Low timing at startup, probably Catalyst heating

[mxatunerjg]

I have been trying to come up with a way to keep ignition timing from running very low, even negative, for a period of time after startup. I've seen it in every Hemi. I know that it is used for catalyst heating, but obviously there are times where this is not relevant. I've tried all types of different changes with no change on a lot of different vehicles. I've asked HP to add some tables to help with this, but so far the tables they have added do not seem to be helping. Anyone have any ideas/thoughts on this?

[spoolboy]

What have you tried so far?
Are the vehicles in question for off-road use without catalysts?

Have you played with the electronic throttle flow tables?

[HaasExp]

Have you tried [ECM] 44679 - Spark Minimum? You might be able to use this table to "cap" the minimum timing advance values.

[Russ K]

I’ve tried raising the min spark table. While this
did stop the negative spark advance on start up, it caused a very high idle rpm on start up. I now leave the min spark table stock.

Russ Kemp

[mxatunerjg]

What have you tried so far?
Are the vehicles in question for off-road use without catalysts?

Have you played with the electronic throttle flow tables?

Yes, off-road no cats.

Yes, I have messed with the throttle flow tables. Usually I get these dialed in to where I have good idle characteristics with reasonable ignition timing values during idle when warm. The only time I run into issues is right after startup, the colder it is the longer it lasts. I can get around it using the minimum timing table, but I don't like doing it that way as there is obviously something causing it to run low timing values in this situation. Looking at logs of factory vehicles, they do the same thing, and they get away with it because the airflow is decent at low rpm keeping the map values reasonable. The problem is when a car has a different cam or a PD blower. This creates a situation in which the vehicle gets to 100 kpa or above 100 kpa at very low throttle opening points. This gets the vehicle into a very low part of the timing map in comparison to a stock vehicle. Warmed up it is fine because it is running the timing value in the Part Throttle table, but when it's cold whatever adder is causing this issue pulls a bunch more timing from that base table and causes in most cases a very negative timing value.

As far as what I've tried, I've eliminated every timing table available in HP Tuners by making them all match (with the exception of the minimum tables because that would not help me find my solution). I've messed with everything I've ever found that seems to have anything to do with exhaust temp, cat temp, cam timing, throttle control, and torque management. HP added some tables last week in beta software after I contacted them about the issue. I've gone through those, but none of them seem to have anything to do with the issue I'm seeing. At this point I just tell people they shouldn't be starting these engines and going out and beating on them until they have some heat in them anyway, but it never fails about once a year I run into someone who is unhappy because they started the vehicle, threw it in gear, and tried to do a pull in front of their buddies with the coolant temp at 86 degrees F.

[mxatunerjg]

I’ve tried raising the min spark table. While this
did stop the negative spark advance on start up, it caused a very high idle rpm on start up. I now leave the min spark table stock.

Russ Kemp

This does eliminate the issue, but it also introduces the issue of not allowing the computer the ability to remove timing for knock events, as well as different atmospheric conditions. So unless absolutely necessary I try not to use the min spark table to make adjustments to the actual ignition timing.

[HaasExp]

This does eliminate the issue, but it also introduces the issue of not allowing the computer the ability to remove timing for knock events, as well as different atmospheric conditions. So unless absolutely necessary I try not to use the min spark table to make adjustments to the actual ignition timing.

Bugger! I was hoping this was not the case.

I too have noticed low ignition timing after startup, particularly when cold. It can make the vehicle a real dog especially when you encounter hills straight of the bat (eg: steep driveway).

There must be some "Catalyst Heating Mode Advance Table" in there that is currently un-mapped.

[LaBrat]

Has anyone else found a solution to this problem? Im having the same issue. I tried changing my "start vvt" and the 5th vvt table (i believe it is "exh LP int Max") to all have more normal values rather than super low 0-5 degree values. This seemed to help the issue slightly but it still persists. just a pet peeve at this point really.

[JoshCP527]

Tstat - tb - cam will all need their own aproach. The idle control is to hit a target trq. Tstat can run but you will notice elevated trq even warm at idle because the temp trq table and keeps the tb base open target for that idle trq high and keeps timing low even hot. The TB if bigger has to be scaled otherwise it will keep airflow high even though it thinks otherwise and pull timing. Both controls also have limits on the pids but that is not the issue at hand. Cam cars will take shifting more trq into the lower areas instead of scewing the tb tables to make them work. Idle control only has so much trq it can shed or add. Easiest to make it the calibration think the engine is still parking at the home point when warm. You still need the added trq for warmup also as that still sets the home point for timing and tb.

[LilSick]

Tstat can run but you will notice elevated trq even warm at idle because the temp trq table and keeps the tb base open target for that idle trq high and keeps timing low even hot.

[JoshCP527]

Also forgot to add you timing from MBT is also a trq calculation. keep a mental note of the variance for certain things like idle and your calculated actual trq. The fueling from lbt is also a calc it does.

[Robergts]

LAUNCH SPARK ,this work for that