emissions testing coming up - system readiness test

I'm running a 411 ecm in my 98 Chevy truck and am currently running COS1 speed density using EFILive. When I look up my OBDII information, system readiness tests are not ready due to the O2 tests not being completed. Have you guys looked to see how long it takes for these O2 tests to be completed? I have driven the truck for at least a couple of days since my last reflash and it still doesn't show ready. I have three DTCs right now pertaining to MAF, EGR, and EVAP systems which are all currently disconnected, but in my DTC parameters, I have all set to "non emissions" so they shouldn't affect the OBDII tests, should they? Any insight on this is appreciated, since I have to get this thing ready for my smog check soon. Specifically I'm wondering how long the O2 tests usually take to finalize...

Max

Allright, I'm about at my wits end here. I reloaded my normal .tun file (was previously using COS 1) to see if I can just get my OBDII stuff squared away with no DTCs or MILs. I started out with all the Engine DTC Processing Enablers unchanged. I got codes for:

P0300 "Engine Misfire Detected"
P0443 "Evaporative Emission (EVAP) Purge Solenoid Control Circuit"
P1637 "Generator 2 L-Terminal Circuit"
P1638 "Generator F-Terminal Circuit"

I switched all to Not Reported and reloaded the calibration...no new DTCs but I'm getting a flashing MIL light, but I get it only at idle and no DTCs while this is happening. If I raise the engine speed, the MIL disappears.

I encountered this problem earlier when using the stock OS using the MAF. I kept getting misfire codes at idle which would trip the P0300 DTC and MIL. When running SD either just with the MAF disconnected and the appropriate changes made to run MAFless, or doing so using COS1 SD...I don't have the misfire problem.

Not to get too focused on the misfire thing, but what the heck is causing this MIL that I can't see? It seems alot like the misfire MIL, but I changed that to Not Reported so it can't be that right?

Please help :master:

Max

Ok...I think I got this figured out but would still like to understand this better.

I increased {C5606} Misfire Detection Min RPM to 2000 so that the misfires are not being detected at idle. I still am not sure though why if I change the DTC processing enabler for P0300 to Not Reported, why I still get a MIL. There are other DTCs that would be tripped that I changed to Not Reported, and did not have to change to No MIL. Is there a simple explanation to this that I'm just overlooking (NOOBIE).

Thanks.

Max

I would expect a flashing MIL with the stock detection sensitivity. The flashing MIL doesn't indicate the same thing as a steady MIL (which indicates a stored DTC.) It just indicates that there's a suspected misfire. I suspect it would get the attention of an inspector in any case as it does indicate an emission related anomoly. You did what I would have done. No more MIL, blinking or steady, and no stored DTC, right?

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Originally Posted by ToplessTexan

I would expect a flashing MIL with the stock detection sensitivity. The flashing MIL doesn't indicate the same thing as a steady MIL (which indicates a stored DTC.) It just indicates that there's a suspected misfire. I suspect it would get the attention of an inspector in any case as it does indicate an emission related anomoly. You did what I would have done. No more MIL, blinking or steady, and no stored DTC, right?

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Correct, no more MIL at this point. Raising the misfire detection rpm took care of that. I am interested in why this happens to begin with when using the MAF and doesn't occur when MAFless. Thanks for the insight on the flashing MIL, wasn't aware of that. :cheers:

Max

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Originally Posted by 350SS

I am interested in why this happens to begin with when using the MAF and doesn't occur when MAFless.

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Any chance your MAFless tune also had reduced knock sensitivity at low RPM? I know w/ or w/o the MAF may be the most obvious difference between the two configurations, but it's not the only one. Would be interesting to know if maybe you are running a bit leaner (or richer?) at idle w/ the MAF.

My understanding is that the only sensors involved in the misfire diagnosis are the knock sensors and the cam and crank position sensors. Anything that induced a change in the rotational behavior of the crank between the two configurations could be a source of your issue. Differences in fuel delivery or spark timing would be my likely suspects. Kind of an academic exercise at this point, but have you thought about or measured how your tunes are different with respect to these?

BTW, can't you have like up to two readiness tests in a not ready state and still be "inspectable"? The DTCs are bad, but you should be able to skate through with one or two not ready (depending on the age of the vehicle). I don't think my catalyst test has ever been ready.

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...no new DTCs but I'm getting a flashing MIL light, but I get it only at idle and no DTCs while this is happening. If I raise the engine speed, the MIL disappears.

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You will get the flashing MIL whenever the catalytic converter is in a damaging condition. Your misfire tables are too low and picking up on misfires. Check C5621 thru C5627 for areas that are in the green. Bump them up and see how she does.
AL