Idle/stalling issues
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
Idle/stalling issues I have a 02 Z28, 6.0, on3 turbo kit w/7875, shorty #60s and SDCL. I've been tuning the car myself and Im having a issue with the idle fluctuating off throttle until I give it gas or it stalls. The car will idle if I don't touch the gas or I make slow transitions from on throttle to off throttle, but for driving in traffic this is difficult. I have checked for vacuum/boost leak by capping the turbo and using a smoke machine to show leaks. Also I've tried adding a little fuel, timing, and base running airflow but I can't figure this out. Car runs good in throttle and w/ boost, makes good torque, no misfires that I can feel and not many according to the ecm. Tommorrow I will do another vacuum leak check to make sure nothing has come loose, but car was solid before boost.
Launching!
Joined: Jan 2018
Posts: 283
Likes: 0
looking at the log the cam is stock or very small. your VE table needs some work in the high vacuum areas. looking at the 3d model is has a big PW variance for standard camshaft
that being said looking at the WB data on the log and considering its not too bad, it looks like it may be an airflow issue
assuming your changes too base running airflow, throttle cracker, follower and rolling idle are having no effect then... it needs more air more air mechanically and start again. increase the throttle blade angle at idle by adjusting the stop screw and recalibrate 0% position. if that's not possible drill and air bleed in the blade. then you'll have some resolution and you can use the listed tables to fix your problem.
that being said looking at the WB data on the log and considering its not too bad, it looks like it may be an airflow issue
assuming your changes too base running airflow, throttle cracker, follower and rolling idle are having no effect then... it needs more air more air mechanically and start again. increase the throttle blade angle at idle by adjusting the stop screw and recalibrate 0% position. if that's not possible drill and air bleed in the blade. then you'll have some resolution and you can use the listed tables to fix your problem.
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
looking at the log the cam is stock or very small. your VE table needs some work in the high vacuum areas. looking at the 3d model is has a big PW variance for standard camshaft
that being said looking at the WB data on the log and considering its not too bad, it looks like it may be an airflow issue
assuming your changes too base running airflow, throttle cracker, follower and rolling idle are having no effect then... it needs more air more air mechanically and start again. increase the throttle blade angle at idle by adjusting the stop screw and recalibrate 0% position. if that's not possible drill and air bleed in the blade. then you'll have some resolution and you can use the listed tables to fix your problem.
that being said looking at the WB data on the log and considering its not too bad, it looks like it may be an airflow issue
assuming your changes too base running airflow, throttle cracker, follower and rolling idle are having no effect then... it needs more air more air mechanically and start again. increase the throttle blade angle at idle by adjusting the stop screw and recalibrate 0% position. if that's not possible drill and air bleed in the blade. then you'll have some resolution and you can use the listed tables to fix your problem.
Some observations:
* injector data doesn't look right. typically injector flow changes with manifold pressure. Yours is flatlined. If that's what you're supposed to do for a boosted car, then OK, but it looks wrong to my NA-trained eyes.
* Raise idle speed to 700. It is easier to dial in a higher idle speed and work it down vs just dialing it in low.
* Idle spark is really not ideal. Idling at 28, there is no room for underspeed correction. In the 400 and 800 columns, I suggest dropping your idle spark to 18. in the zero column, put it at 33. Then, make your underspeed spark correction mirror your overspeed correction. This will likely also require an increase in base idle air.
* VE table really looks strange. if nothing else, maybe just highlight the whole thing and smooth it. Sometimes smoother is more important than perfectly accurate.
* In your transient fueling, change minimum RPM to 1100 so that transient fueling is not affecting your idle.
* Under Engine -- Fuel -- Oxygen sensors, there are two tables labeled "Proportional". Multiply both by 0.25. Might even need to go smaller than that. Your pulsewidths at idle are swinging from 1.6 to 2.0. With big injectors, that's a big fuel swing.
Hope all that is helpful
* injector data doesn't look right. typically injector flow changes with manifold pressure. Yours is flatlined. If that's what you're supposed to do for a boosted car, then OK, but it looks wrong to my NA-trained eyes.
* Raise idle speed to 700. It is easier to dial in a higher idle speed and work it down vs just dialing it in low.
* Idle spark is really not ideal. Idling at 28, there is no room for underspeed correction. In the 400 and 800 columns, I suggest dropping your idle spark to 18. in the zero column, put it at 33. Then, make your underspeed spark correction mirror your overspeed correction. This will likely also require an increase in base idle air.
