n00b needing lsj help, rolling idle

[Sharkey]

so i purchased a stage kit from one of the top companies for cobalt and 3800 performance parts (im sure many can guess who that is, however im not going to say it). my stage kit included a 2.7" pulley, 60lb injectors, wiring harness, and a custom tune. since i had hp tuners they told me they would remote tune my car till the tune perfected for my setup. the tune was way off to start with, however after sending them 3 data logs and receiving 3 refined tunes it was fairly close aside from a couple minor issues. 2 weeks ago was when i received the last updated tune, still have some issues and since then ive gotten no response to my requests for corrections. i was dealing directly with the tuner, when i inquired with the customer service e-mail the response i got was "he is really backlogged on emails, he will get back to you shortly." that was a couple days ago, needless to say im rather unimpressed right now.

so onto the issues im having. full throttle is good, timing map seems good (slight bit of KR however goes away with alcohol on), maf table seems like its set up correctly. the main issues im having is a rolling idle and lean fuel trims during decel. now im completely new to hp tuners (have set up several cars on megasquirt) and this is my daily driver, so i want ot be sure about what im doing.

first, the rolling idle. this happens mostly during warmup, however ive had it when warm, and its mostly with the a/c (defrost) on. i know cobalts seem to have dirty throttle body problems that cause this, however mine is clean and this problem only started after the 1st tuning revision. the original flash i was sent was very lean at idle, to the point it set a p0171 code, it was the very next flash that had the rolling idle. you can see the rolling idle at frame 811, 1310, and 1700. i see the timing fluctuates huge during this. im unsure whats causing this, the timing map seems alright. i notice the idle underspeed table seems quite agressive compared to a couple tunes i looked at in the repository, and the idle overspeed table is less aggressive. any thoughts on this?

the other thing im having issues with is on decel, the fuel trims are very high, sometimes it will set p0171. now my car has always had this issue, and it was getting better as it was worked on, however its still got a few cells that have high fuel trims. this can be seen at frame 1277, 1782-1950, 3144-3500. now i have seen through the revisions of my current tune that the ve table was being changed to correct this, and i know the tuner did not disable my maf to tune the ve table. im just wondering what histogram i should be using to tune the ve table while the maf is active. should i use histogram 3- long term fuel trim for this?

im just unsure how i should be going about fixing this, i have wanted to learn to tune with hpt however im sort of forced into it now being it seems the guy tuning my is ignoring me.

[383_Stroker]

If DFCO if on, then your decel fuel trims will be high.. Though i've never had it set a code for it..

Also, that log shows some pretty significant knock :-/

PS: the timing table is just a lightly modified GM stage 2 table from what i see

[HNRClothing]

I also have never seen DFCO pop a code so it has to be something else. I will look at this when I get home from work today.

[Sharkey]

it actually has the high fuel trims the second i let off the throttle, before dfco is active. however i notice if it hits that cell when i lift the throttle and im going down a hill maintaining speed, even with dfco on, it sets the code.

i inquired about the knock, the tuner said i must have crappy gas. i run non ethanol 94 octane, the only 94 i can get at the pump. going to try some 92 from another station to rule that out. the knock does go away if i run the alcohol injection, however i didnt want the car tune for alcohol. guess i need to work on the timing table a bit as well.

[Sharkey]

i ended up going back to the stage 2 idle overspeed/underspeed tables and increased the idle by 50rpm,it seems to have fixed my idle hunt problem. i think i also figured out the ve table tuning with the maf working, i seem to have gotten my fuel trims a little better. filled up with some different fuel to see how it affects the knock retard.

[laser_racer]

Where did you get your injector settings from? Also when tuning fuel trims either disable the dfco or just take it out of gear when you are slowing down.

[Sharkey]

i originally bought this tune from one of the major vendors for cobalt and 3800s/c parts (ill let you guess who), and was promised they would change the tune as many times as it takes to get it correct, but after 3 revisions im being ignored

[laser_racer]

I will take a look over it when I get home and see what I can do is the log and tune current?

[laser_racer]

Personally I would just go straight maf and once you get that all dialed in start messing with the ve. To tune maf your have to make the maf fail as if it went bad. Best way to do that is change maf fail high to 0 so it will think maf is bad and fail over to just ve.

[Sharkey]

the tune and log is not current, i changed the idle over/under speed tables to correct the rolling idle. i also made a few changes to the ve table, the fuel trims under off throttle conditions are getting better but still need more work. the maf table seemed to be dialed, most of the rest of it seem alright, just the off throttle trim cells are high, even before dfco cuts in.

i was hoping that by purchasing a tune from a well known and respected shop, and having them tweak, it would make it a lot simpler. guess all they care about is making a buck

[HNRClothing]

To change timing in "rolling" idle I would use coastdown. I have found in the 20-2X Degrees stops the idle hunt while coasting... Just my 2 cents.

Sorry to hear about your tuning issue with ZZP.

[laser_racer]

I could give you a better settings for your injectors if you want but you will most likly need to retune your maf again.

