Retard from TPS

[Force Fed Mopar]

How does this work, exactly? Is it adding timing as the TPS voltage increases? Or does it only work when it sees decreasing voltage?

[Force Fed Mopar]

Bump. This was answered in a thread once, but now I can't find the thread :( IIRC it is the amount of timing pulled according to the tps voltage reading. Looking at it on MPTuner it is pulling 25 degrees at WOT. Seems like a lot, especially if it's on top of the timing being pulled according to the MAP reading.

FWIW the SMEC's don't have this table.

[zin]

I believe it was discussed in one of Rob's Turbonator threads, either SBEC or T3?...

IIRC, it would reduce timing as throttle came up, in an effort to reduce the chance of detonation, but I also seem to recall that it was a bit unclear how much and under what conditions it would do so... Makes sense to do so, at least to a small degree, especially if the fuel/conditions are marginal... Once you get detonation started, it can be a b!itch to stop, if you can!

That 25* may be the max it can pull under the worst conditions, at least that's what makes sense to me. I would expect it to be a fraction of that under "normal" conditions, but then again, right now I'm not what I would call a "tuner", so caveat emptor

Mike

[Force Fed Mopar]

Hmm, so it was in the LM code, taken out of the SMEC's, then reintro'd in the SBEC's? That'd be odd. Maybe not so much though.

[ShelGame]

I don't really know what its for. But, it only works (in stock form) over 2psi boost, 1250rpm, and 1.6V on the TPS. It could be a type of anti-lag. As it removes timing from TPS under the conditions above. That would have the effect of retarding the timing at high tip-in under boost. The input is actually DeltaTPS, not the actual TPS. It only removes timing when the TPS is increasing and it removes more timing when the throttle change is high. If there is no change in throttle, or if the TPS is decreasing, it does nothing.

Hope that helps...

Oh, and it's only in the LM code.

[Force Fed Mopar]

Thanks, couple more questions though. What does "Delta" mean in these cals? I see it in regards to map readings and such also, but I don't know what it means.

So when you say it only pulls while tps voltage is increasing, if you are slowly pushing the pedal down under boost it is pulling timing, then if you stop pushing it stops pulling? Like, the amount that it was pulling while the throttle was moving disappears? Or it slowly disappears? I am wondering if this is what causes it to feel flat if, say, I'm at 1/2 throttle in boost and suddenly go 3/4 throttle.

Also, does it affect timing at WOT?

[zin]

Delta is an engineering term meaning "change" or differential. For example you might say: "The Delta p of that SRT intercooler was 6PSI at 20PSI inlet pressure". Meaning the pressure differential or change from one side to the other was 6psi...

Mike

[Force Fed Mopar]

So basically, in our cals, if you see Delta in the table, it is only used when there is a change in the reading from that sensor?

[zin]

So basically, in our cals, if you see Delta in the table, it is only used when there is a change in the reading from that sensor?

Not just a change, but normally a specific "distance" between the target and the current reading. It may act as a buffer, or "ignore" range, so that the cal doesn't try to make mathematical changes/corrections that aren't needed or productive.

I'm sure Rob can give an a good example of how a delta value would be used in the cal...

Mike

[ShelGame]

Basically, in this case, it subtracts the current TPS reading from the average TPS (which is a time-based average of maybe 10 TPS readings). The rresulting value is a 'delta' or a change in TPS from the average. The way the table is setup, the bigger the change, the more timing is pulled. If the change is negative (throttle is closing) the table is ignored and no retard is used.

[Force Fed Mopar]

Aha, makes more sense now. I need to write that down in the description box so I don't forget again :D

[Force Fed Mopar]

Btw in the A171 template it enables at 1.57 tps, 2500 rpm and 2.25 psi.