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Discussion Starter · #1 ·
Maybe some of you turbo gurus can help. I just bought a 91 Eagle Talon TSi AWD. When I bought it it had no transmission, so I had to take the sellers word that it ran. He said it ran perfect. Finally i got the car back together, and it ran, but not perfect. When the engine is warm, and under full boost (about 11 psi), the motor bucks badly. My brother-in-law knows alot about DSM cars, and he thinks its boost creep. I thought I should get a second (or third) opinion. By the way, the previous owner installed a 3" downpipe, and a cat bypass. The turbo is a Mitsu 14b that was just ported and clipped.
Thanks for any advice you guys may have.

By the way, i still drive my 88 EGT and I still love it.
 

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Well shorty...remember fuel or airflow is a primary for bucking. Overboost conditions would create and overly lean condition. The stock 14G turbo is an Excellant turbo to use...porting it was the right way to go without spending big money.

Really look at your wastegate actuator (since its easy to see unlike mine). Check all pressure line that goes to the actuator...might not be sealed completely or something.

maybe time to invest in fuel pressure gauge and really acurrate boost gauge.

(a/f) wouldn't hurt...but its a waste to buy a single gauge for it. Get one that's part of a turbo timer or something like in my A'PEXi turbo timer.
 

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My 95 GSX did that to me once, the air filter center section broke out, and it bucked, might also be called "Fuel cut"? the computer dose'nt like that much boost.
And it had a free flowing exshast, boost creep was probly a problem to.
 

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one other suggestion is this....


if the car's tranny was bad...then technically u would think that it wouldtn hurt to leave the tranny with the car when sold....

so maybe u bought the car w/ out a transmission because the tranny was good and the motor wasnt so they pulled it out...personally, if i was gonna sell a car w/ a shot tranny, i'd leave it in because it woudltn be worth it to get it out, also because u might be able to get a few more bucks out of it because someone might try to get it rebuilt...

only time i'd pull tranny out of a car i was gonna sell is if i knew taht the tranny was good and taht i could get more money for it elsewhere.

My logic behind thinkin that is this....Bucking also occurs in instances wehre the crankshaft is just about to "walk"

walking a crank is where the crank bearings give way and the crank doesnt rotate nemore, it simply moves up and down or back and forth....

These are found mostly in overhead cam engines because most oil resides in the top of the engine during engine operation. being that its a talon and its a turbo, i'm guessin someone beat the shit out of it....

prolly ran it hard and ran it hot alot causing the piston rings or one ring to fry...Which sprays oil on the crank directly. This is what causes bearings to go out and crank walk...

ITs just another option, but crank walk is found alot in overhead engines and also found in turbo engines because they like to burn piston rings. I'd consider that a possibility considering u bought the car in the shape that it was....
 

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Discussion Starter · #6 ·
92gt5spd said:
My logic behind thinkin that is this....Bucking also occurs in instances wehre the crankshaft is just about to "walk"

walking a crank is where the crank bearings give way and the crank doesnt rotate nemore, it simply moves up and down or back and forth....

These are found mostly in overhead cam engines because most oil resides in the top of the engine during engine operation. being that its a talon and its a turbo, i'm guessin someone beat the **** out of it....

prolly ran it hard and ran it hot alot causing the piston rings or one ring to fry...Which sprays oil on the crank directly. This is what causes bearings to go out and crank walk...

ITs just another option, but crank walk is found alot in overhead engines and also found in turbo engines because they like to burn piston rings. I'd consider that a possibility considering u bought the car in the shape that it was....
While you are right that OHC motors can crank walk, the 1st gen turbo motors rarley crank walk at all. The 2nd gen motors, however, are very famous for crank walking.
I have since diagnosed the problem, and it was a combination of a free-flowing exhaust, a bad TPS and oxygen sensor, and a very old fuel filter. As a result of the boost creep, the exhaust turbine took a dump and started shooting ball-bearings out of the exhaust. So as of now, I have installed a 16g turbo, a new TPS, o2sensor, fuel filter, manual boost controller, an I rewired the fuel pump. It runs pretty damn good now (at 16 psi).
All this turbo stuff is really making me want to turbo my escort even more!
Thanks for all your advice, and may this will help some of you guys diagnose similar problems.
 
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