Rebuilt 7MGTE revving problem

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cyanide54

New Member
Mar 18, 2012
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Vancouver, BC
Totally agree that it happens. My second mechanic was much better, just didn't have a ton of experience with supras, he worked on the car for 8 hours and only charged me for 2.5 because he felt bad that he couldn't get it going for me.

Also I never claimed that either mech was my friend lol
Id prefer to do my own work but it was a constraint of time and the rents wanting the car finished asap. With no more ideas, it went to a shop.
 
Last edited:
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
A flow/volume test will verify if the filter and pump are up to delivering sufficient fuel:

Disconnect the fuel supply line at the fuel rail or disconnect the return hose and place the open end of the hose in a container. If you're disconnecting the return hose you'll have to attach another piece of hose to the fuel rail and use that to route fuel into the container. With the engine off jumper the fuel pump on in the dag block to energize the pump for 30 seconds and measure the volume of fuel delivered. A good pump and filter should deliver about one quart in 30 seconds.

Another method is to do a snap throttle test while observing fuel pressure. Disconnect the vacuum hose at the FPR and while monitoring fuel pressure quickly snap the throttle wide open and release it. If fuel pressure drops by more than a couple of psi the system has a supply side restriction.

As for your mechanics, they sound like new school types lost without an OBD-II scan tool. If they're old school they don't know what their doing...
 
Rollus

Rollus

New Member
Jun 2, 2011
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Paris, France
Hi,

cyanide54;2036883 said:
Hey guys,

Little update here.

The car has now gone from my mechanic back to the machine shop as they have a service department as well. They claim the timing is infact bang on...
Click to expand...

With E1/TE1 shunt in diag connector and a timing light?

cyanide54;2036883 said:
They also mentioned that exposing propane to the throttlebody area makes the car rev freely and smoothly, no more issue.
Click to expand...

Wait, air intake is not in the throttle bodie area, you probably have an air leak there. The 7mgte ecu will behave wrong if there is a leak between AFM (the sensor between air filter and turbo) and cylinders.

cyanide54;2036883 said:
They are suggesting fuel system upgrades because of the billet compressor wheel upgrade to the turbo. Would that upgrade to the ct26 alone allow enough extra cfm flow to cause a lean condition even under no load?
Click to expand...

The AFM will see the extra flow and the ecu will trim fuel accordingly. No need for upgrade until you have fuel cut problems while in full load.
 
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cyanide54

New Member
Mar 18, 2012
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Vancouver, BC
Thank you jetjock, when I get the car back I'm gonna do that test.

Rollus, yes with e1/te1 shorted. The motor is making about 18 inhg at idle, could there still be a vac leak? I know that producing propane around the motor and it getting rich would suggest a vac leak, but all lines are new and i triple checked the vacuum layout before dropping the motor into the car.
Your third point is my train of thought considering the compressor works as an impeller, sucking more air past the AFM. While the stock system may be able to support the compressor wheel upgrade at the same wastegate actuation setting, could we still be looking at a dying pump?
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
While it's true propane (or any hydrocarbon) ingested through a pirate air leak would increase rpm consider that any leak large enough to cause the problem you're having would result in a very detrimental effect on idle quality. That said there shouldn't be any change in how the engine runs when propane is applied externally. Also, what is Vf doing?
 
pogoism9

pogoism9

1UZ for me!
May 18, 2007
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fredericksburg, va
It sounds like an air leak to me...Just spitballing here, but check the underside of the accordion hose. There will be a vacuum line that runs down to a valve on the power steering pump. Alot of times that valve will lose a nipple (due to age). This would cause a leak.
 
lilmartian09

lilmartian09

New Member
Apr 1, 2010
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El Paso, Texas, United States
My money is on timing. My stock afm. With 60-1 ct26 and bic ddp. Ran perfectly fine with stock injectors and built motor. Even had the wastegate shimmed. So either timing or broke afm sensor. You need to check it yourself and make sure. Even the cps as well. All has to be synced

Sent from my HTC0P3P7 using Tapatalk
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
4,235
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48
Atlanta
Um, I'm hoping that in the past 6 1/2 months since this issue was last discussed, that cyanide54 has figured out the problem...
However, we will probably never know. He hasn't logged onto Supramania since March.
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
4,235
37
48
Atlanta
That's what I hate about these unanswered threads.
There's many occasions where a final post describing the resolution, would have helped the next guy, who properly
goes through the search function to find an answer to his own problem.
 
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Raggan

New Member
Mar 16, 2015
142
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Maple Ridge, BC
Im pretty sure this is the guy i bought my supra off. I bought it in march with the same problem and same area. It was the fuel pulsation dampener was stuck closed swapped it out and ran like a charm
 
Suprapowaz!(2)

Suprapowaz!(2)

New Member
Apr 10, 2006
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San Antonio, Tx.
And not lost his car to something simple. Something tells me that he didn't know how to work on a car.
The twist in the plot is that the guy who bought his car was his mechanic. Had him rebuild the engine first, then told him it's a lost cause. Replaced the fpd, and had himself a good running MKIII. Muhahaha!

Only kidding... I hope.
 
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