* VE table really looks strange. if nothing else, maybe just highlight the whole thing and smooth it. Sometimes smoother is more important than perfectly accurate.
* In your transient fueling, change minimum RPM to 1100 so that transient fueling is not affecting your idle.
* Under Engine -- Fuel -- Oxygen sensors, there are two tables labeled "Proportional". Multiply both by 0.25. Might even need to go smaller than that. Your pulsewidths at idle are swinging from 1.6 to 2.0. With big injectors, that's a big fuel swing.
Hope all that is helpful
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Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
You guys are definitely right about my wild VE, maybe its because I don't know when to adjust fuel. On my way to work in the morning, 30 minute drive, my AFR error will be negative and in the afternoon after heat soak and my IAT is 100f my AFR error is like 10% lean so im constantly adding then removing.
-My flow rate is flat because I have a Boost Referenced FPR
I made the changes you said and it helped; I forgot to lower to 18 dregrees in park smh.
I'm gonna drive more tomorrow but so far it help
Some observations:
* injector data doesn't look right. typically injector flow changes with manifold pressure. Yours is flatlined. If that's what you're supposed to do for a boosted car, then OK, but it looks wrong to my NA-trained eyes.
* Raise idle speed to 700. It is easier to dial in a higher idle speed and work it down vs just dialing it in low.
* Idle spark is really not ideal. Idling at 28, there is no room for underspeed correction. In the 400 and 800 columns, I suggest dropping your idle spark to 18. in the zero column, put it at 33. Then, make your underspeed spark correction mirror your overspeed correction. This will likely also require an increase in base idle air.
* VE table really looks strange. if nothing else, maybe just highlight the whole thing and smooth it. Sometimes smoother is more important than perfectly accurate.
* In your transient fueling, change minimum RPM to 1100 so that transient fueling is not affecting your idle.
* Under Engine -- Fuel -- Oxygen sensors, there are two tables labeled "Proportional". Multiply both by 0.25. Might even need to go smaller than that. Your pulsewidths at idle are swinging from 1.6 to 2.0. With big injectors, that's a big fuel swing.
Hope all that is helpful
* injector data doesn't look right. typically injector flow changes with manifold pressure. Yours is flatlined. If that's what you're supposed to do for a boosted car, then OK, but it looks wrong to my NA-trained eyes.
* Raise idle speed to 700. It is easier to dial in a higher idle speed and work it down vs just dialing it in low.
* Idle spark is really not ideal. Idling at 28, there is no room for underspeed correction. In the 400 and 800 columns, I suggest dropping your idle spark to 18. in the zero column, put it at 33. Then, make your underspeed spark correction mirror your overspeed correction. This will likely also require an increase in base idle air.
* VE table really looks strange. if nothing else, maybe just highlight the whole thing and smooth it. Sometimes smoother is more important than perfectly accurate.
* In your transient fueling, change minimum RPM to 1100 so that transient fueling is not affecting your idle.
* Under Engine -- Fuel -- Oxygen sensors, there are two tables labeled "Proportional". Multiply both by 0.25. Might even need to go smaller than that. Your pulsewidths at idle are swinging from 1.6 to 2.0. With big injectors, that's a big fuel swing.
Hope all that is helpful
I made the changes you said and it helped; I forgot to lower to 18 dregrees in park smh.
I'm gonna drive more tomorrow but so far it help
Last edited by Lethalwx69; Sep 10, 2018 at 03:01 PM.
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Verdad Gallardo Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
Another possible reason my VE going up and down is because I live in a mountainous region in germany, and I drive up maybe a couple hundred feet in elevation on the way to work. I'm looking into maybe running a MAF and scaling my tune.
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
even a couple thousand feet could be taken care of by STFT.
I would:
1) flatline IAT fueling from the 90* range to the 160* range or if your OS allows it, bias fueling much more toward ECT than IAT. You can add it back later after your VE is dialed better.
2) turn off all fuel trims, DFCO etc and log data at ambient temp and altitude that the car will see it's most spirited driving at.
3) like DarthV8r mentioned put your idle speed right in the middle of a cell on the VE, you can drop it back down later. I suspect with an LS6 cam you could idle very nicely at 800 rpm and 40 or 50 kPa
4) use an AFR or EQ ratio % error histogram to dial that VE as smooth as possible.
