AFM questions

hotwheels · 05-10-2007, 12:26 PM

Ok, so i think my AFM might be bad.
It's still in working order, just not good working order. I'm getting horrible gas milage and running a really rich mixture. I've plugged all existing exhuast leaks, and as far as i can tell, i've got no vacuum leaks. My Idle is also a bit high. about 11-1200 rpms after the engine is warmed up.

I took the AFM out and cleaned it with cleaner, no difference.

I've also heard that adjusting the idle air speed screw is not the best option to do first, because there are many problems that can cause high idle, and jumping to the IAS everytime just covers up existing problems, so i'm leaving that for last.

I dont think the current AfM is worth trying to fix, so i was hoping someone knows of a good aftermarket part that wouldn't suck the pants right off me in an effort to get to my wallet (horrible analogy, but its the best i can do)

any help?

thanks a bunch!!!

Luni · 05-10-2007, 03:10 PM

Not really any replacment options other than another AFM from an MR2.

Makelo · 05-15-2007, 03:54 PM

Whatever you do, DO NOT MESS WITH THE AFM
Trust me I Defenately know this. If you are running rich, I doubt the AFM is bad. I think you are more prone to have a faulty FPR, timing belt/ timing / Oxygen Sensor. have you try to get the ECU codes? this can help you a lot

hotwheels · 05-18-2007, 01:45 AM

Ok, so in the last few weeks, my mechanic friend has been helping me run some heavy diagnostics tests on the car.

Testing for Ohms resistence with a good multimeter, when the AFM was unplugged turned up positive results--all 8 nodes within specs. With the AFM plugged in, ohm resistence was good in all but the leftmost two nodes. The specs sheet says there should be no resistence there, but there is--about 300ohms.

This leads me to believe that the resistence is caused by a short somewhere BEFORE the AFM, possibly in the ECU. I am having that checked out at the shop in more detail tomorrow, so I'll let you guys know how it turns out.

Also, is it possible that a mis-adjusted TPS is sending the wrong signal to the ECU, and creating the weird readings in the AFM?

Next, we got on the internet and found some more tests we could do for the high idle. We plugged a multimeter into two particular slots in the diagnostics box. The specs sheet said that once the car starts, the volts should jump up and down like crazy about 8 times, and then settle. When we tried, the volts jumped--0 times, they stayed dead. the internet said if that is the case, to check the plugs, coil, wires, but i have platinum two-electrode racing plugs in there, and i replaced the wires only a few months ago. It also said to replace the ECU if all else fails...(not my favorite idea).

Also, I KNOW that i'm running a rich mixture cuz i can smell gas coming out of the exhaust pipe, and the plugs, three weeks new, are already all black and sooty, not wet, but a dry kind of sooty black color around the electrode.

any brilliant ideas?

Luni · 05-18-2007, 03:44 PM

You can unplug the TPS and take it out of the loop. It wont even pull a CEL, and it definately wouldnt cause any sort of short/open in the wiring/ECU.

TPS would only cause problems at cruise anyway, not at WOT. It WOULD and COULD affect your fuel trims, but I dont think that it is your problem.

Just for grins, put some stock range coppers (anything but bosch IMO). Your O2 sensor could be causing issues at cruise (closed loop) as well.

There are so many things this could be... Wish we could be more help.

05-10-2007, 12:26 PM	#1 (permalink)
hotwheels elvis Join Date: Mar 2007 Posts: 33 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	AFM questions Ok, so i think my AFM might be bad. It's still in working order, just not good working order. I'm getting horrible gas milage and running a really rich mixture. I've plugged all existing exhuast leaks, and as far as i can tell, i've got no vacuum leaks. My Idle is also a bit high. about 11-1200 rpms after the engine is warmed up. I took the AFM out and cleaned it with cleaner, no difference. I've also heard that adjusting the idle air speed screw is not the best option to do first, because there are many problems that can cause high idle, and jumping to the IAS everytime just covers up existing problems, so i'm leaving that for last. I dont think the current AfM is worth trying to fix, so i was hoping someone knows of a good aftermarket part that wouldn't suck the pants right off me in an effort to get to my wallet (horrible analogy, but its the best i can do) any help? thanks a bunch!!!

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05-10-2007, 03:10 PM	#2 (permalink)
Luni ST185 Powered SW20 Join Date: Oct 2005 Location: Salt Lake City Utah Posts: 2,961 Thanks: 9 Thanked 106 Times in 92 Posts My Google Map iTrader Rating: (8/100% )	Not really any replacment options other than another AFM from an MR2.

05-15-2007, 03:54 PM	#3 (permalink)
Makelo 89 SC Join Date: Mar 2007 Location: Los Angeles, CA Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Whatever you do, DO NOT MESS WITH THE AFM Trust me I Defenately know this. If you are running rich, I doubt the AFM is bad. I think you are more prone to have a faulty FPR, timing belt/ timing / Oxygen Sensor. have you try to get the ECU codes? this can help you a lot

05-18-2007, 01:45 AM	#4 (permalink)
hotwheels elvis Join Date: Mar 2007 Posts: 33 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Ok, so in the last few weeks, my mechanic friend has been helping me run some heavy diagnostics tests on the car. Testing for Ohms resistence with a good multimeter, when the AFM was unplugged turned up positive results--all 8 nodes within specs. With the AFM plugged in, ohm resistence was good in all but the leftmost two nodes. The specs sheet says there should be no resistence there, but there is--about 300ohms. This leads me to believe that the resistence is caused by a short somewhere BEFORE the AFM, possibly in the ECU. I am having that checked out at the shop in more detail tomorrow, so I'll let you guys know how it turns out. Also, is it possible that a mis-adjusted TPS is sending the wrong signal to the ECU, and creating the weird readings in the AFM? Next, we got on the internet and found some more tests we could do for the high idle. We plugged a multimeter into two particular slots in the diagnostics box. The specs sheet said that once the car starts, the volts should jump up and down like crazy about 8 times, and then settle. When we tried, the volts jumped--0 times, they stayed dead. the internet said if that is the case, to check the plugs, coil, wires, but i have platinum two-electrode racing plugs in there, and i replaced the wires only a few months ago. It also said to replace the ECU if all else fails...(not my favorite idea). Also, I KNOW that i'm running a rich mixture cuz i can smell gas coming out of the exhaust pipe, and the plugs, three weeks new, are already all black and sooty, not wet, but a dry kind of sooty black color around the electrode. any brilliant ideas?

05-18-2007, 03:44 PM	#5 (permalink)
Luni ST185 Powered SW20 Join Date: Oct 2005 Location: Salt Lake City Utah Posts: 2,961 Thanks: 9 Thanked 106 Times in 92 Posts My Google Map iTrader Rating: (8/100% )	You can unplug the TPS and take it out of the loop. It wont even pull a CEL, and it definately wouldnt cause any sort of short/open in the wiring/ECU. TPS would only cause problems at cruise anyway, not at WOT. It WOULD and COULD affect your fuel trims, but I dont think that it is your problem. Just for grins, put some stock range coppers (anything but bosch IMO). Your O2 sensor could be causing issues at cruise (closed loop) as well. There are so many things this could be... Wish we could be more help.