What in the World could be causing this Idle / Timing Issue???

[pganci]

This issue is driving me crazy and I have no idea what could be causing it. At first I thought is was just a intermittent timing issue that would go away after a few minutes of driving but I finally found a pattern.

What's happening is every time I go from Park to Drive I can initially drive away with no issue but as soon as I let off the throttle to slow down the idle starts stumbling, if I start giving it throttle it will start sputtering and popping until I give it enough throttle to push through it. Now it does this to me every time I go from Park to Drive no matter if its a cold start or warm start. This is the strangest part, I figured out that once I come to that initial stop and the idle starts stumbling if I come to a complete stop and sit there for a few seconds the idle will stumble and eventually smooth out and I can then drive away as smooth as if it was a factory tune and I can stop and go with no issues. BUT if I stop and put it in Park the problem returns.

The attached scan clearly shows the timing advance going crazy when this happens. I don't know if this is a timing issue or something causing the timing to bounce so much but it is the only thing that is jumping out at me, I also see that TPS is diving when this happens.

If you review the log using Charts in the scanner you can see what the timing advance is doing when this occurs.

Here are some times to look at.

1.27 Put it in reverse and backed up
1.34 In drive starting to move (sputtering)
1.42 I gave it more throttle and it pushed through the sputtering and smoothed out
1.47 Let of the throttle and coasted to a stop
1.55 Came to a complete stop and sat there
2.02 timing smooth's out and idles normal
2.05 I drive away completely smooth
3.15 Came to a stop and put it in park for a few moments
3.22 Put I back in drive and the whole issue starts over again


Something else that looks strange, if you go to 2.16 the current gear shows its bouncing between 1st and 2nd and it definitely wasn't.

I really hope someone can give me some insight.

Thanks

Paul



Default Imperial Paul.cfg
04.21.2015.2.hpl
Ganci E38 T42 Dyno 3.00 Pulley Beta 05.17.2015.3 Modified.hpt

[pganci]

Nobody has any thoughts????

I have it down to a science, once I put it in gear I will drive about 20 feet, come to a stop, sit there why it sputters and stumbles for about 10 seconds then it clears up and I am good to go. No issue again until I take it out of drive, it will even do it when I go from Drive to reverse and back to drive.

[GHuggins]

I'll be honest with you, I haven't seen your datalog, but did "glance" at some tables I thought were your problem. The reason why I say thought were your problem is due to a few things that it sounds like are going on.

It honestly sounds like your going super lean going into full on closed loop too soon. The reason I say this is because of your stumble that you can kinda force through via pedal combined with dished pistons, stroked engine and whipple supercharger. Plus if I remember or am thinking right, you had a lean stumble before right? That was somewhat addressed via injection timing? Or am I thinking of the wrong person. I honestly have no idea at this point, but I think we addressed something in your tune then?

I would recommend going to the tune repository and looking at a 2013 or 12 ZL1 camaro and tranferring all of it's open loop intake valve temp and other like multiplier tables and seeing how that does. I think there were 3 or 4 tables in those two sections that were different that needed to be changed for your setup.

Sorry can't be of more help right now.

[pganci]

Thank you for your reply GHuggins, I am really not sure if its a lean situation or not. I did follow some of your recommendations previously and they helped me clean up the idle surging.

I do believe the IVT tables are involved, when a tuner worked on it he made some changes to them and the problem was more severe, I went through one table at a time switching them back until it was back to the way it was before. I tried adjusting the Open Loop IVT Gains in the same direction that made it better but it didn't help.

I found a 2012 ZL1 running 14psi and my same injectors that I have already been coping some tables from. I will try the Open Loop Tables tomorrow and see what happens.

I have been doing some MAF tuning with the LTFT's and I it is feeling much smoother during normal driving. The tuner previously had the LTFT's disabled and told me they just made up for a bad tune. Something I noticed is that it says when doing this you should disable the Dynamic Airflow by setting the disable to 200 and the re-enable to 150. When I went to change them they were already set to 200 and 100. Should these values have been some thing different, I have looked at some other tunes and see some set 2100, 1900 and others like 3900, 3800.

If I am understanding the write up correctly below these RPM settings the vehicle should be running off the VE Tables, this would mean I am running MAF all the time. Could this be my issue?

Thanks again for taking the time to look at this, it is so frustrating and my ADD makes me want this beast to run like a stock tune...

Paul

[pganci]

Well I couldn't wait until morning, I changed the Open Loop IVT tables to the one from the 2012 ZL1 and the stumbling and sputtering was happening at idle in park. I let it run for a couple of minutes and it leveled off and was able to drive away again at the first stop it would start sputtering until I sat their for a few moments then I could stop and go with no issues until I put went from park to drive again.

It also looked like it was running leaner than before at idle.

Does this tell us anything?

[GHuggins]

It should not have been running leaner... The ZL1 tables add a decent amount more fuel durring open loop even up in the hotter engine restart areas. I'm wondering if you got all of the tables transferred as they all work together. There should have been a couple in the higher of the two open loop sections then a couple - not sure if it was two or not - in the lower of the open loop sections. I would also highly recommend changing any less than "1" settings to 1 in all of these tables.

Sounds like your definately heading in the right area, but I didn't know the VE hadn't been adjusted. The VE is dirrectly used for open loop and transient fueling. YES with your setup or any blower setup, your better off running in blended VE up to around 2500 or so then going straight MAF if your still using MAF. You'll find the lowend to really come alive when right.

I don't have my laptop to look at your tune again, but I remember distinctly that the ZL1 tables for open loop were adding more fuel, so it should not have had the lean start up stumble or been worse driving unless it's overly rich, which I just don't see - what are your fuel trims as soon as the O2's start switching and then what do they go to once the engine starts to warm up? I would highly recommend making sure that those tables all got transferred for IVT Open loop gains and open loop in general (Just the two sections on the left - one above the other - for open loop) These tables have been used to fix a few modded engines like yours having similar issues.

[GHuggins]

Would also recommend staying away from some of those "modded" repository tunes as they usually only show bits and pieces of what the tuner was attempting. If you can find a stock tune for the open loop tables.

Since it sounds like you more or less are in the process of having to redo your tune correctly - going inbehind the so called pro's and all "they did some things and gave you some stories that have me a little worried - is what I meant by that", I would recommend making things a little easier on yourself and applying a 2bar sd operating system then you can still use MAF with a fairly easily tunable VE table.

Hope this helps...

[pganci]

By switching the Dynamic Airflow settings I was able idle using the Open Loop IVT tables from a stock ZL1. It still did the sputtering when I come to the first stop and clears up once sitting still for a few seconds.

I have seen documentation on 2 ways for dialing in your MAF, one shows setting up a Histogram using the LTFT sensor and plotting LOW MAF Airflow VS Output Freq, my system did not show a low only MAF Airflow Vs Output Freq. Then another shows creating a PID with function [SENS.114]+[SENS.116] for the LTFT+STFT. Is one better than the other, when I log both the values are different?

What is involved with switching to SD?

Thanks

[GHuggins]

SD swap is easy. Just go under your OS tab and apply 2 bar enhancement and also apply TCS patch even though you will still be using MAF, I personally still like to do it.

You can use the attached SD Values to plug into your tune to get it running. THIS WILL need to be remapped for your setup. NO if and or buts on that... Use the LS3 with added boost 2BAR for HP table. You will need a wideband installed for this... BUT you can adjust the whole VE table +/- just by watching commanded eq ratio vs what your actually doing while doing your first start ups. Then fine tune after she's running.

I would like to know what the AF ratio is when your sputtering is taking place just to be sure were chasing the right stuff. This needs to be done regardless, but still like to know were going after the right problem...

I like to use this pid simply because you don't have to wait on ltft's to come into play... ((([PID.6]+[PID.8])/2)+([PID.7]+[PID.9])/2))) - Just make sure your datalogging stft's and ltft's for both banks.

[pganci]

My AFR starts going all over the place, I finally got around to datalogging my wideband.

Here is a scan with it logged. If you look at 24 seconds it starts then clears up around 37 as I started driving away, then again at 47 seconds while I stopped and at 50 seconds its gone and does not return.

05.18.2015.2.hpl
Default Imperial Paul.cfg

[GHuggins]

Watched a little bit of your datalog and one thing in particular stood out big time to me. Your Air Fuel ratio was around low 16's while your fuel trims were commanding "-'s". You need to tune in your O2 sensor locations via O2 proportional airflow table and O2 integrator delay table. Multiplying proportional by .835 and integrator delay by 1.2 to 1.4 something should get you close.

You'll need this right before you can get VE or MAF right...

