Just getting into DIY PROM stuff and I have a few questions after my first datalog. First off I couldn't get any readings through TunerPRO datalog trying a variety of configs. As soon as I load up WINALDL it starts reading my information (both are configured for the same com port).

Anyways . . . the truck (which houses the 86 TPI setup) idles poorly. It has been getting poorer as the mods change. I added some Trickflow heads, a 224/224 .052/.052 112LSA cam, and a bigmouth intake base. It surges sometimes when in open loop but once in closed loop it will maintain idle decently (though I had a feeling it was running way rich at idle).

As a side note, all emissions and EGR stuff has been removed (both physically and as far as my "custom" chip are concerned and the EGR has been sealed over and blocked. No vacuum leaks present that are detectable.

Upon my first datalog on this vehicle via WINALDL I found a few odd things. First off my IAC steps always stayed at 145. It is plugged in and is fairly new (probably a year old). This signifies its staying closed correct? Should I replace this unit? I have tried resetting it a number of times with no luck.

Secondly, once it reached closed loop it began reading the BLM and INT readings (what is INT btw lol). My block learn reading just at idle in park was 100. I realize this would probably approach 128 if I was idling in drive under more of a load but this still seems very rich (under 128 is rich correct?) for idle. id like to get my idle in proper position before I start logging/tuning cruise, PE and WOT.

After about a minute of running in closed loop, it went out of closed loop and stopped reading the INT and BLM. No codes were thrown.

Currently I have no VSS however it is not disabled in the chip. What is weird as lately, its been giving me speed readings (though all over the map) instead of throwing a NO VSS code like it normally does. I am going to disable the VSS in my first chip burn until I can get ahold of a VSS that will fit my th-350 transmission.

I am using Moates Burn1 and adapter for the 86 setup. I plan on using a 6E mask but am wondering where I should start.

Any starting pointers/advice would be GREATLY appreciated.

Let me know if there are any more questions that I need to answer to get a proper response.

Thanks all.

Dylan Long

Dylan,

Welcome to the world of chip burning! Tuning your car this way can be one of the most frustrating things you'll ever do, but it will certainly pay off in the end (or so they tell me... ).

First off, what mask are you using? You said that you're thinking about switching to $6E, so that leaves $32 and $32b. What BIN file?

In regard to the IAC, try removing it from the throttle body, leaving it connected, and turn on the ignition with the ALDL A & B terminals shorted out (as if you were resetting the IAC for minimum air). See if the pintle moves -- but make sure that you aren't pointing it anywhere, because the end may shoot off and get lost (don't ask me how I know). Be sure to clean it if it looks carbonized.

The Integrator, or INT, is basically a display of the ECM's attempt to find a stoichiometric air-to-fuel ratio. Your oxygen sensor, of the "switching" style, is designed to operate at an AFR of 14.7:1. Using the INT, the ECM constantly "switches" between rich and lean states -- the oxygen sensor tells it what state it's in. When the time in each state is relatively equal, the correction is "locked on" and the BLM gets updated (or "learned"). Just like the BLM, the INT is a correction factor, though not to the same degree. Your INTs may not always match up exactly to the BLMs.

For both the Block Learn Multiplier and Integrator, less than 128 is rich (removing fuel) and greater than 128 is lean (adding fuel). Remember to take note of the BLM cell that you're working in -- these will vary depending on RPM and load (LV8 on a MAF car). LV8 is a function of airflow and RPM, so the ideal way to get your mixture correct is by tuning the MAF tables. This really isn't as hard as some make it out to be, and some of the "earlier" threads on here nix the idea altogether, but a lot has been learned since then. Still, I would not go hog-wild changing things until you understand how they work (e.g. table scalars), but there is plenty of reading on here about that. Try searching for the word "maf" in the DIY PROM board.

Hopefully some veterans will chime in. I'm pretty familar with the theory behind some of this, but I've only been burning my own chips since the end of last year. My car's been having some problems, which has been slowing things down, but they should be ironed out soon.

Have you checked out any of the stickies at the beginning of the DIY PROM board? Lots of good reading. I'd start there first, just to understand as much about the whole picture as you can.

