7mgte AFM issues, please help!
- Thread starter BoostedRunner87
- Start date
Toyota Computer Control System. The proper name for your ECU...the real proper name for which is PCM
Hey 92 nsx. No comeback but I'll be injecting grief into select threads on occasion
If the engine behaves the same with or without the AFM connected, the MIL is on, *and* an AFM code is present the AFM and it's wiring should be tested. Both can be accomplished at the same time by measuring Ks at the ECU. What's so hard about that? Does not the TSRM invoke that very method?
Another point: from an electrical diagnostic standpoint troubleshooting by resistance should be used only in a small number of situations. This isn't one of them. Measure the circuit or component live. In this case measure the frequency and duty cycle of Ks to verify whether the AFM is dead or alive. If it's dead buy another. Simple.
Thanks...I enjoyed that
Hey 92 nsx. No comeback but I'll be injecting grief into select threads on occasion
If the engine behaves the same with or without the AFM connected, the MIL is on, *and* an AFM code is present the AFM and it's wiring should be tested. Both can be accomplished at the same time by measuring Ks at the ECU. What's so hard about that? Does not the TSRM invoke that very method?
Another point: from an electrical diagnostic standpoint troubleshooting by resistance should be used only in a small number of situations. This isn't one of them. Measure the circuit or component live. In this case measure the frequency and duty cycle of Ks to verify whether the AFM is dead or alive. If it's dead buy another. Simple.
89supracrazy;1460713 said:
Thanks...I enjoyed that
jetjock;1460742 said:Toyota Computer Control System. The proper name for your ECU...the real proper name for which is PCM
Hey 92 nsx. No comeback but I'll be injecting grief into select threads on occasion
If the engine behaves the same with or without the AFM connected, the MIL is on, *and* an AFM code is present the AFM and it's wiring should be tested. Both can be accomplished at the same time by measuring Ks at the ECU. What's so hard about that? Does not the TSRM invoke that very method?
Another point: from an electrical diagnostic standpoint troubleshooting by resistance should be used only in a small number of situations. This isn't one of them. Measure the circuit or component live. In this case measure the frequency and duty cycle of Ks to verify whether the AFM is dead or alive. If it's dead buy another. Simple.
Thanks...I enjoyed that
thanks alot for all the info! i am not a wiring genius so it is a little harder for me to understand some of the testing i will need to do at the ecu. when you say to measure it "live" i'm assuming you mean to test it while the vehicle is running. So i need to find the Ks pinout at the ecu and measure the voltage that is coming from that pin? or the voltage going into that pin? what type of readings should i be getting? because when i test it with the key in the "on" position i get 5 volts. I'm sure when it is running then that voltage should fluctuate
pin out of TCCS/ PCM of what they say out of a 87
EDIT: Edit before confusion could set in
of what they say out of a 87EDIT: Edit before confusion could set in
Last edited:
jetjock;1460803 said:^ Not gonna help
so just checked voltage right at the Ks pinout on the ecu. it always stays right at 5 volts whether the vehicle is running or not. should the voltage fluctuate while it is running? oh and the AFM was plugged in during all this testing.
Yes, it should fluctuate. About 19-22 hertz at idle. Your meter will probably only show something like a volt though, referenced to E1 or chassis ground. Again, you should measure the frequency. Your meter does that right?
jetjock;1460816 said:
i believe it does but i will look. yeah i checked THA Vc and Ks right at the ecu and right at the AFM plug. they all measure 5 volts whether the engine is running or just the key is on. I will check into the hertz on my meter and see if they fluctuate at all
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=51
Should be 2-4 volts. 5 with the engine running indicates a steady state signal. Based on the engine running the same with or without it I'd say it's dead. Only way to know for sure is with a decent meter or better yet a scope. No code 31 though huh?
Should be 2-4 volts. 5 with the engine running indicates a steady state signal. Based on the engine running the same with or without it I'd say it's dead. Only way to know for sure is with a decent meter or better yet a scope. No code 31 though huh?
yeah my voltmeter cant check hertz. if the truck just idles it wont throw a code, but when i try to rev it up a few times it will eventually die. When i restart it, it throws code 31 and goes into limp mode.
I see. Unless I'm mistaken this is the first time in the entire thread you've mentioned code 31. No more withholding eh?
That code is defined as no volumetric air flow signal to the ECU for 2 seconds or more with engine speed above 300 rpm. Assuming the AFM is getting 5 volts on Vc and ground on E1 and further assuming the Ks wiring is intact between the AFM connector and ECU the AFM is toast. That's assuming there isn't something non-electrically wrong with it like say, restricted air flow into it or the pressure sensing holes above the vortex pillar are plugged.
As for your meter all but the crappiest ones will do freq and if all you have is a crappy meter how can you work on EFI? Do yourself a favor and buy something better...
That code is defined as no volumetric air flow signal to the ECU for 2 seconds or more with engine speed above 300 rpm. Assuming the AFM is getting 5 volts on Vc and ground on E1 and further assuming the Ks wiring is intact between the AFM connector and ECU the AFM is toast. That's assuming there isn't something non-electrically wrong with it like say, restricted air flow into it or the pressure sensing holes above the vortex pillar are plugged.
As for your meter all but the crappiest ones will do freq and if all you have is a crappy meter how can you work on EFI? Do yourself a favor and buy something better...
jetjock;1460897 said:
well code 31 is for the AFM right? i thought i mentioned that before. anyways yeah i'm getting 31 and 32, but i have already ruled out 32. i know the HAC is not causing this problem. I know all the wiring is good because i have tested it right after the ecu pins and right at the AFM plug and all the readings are the same. i honestly think i have two bad AFMs. but i cant know that for sure until i can plug in a known good one to my engine. the meter i have is a craftsman digital multimeter, it reads volts DC, volts AC and ohms. idk maybe i just dont know how to use it for testing hertz. i have never been in a situation before where i need to do that
You mentioned code 34 in your other post. That and the lack of a 31 combined with your symptoms didn't make sense. The point of all this diagnostic effort was to reconcile that while finding the actual cause so you don't end up replace the wrong stuff. Buy another AFM. As CRE said, you had some bad luck.
As for meters I'm fond of my Fluke 289. Pricey though...
As for meters I'm fond of my Fluke 289. Pricey though...
jetjock;1460930 said:
i'm sorry i confused you with code 34, i must have mis typed. yeah i think i have two bad AFMs. and i would love to have a fluke meter but i just dont use them enough to justify the price
Runner...please keep us posted on the progress of this problem. I am having the EXACT same issues with my 87' 7m-gte that you are having (code 31, it dies when I try to rev., no boost). I am also not getting any power when going up hill, but that my be a separate issue...I won't know until I get this first problem fixed.
BTW, I was also getting code 32 and installing the HAC Sensor took care of that problem.
BTW, I was also getting code 32 and installing the HAC Sensor took care of that problem.
jetjock;1460936 said:I'm easily confused. Ask anyone
New AFM should get you going again. Good luck....
ha ha! i hope a new one will fix it! i'm not ready to spend the money for a new one though
UPDATE: I installed another AFM this weekend and it fixed all of my problems. I have read several other posts about Supra owners going through several used AFM's before finding one that worked...I guess I got lucky in finding a good one right away. It is too bad that such a temperamental device can cause so many problems...it would be great if someone figured out how to fix these things or at least found a 'hack' for supra owners.
supra22;1466015 said:
I'm glad you got it all taken care of! I'm sorry if I contributed to making it all more difficult than it needed to be. EDIT: getting confused here.... Runner, you had any luck with yours?
supra22;1466015 said:
There's always a way around... it just comes at a cost, $$$.
CRE;1466029 said:
uh the only updates i have is this...... its not fixed!! lol i extensively checked for vaccum leaks and found nothing. I also found out that the afm i bought off this forum is one serial number different than the one that was already on my engine. i talked to a guy who has a 2jz and he said the serial numbers off the one i bought match the serial numbers on his 2jz afm. so i think my original afm is fried from me trying to clean it and the one i bought is not working because it is not the right one. A buddy of mine in Oregon found a very nice clean afm off a 7mgte and is sending it my way. I hope it fixes my problems! it should be here friday, i will keep you guys posted.
supra22 i have a question for you..... before you fixed your problem with a new afm, would your ecu always throw an afm code instantly when you started the vehicle? or did it only occasionally do it?