code 31 and running rich

[supraman508]

There's no way for the ECU to fry an AFM. The ampacity simply isn't there because the current to it is limited inside the ECU. I'm guessing your AFM(s) were already worn. Read used. Not the best way to go when dealing with a vane unit. That said autopsies might have been helpful....many mysteries can be solved by learning the manner in which something failed.

amen herd that before:icon_bigg

 

[grimreaper]

good news time to check this ones hz then.

i feel like i need to stock pile afm's 20 years old these things arent the greatest out of a junk yard then.... maftpro- or new afm....hmmm

now that said, i feel they are gona be plug and play if im buying used. ive read how jj says to bench test them, might need to rigg up a vacuum and funnel with a 12 volt source to bring with me with me to a junk yard.....

 

[jetjock]

Oops sorry, since we're in the N/A section I though you were using the vane type. Barring contamination the Karmans should pretty much last forever. Mine is 21 years old and works like the day it was new.

You might want to check Vc to be sure it's not gone high. That's reaching though. Could be just a case of bad luck. Also check the pressure sensing hole on the ones you have isn't crapped up. Sure the harness connector is OK?

Lol at the vacuum and funnel thing. Been a while since I've done that. These days I use a muffin fan. Maybe a Dustbuster would be better for the junk yard

 

[grimreaper]

VC is in the 156k range in resistance. whats high? i have the bible (shop manual) but it shows nothing what so ever on how to test the actual karman signal, only how to test the temp sensor....
edit: found the basic test at the ecu harness end with it plugged into the ecu. is there some chart on what a healthy afm should read at idle and with higher revs? i know its the ks to e1 i need to look at, but cant find any thing saying what values it SHOULD be putting out.

and for the harness, i just tested continuity from the ecu connector to the plug on the afm side. searching for a better way to determine if maybe i have a wire going bad some where, but not totally shot. ill check the voltage at each end to see if there is a drop unless you have a better solution

 

[CRE]

EDIT:
D'oh! Missed the discovery that you are running a GTE.... Well, I'll leave this info for future reference.

EDIT2: Supraman508 read this, it does pertain to you. Your cap isn't the problem. Fix the cause of the code first, then worry about the little stuff. JJ may be a grump but he got that way from so many people refusing to listen. He's most likely the most knowledgeable person on this forum.


Karman? That's only on GTE's. You'll be testing VS. VC isn't something you want to test the resistance of either. With the ignition on you should read around 4.8v on the VC pin at the AFM harness connector.

VS will vary depending on airflow. I don't know what voltage you should expect to see at idle, probably around 3.5v as the RPM increases you'll see it decrease and it should decrease steadily. I'm not at sea level, so the values I see would be different than yours. (at 4500RPM I see ~.75v, at 750RPM I see about 3.5v)

Testing the resistance of the AFM is good to see if you've got flat spots or shorts, beyond that you should try to always look at the signal that's coming out at VS in VDC.

Use E2 as your ground point when testing voltages for the ECU or attached sensors.

 

[jetjock]

I deny grump. Most knowledgeable is open to argument. Both are little more than vicious rumors perpetrated by my enemies

Reaper: I meant to check Vc's voltage but as I said that's grasping.

The TRSM has resistance tests, which are fairly worthless, and what Ks voltage will typically be when operating. Since the duty cycle remains near 50% (mine runs at 2.6 vdc) that spec is laughable. You really need to measure frequency and preferably look at the waveform to know the AFM's health for sure and it should be done at the ECU connector.

The TCCS books say 17-22 hz at idle, 42-46 at 2000 rpm and 90-95 at 4000. It's going to vary from engine to engine and whether the car is parked or under load, which AFM housing is on it, tune, ect. Mine (a Lex) outputs 18 hz at idle, 38 at 1500, 50 at 2000, 62 at 2500, 80 at 3000 and 92 hz at 3500 rpm. That's parked with the EFI system tuned. Your engine is not my engine but that'll give a sense of what to look for.

If you decide to measure it off the car the formula for Karman street generators is F = .2 X V/D, where F is frequency, .2 is a constant, V is velocity and D is pillar diameter. You'll need something to measure velocity. All that said I doubt a shifted AFM is your problem unless the laminar flow screen is damaged or the sensing hole plugged. Usually the electronics die outright or are murdered.

 

[grimreaper]

jj i have a word doc of a few of your old posts to others (dating back to 2005 or so haha) that i followed earlier. FINALLY read the hz and got .018khz or 18hz at idle warmed up at 650rpms. PERFECT as it seems. wish i had a scope to learn further and to tinker with but at this time i dont. how ever i have fixed the issue so far with about 50+ miles on it today and not a hiccup. voltages read clear across the wires form one end to the other and all test out perfectly at the afm connector as the tsrm describes it should. After pulling the afm connetor apart completly and cleaning it to like new levels it seems to have been my issue. didnt appear to be the connector as it wasnt THAT dirty, but ive been told and read that those circuits have to be in top notch shape to read accuratly.

bout crapped my self when i finally tested the hz and saw accurate and within spec readings lol i was sooo ready to toss in another afm but hated the idea of swapping parts with out testing like so many shops near me seem to do.

its never idled this smooth and consitantly since ive owned it and the performance is on a total different level for part throttle driving and transition into boost. i think i finally nicked this one in the butt (knock on wood).

TEST TEST TEST, my lesson from this, saved me another trip to the junk yard and possibly more $$$

thanks guys!

 

[jetjock]

Shops swapping parts. Ugh. At least when people do it themselves they aren't being charged. Anyway, you done good

 

[CRE]

I deny grump.

Oh, sorry... I was talking about that um... other guy.

Both are little more than vicious rumors perpetrated by my enemies

Well, that's good. With such a short list it shouldn't take long to track down the mouthy bastard responsible. :icon_razz




J/K, JJ. And I stand by most knowledgeable. At least with regard to the stock system, but typically still the better bet for good info even regarding after market additions.




Ok, so, now that the GTE is fixed is there any chance we could get those posts move to the correct section to help prevent confusion?

 

[supraman508]

EDIT:
D'oh! Missed the discovery that you are running a GTE.... Well, I'll leave this info for future reference.

EDIT2: Supraman508 read this, it does pertain to you. Your cap isn't the problem. Fix the cause of the code first, then worry about the little stuff. JJ may be a grump but he got that way from so many people refusing to listen. He's most likely the most knowledgeable person on this forum.


Karman? That's only on GTE's. You'll be testing VS. VC isn't something you want to test the resistance of either. With the ignition on you should read around 4.8v on the VC pin at the AFM harness connector.

VS will vary depending on airflow. I don't know what voltage you should expect to see at idle, probably around 3.5v as the RPM increases you'll see it decrease and it should decrease steadily. I'm not at sea level, so the values I see would be different than yours. (at 4500RPM I see ~.75v, at 750RPM I see about 3.5v)

Testing the resistance of the AFM is good to see if you've got flat spots or shorts, beyond that you should try to always look at the signal that's coming out at VS in VDC.

Use E2 as your ground point when testing voltages for the ECU or attached sensors.

will do