Cal Smog test after Cleaning MAF

[Brad Roberts]

I thought I'll cover my bet

My redneck version is: Bubba, Hold my beer, watch this..

If you *think* you have a problem, have them pre-test the car. Don't touch it



B

[sb01box]

Originally Posted by Brad Roberts

My redneck version is: Bubba, Hold my beer, watch this..

If you *think* you have a problem, have them pre-test the car. Don't touch it



B

have had p1128 and p1130 CEL come up from time to time during the 60K miles that I've put on this car. cleaning the MAF did the trick twice over from 2006 to now.
the smog tech did a pre-check and the smog machine reported that the car was not ready.
I'll be going back to the same technician for another pre-check. and this time, I'll write down the non-ready parameters (if .any pending)

[Brad Roberts]

Cool. I **believe** there is a way to clear the readiness codes without driving it around. I'll have to ping one of my factory trained tech guy's and let you know.

I feel like a smog expert after having our conversion cars to pass smog with flying colors



B

[sb01box]

just an update. put on 300 miles of "driving" and multiple run of the "BMW Driving Cycle". only the evaporator is not ready. I have till end of April to get the car smogged.

[sb01box]

while trying to get the EVA indicator into ready state, my car poped pending P1128 code. The pending code came up at the same time that I pressed the air conditioning button to turn it on. The idle hesitated a little (dropped) and then came back up to 700 rpm.
as I stated in previous thread, my car has had CEL for P1128 and P1130 twice or three times during the past 5 years. both time, cleaning the MAF did the trick. but recollecting the event, it has always been after getting off the fwy and while at stop and idling. (at the same intersection)
getting back to current event, further driving resulted in CEL with both P1128 and P1130 during the last BMW driving cycle (coast to stop, sitting for 5 minutes)
enough of my car's history.
I'm trying to find a simple conclusion on a complex problem.
After reading many thread on P1128 and P1130 condition, the majority of threads appear to point to a mechanism common to both banks of the engine. And if the CEL lights up while at idle, it's likely cause would be maf, intake leak between the maf and the throttle body or the AOS.

Qustion-1: If the AOS is the cause, wouldn't the car be smoking at high RPM or consistently smoke during start up and the idle speed would wander?

Question-2: my OBD scanner reports air flow as 0.46 to 0.55 lb/min. [[ another thread stated that his 3.2 L reports 4 to 5 gm/sec which is normal. When i do the conversion and scale for 2.7L, 0.46 to 0.55 lbs/min is the same as 4 to 5 gm/sec on the 3.2L engine.]] this value was deemed to be normal. is the volumetric efficiency of the boxster engine about 25% to 30% at idle.
back of the envelope calculation for 2.7L at 700RPM, it should be sucking 945 liters(0.945 cubic meter) per minute, air at 1.1kg per meter^3, the MAF should be reporting 17gm/sec? (did not take into account volumetric efficiency with the throttle closed)
what is the expected typical reading off the MAF as it is reported by generic OBD reader?

update 25 mar.
the combination codes became more frequent. also got P0430 during fwy driving.
replaced maf. it did the trick. now my car is ready for smog.

as for my car's behavior, the P1128/30 combination was set when the car hiccuped at idle. I was also able to set it once by turning on the AC at idle.