im just curious how do u read if ur car is running rich through datamaster? anyone have either a link or a good.read on understanding/reading/tuning etc. just want to get in touch with what all these numbers mean

 

You can't really tell much in closed loop (part throttle/low RPM). The long term fuel corrections will be below 128, indicating the PCM is pulling fuel out to prevent it from running rich. But the input from the O2 sensors can be compromised by faulty sensors, and a couple other things.

When you go WOT (actually a table of RPM vs Throttle position) the PCM enters power enrichment (PE) mode and richens the A/F mixture for better power and torque. You can get a rough indication of whether the result is richer or leaner that its supposed to be by looking at the O2 sensor millivolts. 900mV is sort of the dividing line... much higher than that and it may be rich, much lower than that and it may be lean. But the stock narrow band O2 sensors are not real accurate at these rich mixtures, because of a high sensitivity to temperature (a small difference in operating temperature produces a larger mV change than a fairly large change in A/F ratio).

If you have a Datamaster log, I can take a look at it for you. You could also read this and see if it helps:

LT1 OBD-I scanner guide

 

wow i forgot i put this up here. ya i definitely wouldnt mind if you take a look. ill look on that link as well. i feel its a tad rich and im trying to get rid of some of the exhaust pop. thinking maybe my tune can be messed with some to help fix it up. im sure a mail order tune is always going to be on the rich side anyway

 

does the tune really play a part though? i figured the computer would always adjust to correct fuel needs? so unless i have an issue somewhere, ie o2s plugs or wires or something it shouldnt be rich or lean?

 

The further you depart from a a stock engine, the more important the tune becomes. Yes, the closed loop target of a 14.7:1 A/F ratio is hard coded, and the system is designed to keep the actual A/F ratio there. But when you start to introduce elements that upset the system, and cause false feedback to the PCM, you have to compensate in the tune. A cam, particularly one with higher overlap, becomes a problem. Could be as simple as cam surge, or could be massive split BLM's and running extremely rich at idle/low RPM due to high overlap, reversion, etc.

 

ok ok. some day i hope im you answering the questions. My car just passed emissions but i feel its rich. i was surprised when they said i passed. With my car in idle all you smell is fuel. and i have to polish my exhaust tips often so they are chrome and not black. ill see if i can get the log uploaded. Ive done this before and did it wrong the first time. What type of file is easiest to view for you?

 

.uni is OK

 

ok i got that datamaster run finally. email to send it to or how do you want it

 

i have a hard time reading these even going through that site lol the numbers change so often im not sure exactly what im looking at. ill go through it again myself after you take a look at it

 

Either upload it to an FTP site or e-mail it. If you e-mail it include your screen name and the words data log in the topic.

 

sent. really appreciate it

 

Received. Might take a couple days to look at it. I'm working a 60+ hour 6 day work week (salary of course so no overtime pay) and at my age it's killing me.

 

hey no problem i appreciate you taking the time to look at it. id like to learn a little more and maybe help other people when they need it as well. i go through spurts on the forums. but i need to come around more

 

Geez Fred, you've been doing that for years...never a break?

 

7.3 years to be exact...... At least they gave me a new car to drive this year. I got tired of the F-150 (174K miles) so they gave me an Equinox. Not a bad little car.

That's what happens when you get too old for anyone to hire you, and you haven't saved enough to retire. You have to keep working for whoever will hire you. If it wasn't for the ridiculous hours, it wouldn't be a bad job. But every time I walk through my garage and see the Formula buried under an inch of dust, I get sick.