Can someone look at this short cold start log and tell me why it starts fine then 10 or 15 seconds in the thing starts commanding a real rich commanded 8.4 AFR, then a few seconds later goes back to where it should be. Sometimes this will actually shut the motor off. I tried leaning up open loop in the lower temps, but that didn't make a difference. It seems to only happen under 60 degrees outside temps,worse the colder it gets out. i don't have this in the summer time.
Any ideas ?
May want to post your tune
Here is the tune if that will help.
Anybody seen this before ? Any ideas on what to look at to stop this from happening? Please !!!
your injector data or airflow tables (MAF/VE) are wrong, the other tables are simply commanded values, doesn't mean you will get them if your air model and fuel model tables are wrong.
Thanks for the response Higgs, i just wish i knew more about what you are saying. Did you look at my tune and see something wrong?
Your MAF and VE tables will be specific to your application. I wouldn't know if it is right for your car or not by looking at them, but no, I have not seen your tune.
Do you have stock injectors?
What are the mods?
Have you altered your MAF/VE tables?
No not stock injectors,ID 850. Have an E-force supercharger running 10lbs boost,90mmTB, cam upgrade and a meth system,and headers. I have had it tuned on a dyno after each up grade.Started having start up problems after cam change. MAF/VE tables may have been altered during one of the dyno tunes, i'm not sure, i'm trying to learn this stuff.
Did you look at the log in the opening post? Do you see the spot, shortly after start up, that starts commanding a rich mixture? Isn't the truck in open loop at this point, reading from some table? I have had the same tune since May,now since the temps are getting colder going into winter the start up acts this way sometimes,doesn't seem consistent. Most days start up is just fine,seems like out of no where a startup will act up like the log shows
Can you tell from the log, is it trying to add fuel because of an airflow reading or is the timing causing it to try and add fuel? What is triggering what there?
I still haven't looked at the tune or log....Originally Posted by PDYoung
Being in open loop just means it is not using fuel trims to correct discrepancy between commanded and actual.
If the MAF or VE is off in that area you will not get commanded. If the injector data is wrong you will also get bad fueling and the correction will get "baked in" to the airflow (MAF/VE) tables.
ID provides great data for their injectors so log onto their website and pull up the right data (or email them or whatever) and make sure it is right in the tune.
Then correct any errors in MAF/VE.
Then look at adders/multipliers that could skew your fueling.
Your injector data is wrong for the 850's just from glancing at the tune. I would start there.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
My injectors and data where installed by a well known tuner who does hundreds of these,not sure how he would have put the wrong data in. This morning i hooked up the scanner,read the ECT, then i went to that cell in the open loop EQ table and leaned that cell out. Started truck up and there was no commanded rich spot today. I may have fixed it but i'm celebrating yet. I will see how it goes. Higgs, all the things you mention with MAF/VE , adders and multipliers is all over my head. I'm learning bit by bit. Is VE Volumetric Efficiency ? i see it a lot but not sure exactly what it is. I see VE vs Maf tuning mentioned all the time,but what does that mean ? How do i correct errors in MAF/VE ? How do i know whats wrong in those tables? How would i know what and how much to change? Is this too much for a tuner in training like myself to handle ?
I would take Ghuggins advice since he is much more knowledgeable in tuning than myself...
But yes VE = Volumetric efficiency. In laymans terms airflow is measured using manifold pressure. VE & MAF are just two different mechanisms of measuring engine airflow. There are different tables in for each airflow model in the tune. Each need to be adjusted to achieve correct fueling. They are the meat & potato tables in the tune.
My vehicle has been through multiple "tuners", most of them just adjusted the maf and a few idle tables and charged a ridiculous amount of money. Dont be surprised if the guys on here rip your current tune apart. Definitely worth learning it on your own. There are some comprehensive tuning guides out there that can help you get a better understanding of how to tune some basic stuff.
Simplistically speaking to adjust the MAF or VE... you datalog commanded AFR versus actual AFR via wideband and calculate and error %. You will adjust the MAF or VE values by that approximate percentage and hopefully commanded AFR and actual AFR better align. During this process you will need to fail other multipliers and items so they don't skew your data.
