Have an issue with my 93 chevy truck. It has the 305 tbi and when its first started and the engine is cold,everything works fine. Once its warmed up and you stab the throttle it wants to bog and then slowly comes up.Any idea what this might be?Thanks

 

https://www.thirdgen.org/forums/tech-general-engine/500226-i-need-some-help.html


another thread that has been started that contains what your looking for.

 

That link was no good.I`m curious myself.Seems to be a fairly common tbi issue.Mine does it after it warms up as well.My parents had a van that did it.I remember my dad pulling out his hair trying to fix it back in the day.

 

hate when a link gets moved :/ anyways.
can be a number of things to cause this problem. Bad fuel pump, injectors cutting out, ECM failure, vacuum leak, bad spark plug wires, plugs. Any codes? Anything other information would help to try and narrow it down.

 

Well open loop vs closed loop... Cold vs warm operation... O2?

 

Mine does it when its warmed up.guess I could dattalogg it and see if nything looks outa wack.

 

Ill check my codes and see.No engine light on or anything.

 

how is the injector fuel spray pattern? is it a nice cone?

 

i ahd a truck like it too... camshaft maybe?

 

Injector spray pattern looks good.Nice conical spray pattern.I think it may be crappy gears.Or they atleast make it worse.If I punch it from a dead stop it seems to do fine.If I give it some gas and let off because ,say a car is taking too long to turn,It will shift to 2nd.Then I give it more gas and it seems to just bog down and very slowly accelerate.

That describes what mine does anyhow.

 

What is the timing set to? What is the fuel pressure? When did it start to do this? When was the last tune-up? All kinds of things can cause this!!

 

It`s done it since I bought it about 3 years ago.Never checked fuel pressure or timing but when it`s hot out and engine is at operating temp I sometimes hear pinging.I suppose I should check it.It`s my daily driver And I`ve done as little as possible to it while getting my car project running.I do service it regularly.I`ve replaced plugs,cap rotor once and wires twice in the last 30,000 miles.It didnt change how it ran

 

my camaro is doing the samething ive been taking to midas for the past couple of days and we have changed the o2 sensor, fixed the exhaust leak, and replaced the throttle position sensor on the side of the TBI and readjusted the timing it has helped a butt load but you can still tell there is something wrong