Actually, the PRsystem calculation is redundant, it just reminds us that there's some pressure loss in the system through the IC and TB. What you need is to calculate the PRcomp. BoostTarget is required for this. BoostTarget = pre-IC pressure, I.e. turbo compressor outlet pressure. From measurements on my own setup I've found the system loss to be about 4psi (boost gauge signal from compressor outlet vs. UIM), so if your LIM boost is 12psi, your BoostTarget should be approx 16psi. From this you can get the PRcomp.


Back on topic though, is there any method aside from pulled timing to confirm whether the knock sensor is being triggering? An LED on the dash would be very helpful. Seems like detonation and engine mount issues would both trigger the knock sensor, whereas the IAT argument doesn't go near the knock sensor as it's (potentially) another method similar to knock sensor that's used by the tune to pull the timing (haven't quite caught up with the above few posts yet).

 

Gotcha on the equation. I should measure the pressure at my compressor outlet at least out of curiosity if nothing else. Which brings me to wonder, where are others typically measuring?

If we could verify that IAT can in fact influence timing in our cars then an indicator might be useful for understanding when it's in that realm, but might be easier to just monitor IAT and set an alarm or LED at an appropriate threshold?

An alarm to indicate when ECU pulls timing based on the knock sensor would be a bit trickier. It think it wouldn't simply be an output you could monitor. Harlan's det phones and signal processor work are probably the closest thing that I've seen so far.

 

I agree that the limiter tables don't have any effect on the actual load or timing. But I think the question is whether or not an actual increased IAT will trigger the ECU to retard the timing...

I do recall doing that testing. That was a fun ah-hah moment

 

I don't think the IAT has any direct influence on timing. we have seen how Mazda and Subaru have done it. the Naturally aspirated rx8 ecu doesn't account for it or need to.

I stand corrected and bow to Brettus test

 

I think its the bad mount this has been observed before. and possibly Fred Meyer gas :P

 

Hey I get a discount on Freddy's gas


10 cents per gallon will eventually add up to a new motor

 

We have proved with 100% certainty that there is no link between the IAT measured by the IAT sensor and actual calculated load as a reported OBD parameter.

You are the one who posted the formula for calculated load stating that IAT is necessary for the calculation of this parameter .............Therefore YOU are the confused one

If you are still insisting that IAT is needed ..... please tell us where the ECU is getting that information .

 

Yes ..... to date there is no evidence of this .

 

This is all I really care about at this point. If the IAT won't have any impact on timing then I see no sense in going through the trouble of relocating it for my setup. I am pleased with the results I am getting. There is still the mystery of the root cause for my prvious timing issues, but I haven't seen any since pulling back 2 degrees. So meh...


I got a little brave today and added a degree back in and logged 3rd gear. Still no timing pulled and it smoothed out that dip I had in that range previously. Weight was higher in this log because I had my son with me...

 

Unless I'm misunderstanding your question, I believe it's getting it from the IAT sensor.

Oltmann seemed pretty convinced it was being used. I am not so quick to believe it concretely one way or the other. I just don't know and am not fully convinced like yourself.

IAT is a defined data monitor item for both PID & Freeze Frame. It has dedicated DTC codes. According to the Control Sytem Relation Chart it is related to DBW, S-DAIS, Fuel Injection Control, Fuel Pump Speed Control, Electric Spark Advance Control, AIR control, Evap Purge Control, MOP Control, O2 Sensor Heater Control, ECT Fan Control, and Alternator Control (straight out of official Mazda service literature).

It's clearly shown as a data input for the Fuel Injection Control Block diagram.

Same for the Electric Spark Advance Control Block Diagram. In the text it's specifically stated to provide spark advance correction.

Not saying you are wrong, just that I'm not as convinced as you seem to be.

 

Well ................ yes it does crop up in a lot of different maps . But what we were discussing specifically was actual calculated load .
I don't see how you can still think there is any doubt . Why don't you try having a play yourself ? Set the IAT comp table to 2.0 and see if you see any jump in calculated load.
If there is no change .............doesn't that prove it ?

 

Wouldn't a better test be to log idle than change the iat calibration, for us that have it, and log again. A dramatic swing up and down should prove it. Maybe one at 0f, one at 100 and one at 200.

 

If you want to test it, you have to max all the compensation tables. Since we do not know the exact weighting of each variable. Then set each one back to 1.00 one at a time, that might help tell the tale.

IAT, ECT, Fuel VE% all set to 2.00, then idle log. Then set each to 1.00 one at a time....that would be my idea.

 

The Comp Table is not what I'm referring to. It only serves to set the edge of the paper for max Calc Load Max LIMIT. Those three tables being referred to our specifically listed under a folder titled as LIMITERS. That's all they do; set the Cal Load Max LIMIT, i.e. edge of the paper. They can all three be set to 2.0, which can then provide a Calc Load Max LIMIT of 800%. We agree on that 100%.

Again, that is not the same as the actual calc load, which determines where the engine is operating on that sheet of paper where the far edge of the sheet is bound by that LIMIT. We don't seem to have access to that map/formula. It doesn't mean that IAT is or is not being used there.

It's hard for me to test when my car is on jackstands only half assembled. Otherwise I'm doing my best to help us all have a greater understanding of the situation.

I would think that making a log with the std IAT map, then another log with IAT map adjusted to indicate the max possible temp where it was reading at on the first log would suffice.

 

Team that's exactly what I meant, although Kane has a point. Set all fuel tables the same. I would think 1 on ve though. And max out the limiters so they do t Interfear.

I'm a long way away from my car or I'd test it

 

Ok , I see now that you now agree here . I admit I was getting hung up on thinking you still didn't believe this.

Yes .......... excellent suggestion . I can do this no problem .

 

I'm in agreement with you Team regarding the limiter tables. I believe we all agree on that.

Unfortunately, I personally can't test the actual IAT affecting actual load due to the limitations in ATR for my car. I have no access to adjust the IAT calibration. Which is why I've somewhat let it go. If someone else can, and is willing to, test I'd be interested to see the results.

Brettus: saw you are willing to test. I look forward to it

 

New thread on subject here :


Affect of IAT on tune - RX8Club.com

 

Feeling pretty dialed in...




Log attached...

 

Can you explain the boost curve in the graph? Trying to figure out which number represents 0psi and what the max boost pressure is (presumably taken from manifold pressure).

 

It's not actually boost. I'm using the "boost" graph in VD to graph calc load

 

That's right, think you may have mentioned that previously. So what psi were you hitting on that chart above?

 

12psi peak

 

Great numbers man.... you must hate pulling away from the house driving that thing eh?

 

Thx man, love daily driving it for sure Avoiding downtime is the primary reason I don't push it back up where I had it last year!