2012 Challenger SRT8, 6.4L Manual with CompCam 274 & BBK 90mm TB. I'm trying to solve this problem of stalling when coming to stop. I have bumped up all my idle tables and TB air flow but with no luck at all. The car fires up idles with no problem and drives ok, only once coming to a speed bump it stalls. (Attached is my tune) seeking any tips/help.
Have you tried putting the stock TB back on it and put those values back to stock?
1. I doubt it is the BBK but refit the stock TB to rule that out first before wasting a lot of time. (No.1 rule : if it is aftermarket, it is usually the cause of the problem! haha)
2. Hopefully BBK TB is ok or if now moving on with stock unit in place try this:
Put TB flow table back to stock.
Then remove 10-20% from stock Desired Throttle and stock TB Airflow tables.
The Desired Throttle is the mover and shaker table.
The numbers work in reverse to what seems logical.
Smaller airflow numbers open the throttle more....
With a cammed engine you need more air at idle etc so lower the whole table and then tweak the idle areas to get it right.
Stock cam, leave idle area alone and reduce main part of table (.3v and above)
I routinely pull 20-40% out of these tables to get throttle opening quicker.
Much better results when you get these numbers dialled rather than tweaking up ETC tables.
Bonus is you are using lower airflow numbers, so run into less issues with limits etc.
The idle control is good on these, so if it fires up cold and idles, the idle control will usually keep it running, hiding the issue.
Problem is once you are off idle it reverts to main airflow tables.
It won't go back to idle control till VSS is less than 2 kmh.
So just before you stop, the rpm comes down and before idle control grabs it is when you need the airflow numbers to be correct.
Get it right and they are seamless, throttle on/off is super nice too.
Last edited by Hemituna; 11-13-2016 at 07:22 PM.
Actually I don’t think it’s the TB, because it was on the car before the cam install with no issue. ThanksOriginally Posted by Jay@HAP
Exactly what I doubt as well, because it was on the car before the cams and Diablo canned tune with no issues. It just started after the cam install and to explain more the behaviour I will put it this way. The car fires up normal and idles around (+,- 850 rpm) drives ok, but once coming to a stop or sometimes shifting to N the RPM comes down to around (+,- 200 rpm). Sometimes it grabs back but mostly it stalls and shuts down.
So just to give it a try with the settings you suggested let me pls go step by step so I know I am doing it right as still new to HPT stuff.
1. Put back TB airflow back to stock - Under (Engine-Airflow-General-Throttle Body Airflow), Then remove around 0.90~0.80 from (0.30V and above) leaving the rest of the table with stock numbers.
2. Remove around 0.90~0.80 from the whole Desired Throttle table - Under (Engine-Airflow-Electronic Throttle-Desired Throttle- ???) as I have Large & Small Range and other tables so which exact ?. Thanks
Put the TB airflow back to stock so all the tables match again.
As you have a cam, you will need smaller numbers everywhere.
So multiply all 3 tables by same amount...try x .90 first.
If it is better but you need more try x .80
The owner returned back the factory TB and that did not help, so now we know its not from the BBK. Will try to adjust these 3 tables and report back later tonight. Thanks
That's good to know. I've had some problems with BBK on the Ford 4.6 3v engines.
Just to report back, and actually those small number never worked out on all 3 tables !
could not fire up without gas paddle and if starts she can barely stay on for a short time and dies ( log attached)
The next thing I did was to work it the other way around for all the 3 tables. She fired up and was running ! The idle rpm rock solid and exact around 950 just like the map and no more stalling issue when coming to stop anymore (log attached while on idle & short run with stop & go on speed bumps).
So really dont have any idea how they have work the other way around ! maybe different market/region.
Anyways she is doing good so far with no stalling anymore on stops, but the owner told me that the revs hang and dont come back soon, so guess will have to lower the tables a bit at a time to find out where she sits at the best.
desired throttle & TB airflow low numbers log.hpl
desired throttle & TB airflow high numbers log.hpl
Exact same result I had, and exact same hanging rpm issue. What I found aside from the airflow was the car likes to run RICH, it muddies up the idle a little but definitely makes it way way more stable. I think the hanging rpms are a lean condition coupled with too much timing and airflow. You dump some fuel into it and itll idle down quicker.
No explanation on the opposite adjustment to the tables, maybe Hemituna will chime in.
Can you post up the tune file that seems to be working now?