It's unlikely that your base idle airflow is so far off as to cause drivability issues with that small a cam. Are all the in-gear idle airflow tables populated? No manual to auto OS swap?
I would:
1) flatline IAT fueling from the 90* range to the 160* range or if your OS allows it, bias fueling much more toward ECT than IAT. You can add it back later after your VE is dialed better.
2) turn off all fuel trims, DFCO etc and log data at ambient temp and altitude that the car will see it's most spirited driving at.
3) like DarthV8r mentioned put your idle speed right in the middle of a cell on the VE, you can drop it back down later. I suspect with an LS6 cam you could idle very nicely at 800 rpm and 40 or 50 kPa
4) use an AFR or EQ ratio % error histogram to dial that VE as smooth as possible.
It's unlikely that your base idle airflow is so far off as to cause drivability issues with that small a cam. Are all the in-gear idle airflow tables populated? No manual to auto OS swap?
Just one more thing to add to above post. In your log, you got STFT and WB error. Pick one. If you want to tune off the trims that is fine. If you want to tune off the WB turn off the fuel trims.
Looking at the log your injector ms are far more consistent at idle. Maybe add 1-g/sec to base air to compensate for the timing we took out.
Looking at the log your injector ms are far more consistent at idle. Maybe add 1-g/sec to base air to compensate for the timing we took out.
Would like to ask if you do another log, please put IAC position in the log and dynamic airflow. Some other stuff I saw that I would personally change --
* In Idle -- Airflow -- Adaptive Idle Airflow, your min In Gear and Min P/N, I would change from -3 to -0.5.
* Engine -- Fuel -- Oxygen Sensors -- Integral Delay, I would double the airflow mode table.
* Engine -- Spark -- Advance -- Base Settings, I would raise the max speed to something like 400 KPH. This way, when you let off the gas, some of the idle routines can kick in while cruising and help control surge.
* In Idle -- Airflow -- Adaptive Idle Airflow, your min In Gear and Min P/N, I would change from -3 to -0.5.
* Engine -- Fuel -- Oxygen Sensors -- Integral Delay, I would double the airflow mode table.
* Engine -- Spark -- Advance -- Base Settings, I would raise the max speed to something like 400 KPH. This way, when you let off the gas, some of the idle routines can kick in while cruising and help control surge.
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
even a couple thousand feet could be taken care of by STFT.
I would:
1) flatline IAT fueling from the 90* range to the 160* range or if your OS allows it, bias fueling much more toward ECT than IAT. You can add it back later after your VE is dialed better.
2) turn off all fuel trims, DFCO etc and log data at ambient temp and altitude that the car will see it's most spirited driving at.
3) like DarthV8r mentioned put your idle speed right in the middle of a cell on the VE, you can drop it back down later. I suspect with an LS6 cam you could idle very nicely at 800 rpm and 40 or 50 kPa
4) use an AFR or EQ ratio % error histogram to dial that VE as smooth as possible.
It's unlikely that your base idle airflow is so far off as to cause drivability issues with that small a cam. Are all the in-gear idle airflow tables populated? No manual to auto OS swap?
I would:
1) flatline IAT fueling from the 90* range to the 160* range or if your OS allows it, bias fueling much more toward ECT than IAT. You can add it back later after your VE is dialed better.
2) turn off all fuel trims, DFCO etc and log data at ambient temp and altitude that the car will see it's most spirited driving at.
3) like DarthV8r mentioned put your idle speed right in the middle of a cell on the VE, you can drop it back down later. I suspect with an LS6 cam you could idle very nicely at 800 rpm and 40 or 50 kPa
4) use an AFR or EQ ratio % error histogram to dial that VE as smooth as possible.
It's unlikely that your base idle airflow is so far off as to cause drivability issues with that small a cam. Are all the in-gear idle airflow tables populated? No manual to auto OS swap?
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
Just one more thing to add to above post. In your log, you got STFT and WB error. Pick one. If you want to tune off the trims that is fine. If you want to tune off the WB turn off the fuel trims.
Looking at the log your injector ms are far more consistent at idle. Maybe add 1-g/sec to base air to compensate for the timing we took out.
Looking at the log your injector ms are far more consistent at idle. Maybe add 1-g/sec to base air to compensate for the timing we took out.
In drive though, the car idles at 1000-1100 and now Im fighting the converter. As soon as I can I'll upload a new log, but should I take air out in drive?