Calc.VET Logging Mistake is Where???

[spedracr93]

I'm clearly not doing something correct...

I feel like the mistake is either in my MAP or in my PID, but I cannot find it.

Here's the issue: When I log, all of the numbers created in both the VE table and in the MAF table are horribly wrong when the car enters PE. The numbers generated when not in PE seem to be legitimate when comparing the WB reading to the directional change.

What's strange is, I wasn't having this issue before, then it just started. My WB seems to be reading correct and outputting correct, so I don't think it's an issue with the inputs.

Any ideas?

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[joecar]

In the first pic, the MAF pid shows airflow diverging after 6375 Hz (correction starts sliding from 1.0 to 0.1), it just doesn't make sense...

so I looked at how the WB BEN pid was being calculated in the calc_pids.txt file...
I saw couple of ambiguities (scantool was using WB AFR instead of Lambda)...
so I corrected these, please use attached calc_pids.txt file.




Also, unrelated, looking at your log, I see bank2 O2 sensor trimming negatively... check for airleak in bank2 exhaust;

[spedracr93]

Thanks, Joe. Your pid file corrected my issue.

Question for O2 Logs... If a fuel trim goes negative, I thought that meant it was rich and positive was lean, therefore typically you would suspect exhaust leaks with positive trims?

[joecar]

Yes, exhaust leaks, intake leaks, and misfires (unburnt oxygen) would cause trims to go excessively positive.

Injector leaks would cause trims to go excessively negative.

[spedracr93]

Ok, Joe. I've got the car up in the air and ready to remove the headers but I'm not convinced I have an exhaust leak. I don't hear a leak, can't see a leak and can't feel a leak.

I'm wondering if you can take a look at the attached log and let me know your thoughts.

Everywhere I've got excessively positive or negative trims (split B1 vs B2) its when the throttle blade is closed. As soon as I open the throttle blade any at all, it drops back to a 0 to 8 level, while when the blades are closed it's a 15 to 25 level. This is occurring while the car is in motion on the freeway in 6th gear, lifting when I get behind traffic, so the engine is not at idle but it is typically in the 1500 to 2000 range.

My engine is a Gen I SBC in an 89 Corvette. I'm running a TPIS miniram for an intake manifold (which is notorious for poor idle air distribution between runners) and I have a relatively healthy cam for a SBC (224/230 @.050, 110 separation, 106 center) which will cause reversion at idle. All traits that make it a bit different from the LS engines.

I'm just wondering if it could be a result of poor idle air distribution for the intake manifold that causes one bank to see such a difference than the other. The O2 sensors don't reflect the trim swings from what I can see, and my wideband is in Bank 2 as well.

I've bought gaskets and I'm ready to tear into it again, but I literally just put this thing together (mileage wise) with new headers, good gaskets and locking bolts which can't back out.
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[statesman]

I'm just wondering if it could be a result of poor idle air distribution for the intake manifold that causes one bank to see such a difference than the other.

I just had a look at the log from your original post and I don't think that poor air distribution in the intake manifold would cause such a massive bank to bank imbalance. It's either an air leak or an injector issue. You just have to figure out if bank 1 is too lean or if bank 2 is too rich.

Joecar has already summed it up nicely....


Yes, exhaust leaks, intake leaks, and misfires (unburnt oxygen) would cause trims to go excessively positive.

Injector leaks would cause trims to go excessively negative.

But hey, he's just a moderator... what would he know? :laugh:

[spedracr93]

I just had a look at the log from your original post and I don't think that poor air distribution in the intake manifold would cause such a massive bank to bank imbalance. It's either an air leak or an injector issue. You just have to figure out if bank 1 is too lean or if bank 2 is too rich.

Joecar has already summed it up nicely....

But hey, he's just a moderator... what would he know? :laugh:

Ya, I get it, I'm just trying to figure out what makes the most sense instead of arbitrarily replacing stuff. In my mind, an O2 sensor that was reading unburnt oxygen due to an air leak should always be reading that unburnt oxygen, not just in certain situations or parameters.

I also wouldn't be asking his opinion further on the matter if I didn't respect what his thoughts were. I can very easily replace exhaust and intake gaskets, start logging again and have the same issues, so I'm just trying to work through all of the possibilities.

How about injector o-rings? I'm running LS7 injectors with ICT Billet spacers and it was a real pain getting the o-rings to seat. I don't have any fuel leaks, but wondering if I've got an air leak there.

[joecar]

...
But hey, he's just a moderator... what would he know? :laugh:lol, and not a good one at that, lol :chair:

[joecar]

...

How about injector o-rings? I'm running LS7 injectors with ICT Billet spacers and it was a real pain getting the o-rings to seat. I don't have any fuel leaks, but wondering if I've got an air leak there.
Yes, this would be leaks at the intake manifold.

[joecar]

Also check for misfire counts.

Do you have catalysts...?

[statesman]

lol, and not a good one at that, lol :chair:

Don't sell yourself short.... you're one of the best moderators we've got. :cheers:

[statesman]

Ya, I get it, I'm just trying to figure out what makes the most sense instead of arbitrarily replacing stuff.

Let me help you with that one. What makes the most sense is to do some 'tests'. I would only recommend randomly replacing stuff if you exhaust all your testing options and still can't track down the problem... randomly replacing bits is the absolute last resort.

Test for exhaust leaks by partially blocking the tailpipe (being mindful to create the restriction safely and securely, so whatever you're using to partially block the exhaust doesn't get shot out the pipe like a cannonball). Don't seal up the tailpipe completely, just enough to restrict the exhaust flow and allow some pressure to build up in the exhaust system... this will help you find even the smallest pinhole.

Test for intake leaks by smoking the intake. You can take the vehicle to a workshop which has a smoke machine and have them smoke the intake for you... or if you're on a tight budget, you can smoke the intake yourself by purchasing a cheap cigar and filling the intake with smoke that you've made yourself.

Test for leaking injectors by swapping the injectors bank to bank and do another log.... see if the rich bank stays the same or follows the injectors.

When you do logs... make sure you log for misfires. Oxygen in the exhaust from a misfire will make the O2 sensor read lean. Sometimes misfires don't occur all the time, only under certain conditions... so don't rule out misfires until you've logged for it.