My only guess is that with the larger throttle body, you were getting too much airflow with even the stock numbers in the tables, so going LARGER than stock actually reduced your airflow and settled down your idle.
biggest reason why your experiencing these issues because your tune is not setup for the comp 274. I have had personally issues with BBK before, i prefer not to use them. but if it was working fine.
your issues are tune related 100%
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Hi,
Well hope you got over it by time my friend, but as to my situation dont really know how much lean or rich she is running because I know and my mistake no WB is present at the moment !, because I still did not started tuning for WOT as its going to happen on a Dyno as soon I can solve this Big Cam idle and normal driveability condition matter. But for now will try lowering those tables and rich it up on the fuel to see if she behaves better.
Also attaching the tune that worked for now. just +40% on Throttle Body Airflow table and around +30% on both Desired Throttle Large & Small Range.
Regarding your last comment could be very much exact ! dont know how it worked with bigger numbers but all I can say that it worked and settled down the idle.
P.S: Congrats on the low numbers, and for all the support you have provided for the forum.
Omar
Brother Sultan,
I know its tune related at the moment and soon will be solve, as this is the reason for my post seeking help and guidance from more experienced members. I am in no means a tuner by profession just doing it for the love of it, and HPT is a new platform for me which I am enjoying it at the moment like all the other platforms I worked on earlier and where it takes time to go around to figure out what seeting works best for diffrent car setups. So i am wanting to know if someone have better setup on them cams or would like to help/guide. Thanks
Thanks bud - it seems as though the reason for the larger numbers working is that the new throttle body is flowing TOO much air when using the stock tables, so adding airflow to the tables will close the throttle body some more and take out airflow.
What drives most guys absolutely nutz is the fact that these cars will surge absolutely identically with too much airflow and too little airflow, and it makes sense why...if you look at your idle throttle correction tables, almost every single one have the same exact torque correction for an over idle speed as well as an under idle speed, so youll induce an identical surge if you're under or over by 5-600rpms
Hi,Thanks bud - it seems as though the reason for the larger numbers working is that the new throttle body is flowing TOO much air when using the stock tables, so adding airflow to the tables will close the throttle body some more and take out airflow.
What drives most guys absolutely nutz is the fact that these cars will surge absolutely identically with too much airflow and too little airflow, and it makes sense why...if you look at your idle throttle correction tables, almost every single one have the same exact torque correction for an over idle speed as well as an under idle speed, so youll induce an identical surge if you're under or over by 5-600rpms
Just came back with the owner after a good long drive, and happy to report that she is back as normal and almost stock like driveability !
No noticeable surging No idle hanging and most important No stalling. Apart from the cammed car sound effect at idle or low speed she drives and behaves like a stock car. We tried all driving situations ( Nanny, Granny, rental car or drive it like you stole it, up and down hill, with a/c ..etc) and she was perfect.
One thing forsure that the steps with removing some percentage from Desired Throttle and TB Airflow tables did not work in my case ! but other way around definitely did. And yes as you said that these cars will surge absolutely identically with too much airflow and too little airflow, its just that you have to find that sweet spot for it to make it behave like normal.
I hope other members could share or inform if coming back from large TB to stock TB or on big TB with cams and if these tables needed to be raised or lowered will definitely going to help out other members on their future cam project.
Thanks
I guess the lack of vacuum with bigger cams is the key here.
Been doing only stock or little cams of late in the VVT's as I dislike that you can't really utilise the VVT with the comp grinds.
Good thing with VVT is the big power you can make with small cam especially with a blower.
Big hp with a smooth 600rpm idle is hard to go past.
So the smaller numbers def work with cams that have good vacuum.
Seems larger numbers are needed with big cam, but really only in idle and low speed area.
So rather than adding a % to whole table, try adding a number (2,3,4 or 5 etc to whole table)
This will increase low numbers more and barely affect larger ones.
When you add say 20% to whole table, it may sort low speed area, but you will probably notice that the pedal gets longer,
and this will effect shifts on an auto too.
I don't know if this is the same situation I had on a cammed 2010, but if you still have problem go Under (Engine-Airflow-General-Throttle Body Airflow) in the first 0v try to put like 3 g/s or 5 g/s instead of 0 g/s
Have been there before, while that works, better off doing a little rescale and give yourself some smaller voltage values, like 0.05, in between 0.00 and 0.10. If you only have 0.00 and 0.10, whatever values are in the zero and 0.10 you get a straight interpolation and straight slope between the two points. Usually putting 3 or 4 g/s in that half way point does the same as putting in the zero spot. I have had several cars throw fits putting anything but zero g/s in that 0.00 voltage spot.
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