Dansean1

Hey guys,
anyone out there familiar with LT1 edit? I need some assistance with fuel adjustments at WOT and cruising.
thanks
Daniel

Kevin Blown 95 TA

That's not enough info. If you're asking how to tune a car, that's a different subject, besides, the stock tune should be pretty good for you. Maybe you can get rid of some of the excess fuel enrichment at the 5k rpm area. But, assuming you have access to a dyno and/or a wideband sensor, or can log some runs and driving time, you can look at your fueling and see where in the rpms you need to richen it up or lean it out, then make the adjustment in the PE vs. RPM table for WOT, and for closed-loop cruising, you can try to cram in your injector constant to adjust your BLMs as close to neutral as possible. For power tuning, you're basically guessing if you can't measure the power gain/loss somehow, even if you have some arbitrary target AFR. You can also adjust the MAF cal, but that should be left alone in your case, and the VE should also be left alone since it's controversial, anyway. You can adjust timing based on knock sensor activity, but you want to sneak up on it, then back off a couple degrees after it starts to pull timing.

Dansean1

Thanks for getting back to me.

I have an acquaintance with a dyno that will rent it to me for a good price. He'll tune it for me a reasonable price but I want to do it for more of a learning experience. He uses tunercat I believe which I have not seen.

I just did some new bolt ons as seen by my signature: 1.6's, shorty headers, 3.73s and the usual bolt ons. I suspect im running lean while cruising...basically I need to tune the car now, there is some horsepower left as well as better fuel econ.

I understand that PE vs Temp or RPM is at WOT. Moving the numbers down for example decreases fuel and the amount one goes depends on the AFR reading I presume. The PE vs Temp I understand is not used as much, or I dont understand its purpose in regard to temp.

How does one tune fuel when you are not WOT?
For example, your AFR is rich when at 35% throttle doing normal street driving. How does one tune that?

The timing i understand a little better but am not solidified yet.

What table does one alter, why and how?

thanks
Daniel

Kevin Blown 95 TA

If you are cruising around, and are in closed loop, and nothing is really out of whack with your setup, then you are at 14.7 AFR average. If you have a massive vacuum leak, or you have leaky injectors, or bad O2 sensors, and the PCM cannot adjust for it, you may go lean or rich. What makes you think you are lean at cruise? You need some log data and/or a wideband to tell you that.

Dansean1

I dont know if I am going rich or lean on the cruise. I have just learned how to tune fuel in WOT using PE vs Temp and RPM. When would one actually use the temp table since it seems more vague or less precise?

The reason I ask about is if on the dyno, while cruising I see the AFR shows me running as rich, how would I adjust the fuel? Example, the car is in 3rd gear, 3500 rpm and the car is rich, what table do I use for fuel?

Aside from fuel, and doing timing (which Im learning), what else is there to do for tuning?

Thanks

canbaufo

Dan' ...you do have logging software right? Without it you really can't do any tuning, you at least need DataMaster or at the very least a Scanmaster. I use both, with the Scanmaster permanently mounted in my middle A/C vent. That would be overkill for you since you're N/A you don't need to monitor knock retard constantly, so the Datamaster would be good enough.

Tuning for cruise is basically like this: You have long term block learns (BLM = "block learn multiplier") and short term fuel integration ("INT"). The short term is what's happening now, basically, the long term is what is has learned and shoots for. Your long term BLM ideally should be 128, this means no fuel is being added or subtracted, and that your fueling is already approximating 14.7:1 (ideal "stoichometric" cruise A/F ratio). With a setup like yours you really shouldn't be seeing anything too far off, typically you'll see something like 120ish, which means it tends to run a little rich but the PCM is subtracting a small increment of fuel on each calculation based on what the O2's see. This would be normal. However, if you saw 108 that would mean your PCM is pulling the max amount of fuel it can and either you're running way too rich or the PCM just "thinks" you are based on O2 voltage. If you saw 160 that is the max amount of fuel it can add and that means it's either running scary lean or, again, the PCM has a reason to believe it is due to something being wrong and throwing O2 voltage off. There are a variety of ways you can adjust BLM's but you shouldn't need to do that with your limited mods. If you're truly running rich something is wrong with the closed loop system (O2's, exh leaks, vacuum leaks, etc).

Like I said before I suspect an exhuast leak since you've had headers installed, but then again, we don't know your BLM's yet so we can't say for sure. Of course, on a dyno with a wideband A/F meter you will be able to see for sure what your actual cruise A/F ratio is, and it should be around 14.7:1 give or take a little in your case.

Dansean1

I had suspected a miss and a slight intermiten surge at red lights but its seems ok.

I do have datamaster but I was told that one needs a wideband because basing data off stock 02's is not accurate nor wise.

I need to really get a handle and understand how datamaster works as well as LT1 edit.

Lets just say I found that everything mechanical was in order but datamaster showed rich conditions while not at WOT...how would you tune then?

What tables show "int" and blms...I need learn more on that? Still not crystal clear.

Kevin Blown 95 TA

If you are rich at part throttle, then everthing mechanical is probably NOT in order on your stock engine. You probably have an exhaust leak. Just run Pcm Log or datamaster and see where your BLMs are at during cruising around and idling. They tell you if your engine is fueling correctly at part throttle. You can also look at your O2 sensors to see if they are switching like they should be. That's plenty good enough for starters.

canbaufo

Ditto that and also see if there is a significant (large) difference between right and left O2 voltage, this could be a dead give away for exhaust leakage. BLM data should come up on the default screen when you playback Datamaster, somewhere in the middle on the left with the INT right next to it. What Kevin means about O2's switching is closed loop operation, you should see the O2 voltage vary wildly up and down, this means the fuel integration (closed loop activity) is indeed happening. It may cycle up to .800 and down to .200 or even more very wildly, that is normal as weird as it sounds. Have you done any searches on "how to read Datamaster" or something to that extent? ...you may get a lot of info. Wouldn't it be nice if these softwares came with clear, concise manuals? Someone needs to jump on making some, even if they do it for a small profit. You can bet the tuning vendors won't be doing that though lol.