Ok, my car has a good amount of go under 3K but when I try to pull above that, it sputters like crazy, I am really getting mad at this, and I really cant figure this out. I am pretty knowledgable about car stuff, and nothing comes to mind. Plus it changes all the time, one day it will do it, one day it wont, only when hot, only when cold. If you are wondering, cap and rotor are new, new plugs fuel filter, and wires. And by new I mean REAL new, My car is an 89 Firebird with a 305 TBI. My thoughts... Could it be a vacuum leak, that makes my advance bascially not work, or do I have mechanical advance. What about my timing chain, is it bad? Any help would be greatly appreciated. My car would perform so much better if this were fixed. Thanks guys,

 

Also, just for kicks, what is taht little round thing that basically right behind the TB that is supposed to have a vacuum hose on it, but doesnt. I felt the tip with the engine running, and it wasnt sucking through, so I though it was pointless anyways.

 

Any open vacuum lines, junctions, etc. I'd plug just to be sure. I've got a V6 and rarely go to any board besides the sixer board...but...how's your timing? I imagine if your timing is advanced too far you'll have killer low end but the car will struggle at the top. I assume you have a good air filter and there's nothing in the assembly that would be choking it..? So..it sputters at the top end? Sounds like it's not getting enough air to me....I hear the TBI's have a problem with breathing at the upper end but I doubt it's THAT severe.. How's the idle on it? If it's vacuum, it'll BARELY idle. Buddy of mine with an 84 T/A left one vacuum hose off accidentally and the car refused to idle..stalled every time.

 

Sputtering at high RPMs is not usually caused by a lack of air, but rather by lack of fuel. Sounds to me like you have a fuel delivery issue of some sort; you say your filter is new, so if it's not that it could be a dirty injector, weak fuel pump, restriction in a line somewhere including inside the tank, etc.

The little round thing is probably your fuel pressure regulator. It's supposed to be hooked up to a vacuum supply, probably off the base of the TB, with the shortest hose possible. I don't know off-hand where the connection is supposed to be since I don't fool around with TBI, but I suspect if you just look around within 6" or so of that connection, you'll find a vacuum source that's either an open leak, or has a plug on it.

There's a BIG round thing, more than half the size of the air cleaner flange, somewhere near the TB. Again, I don't know exactly where, but it will be somewhere close by. That's the EGR valve. It's supposed to have a vacuum line going to it that comes from a solenoid, also located on top of the intake somewhere near the TB. Having it unplugged isn't a good thing, but won't cause the symptoms you describe.

You don't have either mechanical advance or vacuum advance so that's not the problem.

A bad timing chain will cause far worse problems than you are talking about. It's not that.

 

Thanks for the help guys, I will try fuel injector cleaner, and maybe check my fuel pump somehow. I hope to get this problem fixed. Thanks,

 

You could also check the distributer shaft is not worn, by checking how steady the timing remains through the rev range. It will advance but should hold fairly steady when the engine is steady at revs.

The randomness of it, makes it sound like maybe the timing going out at high revs. It will put everything else out including the injectors.

 

OMG! Thanks alot RB83L69! Yeah, there is a line coming off of the front of the throttle body, and it is supposed to go over to that fuel pressure regulator, but instead, it decided ( ) to go over to a different T-connector that probably had NOTHING to do with fuel and pressure regulating. I am so happy, I went out, and put it in first (Automatic) to see what it would do pulling to 5K instead of the factory shift of like 4250. And it pulled pretty damn good! Now I will mess with the timing and get it right. I am sure this will help my gas mileage too. I hope. Thanks for your input. If I had money I would send some your way, but Im pretty well off broke. Thanks again.