Help trying to find drop in timing at cruse.

[Ramba_ral]

Hi,
Working with a cammed ls1 and dealing with a drop in timing at cruse. Goes from 44 to 4 for a brief second. Can be felt while driving. From what i can tell from the logs I see no timing being pulled from anything and no other strange readings i can see in the logs. Example times are at 1:03 and 1:31. other thing I notice is its going into open loop when the timing drops. Any advice as what to look for would be great.

2nd drive.hpl

current tune.hpt

[Alvin]

Maybe you posted the wrong log.. maybe I'm blind. but I don't see it.

[gametech]

You are trying to log over 100 PIDs. Cut that down to about 20 and you will get more useful information. As an example, I was trying to see what your TPS was doing, and your parameter polling is so logjammed with extra junk that the numbers just jump around in between data points.

[Ramba_ral]

You are trying to log over 100 PIDs. Cut that down to about 20 and you will get more useful information. As an example, I was trying to see what your TPS was doing, and your parameter polling is so logjammed with extra junk that the numbers just jump around in between data points.

Ill get some toned down logs. What all should I leave in?

[Ramba_ral]

They should show up now

[gametech]

Ill get some toned down logs. What all should I leave in?

You have to have rpm, cyl air, map, and ect for most any diagnosis for any problem. After that, just add in what you need for whatever you happen to be trying to figure out. In this case you would want to keep vehicle mph, dyn air, tps position and anything that modifies spark. I guess you would want to keep the OL/CL flag as well. The problem is that there is only a certain amount of bandwidth to monitor PIDs, so if you want a high polling rate you have to limit how many channels you monitor at one time.

[Ramba_ral]

You have to have rpm, cyl air, map, and ect for most any diagnosis for any problem. After that, just add in what you need for whatever you happen to be trying to figure out. In this case you would want to keep vehicle mph, dyn air, tps position and anything that modifies spark. I guess you would want to keep the OL/CL flag as well. The problem is that there is only a certain amount of bandwidth to monitor PIDs, so if you want a high polling rate you have to limit how many channels you monitor at one time.

huh i didnt think that to many pids would be a issue.

Heres the list I got now.

[edcmat-l1]

Need to drop most of the advance pids and add MAF Hz and MAP. You don't need most of the advance pids. Base advance and knock retard and pretty much all you need.

[abc]

I don't see any one spec. that would allow it to pull 40 degrees all at once. For a test, cut back the spark retard limit to a max of pos. 20. Right now it's at neg. 25 or so.

[Ramba_ral]

Alright made these changes. Lets see how it goes

[Ramba_ral]

Alright made these changes. Lets see how it goes

Well with the spark retard limit set to 20 I didn't see any massive drops in timing like I was seeing before. So I guess something is making timing drop all the way out?

[edcmat-l1]

What you were seeing is most likely a scanner anomaly from logging too many pids. It's not real.

[Ramba_ral]

That's what its looking like. I put the stock values in that table and will check again. If its gone ill move on to the other issues I'm having.

Speaking on that should I post them here or in another thread?

[gtstorey]

Not a lot in this post that would carry over. Start a new thread with a very detailed description of what you are working on and a new download of log and tune.

[Ramba_ral]

Alright drove home with stock values and you can see it in the logs at 3:55 and at 4:07. this is during cruse on the highway around 65. Just drops all the way down to 5 degrees then back up to 25.

Only other note is its more noticable with cruse control on

[Fast4.7]

I don't see any one spec. that would allow it to pull 40 degrees all at once. For a test, cut back the spark retard limit to a max of pos. 20. Right now it's at neg. 25 or so.

AC load compensation will do it.

[Alvin]

Its very possible this could be A/C clutch TM.

It's happening at 0 throttle.

Has anyone else compared this against a stock file? There are an absolute ton of changes that don't make any sense. Including to DFCO spark advance..Which who knows for sure if that isn't a subtractor/adder etc.. But it shouldn't have been changed.

TPS hysteresis for idle too..

Changing odd things all over the place leads to weird gremlins like this. I'd start over. See if anyone else compares to a stock file and agrees or disagrees with me.

[abc]

AC load compensation will do it.

Yep, you nailed it ECM 12877.

I would cut 80 percent of that out as a test next.

[abc]

I have a PO1 in a vette. The table is a single axis only for RPM. Max retard is 4 degrees.

[Ramba_ral]

Let me make some changes to the ac clutch tables and see

for the DFCO spark advance should I put it back to stock?

small note about the TPS hysteresis. that has been returned to stock values