[pganci]

Would that under idle>RPM>Adaptive Idle?

[GHuggins]

From your tune.... Although yours is called closed loop proportional and closed loop integrator delay? Usually these are O2 named...

[pganci]

Ok, I have been cleaning some stuff up and the Truck is running almost like a stock vehicle except for this weird issue. Someone shared a Timing Graph config with me and said it will tell me exactly what is going on and I think it did.

When the stumbling occurs the Torque Mgt Advance is being activated. I don't see that I have any Torque Mgt turned on. Is there somewhere to turn off the Torque Mgt Advance?

If you look at the scan at these frames you will see what I am dealing with. WHAT THE HECK IS THIS....

Frame 1362 I started pulling away light sputtering
Frame 1783 I left off the throttle and it is sputtering
Frame 1935 I sat still with foot on brake for a few seconds and it clears up and does not come back until I go back to park then drive.
Frame 3050 I came to a stop put it in park
Frame 3440 I started to take off again and it starts all over


6. LS2 04+ TIMING GRAPH 2.cfg
06.02.2015.5.hpl
Ganci E38 T42 Dyno 3.00 Pulley Beta 06.02.2015.1 Modified.hpt

[pganci]

Holy Crap its resolved, thanks to this post. I followed what TexasGMC08 and brandong007 suggested and problem solved, I only had to change the Abuse Mode torque duration time back to stock and the problem went away.

Now on to making it better and not chasing this stupid issue.

http://www.hptuners.com/forum/showth...653#post385653

[GHuggins]

Didn't think about the trans torque settings... Glad to hear you got it all sorted out. Now time for you to start getting it to do what you want it to do since all of your fueling and torque settings are straightened out...

[pganci]

Well, Its really been a pleasure to drive the Truck without the Torque Mgt Advance always kicking in. It only appears now on some downshifts but it is only a blip.

I have a question that I don't know if it is a issue or not but it just looks strange to me so I want to ask. Is there something that would be causing my engine to idle at .40 to .44 g/cyl, I keep thinking it seems high. When I look at other scans that people post they are idling at like .20 - .24 g/cyl. Is it the make up of my engine idling at 750 rpm or is something off causing it? The original tuner left me with a mess that was barely running and I had another tuner really clean it up but he kept saying he had to dump a lot of fuel down low and he shouldn't have to. I also think my Final Minimum Airflow had to be set high, could there be a combination of non PE air/fuel being way off? This thing barely gets 7 mpg even when highway driving.

I appreciate any thoughts and input.

Paul

[GHuggins]

Mind posting latest tune?

[pganci]

Mind posting latest tune?

Here is the most current tune and a log from the other day.

Ganci E38 T42 Dyno 3.00 Pulley Beta 06.18.2015.1.hpt
06.17.2015.1.hpl

[GHuggins]

I glanced at this earlier today and it looked like your recent tuner did a decent job, but then left off in areas where it would have really made a nice difference for you. Just some basics I noticed going off of a decent guess of what you have from your signature. I'm guessing your compression is somewhere around 9.5ish to 1? Don't have a clue on boost, but I do know the 2.9 whipple depending on pulley and engine setup can run anywhere from 4 to 40 lbs of boost. If it's a stock pulley setup I would have added a touch more timing in the cruising and idle areas. Especially combined with the cam and heads. Then there's the fact that Speed Density is possibly partially touched, but then not tuned at all in boosted regions and then this tuner put the operation into solely MAF. With a supercharger only, that would have "gotten by", but when the cam was thrown into the equation your better off running blended up to atleast 2800. This really helps with cams. Then I forgot to check injection timing which should have been changed with the cam and blower or for that fact I forgot to check injector settings in general. I also forgot to see whether or not the O2 settings were changed for the headers. All of these can add up to hp and fuel economy losses... Oh and I do remember looking at the min airflow. Not sure the reasoning there. About 2 too high in the lower rpms, then about 10 to 15 too high in the upper rpms? Assume he did this to get rid of possible bucking or something? The airflow via tps reading and added fuel is why your showing such a high engine load at idle. Wouldn't worry about the rpm setting too much although it too is a touch high.

Curious, what did she put down to the rear wheels? Better or worse this time around?

Sorry I can't just outright tell you one thing to change since changing any of these will change your fueling. If you have an accurate wideband and are willing to do it yourself, then perhaps everyone on here can help you get this dialed in