Tuning: 3500, 5-speed, 1227730, nAst1, Fiero GT

[robertisaar]

widebands are NOT accurate right after startup. reason being that when a lot of fuel is being dumped in, a lot of it doesn't burn in the combustion chamber and can still be burning/unburnt as it passes the sensor. will cause wonky(technical term) readings.

with a correctly tuned VE table, then you can mess with that kind of stuff, since VE is taken into account for everything except for cranking fuel, which is done in raw BPW... something you may need to adjust anyways since your injector size relative to cylinder size is most definitely different than the LH0 your tune was likely originally setup for.

[LZeppelin513]

I spent some good time (ga$) tuning this weekend. Mostly part throttle tuning and a couple of low rpm WOT just to see AFR. I was doing it all *open* loop with the wideband. What is more accurate for part throttle tuning, *open* loop method or using BLMs to tune?

Also, at WOT 2000-3500 rpm my AFR stays between 10.5-11.5 (haven't touched PE yet) but I usually will get 1 knock count and a tad bit of KR but not at the the same RPM/load. That seems rich enough to not be getting any knock? Using 93 gas.

Edit: i misspoke, meant open loop said closed

[robertisaar]

closed loop IS BLM tuning... if you were in open loop, BLM and INT wouldn't move, meaning you would be watching only your wideband to see what kind of changes to make.

widebands can be fooled and they can lie to you.... so if all else fails, do plug cuts. those don't lie.... they may confuse and possibly draw you to the wrong conclusion, but the spark plugs will tell you what is really going on.

i've had people mention a "rich knock", which goes against all conventional wisdom, and that it cleared up once they ran a more realistic PE AFR. 10.5-11.5 is REALLY rich. i'd look more along the lines of 12:1 at richest, but that's just me. the higher octane fuel will certainly help.

if you want to undeniably determine if that's false knock or real, you would need to run even higher octane fuel. since you're already playing with 93, that's gonna get expensive real quick. as an alternative, you could drop down to 91/89 or even 87 and see if the knock still occurs in roughly the same situation and with the same intensity.

and 1 knock count isn't bad at all.... a lot of factory tunes do far worse with factory engines.

[LZeppelin513]

Thanks for the fast reply, I edited my last post. I wrote closed loop but meant open.

I'll look at my plugs and see if I can find anything. Any links to good info on reading plugs? I have zero experience looking at plugs and would imagine it to be tricky. In your experience, does wideband or CLOSED loop tuning tend to be more accurate?

Good to know about rich knock. Once I get my VE tables dead on and start playing with WOT more I'll shoot for leaner AFR.

[robertisaar]

you can get to a more accurate VE table faster using a WB, IMO... since waiting for the ECM to move the INT to the correct value to cause the O2 to swing around the stoich point can take too long to reach in the conditions that you want to play with. decel is a good example of this. you can let off the throttle quickly and if your DE and VE isn't correct, then you'll see the INT shoot off in one direction, then eventually move back toward 128 or move to a position where the O2 voltage will start swinging around stoich. can take a while though, longer than the amount of time you're in certain conditions at least.

reading plugs: Bruce Plecan comes to mind.

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?50-Plug-readings-by-Bruce-Plecan-AKA-quot-Grumpy-quot-R.I.P.-dedication

[LZeppelin513]

I have been doing some more part throttle tuning in both closed loop using blms and open using the wide band. It seems that i can spend time in an area with the wide band but it can sometimes make it worse when i go back and look at the new blms in that same area. Would this be a good tuning strategy: changing the "open loop target afr vs map vs cool temp (f56)" to 14.7 for the entire table, and then tune with the wideband in closed loop. And then when done revert the table back to the old values.

[LZeppelin513]

Also is there a table to modify the fuel with regards to iac? When my fan comes on and iac increases, afr goes from 14.7 to near 16ish

[robertisaar]

IAC is already accounted for via the MAP sensor. if you're getting a change in AFR from when the fan(or any other large electrical draw) comes on, take a look at your injector offset vs voltage compensation, it may need adjusting, especially if you're running anything other than the injectors the calibration was originally done for.

if that is not the case, then when it comes on, you're(at least) temporarily dipping into a higher MAP range due to the increased load. if that section of the table hasn't been played with yet, that can cause issues, otherwise you'll have to fudge the situation since i've never seen(nor do i think it is possible) AE applied at idle in A1(and nAst1), which would be the "correct" way to do it. but since A1 does AE enterance determination off of D-TPS, not D-MAP, it can't happen.

also: your narrowband and wideband seem to be disagreeing if that's what happens when tuning open compared to closed loop. if you trust the wideband more, you'll have to change the narrowband calibration stuff around so that it will more closely match the wideband. the ZEREFU, ZEREFL, CLOXTHA tables would be good to look at here.