Excellent! That certainly could cause my car's symptoms.
Not wild about getting to the Opti, but I think it's time to bite the bullet and get to work...

 

Not as bad as people make it out to be. Just time consuming and messy if you're not careful.

 

You can probably guess your injector pulse width by watching your stft and ltft numbers.

Check the opti rotor and etc. and see what you find. If nothing is abnormal see what the data reads when the problem is occurring. Would be looking at your timing advance, short and long term fuel trim, and MAP data very closely.

 

True on both points!
I changed the Opti about a year and a half ago. I put in an aftermarket unit for $200-$250 versus the OEM part for like $500! Maybe that's going to turn out to be the wrong choice! That's why I want to be damn certain it's the Opti because, if so, I'm going to spring for the OEM Opti this time around!

Last time around it was a DOA kind of failure and real easy to see the low and high res signals were flatline before diving into putting in the new one.

 

Okay, here's what I'm getting:
Both banks show stft right around zero. Bank 1 seems to have ltft around 7, but bank 2 is about half that, 3.2

Timing is around 18 advance at idle and increases to the mid 20s by 2500 rpm (max I can get). Seems okay to me.

What numbers should I be looking for MAP? The MAP is around 9-10" Hg at idle which correlates well to 18-19" Hg readings on a vacuum gauge (and steady). MAP reads about 28" Hg engine off, I'm a little over 1000 MSL, so that makes sense, as well. MAP increases as the throttle is opened, but there's no load on the engine so it's not a lot.

I also had my scan tool graph the O2 sensor outputs (pre-cat) on bank 1 and 2. Bank 1 seems a little 'odd' compared to bank 2: bank 1 varies more rapidly and 'randomly' whereas bank 2 is almost a sine wave, like the computer is cycling the mixture back and forth around a set-point. Perhaps this ties into the difference in the LTFT between the two banks.

Comments? Would these indications be consistent with the car being crippled, or are they just red-herrings? I.e., issues that might be responsible for poor gas mileage, or less than optimal performance, but wouldn't result in the massive backfires and zero power.

I guess, after all of this, I'm still not sure if I'm chasing an ignition or fuel problem! ARRGGHH!!!



Mike

 

BINGO!
We have THE winner.
I pulled everything apart yesterday, and that's exactly what I found: the rotor screws had come out and were rattling around. I don't now how it ran at all. There's a little plastic pin on the back of the rotor that was sheared off. So, I opted to just get a fresh reman unit and use my old one as a core. The reman was only $130, and the rotor 'kits' were nearly that much!

For others that may read this in the future the factory Opti made it 150,000 miles and the aftermarket unit made it about 25,000 miles before the screws came loose. It was a Richporter (RPT). I will say that everything else looked very good inside: no evidence of moisture (seals in good condition), optical disc in perfect condition, and high voltage towers showed no evidence of wear (plating was fully intact). I was VERY tempted to just re-install the rotor with Loctite and call it good. But, with the sheared pin it just didn't seem like a good idea...

Now, does anyone know where to get the proper socket (for the external star bolts) and bit (for the rotor screws)? It's not a Torx (E4 is too small, and E5 too big), and T10 is not small enough for the rotor screw...is there a smaller size?

Thanks to everyone for their help!!

 

Glad you found the issue and yeah those data number look pretty good... and sometimes its all about being able to determine what kind of issue your chasing. With normal fuel and o2 data readings like that ignition would have been the place to go.

 

https://camaroforums.com/forum/lt1-l...41/#post614528

 

Okay the rebuilt Opti (Cardone brand from Oreilly for $130+core) is back together with RED Loctite on the rotor screws; something else may fail but it isn't going to be the rotor screws coming loose!!

1) I went with using the Throttle body screw and vise grips method to remove the inverse Torx fasteners holding on the cover. Use a T20 bit to remove the screw from the Thottle body. It turns out that the end of the screw is actually WITHOUT threads and is a smaller diameter than the threaded portion. What this means is that buggering it up with the vise grips doesn't ruin it for putting it back in your Throttle body. FYI, it is an E4 if you want to actually buy the proper inverse Torx socket. The set is available from Harbor Freight for $10. My earlier post about it not being an E4 nor E5 was MISTAKEN. As my bad luck would have it, the screw I tested in the store was pre-damaged (yeah, what do you expect with a reman dizzy!) and the E4 wouldn't fit over it! So, I didn't buy the sockets. I had to remove that one with a pair of needle nose pliers, but the Throttle body screw worked great on the other three.

2) Rotor screws are T8. I bought a cool kit made by Husky (SKU 165 355) for $5.97+ tax at the local Home Depot.

With the Loctite, Torx kit, and reman Opti I'm all in for under $150.
Of course, the car's not back together and running yet....

 

Back together and running great!
Thanks for everyone's help!!