Okay.. Aside from the possible IAC/TPS problems I asked about in another post... Something is making my car very sluggish.

The timing is set to 8*BTDC and that runs great. When in neutral it revs up very fast.

I thought it might've been the tranny since that was giving me problems.. but it died and I had it replaced and it's the same. (It just shifts better now. )

It's a 305 tbi.. Both injectors look like they're firing plenty of fuel.. although admittedly me looking at it isn't an accurage gauge. heh The gauges all operate within normal paramaters... the engine doesn't knock or have that many problems.. it's a very smooth ride up until about 90mph when it starts to shake but I think that's more of a suspension problem. heh

Does anybody have ANY clue what might be causing the low performance?

It's almost completely stock.. The tranny is, as I said, new.. The AC unit is a R-134 retrofit... and the muffler is new, and quieter than stock.. although quiet doesn't mean less powerful.

I wouldn't complain so much if I didn't have a friend who's car is all stock but the muffler.. He's got a 92 Firebird 305 TBI... His car could dance in circles around mine. Could GM have in just those three years really have improved the 305 tbi's that much?

maybe I just need one of those 400 dollar tuneups. heh

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89 iroc-z
everything stock, except for a mirror that fell off

 

My car shakes around the same speed. I thought it was probably my front tires being out of balance. They need replacing. Now you have me worried, you are the first person with that problem that I have heard of, and the fact it starts at the same speed.

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Godti
'89 Trans Am (Red)
305 TBI 5spd

 

Alot can happen to a car in 10 years. There is nothing unusual about finding 2 10 year old identical engines, one much slower than the other.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

I have similar problems, but I think they are because my tires are outta balance. At around 5-10mph, my car wobbles from side to side, then around 65-70mph, my car shakes, and my rear hatch rattles like a ****, then at around 85mph, my car starts to shake real bad. I have only had my car up to 85mph once, but I am sure that it will happen again. Wierd. During the periods when my car is not at those speeds, there is absolutuly no shaking at all, and I can't even tell that something is wrong.

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Houston f-body Member Page
Home Page (and pics of my car too!)
1989 305 tbi Camaro RS Red/Red
Flowmasters
K&N

 

According to my Chilton's manual, the TBI motor was rated at 150 H.P. in 1989, and 170 H.P. in 1992. So I guess even if you get yours to run perfectly, you're still looking at a 20 horsepower difference between you and your buddy's car.



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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."