trouble with shelby need help

[Brdokcshelby]

i have a 89 shelby and when you get on it. The car starts jerking. It drives fine under 3500 rpm. would it do that if the turbo is shot?

[AWP9521]

Need more information.

1) What RPM is the engine at when it starts jerking?

2) When the engine starts jerking does it misfire or completely die then come back to life?

3) How many PSI is the Boost Guage reading before it starts jerking?

4) Is there any light blue smoke coming out of the tailpipe?

5) If you remove the outlet hose to the Throttle Body from the outlet of the Turbocharger is there any oil present in the Throttle Body, Hose, or Turbocharger?

6) Does the Turbocharger make any unusual and loud noises when spooling up?

[Brdokcshelby]

Originally Posted by AWP9521

Need more information.

1) What RPM is the engine at when it starts jerking?
3000-3500
2) When the engine starts jerking does it misfire or completely die then come back to life?
it doesn't die
3) How many PSI is the Boost Guage reading before it starts jerking?
0
4) Is there any light blue smoke coming out of the tailpipe?
nope
5) If you remove the outlet hose to the Throttle Body from the outlet of the Turbocharger is there any oil present in the Throttle Body, Hose, or Turbocharger?
willl check
6) Does the Turbocharger make any unusual and loud noises when spooling up?

nope it doesn't get a chance to the car starts jerking before then. As soon as you put you foot into it. It starts jerking. i changed the fuel pump and filter.

[AWP9521]

ok the fact there is 0 boost even at 3000 suggests a turbo problem or possibly the wastgate actuator may be bad ir the arm is broken. pull off the turbo's intake hose and see if you can spin the turbine by hand to make sure it isn't seized up, then check the wastgate actuator and the rod that goes to teh wastgate, sometimes at the very end of the rod it will break off rendering the wastgate useless and keep boost from building. it almost sounds like you have a backpressure problem like a bad catalytic converter or seized turbo and it's not letting the engine breathe. Also I have heard that cam timing may also do that, so you might want to check that.

[600KLancer]

If the turbo is totally shot the car is not going to jerk. It just wont accelerate as fast.

[1thunder]

or maybe over boosting and shutting injectors down
if someone replaced the MAP sensor and installed a natural aspirated one it will go into over boost at very low RPM