Finally figured out what was going on with 91 Camaro Rs Tbi Original intake 350 from Caprice below it. Automatic. Couldn't figure out why my tach keeps jumping around like crazy. Maybe a short in blower motor cause it stayed on the other day and drained my battery. But any ways it was running like crap my tach keeps jumping all over the place. Finally narrowed it down to the electronic timing. I disconnected the brown and black wire on passenger side of engine conpartment. And bam no more rough idle and tach sits still and it doesn't feel like I'm going to throw a rod on the highway. After that I manually adjust timing some to the advance so it would run better on highway, notice a drop in horsepower off the line. But its give and take I've got it now where I can drive it. So I'm thinking I should just be able to put and vacuum adv. and/or mechanical adv. dizzy in there and it couldn't be worse than it is now? Then later change over to a carb. I don't care about gas mileage or performance. I sick to death of this damn computer and I'm making it my goal to rip it out and go all mechanical. I also know by changing the dizzy the computers not going to know whats going on, but it doesn't know what its doing now. Probably already running too rich or lean. I just need to know what kind of old dizzy to get and how to connect it. Like splicing wires to new connector and where to run vacuum line to. If the computer just is going to default and give it (default) gas it probably already is. It idles fine. Just need power back at take off then something to advance the timing on the highway if I'm right on how it works. Any help would be appreciated thanks in advance.....

 

Help....

 

I'd try a new EST module (in the distributor), but you can certainly replace it with a vacuum advance one as well.

 

Got a new ignition module in distributor. Then replace dizzy with stock one from junkyard and still does the same thing when the adv. timing wire is plugged back in. Never heard of EST but I assume its the thing the green and yellow wires come from in the middle. But then they would have to have both been bad. I'm just hoping a vacuum dizzy will work fine.

 

So anybody know?????

 

I thought the ECM needed to control the timing in order to run the TBI in closed loop? Which it would not have with a vac advance distributor.
It may have something to do with the knock sensor giving false knock counts. You need to see if you can find someone with a laptop and WinALDL and do a data log.
It has to be throwing codes if it's running that crappy.
Atleast fetch the codes.
If you change it to a vac advance system, you'll have to convert it to non-cc carb also.

 

Bad ECM?

 

or even loose ground wires.
(that's my "Sofa Bolt" answer)

 

You can't do what your thinking. You need to check the ECM codes and check for loose/bad wires. You might have a bad component in the ESC circut or a bad ECM.