Tweet
So I'm getting back into tuning a bit after a long hiatus of working on other vehicles.
89 Z24 with 94 3.1L swapped in, all stock, except for the tune, BFUZ code.
I did a bunch of tuning in the summer, and now my VE is close and I added a couple degrees of spark and smoothed a bunch of tables out.
Now it's winter up here in Alberta and I'm doing some datalogs and I'm questioning some of the AFRs I'm seeing. Is it really necessary for the ECM to be commanding 7.xx and 8.xx AFRs for the first several minutes after a -30*C startup? I mean, I can understand it commanding ratios that low in the first few seconds, but after it's started, shouldn't the AFRs jump up into the low 10's at least? I mean, this IS a port fuel injected engine, it's not like there's much fuel sticking to the intake manifold like the old TBI's. It's no wonder I'm getting a 6mpg drop in the winter lol (I don't idle my car for more then 30 seconds ever).
So what I'm thinking of doing is drastically reducing my A/F timeout table (from the factory that table is set to -5.0 AFR below -16*C), or reducing the timeout decays, or both. I think I'd reduce the A/F timeout to maybe -2.0 or -2.5 AFR, and reduce the decays by about half.
I'm also looking at slightly increasing my open loop AFRs in the main Open Loop VE table in the cold areas. I originally thought to remove the timeouts all together and only use the Open Loop VE table, but wasn't too sure about that idea. I don't think there's any real damage to be done except for some stalling if I go to lean with a cold engine, so I'm not all that worried.
What (if anything) have you guys done with your cold open loop stuff? Anyone care to post their Open Loop fuel tables and their A/F timeout tables? Doesn't matter if your engine is stock or modded.
I've attached the factory tables, so you know what to look for. Notice the A/F timeout table that has you at -3.1 AFR even at a 44*C warm startup! That seems a tad ridiculous to me.
89 Z24 with 94 3.1L swapped in, all stock, except for the tune, BFUZ code.
I did a bunch of tuning in the summer, and now my VE is close and I added a couple degrees of spark and smoothed a bunch of tables out.
Now it's winter up here in Alberta and I'm doing some datalogs and I'm questioning some of the AFRs I'm seeing. Is it really necessary for the ECM to be commanding 7.xx and 8.xx AFRs for the first several minutes after a -30*C startup? I mean, I can understand it commanding ratios that low in the first few seconds, but after it's started, shouldn't the AFRs jump up into the low 10's at least? I mean, this IS a port fuel injected engine, it's not like there's much fuel sticking to the intake manifold like the old TBI's. It's no wonder I'm getting a 6mpg drop in the winter lol (I don't idle my car for more then 30 seconds ever).
So what I'm thinking of doing is drastically reducing my A/F timeout table (from the factory that table is set to -5.0 AFR below -16*C), or reducing the timeout decays, or both. I think I'd reduce the A/F timeout to maybe -2.0 or -2.5 AFR, and reduce the decays by about half.
I'm also looking at slightly increasing my open loop AFRs in the main Open Loop VE table in the cold areas. I originally thought to remove the timeouts all together and only use the Open Loop VE table, but wasn't too sure about that idea. I don't think there's any real damage to be done except for some stalling if I go to lean with a cold engine, so I'm not all that worried.
What (if anything) have you guys done with your cold open loop stuff? Anyone care to post their Open Loop fuel tables and their A/F timeout tables? Doesn't matter if your engine is stock or modded.
I've attached the factory tables, so you know what to look for. Notice the A/F timeout table that has you at -3.1 AFR even at a 44*C warm startup! That seems a tad ridiculous to me.
Attached Files
Comment