Kfxguy

iTrader: (1)

my warranty had just expired on my 17 silverado.....a buddy of mine did a nice wideband tune on his and sent it to me. I was just about to buy credits and flash it. Then i traded it in on a 19 silverado....gotta wait again lol

AndyTA

Little update:

So I switched over to the 3 bar map sensor OS, as well as plugged in this guy (3 bar map sensor): https://www.summitracing.com/parts/nal-12592525 (12592525)

I set my MAP settings for linear/offset. 312 and ~ -11 at first. But, my Map Sensor would read 15 kPa at key on engine off.
So I messed with the offset at 0v settings until I got it to 88 (I live in Utah). The new offset setting I had to put in was 57.5 for it to read 88.

Now the problem is, the car idles but sticks to 500rpm and the kPa doesn't seem to change when I give it a quick rev either. It sticks to around 88 to 89kpa - almost artificially.
The voltage is pegged at 0.51v - I never paid close attention to MAP readings until now. is 0.51v even in the realm of normal for a MAP sensor?

Could I have a bad adapter harness? Michigan Motorsports:
Could it be that the wire-pinning is off/wrong on the harness, or could it be that a wire got cut/damaged? If there was no voltage going to the map sensor, would it ready any kPa at all?

Also with Key On Engine Off, I noticed the Map sensor spazzes up and down 10 times a second - but the moment I start the car and idle, it stabilizes and reads a steady 88/89 no matter what i do with the throttle.

Thanks,
Andy

I just realized... something is definitely fucky with my map sensor or harness. How could I be idling at atmosphere pressure??? lol. ****** - taking the intake manifold out on this thing to inspect the wiring/pin-out is gonna be a nightmare all over again.

ddnspider

iTrader: (26)

Speaking of need to scale a tune.......

Kfxguy

iTrader: (1)

Man I read your thread. Scaling my tune and redoing this stuff to where it drives as good as it does now, is going to take a lot of time. Ugh.

ddnspider

iTrader: (26)

If you do it right the AFR and idle will be the same after as before. Sure you might make a couple tweaks but it really should be close. Greg Banish has a video where he scales and it starts right up and idles with the exact same AFR.

Kfxguy

iTrader: (1)

Is it in calibrated success? I have that but haven’t watched it in a long time.

ddnspider

iTrader: (26)

Yes, I believe it's the 2nd video.

JimMueller

iTrader: (9)

My VE error is less than 5% (with a TPS>1 filter), but at idle my DynAir is 3-5g/s higher than Idle Desired Airflow. I've read conflicting opinions on which value to use to populate BRAF. I'm using IDA right now and it idles and drives great, except for some bucking at certain combinations of TPS & RPM. In the past when I've had IDA too high in BRAF, it caused side effects. So I think if I plug in the DynAir (which is too high), those side effects will return. If I need DynAir to match IDA, how what else do I need to look at?

On the IAC, the original shape is like a polynomial curve, the new shape is linear, especially after interpolating missing cells. Does that matter? I know years ago people felt that the MAF curve was supposed to match a 3rd or 4th order polynomial curve. Now it seems like the preference is to allow it to be slightly wavy, just not jagged, to be accurate vs a perfectly smooth curve. Does IDA<>DA cause problems calibrating this table?

Edit: I did the IAC process, and I changed my IAC Steps table and BRAF (using IDA) at the same time. Now it seems more prone to stalling when moving the car out of park when warm, and is definitely more prone to stalling when turning on the fan or A/C. BRAF went up about 1g/s

ChopperDoc

BRAF defines what the desired number is, because this number is then converted to the IAC value based on what the effective area is. Normally I use dynamic airflow to find this number. It works for me perfectly fine, since technically the BRAF and IAC Effective Area are linked. Changing one will alter the other. My theory is - if the dynamic air is what the engine is using for fueling calcs, then why wouldn't it also be defined as what is needed on the BRAF or IAC to alter the idle?

It is possible to find sweet spots throughout all the tables, where it will run great under one condition or the other, but I believe other areas may be affected because the numbers are simply off. Having said that, whatever works is what works. But my typical order of doing it is leaning the fuel out a bit (assuming false lean conditions), pulling out some spark, and getting the air ranges right. Spark and fuel are what cause bucking most of the time. That, or if the PCM loses control of the IAC by it hitting the limit on one side or the other. Typically closing all the way off, which is then followed by surging.

It's not uncommon to see AFR's of 15 or 16 at idle with large overlap cams. And spark from 15-20 is fine too. At the end of the day though, if one thing works better for you, then go with that.

Here's a pic of me getting my Camaro tamed down to under 600 RPM. I should also mention I am using the "stall saver" setting on the idle spark tables, by setting the first two columns to 30* and interpolating to the next row. Works great though. My idle is set at 750 on this car, with a 244/252 (297/305 actual) cam.

ChopperDoc

The idle desired, I should note, will change day to day. This was also after I ported my IAC out to 3/8's. Not the blade, but the back of the actual IAC assembly. TB is a FAST 102. If I were to re-plot the IAC on this again, it would change the IAC value itself. I did that a while ago, so the number won't always match up later. It's fine though. This can take a few days and a few cold starts to get solid. I'll hit it up again in December when I get a chance to mess with it some more.

Here's a pic of the stall saver I was talking about...


