Idle Spark issue surging

[fast400]

Where to start... I have a New (400mile) 06 5.3 Truck with 4L60E in a restored 69 Firebird. I am to the point of hating the car...I've been dicking with this freaking tune for years...no I'm not an idiot, but no matter what I do, I can't get rid of the ridiculous idle issue. I've tuned SD=perfect except for idle area. I've tuned MAF=perfect except for idle. I've tried every idle procedure on this site. I've tried removing over/underspeed spark. I've put idle into open loop. I've followed the 'advanced guide to tuning GM'. If I combine MAF and SD it runs like shit. As long as I'm cruising or driving it's great. If I coast it either goes into 'cruise' mode, or almost 'dies' (scary) while still rolling 15mph around a corner. I'm at a loss....someone please look!!
BTW--I'm in Germany, not too many tuners for GM over here, unless I drive 6hrs.

[fast400]

BTW
It's DBW. Does it use IAC number? They never move. IAC always 310, even though 0-10 desired.

[02statesman]

Is the engine and transmission completely stock?

[02statesman]

BTW
It's DBW. Does it use IAC number? They never move. IAC always 310, even though 0-10 desired.

No, IAC is only used on DBC.

[fast400]

Completly stock L59 flex setup

[02statesman]

Go to the repository and get a stock tune, copy every table from the stock tune over to your tune and then start tuning from scratch.

[fast400]

Go to the repository and get a stock tune, copy every table from the stock tune over to your tune and then start tuning from scratch.

I've done this before, but I must obviously be missing something vital. I reloaded the stock tune, started and scanned idle. It didn't take long to start surging. I forced timing down with minimal change. Only when I forced absolute timing and AFR control at 14.7 it idled ok.
To avoid doing it all over: here's what I did first time. Disconnected battery to get LTIT to zero. Started with stock tune. Desired airflow was around 4g/sec LTIT started moving - so I cut the higher temp range of the idle air in gear. Repeated above, no change. Then I started cutting ve table (idle area stayed negative no matter how much I pulled???). I pulled idle timing in gear next--no change. So those are all the things I tried last time. If any of those would have slightly improved idle, I would have at least had something to work with. If I force OL idle it will idle ok, but I don't want to go this route.
Here's the log and tune:

[GHuggins]

What's been done to this motor? Is it using stock manifolds for the year model the tune was taken from? O2 location controls all fueling and if incorrect will cause a surge like this. If you have the tables, try multiplying your O2 proportional airflow table by .9 and your integrator airflow table by 1.25 and see if it makes any difference at all.

It's either "airflows" as calculated, fueling or timing. Sounds like you might have covered timing and fueling. Injectors being programmed incorrectly will cause this too. Did you input the correct injector data for whatever's in your engine?

When you say you took out timing. Did you take it out of the main timing table or idle advance table? Main table won't make a difference typically with this problem. Try taking it out of the idle advance table to where you only have about 8 degrees of timing in your typical "idle area" then turn around and "add" back around 6 degrees into your main idle area in your main timing table.

I assume your using the newer ecm to go with the motor and trans?

Sorry I don't have anyway of looking at your datalog today, but if you watch the scan with the gauges pulled up and slow it down, does the surge follow O2 swings? If it does, do the O2 dial in listed above. Especially if your exhaust has been altered...

[02statesman]

GHuggins, have a look at his 'stock idle' log when you get a chance. It starts trimming before the O2s start switching... I think it might be a fault with his PCM.

[GHuggins]

GHuggins, have a look at his 'stock idle' log when you get a chance. It starts trimming before the O2s start switching... I think it might be a fault with his PCM.

Finally had a chance to check this out. Let me start by saying I'm not sure if the data I was seeing was 100% accurate due to the fact that I didn't have the config file that was originally used with this scan loaded, if one was posted. This has been causing me for what ever reason to get screwy data sometimes from other peoples logs... If I post something that's not correct, just let me know

A lot of things in this log are not making sense and I'm just wondering if the correct ecm was installed with this powertrain. Why is there an iac in the scan for a dbw tb? Also was puzzled by the fact if I watched map in one setting it shows "-" then regular in the table display - probably just my scanner there... Then why is this thing getting to an operating temp of 200ish before "fully" going into closed loop if this is a stock tune file? Should have been hitting full on closed loop by 160ish... Also seeing really really negative fuel trims before going into full closed loop - my scanner setup - don't know - but was seeing something like -40 total for a few seconds in scanner time there? Most likely a couple of mins in real time?

