LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Opti, tune, or something else?

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Old Mar 26, 2010 | 08:18 PM
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Default Opti, tune, or something else?

I finally got the last few things done on my car last month (project I started last March!). I had been waiting forever for the LTs, and didn't bother doing the motor mounts or OTVC wires until I pulled the old mid-tubes.

After I got everything done I notice a bad lugging or almost stumbling when I was in 6th on the highway or in 2nd or 3rd under 25mph (low rpm torque). I also have a problem with it wanting to stall out every time I let it drop to idle (pulling up to a traffic light, etc.). It's running dog rich, so I don't know how much of a factor that plays into it.

- I knew my stock elbow had some tears around the TB mount, so I put a new elbow on to make sure it wasn't leaking.
- I checked all my plug wires to make sure there were no burned wires. (The #6 plug may not have been fully seated, which was fixed)
- I re-screened my MAF after reading some stuff talking about possible air read errors without the screen on.

I'm still getting lugging at low rpms, but it seems to be fine at higher rpms. (I thought the Opti would give a high rpm miss, not a low one?)

I want to get it dyno-tuned when I move later this spring, but am concerned that I'll be wasting money if there is a mechanical problem when I take it.

Does this sound like a bad Opti? (Original still in the car, it was running perfect when I did the rebuild last year so I only replaced the cap)
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Old Mar 26, 2010 | 08:23 PM
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When my opti when out it was only missing at high rpm. Does it run fine under WOT? Is could be O2's. Is it throwing any codes?
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Old Mar 27, 2010 | 07:44 PM
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I don't believe it's throwing codes (at least it hasn't tripped the SES). It seems alright under WOT, but then again I haven't driven very much since I did the motor so it could be losing power without me knowing it.

If it's been running REALLY rich for 800-1000 miles (ever since I did the motor/got the tune), would that kill the O2s? If so, wouldn't they trip the SES (I would think they would even with a PCMforLess tune)
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Old Mar 27, 2010 | 07:52 PM
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Yeah running rich for that long can kill O2's. I would start there
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Old Mar 28, 2010 | 12:10 AM
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when my opti went bad it ran crappy in low rpm,s and fine at wot, so you never know, different symptoms for every car , take it to a shop and let them hook a scanner to it and go from there
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Old Mar 28, 2010 | 12:15 AM
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your symptoms sound just like mine , check that opti I have 2 lt1 ta,s so I am pretty tuned into these junky opti s.
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Old Mar 28, 2010 | 01:17 AM
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well LT headers change things alot, without tuning your car will be running lean down low and rich up top. so i would take it back to the dyno shop and have a reflash update and check your AFR.
get new O2's if needed which can be a problem with chugging also. but make sure there are no leaks, not even pinholes anywhere near the O2's.. this will make the computer think its lean and start dumping fuel... so make sure your exhaust is sealed really tight all the way thru.
but mainly no leaks about 18 inches from the O2's, for every puff of air out, air is sucked back in. hope this helps and let us know what you find
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Old Apr 6, 2010 | 04:13 PM
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I can't find the brand thread for some reason...What brand O2s should I get? Delco? Denso?
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