Fast and Slow?

Is anyones car slow one day, and fast somtimes. Somtimes it hauls and somtimes it's slow, my other one did this, why is this?

Do you always run the same grade of gasoline from the same station? A bad tank of gas can cause detonation, which the EEC combats by retarding timing (by a total of 7 degrees, I beleive). Under WOT when the car is only running about 30º total ignition advance (base ignition timing + computer controlled timing), 7º is quite noticeable. Try disconnecting your knock sensor (be SURE to run premium gas and a safe amount of boost if you choose to do this) and see if you notice a difference.

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Estoril blue 1987 TC 5spd, 136k miles
k&n cone in fenderwell, PRofec B electronic boost controller, kirban adjustable fpr set at 44psi base, walbro 255 hi-pressure pump, Stratmosphere Forge bypass valve, ported e6, volvo front mount intercooler, t3/t4 50 trim / stage III .63, full 3" exhaust, eec-tuner, 55pph injectors, dave compton a/f meter, Nitto 555R drag radials
Best 1/4 mile (before tuner, turbo, injectors, drag radials): 14.120 (with 1.983 60' time)
Best trap speed: 98.44mph

Outside air temperqture can have a big effect on how they run. Cold = good, hot = not as good.

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NATO Member. it's not a vice, it's an obsession
Good judgement comes from bad experience, and a lot of that comes from bad judgment.
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm

Heat & Humidity are the two biggest negative factors on a 2-3T motor.

Same here, it's really weird. The power difference is especially noticeable if I suddenly punch it in second gear. Sometimes it'll shove me back in my seat, other times it doesn't pull nearly as hard.

A good tuneup helps if it's really starting to lose power, but some variation seems to be pretty much normal.