Vince's TBI woes, progressive revelations, and tbi mods.

[Snoots]

I had mine do this once. I drilled an .060 hole in the cap inside of the seal...end of problem.

 

[Vbb199]

Apologies to my friends here lol, i never ask technical questions

 

[Snoots]

Alright then, run it damn near dry then fill it with 91 octane. Run it for 15 miles and then bury your foot in it until the valves float.
Let us know how it runs after that.

 

[Vbb199]

Alright then, run it damn near dry then fill it with 91 octane. Run it for 15 miles and then bury your foot in it until the valves float.
Let us know how it runs after that.

Thats all i run in it. 93.
WONT run anything else.

Spark knocks with anything else anyway

 

[Vbb199]

But ill drill a little hole in the cap to let the gas flow smoother

 

[Vbb199]

Ok,
At half to 3/4 throttle i feel plenty of power if you know what i mean. At wot, its very sluggish.... I heard something I've never heard before just a bit ago. Passing a suv, i got on it at wot and i heard misfiring, maybe even timing retardation.

I could hear the misfire resonating off the car next to me .
It wasnt a harmonous misfire, it was on and off.


So i immediately think to myself , ok maybe the cap is bad, but if it WAS, i should be hearing misfires at all rpm ranges.... then i got to thinking. I bet the bearings are worn out internally in the dizzy causing it to jiggle around and misfire...

So, that said, does anyone have any experience with those accel distributors?

Ill be posting a new thread asking about them

 

[Snoots]

Ok,
At half to 3/4 throttle i feel plenty of power if you know what i mean. At wot, its very sluggish.... I heard something I've never heard before just a bit ago. Passing a suv, i got on it at wot and i heard misfiring, maybe even timing retardation.

I could hear the misfire resonating off the car next to me .
It wasnt a harmonous misfire, it was on and off.


So i immediately think to myself , ok maybe the cap is bad, but if it WAS, i should be hearing misfires at all rpm ranges.... then i got to thinking. I bet the bearings are worn out internally in the dizzy causing it to jiggle around and misfire...

So, that said, does anyone have any experience with those accel distributors?

Ill be posting a new thread asking about them

I just installed one and have less than 100 miles on it. No issues yet. Is it possible that your +12 line to the dizzy is not making good solid contact?

 

[Vbb199]

I just installed one and have less than 100 miles on it. No issues yet. Is it possible that your +12 line to the dizzy is not making good solid contact?

I failed to add, the distributor is 333k miles old. Lol

 

[Vbb199]

Just took the truck for a pull with my vaccuum gauge on the windshield, put the engine under load at WOT thru all gears, and vaccuum never dropped more than it normally would.

So im to assume ignition is the culprit

 

[Snoots]

I failed to add, the distributor is 333k miles old. Lol

Ouch!

 

[1987 GMC Jimmy]

I don’t know the official displacement, upgrades, stock components, etc., but in a stock setup, the first thing that came to mind was oxidation on the distributor cap pins, especially if they’re the aluminum kind (always get brass). If the distributor is that worn, and not rusted, rebuild it. Bushing, gear if needed, a Delco pickup coil, and the rest of it is an easy replacement. If that’s not it, my next suggestion would be the clutch in the torque converter starting to fail. It’s obviously not losing vacuum and likely not fuel either. So I’d keep it to ignition mechanics, ESC/EST, and the like.

 

[Vbb199]

I don’t know the official displacement, upgrades, stock components, etc., but in a stock setup, the first thing that came to mind was oxidation on the distributor cap pins, especially if they’re the aluminum kind (always get brass). If the distributor is that worn, and not rusted, rebuild it. Bushing, gear if needed, a Delco pickup coil, and the rest of it is an easy replacement. If that’s not it, my next suggestion would be the clutch in the torque converter starting to fail. It’s obviously not losing vacuum and likely not fuel either. So I’d keep it to ignition mechanics, ESC/EST, and the like.

355 technically, vortec heads, 10.5:1 c/r.
Cam specs isnt really relevant i guess.
TC is brand new, not a oreilly tc either. HQ from a local bench built company. Trans also has less than 2k miles on it
After discussing with dad, the original dizzy was never replaced. Its as old as the truck.

He just slapped a bare built long block in and put everything back that was on it from the mfg.

But im with you i feel sure this is definitely an ignition problem.

Seems likely it must be the distributor bouncing around internally since its a WOT problem only.

I just placed an order for a accel dist, brass towers.


Ive been wanting to get a msd 6al box and coil for sometime, but not this soon! Lol

 

[AuroraGirl]

a lmost sounds like maybe injectors that arent spraying nice and fine? Clogged?

 

[Vbb199]

The thing straight up feels like im towing 10,000 pounds behind it at WOT.

Terrible.
Not to mention, the knock sensor is detecting those misfires and retarding timing as well!

Double whammy!

 

[Vbb199]

a lmost sounds like maybe injectors that arent spraying nice and fine? Clogged?

Tbi was rebuilt less than 8 months ago. But i did recently look at them, its still a fine mist thru the rpms.