The ECU "Tells" the IAC what to do and keeps track of what it "thinks" it has done. It has no idea if it really did what it was supposed to do. This means that if you see that the ECU thinks the IAC is at 145, it may mean 3 things: 1)The IAC is bad, and stuck mostly closed causing ECU to try to open it, but since it doesn't move, it keeps trying until it thinks it's at 145. 2) The throttle minimum air setting (idle screw) is too far out, and the ECU has to open the IAC that far to keep the engine running. 3) The datalogger isn't reading the ECU correctly. *( 4) ECU is bad, or chip is incorrect or bad, let's hope not.)

BTW, did you change injectors from stock? If so, did you adjust the chip accordingly? I don't know what 32 or 32B use, other than PW vs LV8 and RPM ($6E uses two injector constants). I'm not sure if with that code if that's the right place to make an injector change. It would work, but it's a lot of typing.

Edit: Am I smoking dope? I just took a look at some $32 ecus and they use injector constants and the MAF tables like $6E. I wonder where I got that idea in my head? somebody set me straight here. Maybe I'm thinking of some other MAF system. Maybe what I just downloaded is bullhonkey.

Edit #2: Nope. just didn't look at it close enough. Still MAF tables. But also PW table. I don't know what all you'll have to change with injector swapping on $32.

RednGold86Z, with reference to the $6E, the PW can be either calculated or looked up from a table. There is a flag that sets this option... in my base ARAP bin, the "calculate PW" flag is checked, which I assume to mean that the PW vs. LV8 vs. RPM table is not used. I haven't verified if this is really how it works, though.

Might be similar in the $32/$32B masks, too.

In $6E GM dropped support for the PW tables and the digital MAF. Can only use a calulated PW and an analog MAF in $6E.

RBob.

What does that do as far as tuning? I've read a lot of the sticky's however most of them concern tuning with the 32b mask. Isn't the 6E supposedly the latest mask (and what people recommend using)?

And could you explain analog vs. digital as far as MAF are concerned? Aren't the stock style MAF's from 86 analog anyways?

Also (and this might be a stupid question but regardless I shall ask lol) as the IAC approaches higher values, it is closing or opening. Does a value of 160 mean its fully closed or fully opened? My setups keeps searching for idle (surging sometimes) until it hits closed loop when the idle evens out (though very rich).

Tune via the MAF tables.

Yes, GM must have felt that calculating the PW directly from the airflow was better then using PW tables.

Analog has a varying voltage output. The higher the airflow the higher the voltage. A digital setup uses a frequency modulated output, a square wave. The higher the air flow the higher the frequency. '85 TPI's used a digital MAF, along with all of the MAF V6's including the TTA.

IAC steps of 160 is fully open, 0 steps is closed. Surging is typically caused by a lean area(s).

RBob.

Could complications arise from using an 85 MAF on an 86 TPI?

At idle, my BLM's are at 108 (possibly lower but the lowest allowable BLM value is set at 108 in this chip). Usually the IAC goes to 160 in what I assume is an attempt to bring in as much air as it can to de-richen the mixture. I am going to play with the MAF tables a bit and try and clean up the idle before I start tuning the part-throttle.

I am also going to verify that the IAC is actually moving properly.

Any other tables/areas that I should be looking to as far as tuning the 6E?

Any and all advice/suggestions/anything is always welcome and appreciated.

Thanks a bunch all.

Dylan.

Still trying to get the idle tuned in. Did a bit of datalogging just in the driveway. If anyone wants to take a look and see if anything in particular stands out Id be most appreciative.


Idle Datalog file

Thanks.

The ECU does not use IAC to control the air fuel ratio. It just opens it if the RPMS are lower than desired, and closes it if the RPMs are higher than desired, regardless of A/F.

If the IAC counts climb higher and higher with no change in RPM, then yeah, there is a problem somewhere in the IAC circuit or motor, most likely.

Thanks for setting the PW thing straight RBob.

THanks for the info. In park/drive idle, I cannot reach the programmed RPM of 750 (where it idles great based on my cam) even with the IAC at 160. Perhaps its time to fix the stripped Throttleblade adjuster screw and open up the throttle blades more to reach the desired RPM and let the IAC steps climb back down. Am I on the right train of thought?

BTW I messed with the MAF table 1 and timing a bit and got it to stop idle hunting. It idles without surging now, just at a lower than desired RPM.