Failing AFM symptoms

[gtsfirefighter]

My searches have not revealed what I'd like to know specifically.

When the air flow meter begins to fail, what are the most common symptoms associated with that? My application is a Lex AFM with 550/mod and SAFC II.

Thanks
Ken

 

[hvyman]

What are your symptoms?

 

[gtsfirefighter]

Wideband all over the place but runs mostly very rich at 10-11. Idle surging or idling a little high around 1k rpms. No vacuum leaks to be found.

 

[jetjock]

The load signal is one of two (other is speed) that are critical Ken. Can cause all sorts of drive-ability and mixture problems. Look for a code 31.

 

[gtsfirefighter]

Code 43 only. That's because of a "fix" I have with a relay so I don't have to worry about the car not starting sometimes. I might take the electronics off my Lexus SC400 and swap 'em out to pinpoint or rule out it even being the afm.

 

[JStoked]

Look for a lose ground. I had the same prob and I had bad ground to my safc.

 

[jonahs_supra]

Look for a lose ground. I had the same prob and I had bad ground to my safc.

yup same here. had dirty grounds on intake manifold

 

[RazoE]

Definite sympton is running like crap and dying when the gas is pressed.

 

[gtsfirefighter]

Definite sympton is running like crap and dying when the gas is pressed.

Well mine idles a little rough and sometimes surges. When I press the gas it takes off and never chokes at any rpm. It'll still shit and get but it's just pouring gas out the exhaust. I be worried for anybody smoking a cig when I pass by. I'll check into the grounds.

 

[gtsfirefighter]

I swapped the electronics from my sc400 afm to my supra and there was no change so I can rule that out. All my grounds looked ok. This problem appears to be above my pay grade. I'll keep yall advised of my findings in case someone else has a similar problem.

 

[gtsfirefighter]

Ok folks. I'm pretty sure I found the problem and it's the Tial BOV. Another symptom my car has had since I bought it is that is frequently stumbles or dies when you suddenly left off the gas. Well the current BOV I have vents to atmosphere. Also my wastegate has a 13lb spring in it and I've notice recently that at full throttle it's only boosting up to about 10-11 lbs. I disconnected the vacuum line from the bov and plugged it and the car idled better and didn't stumble at all when I would goose the butterly on the throttle body (of course I did not drive it with the bov disconnected). Aaaaand after researching a little I found this little tidbit of information in a ad for a Tial recirculating bov.

Many factory turbo setups feed blow off valve discharge air back into the intake after the air flow meter. The factory air flow meter is expecting this air to be there, and sends a signal to the ecu to provide enough fuel from the injectors to provide for it. If you upgrade to a non-recirculating blow off valve that dumps to the atmostphere, the discharge air is no longer feeding back into the intake after the air flow meter. This creates a problem because the ecu, and air flow meter do not know that this air is no longer making it back into the system, but its still assuming it is, so it continues to provide more fuel for the air its not actually getting. This creates a "rich" condition where the air fuel ratio gets unbalanced by having too much fuel and not enough air during "off throttle" conditions like shifting or decelerating. This can cause the car to stall, sputter, and decrease drivabilty in general. Even worse, it can cause spark plugs to become fouled, ruining them.

So a Christmas present to myself will be a new recirculating BOV. Tial offers them and I will look there so I can just unbolt my current one and slap a new one on the same flange. I'll update once that's done. Could be after the new year. My childrens presents will come first of course. :icon_bigg

 

[Zrain25]

My car would stall when I would go above 2500 rpms and let off the gas and it would die because of my bov was vent to atmosphere

 

[gtsfirefighter]

Just to clear up what the problem was it was the BOV. I've since put a recirculating BOV on and it's running much better and not stalling out and running too rich. I hope this thread helps someone else.