Bad AFM electronics or something else?

[suprafanatic]

So I was sitting at a stop light, when the light turned green and I went to accelerate and the car instantly died and the check engine light came on. Tried to start the car again and it fired up, but then died again when I touched the gas. Ended up pushing the car off the road. Popped the hood to look around and I couldn't see anything wrong. I kept trying to start the car but it would only fire once or twice then die. Finally, I got the car to stay running and limped the car back home. I had to touch the gas very gently and drive slow. If I pushed on the gas to accelerate normally the car's RPM's would immediately drop and the car lost all power and would die unless I let off the gas fast.

I checked codes and I got code 31 and 34. I'm guessing code 34 is from hitting fuel cut a few times, but 31 is for an AFM problem. The car will idle fine now, but if I try to rev it while parked the RPM's seem to only go to about 2k then drop then bounce back up and so forth while I'm holding the gas. Seems like every once in a while when I was revving it it would go above 2k, but not very often. I unplugged the AFM while the car was idling so see if it would have any affect on the car, and the car wasn't affected at all by me unplugging the AFM. I then went to rev it up while it was still unplugged and the car was running the exact same. So would this mean my AFM electronics are bad and not doing anything for the car? I looked over the Connection and couldn't visibly see anything wrong with the wires or plug.

 

[jetjock]

AFM condition aside (it should be actively measured) the engine should rev to 3K with the AFM unplugged. That it does not indicates multiple problems. No surprise there.

 

[suprafanatic]

I forgot to add, I also checked for any loose intercooler pipes or rips for a boost leak but found nothing wrong with the IC piping.

 

[suprafanatic]

Well to make you happy I test the AFM with a Ohmmeter following this link:

http://www.supracentral.com/foundation/files/6613/3056/3821/FI_096.gif

I had the AFM at 68 degrees so it should have read between 2,000-3,000 on the Ohmmeter. However, every time I tested it I would get a reading between 975 and 1921 So I'm going to say my AFM is shot.

 

[jetjock]

Not gonna make me happy. Not even close. I said actively. And I meant measure the AFM. You might want to stop anal-izing everything and actually learn how the car works...

 

[suprafanatic]

Im trying to, but your posts aren't helping me learn or figure out exactly what to do. You keep telling me everything I do is wrong but you don't help me to do the right things. What exactly do you mean measure the AFM? Can you be more specific, That can be taking in several different ways. If anyone else has any ideas please help. Thanks.

 

[jetjock]

Measure the AFM means exactly that. Why would a bad trim signal cause the symptoms you're seeing? Have you read the TSRM? Do you even understand EFI basics? It appears you do not.

 

[suprafanatic]

Once again not a helpful post. I assumed it meant measuring the Ohm's as it says to do in the TSRM, I don't know how else to measure the electronics. I did read the TSRM it says replace the AFM electronics if the Ohm's are not within proper range. This would be why I assumed it would cause my problems because I threw a code 31 which says the test the AFM, which I did. So one would assume that means the AFM is bad. At least I did. If you don't think the AFM is my problem can you atleast help me figure out what else could cause this problem??? I made this thread to get help, not to get ripped on about my ignorance. Clearly there are things I don't know or can't figure out, other wise I would not have made this thread.

 

[MightyAl]

I believe that I understand efi quite well and I am unsure what you are getting at. How can you measure the afm without a scope since it uses a frequency signal?

OP: all the ohm's tell you is whether or not the temp sensor in the AFM is working properly otherwise you would need a scope to measure the response.

Or I could be wrong but I ain't proud.

Jetjock: I am confused by your overtly aggressive response. If a code 31 is popping up apparently there is something wrong with either the AFM or ECU. How else would you approach the problem?

 

[Turbo Habanero]

Jetjock: I am confused by your overtly aggressive response. If a code 31 is popping up apparently there is something wrong with either the AFM or ECU. How else would you approach the problem?

They have a weird Father son type of relationship Lol..





On the other note SupraFanatic AFM seem to be everywhere these days i would swap yours out and see if it fixes the problem if not then look elsewhere Can't be more simple then that.

And don't feel so bad because i don't understand everything some of the Seniority guys tell me either but only one way to learn my friend.

 

[suprafanatic]

Well even if I got a new AFM and it fixed my problem he would say it didn't fix my problem. Just like with other problems I've fixed, but whatever. Anyway, if measuring the Ohm's on the AFM doesn't tell you much or really matter at all then why would the TSRM say to replace the AFM if the Ohm's aren't within spec? You seemed to be preaching about the TSRM, So do I go by what the TSRM says or not? Because clearly the Ohm's on mine are not within spec, and I also happen to have a problem and a code being thrown for the AFM... Coincidence?? Also you need to listen to the codes that your car is throwing. So If my car is throwing a code 31, telling me something is wrong with the AFM. I then go to the TSRM, it says check Ohm's. So should I just totally ignore my car and the TSRM on this one? And I plan on getting another AFM, its just going to take a while to source one. No one around me owns a supra.

