Is it swapping from one main timing table to the other?
Is it swapping from one main timing table to the other?
I don't think so. The main pulse base timing and low air Dens. Tables are very similar and i am seeing a 10* variance. I thought the difference was related to the OS extended datastream upgrade but now I'm thinking possibly it is related to IAT and IAT coefficient adder tables. I am seeing a large swing in base injection timing with small IAT change.
Here are stock logs from this morning
I see the same thing happen. I have not found which table effects it yet. This time of year having the timing limited that much by IAT really shows up. If I make back to back runs, the first one will have low timing (not good), and the second one will be very close to the value in the base table. It shows as running normal in the limiter. Still looking for the reason.
So you are saying you are seeing lower actual timing instead of too high of timing Paul? Or are you seeing a combination of both?Originally Posted by paulb
What year of truck?
Can you post your most recent log showing what you've got going on Paul?
Last edited by Moparmatty; 02-11-2016 at 01:59 PM.
Actual timing is lower when IAT is cold. I have not seen it going higher.
It's a 2005. I'll post a log later.
I find it strange that the stock tables call for so much more added timing when engine temp and IATs are higher.
I mean, I have a limited understanding of diesel tuning, but it seems to me that you would want extra timing in colder temp (both ECT and IAT) conditions, rather than warmer conditions.
Is my thinking flawed?
I mean, the pilot coefficient table for ECT x IAT in the '05 calibration is multiplying most of the adder table by 1.0 to 1.2 in the colder temp ranges. But the moment you hit 180*+ ECT and 90*+ IAT, the multiplier jumps to 5 and as high as 7.
And it's multiplying against adder table values as high as 15*+ and then base table values as high as 52*.
So, with a base table command of 52, then the adder table value of 15 being multiplied by the coefficient of 7, you could be seeing as much as 157* pilot BMI (7*15+52=157).
That is, unless the table doesn't function as I'm seeing it.
But last night, I was seeing 82.5*+ pilot being logged in the scanner. After some conversation, I went and remapped the adder and coefficient tables so that pilot timing would be more reasonable, and afterwards was seeing 43.5* pilot in the scanner instead of 82.5*.
I've digressed, but again, I ask, doesn't it seem backwards to add so much extra timing in warmer conditions rather than in colder?
Strange. My 2004.5 follows my main timing table pretty much no matter what the ECT is.
What is your ECT when you are seeing the timing being low?
Last edited by Moparmatty; 02-11-2016 at 03:44 PM.
ECT is not the issue, it's IAT.
Warmer air is less dense, therefore you need more time to compete the combustion process.
I am seeing the opposite on this early 04. The timing seems to run higher with cooler IAT and as temps increase above 70* timing decreases to base timing table values.
I see it more based on ECT vs IAT on the early trucks....
But isn't it also true that warmer air means less lag time between SOI and start of ignition?
I reduced the Coefficient table to Zero in the 60-70*F range and got another log from this morning. It looks like He is getting some added timing with cooler ECT like Les suggested but as ECT comes up and IAT hits 60*F I am getting close to my Base commanded injection timing. So It does seem that these early trucks are very sensitive to IAT and also ECT. I can not understand why the IAT at say 60*F is so aggressive with timing though? To go from say a IAT of 75*F and 5* base timing to a IAT of 60*F and timing at 15* seems crazy? I see on the later trucks this coefficient table is zeroed out, probably why I never seen anything like that on the 06-07 trucks with the other tuning software.
Same at not long after start up:
Untitled (1).png Untitled (2).png
Your at 20mm3 & 750rpm
Main timing base map at 37mm3 and 2000rpm gives you about 3.1* SOI
You have a coolant adder value of roughly 7*
Coefficient value is 0.91
(7* - 3.1*) x 0.91 = 3.6* of Main SOI
Scanner shows 4.0*
Close enough for me.
I know it is running as commanded now. I did not touch any ECT tables. I said that i zeroed the IAT coefficient table in the 60-70*F range. "Now" in that range i am seeing base table timing numbers in my scanner due to me zeroing out the coefficient in that range. With a stock setting in the coefficient i was seeing 15* injection timing at 60*F IAT and approx 5* injection timing as IAT increased to 70*F. A 10* timing variance based off of a 10* IAT change. The ECT adder doesn't concern me at all. It's coefficient goes to zero after 170* ECT which is well below normal operating conditions.
So what you're saying here is that you need to subtract the base table timing value from the adder table value, and then apply the coefficient?
It was the only way the math worked out.
Last edited by Moparmatty; 02-12-2016 at 08:45 PM.
I erased my first example by accident.
So here it is again:
Untitled (1).png Untitled (2).png
Basically at 2000rpm, 38mm3 and 140*F ECT
Main timing base table value roughly = (5.1* + 2.1*)/2 = 3.6*
Main timing ECT adder table value = 15*
Main timing ECT coefficient = 0.85
(15* - 3.6*) x .085 = 9.8* main timing SOI
Log shows 9.6* main timing SOI
Last edited by Moparmatty; 02-12-2016 at 09:01 PM.
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