[Speedytec]

To change timing in "rolling" idle I would use coastdown. I have found in the 20-2X Degrees stops the idle hunt while coasting... Just my 2 cents.

Sorry to hear about your tuning issue with ZZP.

Same issue here, a rolling/hunting idle of my LSJ on coast down with pressed clutch or out of gear. (lightened flywheel an light RWD car...)
I assume you changed the upper left part of the idle coastdown table to ~20??

(decreased the over/underspeed tables a bit, but it still hunts. Was thinking to make the base and coastdown table the same advance there...?)

[Sharkey]

ive got the idle fixed now, and for the most part my ve table is worked out, ive only tweaked it once and the fuel trims are fairly close now. i do have one cell that the trims go to 19.5, its right when i lift my foot. i have my scan gauge on ltft and as im lifting my foot it flickers to 19.5 then back down to around 3. i havent had a chance to log again, i figure a couple more tweaks and ill have it.

laser_racer: id appreciate having a look at some other injector settings. just out of curiosity, what would you do different and what are the benifits of it?

[laser_racer]

When I get home later I will send you well post the 60 settings I use on cars.

[Leafy]

coast down tables only do something when the car is at zero throttle but moving and in gear, aka coasting down. Its basically there for when the decel cut isnt engaged.

[BlurrSpeed]

This is based on my limited experience with my 2005 NA 2.2 Cavalier.

I ran your log through my gauges and I think the P0171 code may be caused by maxing out your fuel trims. STFT adds almost 40 & takes out about 30. LTFT goes from 20 to -13. Mine never hit 10 on either side, but I am not boosted.

Looking at throttle position and MAP I am guessing you have too much timing. I did notice TP never goes below 20. Im not sure whats up with that. The MAP reading matches as being high. I usually see 4% TPS at idle. The reading for the MAP & TPS coincide when you are driving so I dont think one is bad. The KR did not look too bad to me. I did not set a histogram for the KR so you could have boat loads its never goes past 5 deg. Its still unwanted. Others above mentioned the timing so I would listen to them. Its better to have too little timing that a melted piston.

Another interesting thing about MAP/TPS is mild acceleration does not use relatively high TP or MAP. This is nice. But cruse seems to take an oddly high MAP & TP. It may be due to the blower. High TP with a low MAP is a sigh of less fueling. I noticed that with my lean burn tune.

As Leafy said coastdown is for moving, no throttle and out of gear. My coastdown fuel table (I dont have CD time) needed large number changes to make a difference. My car does 3 seconds in the coastdown table when I let off the gas in gear before it goes DFCO. FYI: I have dropped my coastdown above 1800 to zero fuel so if Im above that it goes straight to DFCO when I let off. I did not see this table in your tune nor did I see the the idle over/under that was mentioned. Nothing else jumped out as anything that would have to do with coastdown. Enlighten me & Ill take another look.

The fuel trim that jumps to 19 seems to be at 2000 RPM at 20 MAP. If you look at the "Primary VE vs MAP vs RPM" table under Airflow, General in combo graph table mode you will see the graph shows a big drop there especially with the high peaks at 2800-3000. The numbers in the table dont look like there is a big change but the graph shows it. I would look in to adjusting that to see if it helps. There are probably other tables that effect this like the coastdown table. I am not a big fan of using the average function for a full table cause I have had to backed out the few times I did it but you might try smoothing a few cells around that area.

Take this info as suggestions not hard advice. I have not tuned anything with forced induction.

[Sharkey]

ive read through the diagnostic info on the p0171 code many times. the code is set when the ltft cell its in is above 18% for more than 6 seconds. now when dfco cuts in, if its in that trim cell thats high, despite the fact that there is no fuel being injected, its still in that trim cell and will still count for the p0171 code. this is what ive figured out from 2 years of this code on and off. previous owner of my car screwed with the tune, i went after everything mechanical coming up with nothing.

the reason my tps never goes to 0% is because the cobalt has electronic throttle. with no idle air control valve the throttle blade does not close all the way, it has to stay part way open for idle.

thanks for the info. most of the tuning issues im having are out of boost, general driveability problems. ill have to have another look at the tune and see what else zzp screwed up in it.

[HNRClothing]

Same issue here, a rolling/hunting idle of my LSJ on coast down with pressed clutch or out of gear. (lightened flywheel an light RWD car...)
I assume you changed the upper left part of the idle coastdown table to ~20??

(decreased the over/underspeed tables a bit, but it still hunts. Was thinking to make the base and coastdown table the same advance there...?)

Yes set the upper left part of the coastdown map to somewhere in the 20* of timing and it should help the hunt.

coast down tables only do something when the car is at zero throttle but moving and in gear, aka coasting down. Its basically there for when the decel cut isnt engaged.

Its when the car is in nuetral it will hunt, its common, in gear coastdown I dont think I have ever seen a hunt since there is a load. Coastdown table in the 20's* will help the RPM drop and sit at desired RPM and not plummet. Doing this will also reduce hunting significantly or reduce totally.

[laser_racer]

Try these injector settings just leave your stoich value the way it is. Also when dialing in the maf take the car out of gear to slow down so you can dial in with out error.