Sorry for this being long winded.

I've upgraded my 85 ECM to a 165. I'm using the ARAP 6E BIN as a starting point with changes for injector size and target AFR. This is a 396 Super Ram with AFR 195s, 221/230 cam and headers. I've also installed a heated O2.

I was finally able to get some good data logs. Basically, it's running lean across the entire range. BLMs range from 150 (idle) to 135. O2 is working fine. I also have an AFR gauge that reads mid 13's most of the time so I don't think I'm doing any damage. I assume the AFR is displaying corrected A/F ratio. I'm data logging with TunerPro RT. I use Tunercat to burn chips.

I suspect I need to modify the MAF tables due to cubic inches and increased air flow. When I look at the MAF tables in Tunercat, they are set up for gms/sec vs. counts. In Tunerpro, the tables are set up for gms/sec vs. volts. Can I assume volts are for the throttle position sensor? If so, am I being too simplistic to think I can use the data logs to input the measured gms/sec at the various TPS voltages?

 

Long story...attempt to make it short.

The $32/32B/6E masked bins were really designed around a digital maf sensor...like a turbo buick. The software was also adapted to deal with an anolog maf. Note: Only analog mafs were used in production.

The MAF tables were designed to accomodate either signal type, so they can represent flow vs volts, or flow vs counts depending upon the application/switch.

An external editor like tunerpro or tunercat must make some assumptions, so that their tables/scalars make sense for a given application. Since all of the production bins use an analog MAF. Flow vs volts is most appropriate. User must understand what they are working with.

The maf tables (in theory) simply represent the transfer function of the sensor. Simply put, a given air mass flow rate should result in an an appropriate voltage (or frequency) output from the sensor.

In practice, there seems to be a large variation in sensor output, since no two sensors seem to flow the same. This is effect is exagerrated since many sensors have been descreened and/or contaminated over years of useage. There is no such thing as a perfect universal MAF transfer function. Fortunately, closed loop does a good job to compensate for minor errors.

enough of this babbling...

Unless you have a flow bench at your disposal, you can adjust your maf tables/scalars as required to fit or bring your blms in line. Of course, this approach is limited....but like most things, can be overcome with technology.

Just need to remember with MAF cars, everything is relative to the maf, injectors and O2 sensor behavior. Nothing is absolute without an external reference, so every combination is a bit different.

What was the question again?

 

That was a nice way of saying I was way off base. And it helps as usual. I'm assuming now that if I increase the gms/sec values, the ECM should increase the BPW. I'll try this in small steps. Thanks!

 

I'm feeling simple here, and I'm hoping this can be broken down a bit. If the narrowband is reading lean, but the wideband is rich at 13:1, they can be equaled by modifying the maf tables to both be correct? Maybe I just don't get the correlation here?

 

That's my dilemma. I also don't understand why I'm seeing such high BLMs when the INTs are hovering from 126-130. I thought BLMs fluctuated when INTs were out of range too long.

 

Okay, so let's assume the narrowband is operating correctly for the moment. BLM counts are above 128 and the ecm is adding fuel, and doesn't seem to hit max add at 160. Cross counts are occurring switching from rich to lean as the o2 reads and adjusts (I don't care much for the intergrator reading reading, because they just help to adjust the BLM, and staying between 126 and 130 is saying BLM is set) BLM based on a set AFR of 14.7, or whatever it is set too. Because BLM counts are high we should be able too adjust flowrate downward to richen the mixture, or increase fuel pressure to achieve the same result.
If this can't be done then I have to assume the wideband is correct and the fault lies in the setup of the 1227165? Voltage interference to O2, or a ground not completed?
Keep in mind I'm just thinking out loud, because if we can't adjust fuel something is off.

 

I am confident this is a matter of tuning. Before doing the ECM upgrade I was seeing BLMs at idle between 112 and 118. They would increase as the load and RPM increased. So this is a complete reversal and nothing has changed on the engine. What's interesting is that the wideband measurements have changed very little.

 

I've made some progress. In MAF Table, I increased the gms/sec. I did it in steps and logged the results at each step. I increased all the points by 1.5 gms/sec. I now have a BLM of 128 at idle with INTs between 125 and 129.

The last point on the table is now maxed out. So I need to figure out how to change the scale of the graph. I need to do that before proceeding to Tables 2-5.

The AFR gauge did not change much at all. Still in the 13's.

 

Here is just a thought. An old pro indicated his method to tune a MAF car. Set the FI constant to the actual injectors you have, and correct fuel pressure. Next force ECM to run in open loop only. Use WB to log your AFRs. Adjust MAF tables to get desired AFR. This basically calibrates your MAF tables to your engine.
Not saying i have done this, but i have it written down. It would be fun to try.

 

Well that is good, i guess. With your large engine, you may be hitting the limits of the MAF tables. One thing to know, make sure the first and last entries in the tables match the next table. eg, if one table ends at 130 gm/sec, then the next table better start with 130. And make sure your scalers match the tables as well. I havent changed mine much, so my scalers have stayed the same. With a MAF engine, dont expect to nail all your BLMS right at 128. If you can get +-4, you are doing good.
For MAF table #1, in ARAP, the scalar is 23. So you are up to that value for the last entry in table 1?

 

Here's the latest. I was unable to address high BLMs for all the MAF tables. I did bump up against the 23 gm/s scalar in MAF 1 as well as the upper limit for MAF 2. So I tried changing the injector flow rate to fool the ECM into increasing the BPW. That helped a little. Then I increased fuel pressure a few psi. That also helped. I'm now recording BLMs from 125 to 133. That seems to be as close as I can get. Whether or not this will pass smog is yet to be determined.

 

Congratulations, and did the different O2's ever agree, or have you had any thoughts on why they're so different? If you have smog issues with idle you might consider pulling a few degrees at idle from the spark table. I would think it should lean it out a bit, but my guess is 14.7 AFR should be okay.

 

I'm still unsure about AFR readings. They really did not change much. I'm still seeing low to mid 13's at idle. Under moderate load they go into the low 14's. I thought I would drive this tune for a while and see if the learning process helps. Then I'll see if I can get the local smog guy to do an off the record sniff.

I contacted Vader86 about his tune. He and I have identical engines to include the same injectors. He said his tuner felt it was a little rich at idle but better than being lean.

 

I wouldnt worry too much about the AFR readings at idle. Just tune it for the BLMs. How does it run at idle? Smooth, or smell rich? WB O2 meters are better used for WOT, and PE/AE modes. My WB bounces all around at idle on my F-body.

 

The idle is pretty smooth. I have the target idle set at 800 RPM. It varies by maybe 20-30 RPM. I do need to adjust the throttle body to bring the IAC counts down. The IAC is currently at 60 for idle. I'd rather have it around 45.

The BLMs at idle are almost dead on. I'm seeing some leaning (133) on the upper end of MAF Table 1 and lower end of MAF 2 but there's not much I can do about it. I read that the 89 ran better with higher fuel pressure (41-47). I might add a couple psi more to bring down the lean counts and then adjust the MAF tables to reduce fuel where needed.

One thing I have not tackled is a tendency to want to stall when I rev in neutral. I see there are stall tables that can be adjusted. I'm just not there yet. Once I finish working on the above things, I'll see if the stalling is still there.

Thanks for the help. Mr. ****** got me started with the initial bin and some good advice. Thanks Scott.