OK, thanks for the input daveonline, every little bit helps. I don't have a wideband installed yet,but i do look at the commanded AFR while logging. I do understand that this doesn't mean much because commanded and actual AFR need to be checked with wideband. What i don't understand is. I'm commanding 14.69 in closed loop then when it goes to PE i only see one value of 13.59 commanded for the entire time while in PE. Why don't i see a progressively richer mixture commanded as i get into the pedal deeper? I also thought that Ghuggins and Higgs Boson was the same person posting until i just went back and looked and seen that the posts above where coming from different people. Thanks to all that have gave me input on clearing some things up. I'm green as could be on tuning, but very eager to learn and open for all advice. Happy New Year to all you Mo Foes !!!!
Last edited by PDYoung; 01-01-2016 at 12:51 AM.
I'de say Higg's probably knows more than I? After you last post I went back in... Under PE "your" tuner flat lined the PE table to 1.086. SO with this you take your 14.69 stoich setting "divide" by the 1.086 PE setting to come up with 13.5267... THIS is dangerously lean for a boosted car, so that only leads to one "most likely" reasoning... Your tune was possibly rushed and your "tuner" used PE to hit a air fuel target of who knows what? I've seen tuners use the MAF or VE table to hit PE and set the actual PE table to 1... Never seen one do it like this? The 850 injector data unless my own injector data for the 850's is wrong looks almost "scaled". In other words it doesn't go out the flow kpa table like it should = scaled 90some percent? Again, this depends on whether or not my own 850 data that I use is correct? Mine came straight from ID's website? Would go there, go to the 850 injectors, tune data and copy and paste into yours for comparison without scaling to see... Lots of "weird" things I'm seeing and didn't dig through it much? Injectors are what the tune centers around. Would start there and work your way back after getting a good wideband. PLX's I understand are very accurate and reasonably priced?
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Would the fact that i'm running meth be why the PE setting is set to 13.52?
There is no reason to "rape the PE tables." It's a shortcut for not doing it the right way but as usual the right way is the hard/long way. No shortcuts....
My apologies for not looking at the tune yet. Get the right injector data in there. It sounds like the whole tune may need to be redone, honestly.
Where do you live?
i live in Maryland. My truck runs great just a few quirks at cold start up. Do i need a whole new tune for this ? Would bad injector data make the truck run real good other than cold start. It runs low 12's all day long. I've had three different tuners tune my truck as i made mods, the two tuners who tweaked the original tune with the 850's in there never said anything about the injector data being wrong. I compared tunes done by all three and they all look to have tweaked the same things. I also have a 2011 CTS-V that has the same 850's tuned by the same guy out of Tampa who tunes a lot of these,he's just too busy to take the time to work on my cold start. You have to pretty much have to own the vehicle to get that right, to be able to start it every cold morning. i only get one shot per day to make a change and see what it does. There is no way,in my opinion, to have someone else get cold start issues fixed, so thats the reason i'm digging in and trying to figure it out. My truck cold starts fine for the 23 seconds that i have in the startup over/under time table then the commanded AFR starts going real rich for just a second or two, making the motor stumble and sometimes stall below 50 degrees. But this is not consistent,sometimes it doesn't do it and stays running fine after the start up time is reached.I'm beginning to think that there is not going to be a way to stop this and i'm going to have to live with it or sell the damn thing
???? Really not sure what to say here. Your injector data's off... This effects ALL fueling tables... Not sure how many times we can say this??? You can handle this by either fixing the injector data which WILL require re-doing the MAF and VE tables or "continuing" to "patch" the tune... ALL you have to do is go to injector dynamics website and look at the injector data yourself. IT'S WRONG... Don't care how many "tuner's" have had your truck. This is starting to sound like you don't want to fix it correctly and just want someone to say "try this"? Here's the website - http://injectordynamics.com/injectors/id850/
Sorry to come off sounding like an ass. Just not sure how to "go about" this "thought process"? Even attaching the spreadsheet from ID's website...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Reply With Quote