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Discussion Starter #1 (Edited)
Fast/slow/fast/slow....

I am looking for some advice if anyone knows WTF is wrong with my 93tt. Sometimes the thing just flies and other times its damn slow.
I have replaced the fuel filter, plugs, clean k&n and no consistency. I am running 12psi on a stand alone mbc.

It seems like sometimes at 1/3 to 1/2 throttle the car wants to go faster than WOT. I've checked the tps >ok, I'm thinking maybe injectors, just wondering if anyone has encountered any symptoms similar to this. It will take off from a stop and I can actually feel the power drop off in first ; also if I try to hold the revs at approx 3k it stays for a few seconds then drops to 2500, is this normal? Any help would be greatly appreciated. Oh yeah intake pipes are tight. Thanks
 

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Vacuum Lines

check all of your vacuum lines (connections, condition, cracks....) You described the exact prob. my 300ZX Turbo was experiencing....it was deteriorated vacuum hoses/lines

Demetre
 

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Vacuum Lines

check all of your vacuum lines (connections, condition, cracks....) You described the exact prob. my 300ZX Turbo was experiencing....it was deteriorated vacuum hoses/lines

Demetre
 

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Discussion Starter #4
All the vacuum lines are fine, I've checked them all, although I have gotten a Check Engine light for O2 sensors a few times, which could point to an intake leak somewhere.
 

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EGR

The check engine light could also indicate a problem with the gas-resurculation system (EGR), which is vacuum operated...check the EGR routing for leaks...

D
 

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Discussion Starter #6
All the vacuum lines are fine I spent a day checking them all . I guess this is one of those times you keep f'n with it till you get it. I just want to drive fast. Any other input is appreciated.
Thanks
 

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Wastegates

Try looking at the Turbo wastegates or the wastegate selonoid...it could be opening / closing prematurly....try a search to find the diagnosis if you don't have the repair manual

Demetre
 

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Discussion Starter #8
Been there done that. I am running a manual bleeder with a check valve so that eliminates the possibility of the solenoid or a vacuum leak. Maybe my car is possessed?? I have followed the factory service manual. Running out of possibilities , maybe I should hook up an a/f guage to see it its my injectors dropping off.
 

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leaking BOV?

don't just visually check your vacuum hoses, build yourself a pressure tester for the intake and test it at like 7 psi and then work your way up from there till you hit the 12 psi you are boosting at. Maybe you'll find a leak that otherwise couldn't be detected my just looking at it.

If you have a CE light for the O2 sensors, then replace them. Replace the obvious stuff first :). You car will run rich with the CE light so throttle response won't be what it should be.
 
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This happens to me also. My car is smooth and more powerfull at 80% thottle than WOT. She will allways run 100% at 80% throttle but at WOT it is weaker and seems to sputter a bit. A/F still shows rich, so it is not a fuel cut out prob. The hesitation in and out is not severe or a hard jerk, but I can feel it. Like a slight miss. So mostly I run her at 80% throttle when I want speed.

It's real annoying!
 

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Discussion Starter #11 (Edited)
I have an APEXi BOV and I did pressurize the vacuum lines, tight as can be. I was also considering changing the 02 sensors but every thing I read says a bad sensor does not affect WOT,it achieves closed loop and ignores it, but who Knows , I figured the same about the 02 sensors , thinking that if the computer sees a certain reading before WOT it adjusts everything else accordingly giving less fuel and timing.?? The light rarely comes on and come to think of it I haven't had a CE light in quite some time but still I get the same behavior .I think its time to buy a datalogger. Anyone have any experience with one?
 
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