Analyzing log files

[Rich Z]

From swintangs comments and your replies:

1. did you select the pids LONGFT1/2...? did you place these on a chart...?

Yes, as best I can tell. I went though all of my logs and looked at the PIDS, DATA, and dashpages, and they are there.

2. that O2 wiring is not acceptable.

You don't know a tenth of what my car went through. Well, maybe you do if you have looked over that thread I pointed you to.

5. use the units kPa (scantool: PIDs tab, on MAP do rightclick->Metric; tunetool: Edit->Configure Display Units, look at B0101).

I'll be honest, I really don't remember how I may have set this up or changed it. kPa just doesn't compute quite yet with my old SAE brain.

7. for electronic throttle, look at the pid GM.ETCTP.

I'm using Absolute Throttle Position (%) as far as I can tell. SHOULD throttle position be ZERO when my foot is off of the gas pedal?

When selecting pids, make sure the pid channel count is no greater than 24.

It looks like I have 22 PIDS selected in my log files.

I'm on the Mac so I can't view the log files right now, I'll view them later tonite.

Going to be a few days before I will have my car back on the street again. I'm putting in PTFE fuel lines and replacing those stinking rubber lined ss braided lines that were put on my car. Those rubber lines seep gasoline through them like it's no body's business. You can actually see the gasoline stains with UV light.

Thanks for your help.

[Rich Z]

Quick question, are the front and rear O2s the same on your year Vette? I know on both of my TrailBlazers the front and rear O2s are different part numbers...

And yes, that wiring is a hack job. I would be embarrassed if I did anything like that for a customer (or myself), good call not going back to that shop.

They would have to have different part numbers, since the harness ends are different. The front O2s have a 4 wire flat connector, and the rear O2s have a 4 wire square connector, if I remember correctly. I forget who it was that suggested that I use the rear O2s as the fronts with an adapter. I've gotten a lot of advice from a lot of people once I had to do my own wrenching on my car. If I need to actually put FRONT O2s in place, this would be a great time to do that. I have my exhaust off of the car and the tunnel plate removed so I can get to the funky fuel lines to replace them.

Yeah, my car was in two shops for two and a half years, and I honestly can't see which shop screwed me over the worst. I must be extremely gullible, I guess. That really put a hurting on the finances for what was supposed to be a retirement spent doing fun stuff. Amazingly enough my wife has been behind me the entire way. I was ready to just give up MANY times and just part the car out.

So heck, I've been crash coursing my way through learning the mechanics of this Corvette, so it stands to reason that I might as well learn the tuning while I am at it.

[ScarabEpic22]

IMHO, Id get front O2s then buy some O2 extensions that are plug n play. That way you KNOW they're the right sensors and the wiring is done right.

Something like this: http://www.casperselectronics.com/st...oducts_id=1161 $26 and Caspers has them in lots of different lengths and square or flat connectors. Interesting about your wiring, I thought the fronts were usually square with the rears being flat. Then again, my TBSS uses square fronts and rears so who knows how GM determines it.

[Blacky]

I'm using Absolute Throttle Position (%) as far as I can tell. SHOULD throttle position be ZERO when my foot is off of the gas pedal?

The corvette, with its ETC (electronic throttle controller), holds the throttle blade open to control idle air flow. So even when there is no pedal input the throttle blade will be slightly open to allow enough air to enter the engine to keep it idling.
For vehicles with a cable throttle, the throttle body usually has a bypass called the IAC (Idle Air Control) which the PCM uses to control the idle air flow while the throttle blade is shut.

Regards
Paul

[Rich Z]

IMHO, Id get front O2s then buy some O2 extensions that are plug n play. That way you KNOW they're the right sensors and the wiring is done right.

Something like this: http://www.casperselectronics.com/st...oducts_id=1161 $26 and Caspers has them in lots of different lengths and square or flat connectors. Interesting about your wiring, I thought the fronts were usually square with the rears being flat. Then again, my TBSS uses square fronts and rears so who knows how GM determines it.

Actually I wasn't clear on the wiring problem. If there is a problem with the wiring, it will be on the PCM side of the connectors. Quite honestly, I don't know where exactly those cut wires went to that I saw in the harness. Now that I am thinking about it, those wires MAY have been for the alarm buzzer for the STS scavenge pump, as I have not yet found that little bugger. As it is, I had to buy a new after-run timer and re-wire that into my system. The wiring for the STS turbo scavenge pump was COMPLETELY wrong.

The photo earlier in this thread of those butchered O2 sensors shows that the fronts have the flat connectors. What the guy did was to splice extension wire into the O2 harnesses (which is a NO-NO according to GM) instead of putting the extensions on the end of the existing harness. And according to him, that's how he does ALL of his O2 modifications when he installs headers for customers.

As for operationally, I really don't know if there is any difference in the signals coming from the front or rear O2 sensors themselves. Wouldn't be the first time I was given bum advice, though.

[Rich Z]

The corvette, with its ETC (electronic throttle controller), holds the throttle blade open to control idle air flow. So even when there is no pedal input the throttle blade will be slightly open to allow enough air to enter the engine to keep it idling.
For vehicles with a cable throttle, the throttle body usually has a bypass called the IAC (Idle Air Control) which the PCM uses to control the idle air flow while the throttle blade is shut.

Regards
Paul

Ah, I see. That's why it is called the "absolute" throttle position, rather than the "relative" throttle position. That makes sense.