As for your idle surge, it is being caused by O2 swings. Once it fully goes into closed loop you can watch the rpms jump up and down with O2 switching. There is some idle surge, due to fueling and timing before going into closed loop - in fact right after starting the engine, but after closed loop = definately O2 related...

Really wondering like 02statesman if you ecm is incorrectly wired, wrong OS, wrong for powertrain in general, incorrectly grounded or just plain screwed? A lot in that datalog just isn't adding up for a "stock to original vehicle tune"........ I might personally bight the bullet so to speak and grab another new ecm and have it flashed via gm then install that and see what it does? A lot just isn't making sense with what I saw?

[fast400]

What's been done to this motor? Is it using stock manifolds for the year model the tune was taken from? O2 location controls all fueling and if incorrect will cause a surge like this. If you have the tables, try multiplying your O2 proportional airflow table by .9 and your integrator airflow table by 1.25 and see if it makes any difference at all.

It's either "airflows" as calculated, fueling or timing. Sounds like you might have covered timing and fueling. Injectors being programmed incorrectly will cause this too. Did you input the correct injector data for whatever's in your engine?

When you say you took out timing. Did you take it out of the main timing table or idle advance table? Main table won't make a difference typically with this problem. Try taking it out of the idle advance table to where you only have about 8 degrees of timing in your typical "idle area" then turn around and "add" back around 6 degrees into your main idle area in your main timing table.

I assume your using the newer ecm to go with the motor and trans?

Sorry I don't have anyway of looking at your datalog today, but if you watch the scan with the gauges pulled up and slow it down, does the surge follow O2 swings? If it does, do the O2 dial in listed above. Especially if your exhaust has been altered...

Thanks for the tips. So far I've taken care of the proportional and integral tables without messing with the stock tune (way rich). Doing that seems to have improved things a little. Tommorow I'll try to tune VE, and see how it is with the table being closer to zero's.
The engine and trans are completely stock except for longtube headers and intake. The o2's do sit further back a bit.

[GHuggins]

Just longtubes and an intake? OK, dial in O2's, MAF and SD and see how it does. If changing the O2's only "seemed" to improve things, try mulitiplying integrator delay by more. I would always return it to stock before experimenting further. You can even try increasing your O2 proportional airflow table by something like 1.1, but typically lowering it does better. "Certain" applications do like it to be increased however... So you'll never know until you try it each way

I still find it very odd that the engine and powertrain are otherwise stock and your experiancing this magnitude of problems. Fueling I can somewhat understand with the intake and headers, but it shouldn't be hitting 200ish before going into closed loop and I shouldn't be seeing iac or anything of the such in the datalog? Someone correct me if I'm wrong here please

Still questioning that ecm and harness...

[fast400]

It's in closed loop the entire time. If you look at the table in the scanner (bottom right) you'll see that. The O2's swinging is when I forced -20 degrees timing. That's the only time I could get them to oscillate. It seems I can move the sensor value up and down, but they won't start oscillating. I agree with you in thinking that the o'2 not swinging may be the issue, but I can't seem to get them going.

[02statesman]

The O2's swinging is when I forced -20 degrees timing. That's the only time I could get them to oscillate.

Well that's interesting. Sounds like your O2 heaters are not working. Check your O2 heater fuse.

[GHuggins]

Or use a decent test light or back probe with volt meter while running. should be the two black colored wires. At least typically.

[fast400]

Heaters have been tested, and are functional.

[02statesman]

Okay, lets go back to basics.

This is a truck engine and transmission transplanted into a Firebird. Are the PCM and wiring harness from the donor truck? Are you using the original operating system from the truck's PCM? Has the wiring harness been modified in any way? Has anything else been done to the engine, exhaust or electrical system that we don't yet know about?