chugging. WTF I thought? so I kept going but I could not go over 1900 RPM had to keep shifting just before or it would miss and lurch like crazy. As long as I stay under 1900 RPM she runs fine, drove her about 40 miles like that to a shop that I hoped could look at it but they were too busy.



Forgot to mention a few things, the car has only less than 7000 miles but the engine has maybe 1000 miles since its second rebuild. Yes 2 rebuilds on a new engine because the first shop screwed the first rebuild. So now it is a 383 built bullet proof with Vortex supercharger and Bigstuff 3 computer that another bad shop talked me into but forgot to mention to me they had no idea what they were doing. But I finally did get it tuned properly with a mild street tune by a great company in Michigan so on the dyno she is 495 HP to the ground. But not today, today she is probably 75 HP. LOL No Check engine lights are on because when they installed the new computer all that got disconnected, that's why the shop couldn't look at it today, he did try but when he hooked up there was nothing so he told me this will take some time as we have to get a laptop, get the program down loaded then try to figure it out. I cant get to the shop in Michigan as I am in Canada. Moran Motorsports is the place that tuned it, great guys wish they were closer to me.

I looked around under the hood but I cant see anything obvious but I feel it must be something simple, just cant put my finger on it. Everything is newer than new, nothing strange led up to it. It started normally and drives fine, just don't go past 1900 RPM.


Thanks for reading, sorry about the rambling. If anyone knows what I can check it would be appreciated.

Thank you
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post #2 of 4 (permalink) Old 06-12-2019, 07:32 AM
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Welcome to the forum.

The first thing I usually recommend is a code scan & running sensor scan with an obd 2 scanner. But since you don't have an aldl anymore, you can't do that. And all the work you've had done makes your problems hard to diagnose.

But here are some things you can do. Get a fuel pressure tester. You can get one at Harbor Freight or auto parts store.

Attach tester to port on fuel rail. Do a key on prime. You should have around 43 psi. Start engine & let idle. Pressure should be in mid 30's psi. Now tape gauge to windshield and take a drive. Except for idle, pressure should be at least 40 psi. Take engine past 1900 rpm. See if fuel pressure falls off.

Next test will involve an oscilloscope to test optispark low & high resolution signals to pcm. You can buy a PC based oscilloscope for around $70 on Ebay, Amazon, etc. Every lt1 owner should have a scope. You need to see if low & high resolution signals are the proper square wave. And no drop outs of signal, or wave form changing shape.

If you have an opti that isn't a GM, Delco, or Delphi, there's a good chance that it is the problem.

Next check is to mist plug wires with some water and run at night. See if there's spark leakage. Have car up on jack stands so you can check under engine also. Last check would be to look for the infamous intake elbow leak. Check where elbow goes into throttle body.
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post #3 of 4 (permalink) Old 06-12-2019, 10:44 AM Thread Starter
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Thank you for the info, I downloaded the Bigstuff program on to my laptop and connected it to the car. I started the engine and checked to make sure I was connected and getting readings. Sadly I am not familiar with the program and not very good at figuring out how to use it. I was hoping there was diagnostic icon I would just click on and it would give me a fault or code or tell me something. LOL But nope, I have to wait to get someone to help. Need someone to drive while I check the readings or vice a versa. I find it difficult to try to do that while I drive, as well here in Ontario there are huge fines if the police catch you on electronic devices (phones, laptops etc).
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post #4 of 4 (permalink) Old 06-12-2019, 12:50 PM
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I have a pdf file called "scanner readings and what they mean". PM me with your email address and I'll send it to you. The file does a good job of explaining what the scan data means and how to tell out of spec data.

Yes, the running sensor scan is a 2 person job.
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