I've been tuning for a while and getting things fairly close, my blm is around 125, and the ve learns are asking me to take away fuel, but the engine acts lean, watching the o2 graph shows that the voltage goes to 0 volts at cruise for long periods of time. Any Ideas what would cause this? it has a lean surge at cruise as well. Why would the ve learns want to lean it out when it's already too lean? #1 cylinder is pumping some oil past the rings, it will puff some smoke only when you get on it hard. It doesnt have a missfire, and all other cylinders have good even compression. Wouldn't this have the oposite affect if anything?

 

O2 voltage dropping at cruise sounds like highway fuel is enabled.

 

I double checked that, the box is not checked.

 

There is no check box or option flag for lean cruise mode. A data log and possibly the BIN would be helpful in describing what is going on.

The ECM targets the O2 table values via feedback from the O2 sensor. Any chance those tables were changed?

RBob.

 

Option Word 4 - Bit 0 - OpHwy is not checked. I thought this was for hiway mode in tuner pro. Thought I read somewhere that hiway mode was availible but not used by GM. Is this correct?
I cannot find any o2 tables in tuner pro, just some various filters. Where do I find them? I can check and report back.
I have not changed anything regarding o2, that I am aware of, that doesn't mean I could have by mistake. The changes I have made so far have been sa and ve, trying to solve an idle surge, working with pe, hot restart, and cts filters. Did I cause any problems in the process?

 

That flag is to allow highway mode during open loop operation. Either do a playback of the log file or look at it in the analysis display/dump. If you see the ECM going into open loop and commanding a lean AFR (15 - 16) that is highway mode.

O2 window tables:

INT - Mean R/L
INT - Rich O2 (Upper)
INT - Rich O2 (Lower)

Idle surging can be tricky to fix. Sometimes it is from trying to use too low of an idle speed with a modified engine. It can be helpful to zero out the idle compensation SA tables (2 of) and add some fuel in that area via the VE table.

Once things get settled down can then fine tune it.

RBob.

 

My bin file is ebl v31xdf. I looked at the tables, everything is roughly around that 500 mark, I would post the tables, but I don't know how to do that! I'm running what is know as a lt4 hot cam, which is mild by my standards, (i'm used to raspy carbed v8's), but it does idle smooth in open loop, idle speed set at 650. I've raised the idle and it didn't help, and the idle sa comps are at 0. I can get ve learn from thee idle most of the time and it fills in 0's in the boxes. I was wondering about a little more fuel, but it does need to pass smog.
Is it possible that I just need to adjust the afr in hiway?

 

Smooth idle in open loop and surging in closed is usually due to too much proportional gain. Work with the gain table and value:

PRP - Prop Gain Offset for Idle
PRP - Gain vs O2 Error

Likely need to be reduced.

RBob.

 

Thank you, I just reduced them and I will see how it runs. What does prp stand for and what does it do?
Am I right about adjusting the afr in hiway mode?

 

prp is short for proportional gains. The ECM uses them to force the AFR to oscillate. When the O2 reports lean it increases the injector PW, when the O2 reports rich is shortens the injector PW.

Not sure about the highway mode, does it run OK when in lean cruise? If so then no need to adjust anything. If you don't want the lean cruise mode can set the MPH threshold for it high.

RBob.

 

It has a lean surge at cruise, I assume it's in cruise mode because I have never done anything with it. I'll watch a datalog and make sure, then adjust from there.

 

If you are still tuning the VE tables then disable highway mode for now. Then once everything else is in place enable highway and do any tuning required for it then.

RBob.

 

have you considered OL idle? Just set the option flag and see what happens. I currently idle OL. You can also enrichen OL idle cells (rpms/map say 600-800 rpm and whatever map you idle at). Being emissions complicates things a bit.

 

I want it to pass emissions, so I will do that as a last resort, I could probably still get it to pass that way, but if I can have it in cl, I would prefer it.

 

I have disabled hiway mode,(thought it was dissabled all along with the flag unchecked) and getting the tune back in check now. I've been making small adjustments reducing the tables for the idle surge, and I'ts getting better each time.
the last 2 issue's I'm dealing with, and cannot find the fix for, is this.

It runs too rich during the warm up cycle. I start it up and let it warm up a minute or so, drive very easy and slow till it warms up. It runs very rich for about 5 minutes untill the o2 starts working. I've tried a few things, but cannot fix it, Is there a way to do this?

How do the tables work for ae? I started off with it being too rich under all conditions, now what I have is it stumbles rich with light accel. from a stop, and a lean hesitation with any sort of quick movement of the gas pedal. I see that the ae filters all have a cts table, so I'm not sure how to adjust it.

 

Locate the coolant based open loop table and make a small change.

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Light accelleration? May need to reduce the AE-throttle follower table. If the light accelleration is a small change in TPS then address the TPS tables for AE at the %TPS you see it occurring in logs. Hit the spacer bar to label min/sec in log.

Quick movement of T? that may be further up the TPS% AE table and also it may involve the AE MAP as VAC may be dropping with that.

 

Thank you for the help! Ive been making small adjustments and it is improving. It's fairly simple once you learn what to do, I've made some bad guesses and had to change a lot of things back! I have the iac gain tables zeroed out, and it is much better, but not completely gone, is there anything else I can do?