I am trying to diagnose a weird problem that I brought up in the LT1 forum.

check the thread out at : http://web.camaross.com/forums/showt...threadid=54243

I am trying to figure out if I have a missfire, a detonation or even valve float; but I had a thought about the tuning yesterday:

I used to live in Hawaii where the humidity is very high. I tuned the car there and had it pretty lean on the top end, still safe but with little margin.
Now I am back in California and I wonder if the change in humidity could throw my tuning off and if I could be getting detonations.

All my tools, etc are still in the hands of the movers so I am stuck trying to do guesswork here; I may be able to borrow a laptop around and record an acceleration on the hwy because I took my cable with me, but I am not sure when I can do that.

I have burnt spark plug wires so it could be the problem too, but I do not think it would feel like I am hitting the rev limiter. Maybe valve float does, but why would it happen suddenly... I don't know what valve float feels like anyways... (btw, I have dual springs with 40k miles on them)

 

Weird!

We managed today to get a laptop, put Datamaster on it and I had my cable with me.

so, we went for a logging session and I got very weird results:

At WOT, from 4krpm to 6050 rpm (it didn't climb any higher) the o2 values are dropping steadily, from 900 to ... 200! The injectors reach 19ms pulse around 5k or so and stay there the whole time, as the o2 keep dropping.

There is NOT a single thing recorded by the knock sensor (yes, it works), when it sputters on the top, it doesn't sound like detonation either, it really feels like a rev limiter.

So, it looks like the bad ignition wires are not related to that.

Now, here is the interesting one: I brought the engine to 6k rpm with no problems at all using partial throttle. So I am wondering is my power enrichment tables are not screwed up, however it was working perfect before.

The values are identical on both side, so the fuel filter / pump are still good candidates. I assume it rules out valve float as well.

Any help, idea, suggestions, etc appreciated


Brin

 

Not sure if there is any benefit in pursuing this subject on two different boards and then cross-linking them. You should have posted the DataMaster results on the thread on LT1 Tech, not started a new thread here.

I would suggest you copy and paste your second post above to LT1 Tech. In the meantime, this one will be closed.