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Discussion Starter · #1 ·
I recently finished rebuilding my 7mgte engine from an 1987 supra. I installed an upgraded ct26 turbo with a 60-1 trim package. the problem i have with my car now with the engine in it is that once it gets warmed up, it hesitates and "stumbles" at around 3000 rpm and up and wont seem to rev up or accelerate. the hesitation seems to occur when the turbo is spooling up. I figure either the fuel pressure is dropping or the ignition is cutting out but dont know exactly what to do. Please help!!!!!!!!!!!!!!
 

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What are your other mods?

With a 60-1, you also need supporting fuel mods and a tune.
 

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It might run right......?
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where u at in NC? i can come help ya sort it out
 

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Noob! The issue you're having is most likely fuel cut. Too much air combined with not enough fuel, and the system will shut you down Pronto! You need to supply more fuel NOW! Don't keep driving it, or at least baby it until you can do the upgrades.
 

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Discussion Starter · #8 ·
The check engine light is not coming on and the turbo is only pushing stock boost. The car will run fine for 10 to 15 minutes even when the temp. gauge shows it is at normal operating temperature. I switched around the VSV valves (the little red vacuum switches under the intake manifold) but that didn't help, its still cutting out around 3000 rpm.
 

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A Happy Dad
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what do you mean fine? runs great past 3k then after 15 minutes starts cutting out?
do you have any codes?
 

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The check engine light is not coming on and the turbo is only pushing stock boost. The car will run fine for 10 to 15 minutes even when the temp. gauge shows it is at normal operating temperature. I switched around the VSV valves (the little red vacuum switches under the intake manifold) but that didn't help, its still cutting out around 3000 rpm.
Doesn't matter if you are at stock boost.

You have more volume of air going into the engine.


That is fuel cut.
 

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A Happy Dad
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I'm not sure it is degree, the check engine light isn't coming on.
OP, we need to know all the mods if any and codes
 

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Discussion Starter · #12 ·
there are no codes showing up on the computer. the car will pull hard for 10 to 15 minutes when warm but then it dies at 3000 like previously mentioned. do i need bigger injectors? how do u tune MK3's?
 

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MUDKIP FARMER
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I would highly doubt this is fuel cut. You need to be in boost to hit fuel cut, all things equal stock turbo in vacuum should behave the same as a 60-1 in vacuum.

I'd saaay the air fuel ratio is skewed.
 

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Discussion Starter · #14 ·
other than the turbo, there are not any other performance mods (no intake, exhaust, ignition, injectors, etc....)
 

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MUDKIP FARMER
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other than the turbo, there are not any other performance mods (no intake, exhaust, ignition, injectors, etc....)
well here is the interesting thing about forcing a whole bunch more air into the engine.

The engine needs to breathe in more air, expel more gas, and have more fuel to properly run.

You're likely running very lean...

Why in the world would you run a bigger turbo without addressing anything else? Research...
 

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Overlooked
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Check you knock sensors. Even without codes they can be trying to adjust the engine to cause your problems if that makes sense. Check you vacuum system too, not for leaks but that it's routed correctly. Some lines "open up" more when warm.

Vacuum system:
http://www.cygnusx1.net/Supra/Library/EPC/291220/catalog.aspx?F=1708&P=6

Also, what about your EGR system? Did you remove it or anyting? This seems to me to be the culprit.
 

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A Happy Dad
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I'm not convinced you are running great for 10-15 minutes, I think you need to back up and re-check everything, timing, plug gaps, hose routings and connections, wiring to afm and sensors, etc.
BTW, you desperately need to include some supporting mods for that turbo before you turn it up cause it will go booom.
 

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I'm not sure it is degree, the check engine light isn't coming on.
OP, we need to know all the mods if any and codes
When mine was hitting fuel cut, it didn't show a check engine light unless I was WOT, and even then, it would go out immediately. It's definitely fuel cut due to too much air.
 

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Discussion Starter · #19 ·
Thanks for all the suggestions! i will more than likely spend the whole day tomorrow checking everything out. Probably post some more info. tomorrow if i can get this glitch worked out
 
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