Ponyhntr

iTrader: (9)

Yea, it does-sorta. On the dyno the car starts jerking back and forth violently. On the street it kinda shutters. Here's my 2 graphs, the first is blown, the second is NA:

dhdenney

iTrader: (53)

I have dyno graphs that look very similar. It even starts at about the same RPM. Mine was opti related, even with the Delteq. So obviously it was the optical lens. Now with the new optical and Delteq it runs like a dream. In your case I don't know what to tell you. I guess I got lucky that I was able to track mine down. Did you do a wideband reading during these runs? That can tell you what's going on with the fuel. Even just visually, what was going on with the exhaust? Mine was puffing huge clouds of black smoke. Obviously a lot unburned fuel where it wasn't sparking.

blkchevyz

damn yours is way worse then mine, i dont feel so bad now lol


i've checked the grounds and actually added a second one to the head.
my plugs are gapped at 40

Ponyhntr

iTrader: (9)

Yeah, thanks!


I'm beginning to think I got a bum opti from GM, but I am VERY reluctant to buy another one to try.

dhdenney

iTrader: (53)

They have a one year warranty. Take that one back. The likelihood of getting two bad ones is small.

Z-nos

Maybe it is the tuning?

Ponyhntr

iTrader: (9)

Well, I'm pretty sure mine is not the tuning...a couple of the best tuners in the country have had their hands on it, and it still does it. We've tried more timing, less timing, more fuel, and less fuel and it is still there. Not a whole lot else you can do at WOT.

Ponyhntr

iTrader: (9)

Well, for ***** and grins I did a compression test yeaterday just to check the condition of the engine. All checked out good, maybe a little low, but I had one that was 170, 3 that were 155, and 4 that were 160. So it's not a problem in the shortblock. Next I will check the spring pressures and go from there. I highly doubt that it's an engine problem, but I'm going to cover all my bases.

I'll let you guys know.

LTSpeed

I fixed mine by replacing the 1/4" vacuum line running from the evap canister purge solenoid valve (passenger side of air intake) to the purge vacuum diag switch (2" away).

Others have fixed this by replacing the vacuum line on the fuel pressure regulator, and some by replacing the regulator itself.

Still others have fixed this by replacing the fuel pump and/or fuel filter. For others, it's the injectors.

Then there's the coil, or the wires, or even the plugs. There's a lot to cause this besides the opti.

I've even seen bad throttlebody seals cause this, or worn pushrods, or old valve springs, or mis-adjusted rockers.

There are so many things that cause the exact same dyno chart. I always start with the cheap stuff and move on to the next. Been lucky so far, but there is still a new opti in my future (I'm at 150K).

Ponyhntr

iTrader: (9)

Well guys, I found my problem! It was the vacuum line going from the intake to the fuel pressure regulator! It had been pinched at one time, and had a hole in it. Replaced it, and wala! Went to the track yesterday, and had 0 problems! Ran a new best also, times in sig!!

Just wanted to let those that had subscribed to this thread what I found!