OneQuickSS

Look at my signature and tell me if Im running lean or rich. I know that my tuning on it isnt up to par. I know it has to be a little off if not alot. What can I use to correct it?

<small>[ November 30, 2002, 03:44 PM: Message edited by: onebadss ]</small>

Brother J

My guess is your running lean with headers and the HPP3. Just a guess, so you should book a session on the dyno w/ wideband and have a way to tune it, like LS1Edit or at a minimun a MAF Translator.

Colonel

"Look at my signature and tell me if Im running lean or rich."

I'd need to be psychic. Your sig tells us absolutely nothing about your fuel/air mixture. A wideband O2 sensor will tell you exactly what's going on or Autotap (a must have, IMO) will give you a good idea.

JWRENCH

Colonel's got a point there, but looking at your mods, most of them generally increase air flow so I'd have to say your on the lean side. If I'm right then you've got very crisp throttle response and it noses over a little on the top end. Again that's just a guess, You'll have to dyno it to be sure.

Colonel

Increasing the airflow doesn't necessarily mean leaning the mixture. The PCM learns as it goes. It might be leaner to begin with when new mods are made but before long the mixture will most likely be right back where it was.

Actually, it's been my experience that suddenly increasing the airflow (like installing a lid or removing the filter) causes a richer mixture temporarily due to the PCM overcompensating initially. I can remove my filter and watch my WOT O2s go from .870mv to .930mv. Make another pass and watch them fall to .890. After another couple of passes they'll be back down to .870mv.

OneQuickSS

Colenel: Is there anything else that I could use to determine if I running lean or rich. Ive had lots of people tell me a MAF translator and then some tell me to dyno it. Oh by the way, whats an O2 wideband sensor and where can I get it. Do you think that I could take it to a performance shop and they can tell me where I stand if I didnt want to purchase an Autotap? Then on your last reply you said that the PCM learns as it goes, so does that mean that my car will eventually go back to its correct ratio after a while. Could you give me what each of my mods would do whether it would be leaning or richening it up.

Colonel

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by onebadss:
<strong>Colenel: Is there anything else that I could use to determine if I running lean or rich. Ive had lots of people tell me a MAF translator and then some tell me to dyno it. Oh by the way, whats an O2 wideband sensor and where can I get it. Do you think that I could take it to a performance shop and they can tell me where I stand if I didnt want to purchase an Autotap? Then on your last reply you said that the PCM learns as it goes, so does that mean that my car will eventually go back to its correct ratio after a while. Could you give me what each of my mods would do whether it would be leaning or richening it up.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A wideband O2 sensor is what dyno shops use to monitor fuel/air. They are quite expensive (a couple thousand dollars I believe.) I was saying that if you really want to know exactly what your fuel/air ratio is you need to go to a dyno shop that has a wideband O2 sensor.

Or, if you can't find a shop with a wideband you could at least get a good idea of your air/fuel ratio by checking the WOT O2 readings.

I can't think of one reason any LS1 performance enthusiast should be without Autotap or some other diagnostic scanner.

A MAFT does not tell you fuel/air. It allows you to adjust your WOT fuel/air and adjust the base settings to get Ltrims inline.

"so does that mean that my car will eventually go back to its correct ratio after a while."

Your PCM will adjust until it can maintain a stoic mixture (14.7:1) during closed loop operation (you are in open loop during WOT operation.) Wherever your WOT mixture (see, your WOT mixture is based on what the PCM has learned while in closed loop so indirectly PCM fuel cell changes do effect WOT operation) is once this is accomplished is where it's going to stay unless you change it with a MAFT or programming. So the answer to whether your fuel/air will adjust back normal is yes and no.

BTW, the PCM only has but so much range of adjustability. Once the Ltrims reach + or - %25 no more adjustment can be made. Autotap will tell you what your Ltrims are.

As I've said before, closed loop fuel/air should not be effected long term by airflow increasing mods so long as the fuel system is adequate since the PCM will make corrections to maintain stoic. WOT can be indirectly effected though. Just because the WOT is based off of the closed loop doesn't mean that the WOT will be corrected as accurately as the closed loop.

Here is my best advice. Get it dyno tuned with a wideband O2 sensor or at the very least use a diagnostic scanner like Autotap to set your Ltrims at + or - %5 during part throttle steady state cruising, your O2s at .870-.910mv during WOT operation, and ensure that you're getting no knock retard (knock retard is a whole nother discussion.) You'll thank yourself for getting a diagnostic scanner when problems arise (such as when your SES light comes on and you don't know why) and if you're serious about getting the most from your car you'll end up getting it eventually anyway.

Colonel

I'm moving the to Computer Diagnostics and Tuning... <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />