Idle problem that is coming and going.

[Chevelle_LS]

Hello!

I have a issue with my idle that keeps coming and going. First everyting is fine but after some highway driving as i come back to town it stalls out when i come to a stop. After that it becomes nuts
and dose not whant to idle, it keeps reving up and then surging och reving up and then again surging until it stals. It's like this for som time and then frome nowhere its back to normal.

Could this be a bad oxygen sensor? Im running long tube headers and a mild cam. Throttle is a 102 Holley and a Fast LsxR intake. It is also stroked out to 396, it was a Ls1 from a Camaro.

Some times as I am wating for it to get to working temp it also starts reving and surging but then it never stalls unless I trie to put it in gear then it surges and dies.

Any idees anyone?

[cobaltssoverbooster]

post a tune file and log or we wont be of much help

[Chevelle_LS]

I wil log it ands get back to you as soon as I can.

[Chevelle_LS]

Hello again!

Here is the tune and a logfile that I did earlier this evening, BUT of course it didnt develop the problem the time
I was login. It only died when in the begining when I wanted to put it in gear....

Anyway, I ran out of battery in the laptop and could not log eney more.

I will log it again tomorrow if i get some spare time and see if it happens again.

The tune is done at a shop by a "professional" tuner...

[cobaltssoverbooster]

from what i see your running airflow isnt correct. in park at 850 rpm and 185* your desired idle is requesting 12 g/s but your raf is way lower at 9 g/s. when in gear it was targeting closer to 11 g/s but your table shows values of 3 g/s
this has a lot to do with idle quality. if this is wrong then i wonder what other idle airflow settings are not correct either. It seems there is definitely an idle issue because i watched the trims at idle dive to -30% multiple times.

the reason it wants a higher idle airflow in p/n than when in gear is because this guy has the p/n rpm set higher than the in gear rpm by 100 rpm more.

throttle voltage and iac position seem fine at this time but could change if this were to be re-calibrated using the idle specific instructions commonly referred to as the RussK method. i want to say this guy went wrong in calibrating the idle airflow and tb tables which is why this seems to have an issue.
this guy also has your power enrichment set very rich at around 11.7 most of the time to its leanest at 11.9. if this is truly an NA application as the OS for the ecu insists then this guy is missing out on power. typical NA engines are set to rich safe of 12.3-12.5 and most ls tuners in here will test the lean side to see how the engine likes it in the 12.7-12.9 range. if he changed these values to hit the desired afr then he is by no means a "professional tuner".
when i tuned my yukon an 11.9 afr was a whole second slower in the 1/4 than when i had it running at 12.5 afr.
if you can i would install a wideband for safety and afr tracking reasons. the stock sensors dont give us good data when in pe mode which is why the wideband is always a suggestion to every user that drops in here on the forum.

id like to see what another user comes up with as well to be sure.

[Chevelle_LS]

Hello again and thank you for yout thaugts on this. The engine is a NA application yes.

Unfortunately I dont have acess to a wideband at the time, I found the RussK metod here on the forum and to do that I also have to have a wideband sensor.

But if I am undrestanding you correctly the problem is that the AFR way of and the engine is runig way to "fatt". I remember him talking somthing about the engine lining out at WOT so he hade to give it more fuel. This was last summer and I kind of lost interest in the car seens it didnt run very good att idle but now im back at it.

Is there any way I coud re-calibrate this whit out a wideband?

THX!

[Chevelle_LS]

So i got some more logs last night. And this time it went nuts right of the batt.

The first one is from cold start to hot, and as you can see the rpm:s start going up and down untill it finaly
dies. Log 2 is acuallty not that dramatik but then again in log 3 as I come home an get out of the car to open the
gate an get in again to putt it in gear it acts out.

Just want to show you more of what I am talking about.

[Chevelle_LS]

I also whent in and change the rpm:s so that they match in gear and P/N so now it?s not 100 rpm more in P/N.

[Chevelle_LS]

Okey,

As im diging deeper into this tune im geting more and more frustrated and although I am a total newbie at this the first thing I notest was that in the injector control he has put in the 41,9 all thru the
diagram. I am running Holleys 48Ib/hr@43PSI injectors and that in real life is 55,7 Ib/hr@58PSI, right? So sould?nt that be the absolut lowest value?

As he has put 41,9 from 0 to 80 that means that the injectors are "open to long" as they think they ar smaler than they realy are, right?

So if i put in the right value at 55,7 from 0 to 80 will that hurt the engine as it will be geting less fuel? I know the value should increas as the vaccum goes up but when I dont know ho much
then this is better than nothing right?

Is there enyone that has the right spec. for this att hand?

Holley 48IB/ht@43PSI #522-488 Flow rates and multiplier eg.

[cobaltssoverbooster]

according to deatschwerks you would be correct. The fuel flow rate is incorrect and should be around what you calculated ~56 psi. Do you have a vacuum referenced fuel pressure return-regulator or a non-return fuel system?
that will also change how the injector data is populated.


you can have the completely wrong injector information and still get the injectors to open for the proper time to make the afr's come into check. you just end up slaughtering the maf and ve values to make it happen.
idle quality would also be improved if the values are correct for the application.

[Chevelle_LS]

I have a non-retun style fuel system so the injector data should increas as the vacuum gets higher right? I've been looking at stock tunes and the offen increas the value from
5 to 80 by 0,2 per step.

The problem is that Holley does not provide the needed data to do this correcty in HP tuners so there is some guess work in it... I've sent emails to Holley asking for the
data to put in but the haven't gotten back to me.

So, ones again if some one is using thees injectors an have good data please share it with me so I can get this right.

[Chevelle_LS]

Orderd a AEM Wideband today part # 30-0334 that I sould be geting soon, and then just find the time to install it. Been looking at some setup files as the RussK one but when i load them to the program it always says its for a older version.... Is the any one that har "new" setup files like for 3.0 and newer?

Or can someone tell me how to properly sett it up so that I can make the file fore 3.0 and later and then post it.

YES i'm a newbie at this......