89 Supra rebuild help please won't rev past 3,000 Slow revs.

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Raggan

New Member
Mar 16, 2015
142
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Maple Ridge, BC
Hey guys I just recently bought a 1989 Targa top Supra with a freshly rebuilt 7mgte and a newer paint job, the car won't rev past 3000 Rpm. The guy before me had the engine rebuilt by Canadian engines and put it in with his dad. He could never get the revs above 3,000 rpm after he installed the engine. He had it towed to a few different shops that couldn't figure it out and told him to take it back to the people who built the engine, he couldn't afford it anymore he told me. What we have been doing is testing every sensor by the book and we have also re calibrated the TPS and made 100% sure that the cam position sensor is in the right spot. We have tested every sensor to be within specs and we still cannot get the car to rev past 3000 RPM the fuel filter has been changed fuel pressure is 45 PSI. I have 3 different used AFM sensors and I have no clue if any of them work there is no check engine lights(bulb works). If I press the gas hard and hold it the car bogs and pops out the intake, unplugging the air flow meter makes the car not start. If i slowly rev it we can get 2500-3000 RPM.

I'm kinda losing my mind on this one any idea's would be much appreciated also please let me know if you need more information as I am kinda tired so I may have missed a few things.
 
nosman4

nosman4

Member
Nov 10, 2007
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Bend, Oregon
I assume the check engine light works since he said it does in the 1st post...... How does the car idle? When it only revs to 3000 is it because it is missing and has a hard time getting to 3000 and just can't get above that? Or does it run fine up to that point and then stops going higher? I know you said it pops from the intake when you press the gas hard, just curious if it runs fine when pressing slow? My thought is maybe a cam position sensor that is out of spec or bad internally, that is if timing is set correctly, but it won't idle good if it's not. If you know anyone that has one you can try or find one at a junk yard, that would be where my money is.
 
3p141592654

3p141592654

90T
Oct 11, 2005
3,816
16
38
Thousand Oaks, CA
There is a 3k rev limit imposed if the AFM is bad and code 31 is set. I know you have checked the AFM out, but have you verified no codes are present by shorting TE1 and E1 in the diag box and get a constant flash from the MIL?
 
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Raggan

New Member
Mar 16, 2015
142
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Maple Ridge, BC
There are no codes present. It has a hard time starting cold 2-3 turn overs....idles okay. Slowly revving it is the only way to bring the rpm's up to 2000-3000, if I press the gas hard it will stay around 1500 and make hard popping noise and shake violently. The cam position sensor is in spec tested air gap and ohm's readings, we have tried several different timing spots from 0 to 15 degree's. No idea what's wrong I have opened the ECU and checked for fried components. Checked all grounds and sanded them. Every component is in spec from vsv to fuel resistor pack, injectors working, took exhaust off at the turbo to see if it's restricted... for some reason she just doesn't want to go outta limp mode.

I'm thinking it's the afm sensor.... I know another guy with a supra but he keeps blowing me off every time we set up a meeting. I don't want to send mine off to get rebuilt if it's not the problem it's about 400 bucks...and I've already bought a used one and it didn't do the trick.
 
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Raggan

New Member
Mar 16, 2015
142
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Maple Ridge, BC
I'm thinking that's what it is myself as well but usually there's a code and the ohm's reading's are Okay but the only real way to know is with a scilliscope.
I've tried 3 used one's i'm wondering if I should just pay to have an old one rebuilt
 
3p141592654

3p141592654

90T
Oct 11, 2005
3,816
16
38
Thousand Oaks, CA
If there is no code 31, then it is pretty unlikely to be the AFM, ecu or wiring. You will not get a 3k rpm limit without a code 31.

Since this is a fresh rebuild, I would check that 0 BTDC on the pulley actually matches 0 BTDC by sticking a chopstick in a spark plug hole or some other mechanical check. Also check that the cam timing is correct.
 
R

Raggan

New Member
Mar 16, 2015
142
0
0
Maple Ridge, BC
I just checked the cams position it's matching up all marks line up at TDC.

Bought a lexus body and AFM black box today tried installing JUST the black box and still won't rev past 2500-3000.
 
S.A. supra

S.A. supra

New Member
Feb 15, 2009
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Buda, Texas
Did you take the tps off the tb at any point? I did that once and I did not install it probably. the car would idle perfectly but hit a wall at 3000rpms. The tps was not catching the wing nut looking thing on the tb.
 
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585Soup

New Member
Mar 12, 2015
84
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Colorado
were the right injectors installed? is it running too rich? i had a motorcycle that would do that to me. took me forever to figure out what the issue was, until i leaned out the carb and it ran fine.
 
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Raggan

New Member
Mar 16, 2015
142
0
0
Maple Ridge, BC
stock injectors the car has the wrong black box i just ordered the proper one ending in 42020 mine are all 42011 and 42010. Mines an 89 it takes a 42020 guy before me had the wrong afm see if it does the trick
 
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