RPM Dropping When Slowing Down

General Tuning Questions And Discussions
User avatar
Posts: 6339
Joined: Mon Oct 08, 2012 6:41 pm
Location: Kyneton, Vic

Re: RPM Dropping When Slowing Down

Postby vlad01 » Wed Mar 27, 2019 2:44 pm

looking at the calcVE vs the actual VE on the monitor it looks like the VE is out some below about 800 rpm and producing the lean spikes. You probably have a dip in the VE just bellow than RPM

I'd say it's just a bad area in the VE that needs fixing. Try manually increasing that area. Can you post up a pic of your VE table? Sometime using calcVE around idle can have a delay effect and cause out of tuning which brings about the hunting which feeds back into the delay and you get a feed back loop. Had it happen on one engine before. The more I tried to tune it out using calcVE the worse it got, just had to look at it logically and manually correct the area around idle to be more smooth and it was happy and ran good after that. It look to be that case from what I can see.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

User avatar
Posts: 9758
Joined: Sat Feb 28, 2009 9:05 pm
Location: Tenambit, NSW

Re: RPM Dropping When Slowing Down

Postby Holden202T » Thu Mar 28, 2019 10:44 am

yeah i'd be focusing on the idle areas of the main ve table.

also try setting the AFR table to like 14.2 or something that which will stop it going closer loop at those points so you can make sure the wideband is what you want to show, then change the ve to be right for 14.2 then once your happy change the AFR table back to what it was.

Posts: 69
Joined: Sat Nov 25, 2017 8:13 pm

Re: RPM Dropping When Slowing Down

Postby K1ng0011 » Thu Mar 28, 2019 1:28 pm

Did not have time to get to testing it today life got in the way. I will try tomorrow or the day after and update you guys when I am able to do it. I am going to hit it with 100VE in the 40KPA cells at 600RPM where the RPM is dropping and force open loop. If neither of those issues fix it then I am going to have to change my whole VE table. Low end of of my VE table is in the 60s which is pretty high. I am running 22lb injectors on my chevy 350 but I will likely have to set the kinjflow to 17-18lb injectors to get the VE table lower for more adjustment if the 100VE does not work. My current kinjflow is set to 20lb injectors.

Posts: 69
Joined: Sat Nov 25, 2017 8:13 pm

Re: RPM Dropping When Slowing Down

Postby K1ng0011 » Sat Mar 30, 2019 12:50 pm

I rebuilt my tune from scratch. Figured since I was troubleshooting this issue I would fix the high VE issue along with it. Before the low end of my VE table was 60-70s. Now the low end of my table is in the 40-50s by adjusting the kinjflow rate to richen up the whole fuel table to lower the VE. I did have a chance to drive it today after everything has been tuned. I was still having the issue then I richened up the 40kpa area of the VE table and it might be fixed. The RPMs did not seem to drop in the short drive I took when I was slowing down. I will drive it a bit more over the next day or two when I get a chance see if the issue is still there and update everyone on what I find.

Posts: 69
Joined: Sat Nov 25, 2017 8:13 pm

Re: RPM Dropping When Slowing Down

Postby K1ng0011 » Wed Apr 03, 2019 5:42 am

So it seems the issue was just low VE in the 40KPA area of the table at low RPM. After I adjusted the kinjflow and lowered the VE all around on the table. I was able to adjust the VE table in the areas more and resolve the lean spot issue on decel. Thanks for everyone's input on the issue. Took more work to resolve the issue than I expected but glad the problem is taken care of. I am much quicker at tuning from the beginning than I used to be.

User avatar
Posts: 6339
Joined: Mon Oct 08, 2012 6:41 pm
Location: Kyneton, Vic

Re: RPM Dropping When Slowing Down

Postby vlad01 » Wed Apr 03, 2019 9:44 am

:thumbup:
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

Previous

Return to General Tuning Discussion

Who is online

Users browsing this forum: No registered users and 4 guests