This is directly from that tune, and is current.

ChopperDoc

And here are my settings for the BRAF table. These are my dynamic air values. For whatever reason, the "desired" number changes day to day, even though this is where is comes from. I really wish I knew the calculation, and I was working on that for a while. A hidden calculation behind the scenes determining what the changes need to be to change the RPM "x" amount.

Also, if you have large injectors, have you set your min fuel mg down under the transients? Set it to .015 or .010 to help with idle surging. It's what that number controls. Another thing that can help. Hopefully this is helpful. Note that at the bottom, the BRAF defines the IAC value. That's why I use dynamic, because it's the closest thing to a known value of what is actually needed to run the engine. Again, I'm not trying to say to change yours, as other methods work perfectly fine, but just trying to show another way of looking at it.

turbolx

Yes. We even broke up the older videos into smaller segments if you want to watch them individually on our streaming site.

<The Scaling discussion using my method can be found HERE>

Kfxguy

iTrader: (1)

is it the exact same thing found in your videos? If it’s the same, I’ll find it. If it’s different or more in depth then I’ll buy the online video.

AndyTA

Figured it out. Prepare to laugh (or call me an idiot):
Low battery. I kid you not. Unfortunately, I figured this out *after* removing my intake manifold, LOL.

Little obvious PSA for anyone who reads this:

HPTuner will claim a "write" was successful and go on "business as usual" even if the write was *not* successful - which was caused by a low battery voltage. Long story short, make sure you've got good life in your battery. I know I know, rookie move. My battery was low because I had it on/off all day without the engine running while messing with stuff/tuning, etc. PLUS, it's old...

Anyway "nothing to see here folks" moving on...

Thanks,
Andy

AndyTA

Hey Chops (Calling you chops):

Would this table help me with my extremely lean idle at start up? (19.5 afr) (36F outside...effing Utah)
I assume I'll have to fatten this up some?

Thanks,
Andy

turbolx

Yes, as I said, we broke up the existing videos into smaller (cheaper) segments for the streaming channel. It is currently the exact same video segment that was included as part of SME-DVD-2, our longer "GM Advanced" DVD. We may update these later with fresh content, but for now they're the original footage.

Kfxguy

iTrader: (1)

No. Thats your airflow for your iac motor essentially. Dont have my laptop with me so I cant tell you what table it is, but its a coolant temp based table. I would try adding to your VE fueling, likely its lean until your LTIT and STIT kick in and goes into closed loop. What are your trims at idle?

I disabled my LTIT, dialed in my ve close, and it is much more stable and consistent now.

AndyTA

Thanks for the response - The other problem I have, is that if I drive to operating temperatures, park the car, come back 10 minutes later and start it - it's lean every where because of hot under-hood temps. After driving for a while and the IAT's come back down, it's spot on (SD Tune).

I've looked through the different tables, and there isn't one that has a logic of "if IAT = x, then increase fuel by x amount" or "if ECT = x, then increase fuel by x amount" - so I assume it is embedded in one of the other tables, like the IAT table? Or something else?
How does an SD tune figure out how much fueling adjustment is needed based upon temperature of either IAT or ECT?

Could this fall back to maybe "not totally accurate" injector data?

Thanks,
Andy

Kfxguy

iTrader: (1)

there is an air coolant map. But I don’t think that’s your issue. I think your ve is off and closed loop ends up correcting it. I’m 99% sure that’s your issue. If you have a cam, eoit (end of injection timing) can have a small impact on that also. But I think the ve is your issue.

also, depends on your ecm, I’m not sure which ones do this or not....but mine does, if you leave the rear o2’s unplugged, after a certain time the car is off and cranked back up, the ecm performs a “test” on the rears. Even if you disable them in your diagnostics. I’m not sure if this affects all, some, or very few ecms (mine is an Australian based car) but it absolutely affects mine. When it does this test, my afr’s get wonky. I don’t remember exactly what they were doing. But I told my buddy who’s been tuning for years and he told me to plug both o2’s in and zip tie them somewhere and try it. When I did that, a consistent problem I had, went away and never came back. That was over a year ago so my memory is cloudy on the details. So there’s an idea.

AndyTA

Hey Kfx,

Thanks again. I'm actually running open-loop speed density tune. When I'm at 180ish ECT, my VE table is spot on. It's 14.4 to 15.0 at any given moment. Pretty good and tight window.
If I start adjusting my VE to give me more fuel based upon higher temperatures, all that ends up happening is that I now run rich when I'm back down to 180F (where my car normally operates).

It's when I leave the car off at a parking lot some where and allow the temps to go up because of trapped heat and lack of air from moving and I assume raising my IAT's, when I start it, it's lean every where and stays lean until I'm back down around to 180F ECT once I get moving and air is flowing through the engine bay. Once I reach around that temperature of 160F to 185F, I'm back to good stoich operation.

That rear o2 thing is interesting...

It's a Gen 3 stock PCM that comes with our cars. (1999 trans am/camaro)

Thanks,
Andy

Edit:

At first I thought it was fuel pressure/vapor lock issue, but that can't be the case with an FPR set at 60psi to the rails at all times.
AIR Pump is disabled already
I don't think 1999 PCM's had a properly functioning Cylinder Bias Temperature unfortunately.

Maybe I need to fudge with the OLFA table.