rebuilt 7mgte problems

Rob1 · 06-03-2011, 06:21 PM

Ok i just dropped my engine back into my 89 supra 5-speed turbo.

, its a 7mgte with a t61 turbo, 550cc RC injectors, 3 inch turbo back exhaust, Apexi super air flow converter, and i think the MAF sensor is the lexus one

. I started it up and it has a very rough idle and upon acceleration it spits and sputters and just dous not go correctly. I drove it about a quarter mile down the road because i could not go far due to having no fan belt therefore no water pump, and it went but ran terrible.

On the way back it was running the same but i stopped at a stop sighn and it started making a God awful noise like metal on metal grinding that definatly gets louder when i hit the gas. i think i forgot to tighten down my fly wheel when i put it back on because i was rushing a bit at that point(my fault)

but the same time that happened it also got to where it would still rough idle bit when givin gas it tried to die. The only way to get it to rev is to flutter the pedal and it will try to rev up a bit more.

I am throwing a code for MAF sensor, TPS, and o2 sensor. as mentioned above it has an Apexi SAFC that was installed on it and before it blew up the car ran fine so during the rebuild i had to remove the engine harness so i cut the T-taps for the SAFC then just re tapped them when i reinstalled engine.

Obviously the tune that was on it was prob lost could this be the reason its running bad? could it not be properly adjusting the MAF to adapt to all the other upgrades due to no tune after rebuild? im at a loss.

Any help would be greatly appreciated.

P.S. i also disconected the TPS while it was running and it made no change in how the car ran so i replaced it with another used one i had at the house and still nothing changed

El Supracabras · 06-03-2011, 06:59 PM

I hope you figure out the metal grinding noise.
Find out if you have the Lexus kvafm or not. It's important.
Disconnecting the SAFC2 wont change the settings ("tune") unless you physically reset them, not sure about the SAFC1 but they aren't much different. You really don't need it but they are cool. If you think it's a problem just rewire the afm back to stock, the safc doesn't affect anything else.
As for the codes, I would check the grounds under the intake first.

Rob1 · 06-03-2011, 08:25 PM

Ok thanks thats gives me somewhere to start would those grounds being loose cause the running issues I explained earlier?

El Supracabras · 06-03-2011, 09:30 PM

Oh yeah. Those are ecu grounds. They commonly get overlooked when re installing the engine.

Rob1 · 06-03-2011, 09:58 PM

Ok so I could pull the wire diagram for the ecu and trace the grounds back from there to make sure I got them all hooked up? And also do they havent to be grounded on the engine or coulson they be cut and grounded near the ecu?

El Supracabras · 06-03-2011, 10:26 PM

That shouldn't be necessary, I would just make sure they are connected properly and in good shape. I think those are the only two for the ecu. Look at the diagram just to be sure. It might not be your problem but the ecu MUST be grounded properly and it never hurts to be 100% sure the grounds are good to eliminate them as suspect.
Have you cleared the codes and tried running it again to see if the same ones come back? The computer can sometimes "remember" if you unplug something while it's running. Having to feather the gas to rev the engine is a symptom of a kvafm issues. Can you get the screen on the safc to show the kvafm signal? Check if afm is doing anything. (I can watch the afm signal change with the airflow increase as I rev the engine with the safc2)

06-03-2011, 06:21 PM	#1
Rob1 3" Exhaust Join Date: Aug 2009 Location: tennessee Posts: 137	rebuilt 7mgte problems Ok i just dropped my engine back into my 89 supra 5-speed turbo. , its a 7mgte with a t61 turbo, 550cc RC injectors, 3 inch turbo back exhaust, Apexi super air flow converter, and i think the MAF sensor is the lexus one . I started it up and it has a very rough idle and upon acceleration it spits and sputters and just dous not go correctly. I drove it about a quarter mile down the road because i could not go far due to having no fan belt therefore no water pump, and it went but ran terrible. On the way back it was running the same but i stopped at a stop sighn and it started making a God awful noise like metal on metal grinding that definatly gets louder when i hit the gas. i think i forgot to tighten down my fly wheel when i put it back on because i was rushing a bit at that point(my fault) but the same time that happened it also got to where it would still rough idle bit when givin gas it tried to die. The only way to get it to rev is to flutter the pedal and it will try to rev up a bit more. I am throwing a code for MAF sensor, TPS, and o2 sensor. as mentioned above it has an Apexi SAFC that was installed on it and before it blew up the car ran fine so during the rebuild i had to remove the engine harness so i cut the T-taps for the SAFC then just re tapped them when i reinstalled engine. Obviously the tune that was on it was prob lost could this be the reason its running bad? could it not be properly adjusting the MAF to adapt to all the other upgrades due to no tune after rebuild? im at a loss. Any help would be greatly appreciated. P.S. i also disconected the TPS while it was running and it made no change in how the car ran so i replaced it with another used one i had at the house and still nothing changed __________________ My work in progress!!! 1989 toyota supra turbo targa top 7mgte, Five speed left hand drive.

06-03-2011, 08:25 PM	#3
Rob1 3" Exhaust Join Date: Aug 2009 Location: tennessee Posts: 137	Ok thanks thats gives me somewhere to start would those grounds being loose cause the running issues I explained earlier? __________________ My work in progress!!! 1989 toyota supra turbo targa top 7mgte, Five speed left hand drive.

06-03-2011, 09:58 PM	#5
Rob1 3" Exhaust Join Date: Aug 2009 Location: tennessee Posts: 137	Ok so I could pull the wire diagram for the ecu and trace the grounds back from there to make sure I got them all hooked up? And also do they havent to be grounded on the engine or coulson they be cut and grounded near the ecu? __________________ My work in progress!!! 1989 toyota supra turbo targa top 7mgte, Five speed left hand drive.

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06-03-2011, 06:59 PM	#2
El Supracabras 3" Exhaust Join Date: Feb 2010 Location: Chicago Posts: 240	I hope you figure out the metal grinding noise. Find out if you have the Lexus kvafm or not. It's important. Disconnecting the SAFC2 wont change the settings ("tune") unless you physically reset them, not sure about the SAFC1 but they aren't much different. You really don't need it but they are cool. If you think it's a problem just rewire the afm back to stock, the safc doesn't affect anything else. As for the codes, I would check the grounds under the intake first.

06-03-2011, 09:30 PM	#4
El Supracabras 3" Exhaust Join Date: Feb 2010 Location: Chicago Posts: 240	Oh yeah. Those are ecu grounds. They commonly get overlooked when re installing the engine.

06-03-2011, 10:26 PM	#6
El Supracabras 3" Exhaust Join Date: Feb 2010 Location: Chicago Posts: 240	That shouldn't be necessary, I would just make sure they are connected properly and in good shape. I think those are the only two for the ecu. Look at the diagram just to be sure. It might not be your problem but the ecu MUST be grounded properly and it never hurts to be 100% sure the grounds are good to eliminate them as suspect. Have you cleared the codes and tried running it again to see if the same ones come back? The computer can sometimes "remember" if you unplug something while it's running. Having to feather the gas to rev the engine is a symptom of a kvafm issues. Can you get the screen on the safc to show the kvafm signal? Check if afm is doing anything. (I can watch the afm signal change with the airflow increase as I rev the engine with the safc2)