No idle closed loop 7427 $0D

[96lt4c4]

Like we both saw, the low vacuum/higher MAP so thought it was a bigger cam. But if small cam then yes it could be a vacuum leak. But IAC count of 63 does not indicate vacuum leak? Yes more timing with large cams will increase vacuum/lower MAP.

Beginning of that log was dead? Took awhile to get going then was short.

Your right about open loop, but if OL BLM should be 128? So I'm confused...

What is that bin based off?

Yeah I dont know why the log did that. He is going to check for vaccum leaks. I think the BLM'S were at 104 after a drive. When we came to a stop it went back into open loop which is when I restarted a new log to capture what it was doing. I know the thing is really rich. I am thinking that he may have pretty crappy cam as well. He is trying to dig up the cam card, but said it was recomended to him by this guy who said this guy....so I dont know yet. I do know its flat tappet, I mentioned the "RV CAM" he said that sounded right. Anyway, I am going to try and get cam specs, he is going to look for leaks. The motor is only about a year old.

I used the stock bin from my 94 Blazer, this truck used to have a 6 cyl. in it and its a 93 so we swapped in a 7427 when he went V8. Here is the stock bin I used for a starting point.

Also here is another log while driving, if anyone wants to look, like I said, I know its rich.

[EagleMark]

Yeah I dont know why the log did that. He is going to check for vaccum leaks. I think the BLM'S were at 104 after a drive. When we came to a stop it went back into open loop which is when I restarted a new log to capture what it was doing. I know the thing is really rich. I am thinking that he may have pretty crappy cam as well. He is trying to dig up the cam card, but said it was recomended to him by this guy who said this guy....so I dont know yet. I do know its flat tappet, I mentioned the "RV CAM" he said that sounded right. Anyway, I am going to try and get cam specs, he is going to look for leaks. The motor is only about a year old.

I used the stock bin from my 94 Blazer, this truck used to have a 6 cyl. in it and its a 93 so we swapped in a 7427 when he went V8. Here is the stock bin I used for a starting point.

Also here is another log while driving, if anyone wants to look, like I said, I know its rich.

An RV cam will not cause this. But a vacuum leak will, just a little vacuum leak to one cylinder on O2 sensor side and POOF! Data is wrong!

I looked at the bin and log. Couple things I didn't like was Max Timing increased past 41.8, not good to go past a built in fail safe of firing wrong cylinder. Then Main Spark Bias of this bin is 9.8. Your's is 0? But your timing table is about the same around idle, way more other areas. I never change this in bin because there's to many other things that could be affected. The $0D XDF says this bias is built into mask, that said timing table should be actual. Now without bias where is it? I don't know, it's just something I was taught to leave alone, do leave alone and work on bin as is. You definatly can change bias if you know how it affects every other spark setting. But that's to much work for me... KISS works well here and you don't find an extra 9.8 degrees somewhere!

"So where do you say your timing is?" Check with a timing light and compare to data.

Idle does not look steady? Timing and cells are constantly changing, timing is varying a few degrees, so flatening timing at idle could help.

But that is not what I found that could be affecting this. You've changed a lot! All I saw was good tuning. Except some of the 02 settings I don't understand, like Mean/Rich, Proportional and Lean limits. Some are same both ends? I started looking closer at these differences from stock bin when I saw cross counts stop while still Closed Loop. Also saw INT of 128 and BLM of 99 and stay there with no cross counts, still Closed Loop... I'd copy in stock 02 settings for now and see what happens. Also pull power and clear BLM learn, it's probably a disaster at this point.

HTH!

I'm curios and would be intrested in hearing results of timing at timing marks as is. Then with Main Spark Bias back in place as well.

[woody80z28]

Cam in my truck is actually very mild. It's a stock F-body LT1 cam (204/207@.050). If the cam was the problem, then the wideband would also be reading incorrectly. My wideband read it fine, and I could see watch the AFR spike lean before it stalled. FWIW, closed loop idle was unchecked in my factory bin. I turned it on to help band aid any issues with my VE tuning, but disabled it since it caused problems.