I finally got what It think is good inj constant and feel power nice idle and sound and have a tune from 2 days ago ran at 128 across the board. hot dry day 85deg typical Florida weather

now same tune, and raining out, car still runs and feels the same, and few more tweaks but all my BLM read 140 range? I made some MAF and small tweaks and still the same no matter what

loaded same tune after several runs to confirm I wasn't crazy and same tune now is all 140 range but sounds ok.

it was raining out and humid could that throw off o2 and maf? anything to check in bin for weather

I checked BLM vs TEMPS and it stayed the same across temps

 

I have seen this before it was low fuel tank and pump starving

I checked ecu and voltage and no changes still 140blms

But I am pretty sure I was 3/4 full I will fill it up since gauge usually is either full half then empty
Maybe it broke if it is full then

What would cause pump to run lean when not even hot or during rain?

 

This is just a theory, so don't take it as fact......But high humidity makes it harder to burn (try burning damp wood in a fireplace). As such, it's going to take more air to get good combustion in an engine when it's humid outside. More air is then going to ask for more fuel to be added (high BLM's)

 

The mass air flow will not be effect by humidity much unless the coil gets wet and cools it down. either way then you would see excessive high Maf readings and therefore call for more fuel in turn running a little richer but I didnt see too high readings. maybe just at PE i was hitting 200 when I should be 180. but it shouldn't effect idle.

i think from my other post it was low fuel and my pump was starving the engine since it was across all BLM points and MAF.

 

Molecules of water are taking up the space that molecules of oxygen should occupy?
It's a Florida thing.

 

I presume since you have an 88 that you're running a MAF system. My 89 is also MAF. I have noticed a difference in the tune during rainy days. Here in Alabama we have a lot of humidity even on dry days but during the rain it would go richer. I run in open loop now so BLMs are not changing but I have noticed it too. I don't have a theory of why but you're probably not crazy.

I tune for the "average" and let the extremes do what they do. So what if the BLMs go up on rainy days, it's doing what it's supposed to do- compensate for changing conditions. If it's "right" for the typical day I wouldn't worry about it. Now some of these guys (like Bob) who can really get into the code may be able to figure it out but if you're like me you are limited to whatever your XDF is set up to adjust. I think having the ability to tweek MAT related adjustments may help.

 

That is why EFI is so beneficial. It compensates for many changes....

 

Try doing that w a carb.