 

[jetjock]

I believe that I understand efi quite well and I am unsure what you are getting at. How can you measure the afm without a scope since it uses a frequency signal?....I am confused by your overtly aggressive response. If a code 31 is popping up apparently there is something wrong with either the AFM or ECU. How else would you approach the problem?

While a scope is nice the freq function on any decent meter is plenty adequate. Regardless, one needs to measure the load signal, something he isn't doing. In other words he isn't measuring the AFM. Nor would a trim signal (what he is measuring) cause his symptom or code.

I've tried to help the guy even though he's basically clueless. I don't hold that against him though. The real problem is he's clueless he's clueless yet it's the furthest thing from his mind. He doesn't know what he doesn't know, all while believing he's got a very good grip on things. The above post makes that abundantly clear. Since he's Dunning-Kruger to the point where trying to help results in frustration on both sides I'll no longer be making an effort.

 

[shipkiller]

you aren't trying to help him you are just telling him he's wrong and that's it...

 

[suprafanatic]

While a scope is nice the freq function on any decent meter is plenty adequate. Regardless, one needs to measure the load signal, something he isn't doing. In other words he isn't measuring the AFM. Nor would a trim signal (what he is measuring) cause his symptom or code.

I've tried to help the guy even though he's basically clueless. I don't hold that against him though. The real problem is he's clueless he's clueless yet it's the furthest thing from his mind. He doesn't know what he doesn't know, all while believing he's got a very good grip on things. The above post makes that abundantly clear. Since he's Dunning-Kruger to the point where trying to help results in frustration on both sides I'll no longer be making an effort.

I'm not clueless that I'm clueless. I've clearly admitted that I don't exactly know what I'm talking about here. I've simply posted what I believe to be right, that doesn't mean I'm right. This is why I've made a thread, to get help with the issue I'm having, and have people correct me if I'm wrong about something. I want to be corrected if I'm wrong, I want to learn, and I want to fix the problem. But you do not help, you simply point at me and make me look like an idiot. While telling me that I'm wrong you do not correct me and explain things properly in a way that helps me or anyone else out. If I say I don't understand what you mean by something, and you say, "it means just what you said." clearly that won't help me learn. Cause obviously I don't know what you mean or I wouldn't have said other wise.

And it's obvious I'm not the only one who feels this way. It would be nice if you could actually help me with this, I know you are a very knowledgeable person. I'm just frustrated because you aren't helping.

 

[jetjock]

I've helped in every post thus far. You have the same problem with the book: you read but make little effort to understand. It's all very mystifying for a guy who thinks everything to death. Or maybe it's not...

 

[Supracentral]

Ok everyone, let's tone down the hostility a bit.

I will admit, jetjock's bedside manner leaves a lot to be desired, he doesn't coddle people and often comes across as brusque and unsympathetic. However, it's worth noting that his teaching style, while rough on the student, yields better long term results than anyone I've seen. JJ rarely gives answers. What he does is forces you to ask the right questions and to find the right answers on your own. Admittedly it's frustrating, sometimes painful and often a bit humbling, but if you can put your ego and emotions aside you'll learn an awful lot.

Also, if you say "I don't want your help", he'll go away and leave you to lesser instructors.

I can tell you this, he's one of the few people around here who have earned my respect, and that's not something I easily give.

With that said, let's not let this thread turn into a flamewar.

 

[suprafanatic]

I understand this, and I have never once said I don't want his help. In fact, quite the opposite. Perhaps his way of teaching is over my head, and maybe he isn't willing to dumb down a little to help me out. Either way I'm still clueless as to what the problem is with my car, I still need some help.

 

[suprafanatic]

So I went out to try and start the car today. It kept firing up then dying immediately when I touched the gas pedal, Kinda like its a kill switch lol. I got it to rev up once, and it revved up just fine, but when I let off the gas the RPMs immediately dropped and the car died. Any ideas guys?

 

[suprafanatic]

Starting to seem more like a boost leak, the car smelled really rich when it did fire up. I just cant seem to find the leak, And I don't have an air compressor at my house to check.

 

[jetjock]

Nobody said it wasn't your AFM or associated wiring. After all the code points there. Just that everything you did was useless in verifying it was bad. Put another way if you're not going to troubleshoot the car properly you might as well simply change the thing and hope for the best.