Cammed 4.6L won't come back to idle without cutting off.

[C10Racer]

I'm in the process of fixing someone else's screw up with a BIG cammed 4.6L 3V in an F150. I don't know what exactly the cam is but large by huge is a good guess. The truck is pretty stock otherwise down to the manifolds and intake (with a K&N CAI). No matter what I do if revved in neutral or coming to a stop it dies about 75% of the time. I've messed with the dashpot settings, timing, airflow, etc to no avail. The truck also starts hard when warm. I'm working off the tune that was in the truck so feel free to point out any weirdness...12-15-18 #5.hpt

[Cyle_greenhill]

try these settings. this works for me pretty universal on the 3 valve setups

[C10Racer]

try these settings. this works for me pretty universal on the 3 valve setups

GREAT, I will try them in a bit, thanks!

[C10Racer]

1-4-19 #1.hpt Based upon the tune above (THANK YOU! Cyle_greenhill) and what I'd already done this is what I've come up with so far. The tune is A LOT better but still wants to die coming to a stop (to a much smaller degree) and occasionally will. I'm also noticing that at cruise when you transition the throttle it will momentarily flash lean then go back to stoich. Any ideas?

[C10Racer]

It also cold starts fine but won’t hot start worth a damn.

[C10Racer]

I've worked with the torque tables which has made for a stronger idle, I've messed with dashpot settings and now when you decel it'll come down to 1k rpm and stay there until about 20mph then it just cuts off. It seems like its just shutting the throttle plate or cutting timing?

[C10Racer]

77.hpl ; Here's a file where it dies...it really doesn't make any sense because nothing else changes? The motor just cuts off; throttle opening and spark don't respond until after RPM has already started to drop and even then it's just a reaction to the motor cutting out. It's almost like fuel is being cut; DFCO is off btw.

[C10Racer]

https://patents.google.com/patent/US6705286

"As is known in the art, a torque monitor function is used for engines equipped with electronic throttle control. This function achieves a high level of safety by checking the desired engine torque, (i.e., driver demanded torque from, for example, a sensing of driver accelerator pedal position) with two independent measures of torque, for example, a throttle based (e.g., throttle position) estimate and an air-meter (i.e., Mass Air Flow, MAF) based method. If the air-meter based method calculates a torque that exceeds the driver demanded torque, the torque monitor function will intervene by one of several methods including shutting off fuel to cylinders."

I think it IS actually cutting fuel; I'm beginning to think driver demanded torque is shown to be lower than torque produced and it's cutting fuel...so if I turn off the ability to cut fuel based upon driver demanded torque being out of correlation with torque produced it should fix the issues...right?

[C10Racer]

https://patents.google.com/patent/US6705286

"As is known in the art, a torque monitor function is used for engines equipped with electronic throttle control. This function achieves a high level of safety by checking the desired engine torque, (i.e., driver demanded torque from, for example, a sensing of driver accelerator pedal position) with two independent measures of torque, for example, a throttle based (e.g., throttle position) estimate and an air-meter (i.e., Mass Air Flow, MAF) based method. If the air-meter based method calculates a torque that exceeds the driver demanded torque, the torque monitor function will intervene by one of several methods including shutting off fuel to cylinders."

I think it IS actually cutting fuel; I'm beginning to think driver demanded torque is shown to be lower than torque produced and it's cutting fuel...so if I turn off the ability to cut fuel based upon driver demanded torque being out of correlation with torque produced it should fix the issues...right?

[Thatwhite5.0]

Increase Idle Airflow tables by .4 at 1200 RPMs and less.
Incrase dashpot decay in the bottom 4 rows.

It doesn't show fuel cut and it has plenty of spark. Maybe not enough air.

Driver demand is low. This is how I have a cammed 3v set up.
3vdd.JPG

[C10Racer]

Increase Idle Airflow tables by .4 at 1200 RPMs and less.
Incrase dashpot decay in the bottom 4 rows.

It doesn't show fuel cut and it has plenty of spark. Maybe not enough air.

Driver demand is low. This is how I have a cammed 3v set up.
3vdd.JPG

Ok, going to try that and see how it goes. How big is your cam?

[C10Racer]

Increase Idle Airflow tables by .4 at 1200 RPMs and less.
Incrase dashpot decay in the bottom 4 rows.

It doesn't show fuel cut and it has plenty of spark. Maybe not enough air.

Driver demand is low. This is how I have a cammed 3v set up.
3vdd.JPG

What is the best way to define that table? Is It just a matter of driving it and going by feel or is there a quantitative way to set it up?

[C10Racer]

1-7-19 # 2.hpt1-7-19 # 2.hpt

I knew I should have started from a fresh tune, that driver demanded torque table was Bananas. This is where I'm at now...issue is it still dies if you rev and let it come back to idle.

[C10Racer]

I'm narrowing down whats going on; when throttle is blipped Idle Speed Control Mode goes from "RPM Control" to "Pre-Position" momentarily then to "Dashpot" and throttle close to as low as 1.7% and it kills the motor. No matter how much Dashpot I dial in it still does it, why?

a2.hpl
1-7-19 # 6.hpt

[C10Racer]

Figured I'd update my trials, its golden! I ended up having to completely rebuild the torque models and lower the expected torque down low by as much as 200% in some areas. The Thumpr cam in this motor makes so little torque down low that huge changes are needed to make it happy. I could tell the minor differences changes to the dashpot and idle airflow table made but ONLY ONCE THE TORQUE CURVES WHERE RIGHT! You can change everything in the system but until the idle torque parameters are lowered nothing else matters.
1-8-19 #1.hpt
b6 pull.hpl

[Thatwhite5.0]

What is the best way to define that table? Is It just a matter of driving it and going by feel or is there a quantitative way to set it up?

Driver demand is somewhat like your throttle angle converted into ft lbs requested by the driver. ETC Torque Request in the scanner. Yes it plays an important role, it can fix or confuse idle on any vehicle, aftermarket cam or stock cam.
The cam on that one has a 273/308 duration and I think .47 lift.
How does bananas run? The car actually runs amazing and surprises a lot of coyotes. The most noticeable difference with driver demand is taking off from a stop. It's easier to accelerate from a stop and it sounds and idles real good.