Only runs without MAF

mr3 · 10-15-2009, 09:58 AM

Just about done the 20v swap and the only way it will run is without the MAF. I went to the junkyard and got one out of a 90 corolla I think and tried that and it stilld doesnt run with it plugged in. The one out of the corolla was a newer looking one and didnt have a toyota part number so I couldnt check to see if it was the right one but it was the same shape and had the same pinout as the one that I had. The fuel pump does turn on when I push the flap in when its plugged in but I wont get spark. Should I get a new maf from work or is there something else that could be the problem?

mr220v · 10-15-2009, 10:07 AM

A 1990 Corolla? Is this a corolla with a 4age? I'm guessing so since the 4afe corollas use a map sensor.

If you picked up a 4age afm, you have a rising rate afm, and an incorrect signal for the 20v ecu. The corolla 4age is the same as the mr2 16v afm.

You want to get a afm from a 1991 or so camry 3sfe 4cylinder. It gives the correct signal, and while running it, you'll get 30+mpg.

If you've been running 16v afm's all this time, then this is likely your problem. Your CEL should have come on.

Also, the older afm's don't have the same pinout. The main difference is the +b/12v's at pin 4.

mr3 · 10-15-2009, 10:17 AM

I'm not sure what it was that it came out but I think it was a 1990 though. I have the right part number one that came with the engine. The CEL I have is still for the o2 sensor which was replaced. I'm going to get a new one from work tonight so I'll see if that's the problem and post back tomorrow. Thanks for the info again.

mr220v · 10-15-2009, 10:24 AM

If you only have a code for the o2, and are running a compatible afm, then I would say check for leaks in the airbox and intake hose between the afm and the throttles. If airflow past the afm drops below a point, the door doesn't stay open enough to keep the fuelpump switch tripped.

mr3 · 10-27-2009, 06:49 PM

I cleared my codes and now I got 2 new codes. I'm finally throwing a AFM code. Code 31. I also have a code 24 which I believe is intake air temp sensor signal. I had the car running with the AFM today. I started the car and then stuck the afm on and tightened it down. It ran but when I sat in it to rev it up it kinda bogged out when it hit 3000 rpms. I'm looking for a known working condition afm now. If this thing doesnt work out, the 20v is coming out and a BEAMS is going in.

10-15-2009, 09:58 AM	#1 (permalink)
mr3 Cage Fighter Join Date: Jun 2008 Location: Plymouth Mtg, Pa Posts: 845 Thanks: 19 Thanked 26 Times in 25 Posts iTrader Rating: (2/100% )	Only runs without MAF Just about done the 20v swap and the only way it will run is without the MAF. I went to the junkyard and got one out of a 90 corolla I think and tried that and it stilld doesnt run with it plugged in. The one out of the corolla was a newer looking one and didnt have a toyota part number so I couldnt check to see if it was the right one but it was the same shape and had the same pinout as the one that I had. The fuel pump does turn on when I push the flap in when its plugged in but I wont get spark. Should I get a new maf from work or is there something else that could be the problem?

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10-15-2009, 10:07 AM	#2 (permalink)
mr220v Beams Owners Group Join Date: Mar 2006 Posts: 1,791 Thanks: 13 Thanked 139 Times in 117 Posts iTrader Rating: (9/100% )	A 1990 Corolla? Is this a corolla with a 4age? I'm guessing so since the 4afe corollas use a map sensor. If you picked up a 4age afm, you have a rising rate afm, and an incorrect signal for the 20v ecu. The corolla 4age is the same as the mr2 16v afm. You want to get a afm from a 1991 or so camry 3sfe 4cylinder. It gives the correct signal, and while running it, you'll get 30+mpg. If you've been running 16v afm's all this time, then this is likely your problem. Your CEL should have come on. Also, the older afm's don't have the same pinout. The main difference is the +b/12v's at pin 4.

10-15-2009, 10:17 AM	#3 (permalink)
mr3 Cage Fighter Join Date: Jun 2008 Location: Plymouth Mtg, Pa Posts: 845 Thanks: 19 Thanked 26 Times in 25 Posts iTrader Rating: (2/100% )	I'm not sure what it was that it came out but I think it was a 1990 though. I have the right part number one that came with the engine. The CEL I have is still for the o2 sensor which was replaced. I'm going to get a new one from work tonight so I'll see if that's the problem and post back tomorrow. Thanks for the info again.

10-15-2009, 10:24 AM	#4 (permalink)
mr220v Beams Owners Group Join Date: Mar 2006 Posts: 1,791 Thanks: 13 Thanked 139 Times in 117 Posts iTrader Rating: (9/100% )	If you only have a code for the o2, and are running a compatible afm, then I would say check for leaks in the airbox and intake hose between the afm and the throttles. If airflow past the afm drops below a point, the door doesn't stay open enough to keep the fuelpump switch tripped.

10-27-2009, 06:49 PM	#5 (permalink)
mr3 Cage Fighter Join Date: Jun 2008 Location: Plymouth Mtg, Pa Posts: 845 Thanks: 19 Thanked 26 Times in 25 Posts iTrader Rating: (2/100% )	I cleared my codes and now I got 2 new codes. I'm finally throwing a AFM code. Code 31. I also have a code 24 which I believe is intake air temp sensor signal. I had the car running with the AFM today. I started the car and then stuck the afm on and tightened it down. It ran but when I sat in it to rev it up it kinda bogged out when it hit 3000 rpms. I'm looking for a known working condition afm now. If this thing doesnt work out, the 20v is coming out and a BEAMS is going in.