What is the difference between the 2 tables? Both tables cover the same RPM range and vacuum, but there are 2 different tables. Which table is used when? (16197427 BJKW $0E)

I think the difference is because of vehicle speed.

dave w

Ok, that may make some sense. Is the assumption that free revving the motor uses a different spark curve than driving it?

I know that in 0D and 31 the two tables are open throttle and closed throttle. I would expect 0E is the same but I'm not sure.

Ok, so this is going to sound like the dumbest question ever asked on this forum, but what is the difference between open throttle and closed throttle?

What I'm really asking is wouldn't closed throttle be like 20 KPA at all RPMs? Why would it need a complete huge table? I'm assuming I don't know the ECMs definition of closed throttle.

Closed throttle with the engine at idle is about 30 kPa. Wide open throttle with the engine running is about 100 kPa.

My 350 TBI is usually 50 ~ 60 kPa when I'm driving about 60 MPH. My engine RPM at 60 MPH is about 1700 RPM.

My 350 TBI is usually 40 ~ 50 kPa when I'm driving 40 MPH. My engine RPM at 40 MPH is about 1200 RPM.

The tables are for the different engine loads. If my 350 TBI was really loaded down with extra passengers / luggage or I was really exceeding the legal speed limit the kPa would be different and the engine speed would be different. For example passing a semi-truck at 80 MPH the engine speed would be 2800 until the OD kicked back in, the kPa would be about 70 ~ 80 until the overdrive kicked back in. Once the OK kicked in, my engine speed would drop to 2200, and the kPa would drop to 60 ~ 70 kPa. If I was driving at sea level the kPa is different, than if I was driving at Denver Colorado where the elevation is about 5000 feet above sea level. The maps are for different engine speeds, engine loads, and to some degree, different elevations.

dave w

Closed throttle vs open throttle is based on TPS, if the throttle is open or not.

I agree, with the $OE definition, fuel tables are determined by both TPS and VSS. I don't see any $OE definition constants or scalars using TPS for spark, only VSS for spark.

dave w

Wouldn't a different load cause the engine to just be a in different cell anyway? In other words, If I'm cruising a 70 mph, my RPM is around 2600 RPM KPA around 55. If I'm towing, the engine RPM is the same, but the KPA may be 70. Won't a different load always result in a different KPA for a given speed? The way I'm picturing it is that the engine would always operate in a unique cell based on load and RPM. Its seems this must be wrong, or there wouldn't be 2 tables. I could see Baro effecting it, but that's a separate calculation.

Yes

Yes

The engine is always operating in a unique cell not only based on load and RPM, but changes tables based on Vehicle Speed and Throttle Position Sensor position. The way I see it, when a vehicle is placed on an Emissions Tread Mill (Dyno) the minimum emissions can be achieved with a near idle / off idle table for the engine to operate under.

dave w

So this is another EPA duping like HWY mode was, only less covert? In other words, should I ignore the second table and set the threshold to zero?

I'm not thinking the dual table is an emission feature is like the hwy spark mode in $8D.

I have experience tuning $E6, $OE is similar. I use DataMater software to data log. I've made adjustments to both near idle and off idle fuel VE tables. Depending on the TPS %, I determined which fuel table (near idle / off idle) to adjust. I have not adjusted the spark tables, but my spark tables have more advance than the stock prom. I don't think the engine will run if either near idle or off idle tables were eliminated.

dave w

The dual tables allow for less timing at a closed throttle, to control the coasting deceleration. Less timing will cause the vehicle to slow quicker when you come off the throttle.

I suppose the most confusing part is the max speed for idle spark is set to zero in every BIN I've looked at. This would also seem that the other table is never used.

Of course I guess I would have some fun with it, and set the near idle table to all zeros and see if there is any condition that makes it just die. I'm running a Moates GP3, so I can switch out of it if its a problem.

If I not mistaken the max speed for idle spark is used with the routines that fluctuate the timing at idle to help control idle speed and is not used with the closed throttle spark table.

Its set to 4mph is BHDC and BMHK and 5mph in BDJR, the only other 3 I have are 0 though.