[ScarabEpic22]

Actually I wasn't clear on the wiring problem. If there is a problem with the wiring, it will be on the PCM side of the connectors. Quite honestly, I don't know where exactly those cut wires went to that I saw in the harness. Now that I am thinking about it, those wires MAY have been for the alarm buzzer for the STS scavenge pump, as I have not yet found that little bugger. As it is, I had to buy a new after-run timer and re-wire that into my system. The wiring for the STS turbo scavenge pump was COMPLETELY wrong.

The photo earlier in this thread of those butchered O2 sensors shows that the fronts have the flat connectors. What the guy did was to splice extension wire into the O2 harnesses (which is a NO-NO according to GM) instead of putting the extensions on the end of the existing harness. And according to him, that's how he does ALL of his O2 modifications when he installs headers for customers.

As for operationally, I really don't know if there is any difference in the signals coming from the front or rear O2 sensors themselves. Wouldn't be the first time I was given bum advice, though.

Ah I see, Ive been looking at possible header O2 extensions and GM states do not splice wires so I was going to buy an extension. I was only referring to any butchered wiring for the O2s, I didnt know you had other wiring problems (joy).

I have no idea if the signals from the front/rear sensors are different either.

[Mr. P.]

OK trying to help here:

The O2 sensor debacle - there is a big difference between front and rear O2 sensors, they ARE NOT interchangeable, even if you pull a Tim Tooltime Taylor and "rewire" them. If you are NOT running the PCM in strictly speed-density mode, then the O2s are a critical component. I agree with Scarab, the RIGHT thing to do is to get O2 extension harnesses, they're like $20 each (in my truck, I only needed one!). As you stated earlier, one never hacks-up the main harness of the car; what a bunch of gorillaz...

kPa - yes I know in the old days we measured manifold vacuum in SAE, but take it from me it's mentally easier to think in terms of kPa; 0 kPa is a perfect vacuum, 100kPa is "wide open" aka 0-inches of manifold vacuum, anything over 100 kPa is "boost". Since each 100kPa is "an atmosphere" then 200 kPa is saying you are at 15-lbs of boost. The reason to switch to kPa is because the PCM itself thinks in kPa!

Injector Duty Cycle - I looked at the logs, those INJ DC figures look just fine.

"At low RPMs driving down my dirt road the spark advance looks like a saw blade." - yeah this is "normal", I already have an active post on this topic, the spark is being manipulated when the vehicle is either coasting or standing still; it's totally ok because it's not costing you power or MPG (the spark lines right out under power) but looks erratic. I personally think that it has something to do with the "stall saver logic" in the PCM; it has nothing to do with your cam or heads or tune etc, my bone stock truck does it too, it's a "feature" of the PCM.

"The car does often surge while driving at under 10 mph." - then it's not tuned right. Period, end of story. The sucky part is, idle/low-speed tuning is the *last* thing you dial-in, one of the most difficult to get right, and one of the easiest to make harder on yourself when aftermarket injectors and intake plumbing is concerned.

CALC.POWER_RW - yeah the formula for that PID is not accurate IMO.

- Steve.

[Mr. P.]

What operating system is in the car's PCM?

Is the PCM tune in speed-density mode? If you are making over 8-psi boost I SERIOUSLY suggest you consider it.

I would make sure you are using an EFILive custom operating system (maybe COS-3?).

If the turbos are large enough, the MAF may be useless! Meaning you should just ditch it and go speed-density COS3 anyways!

I looked at your log - your tune is assuming that the stoich for fuel is 14.63:1; that was true 10-years ago, with E10 fuels now (in all 50-states) this needs to be changed to 14.17:1 or else you're gonna run WAY LEAN under EWP.

When Logging, I would ditch the PIDS for injector duty cycle & injector pulse width for Bank-2; it's redundant unless you are troubleshooting a specific fueling discrepancy between the left & right side of the motor. I don't think you need to monitor FUELSYS-B either.

DON'T DESPAIR - from what I read you are making progress now and are closer than you think!!

- Steve.

[Rich Z]

I have a 2 bar MAP sensor and I believe my tuner did a 2 bar map tune, as nearly everyone recommended what they were calling a "2 bar MAP speed density tune". I could attach the original tune for you to look at if you wouldn't mind reviewing it to tell me what you think. The tuner did send me a later tune, that I think he re-enabled the O2 sensors with. But heck, I'm not sure. I still don't know what to look for to be able to determine such things.

So stoich should be 14.17:1? I did a log using my newly installed wideband and during cruising it appeared that the actual AFR was sine waving around the commanded AFR rather nicely. I thought that was a good sign. :(

Yeah, I think the mechanical stuff is pretty much straightened away now. The only thing that is left that I haven't torn apart, fixed, changed, or puzzled over in aggravation is the internals of the engine itself. So I'm HOPING that is OK.

As for the tuning, heck the tuner did me a world of good just showing me that my car COULD be tuned. And he has invited me to bring the car up to his shop so he could do a REAL tune on the dyno and get things all up to snuff. So it's not at all like he just did a quick and dirty tune to grab the money and run. I'm thinking I should take this opportunity to learn EFILive and tuning. After I would have the car tuned to perfection (if there really is such a thing), I would lose much of the incentive to dive into this myself. When I get to the point where I need a dyno, then that would likely be the time to drive the car up to him (he's about 5 hours away). Plus, to be honest, I just don't TRUST the car yet to drive that far with it.

Oh yeah, I just read back over your earlier post. So my using the rear O2 sensors in place of the fronts is a no-no? If that is the case, NOW sure would be the time for me to do that while I've got the car torn down with the exhaust out, and fuel lines disconnected. But what symptoms would I be seeing to support the case that they ARE wrong? Not disputing what you are telling me, just trying to understand the "what" and "why" of all this.

Thanks..