Charge Temp Blending, no MAF

[12_Square]

If the MAF is disabled, does charge temp blending still function?

[joecar]

Yes.

[ddnspider]

Does this b4901 work on 98's?

[joecar]

My understanding is that it does, regardless of MAF, on 1997/8 also.

[12_Square]

What would really be great is the option to edit the PCM’s IAT fuel adjustments. Seems it’s not tunable in the 1998...? Moving the IAT sensor to a location where temps are more consistent has helped tremendously - I’m no longer running lean after sitting in a parking lot… but I’m still running a tad too rich in cooler weather. I’ve got my tune right where I want it, now I’m anticipating a 95+ degree Florida summer soon. :doh2: Do I need a better operating system? Or have I overlooked something?

[joecar]

Should be ok... altho some people swap to 0411 PCM (requires harness mod, IPC wiring mod, and fuel system segment).

[ddnspider]

That's good to hear cause I kept reading that 98's had this table as a "dummy" table. Since the weather has warmed up in FL, I noticed that after my car runs for awhile and the ECT/IAT's are up, I lean out. This is with an OLMAF tune currently. Struck me as really odd since I tuned the car in the cool weather, until I started digging into it and realized the PCM thinks theres less dense air so it commands less fuel.

I also wish for an IAT vs. fuel enrichment, but no such luck for the 98's.

[12_Square]

That's good to hear cause I kept reading that 98's had this table as a "dummy" table. Since the weather has warmed up in FL, I noticed that after my car runs for awhile and the ECT/IAT's are up, I lean out. This is with an OLMAF tune currently. Struck me as really odd since I tuned the car in the cool weather, until I started digging into it and realized the PCM thinks theres less dense air so it commands less fuel.

I also wish for an IAT vs. fuel enrichment, but no such luck for the 98's.

Have you relocated your IAT sensor? I used a 24" extension to put it behind my right marker light, down away from the hot engine. Picks up actual air temps now, and so far, the lean issue is gone.

[joecar]

You could run an experiment: drastically alter this table and see how engine runs.

[ddnspider]

Have you relocated your IAT sensor? I used a 24" extension to put it behind my right marker light, down away from the hot engine. Picks up actual air temps now, and so far, the lean issue is gone.
I plan to relocate the IAT in my bolt on z28 to use the EGR opening in the intake manifold after seeing others do it with good results. However on my 98 turbo TA I need it in the intake track to keep a handle on IAT's and spark retard.


You could run an experiment: drastically alter this table and see how engine runs.

That is actually the game plan to try.....now just need to get the time to play with it lol

[jnjprfrmnc]

You could run an experiment: drastically alter this table and see how engine runs.

Which table? I can't see anything in the post. Thanks

[joecar]

Table B4901.

[ddnspider]

I made a fairly large swing towards ECT in the low airflow rows and it seems to have given me a more stable A/F at idle/cruise.

[joecar]

I made a fairly large swing towards ECT in the low airflow rows and it seems to have given me a more stable A/F at idle/cruise.With no MAF...?

[ddnspider]

With no MAF...?

This was OLMAF only. Using the MAF exclusively. When I swung the charge temp blend more towards ECT, i did have to add fuel to my MAF curve as it would lean me out, but once I readjusted that I noticed a more stable A/F over time. Meaning when I drove the car for awhile and did hot stop/starts, the A/F remained the same whereas previously I would lean out over time.

[joecar]

Good deal :cheers: