TBI timing issues, runs good with tan/black wire disconnected

[cmobile]

95 350 TBI suburban. Base timing is set to 2* with tan wire disconnected and runs okay. when I shut engine off, plug in tan/black wire, it barely runs.
Why won't it run with base timing at 2, and ecu wire plugged in?

When the wire is plugged in, it back fires around 2500 RPM, shudders and shakes, then dies.

Stumped.

 

[Fordum]

Isn't it supposed to be set at 0* with the wire unplugged? Someone will chime in to tell for sure, but I know a lot of them are that way...

 

[cmobile]

Yea, I believe 0* is factory, but lots of folks advance 2-4 degrees for some better performance. I put mine at 2 and realized better gas mileage for the past few months. No pinging that In can tell.

I was gonna try 4*, so I set base timing to 4, then Re-Oringed the TB and put in new regulator diaphragm. I have Ultimate TBI Mods, and adjustable fuel pressure regulator. After this, I start the truck, and herein lies my problem. not sure what I did.

 

[smier]

Did it run ok before you changed everything? If so I'd reset timing to 0*, I've read you can get away with as much as 6*. Then reset the computer, and then don't forget it takes 20 or so minutes for the computer to "relearn" how to run... I'd start there, double check everything is working properly and then tweak one thing at a time... I try to only do one mod at a time so I know if and when I screwed something up. You mentioned an adjustable fuel pressure regulator, what's it set at?

 

[cmobile]

okay I found out some more info. It ran great for months at 2*. I planned on putting it at 4 to test.

A buddy of mine and I were working on it changing front pitman and idler arms. I left to run some errands. I cam back and my buddy said he tried to adjust timing but couldn't find my timing light. So he adjusted the distributor "by ear". This was the other day. Turns out he couldn't get to the dizzy hold down nut so he thought the distributor was loose enought to tap on the side of the cap screw with a long screw driver and a hammer. I noticed when I saw the edge of my cap where the screw hold down is all munched.

Since that day, I have been driving with the wire disconnected, I assumed he had the timing all off since he did it "by ear". Yesterday is when I went to adjust my timing back to normal and replace the diaphragm. I assumed when I set the timing back to spec, it would be okay. Unfortunately that's not the case.
Gotta rent the fuel gauge to see where fuel psi is at, but I marked the disc and I know it is close based on the mark and current spray pattern. Will rent it today to know for sure.

Did he screw something up by knocking on the distributor cap hold down screws with a screw driver and hammer?

At Base 0*, it will barely run if the wire is connected.

I am at a loss. the dizzy is new.

 

[4X4HIGH]

Tell your "buddy" to go beat on his own crap with a hammer and screw driver and leave your stuff alone from now on.

I would pull the cap and take a peak inside the distributor to make sure the rotor isn't making contact with the cap anywhere and that the wires from the pick-up coil to the ignition module aren't bare and grounding out somewhere. "Might as well" install a new cap and rotor since you'll have it off anyways if it hasn't been changed in a while.

 

[cmobile]

His only saving grace is he installed the idler arm without any help from me. Told him don't touch the technical stuff. Anything with a wire to it.

I'll check the cap this evening. I just put that cap on. Came with the hypertech High Power coil.

Gotta figure out why timing reads okay but acts like it is so far off. I set the timing at 15* base and then plugged in the wire, ran much better but of course the computer retarded it back to 8*. I think he did something else and is no telling me, the knucklehead.

 

[sweetk30]

just a idea here

if he used a hammer / screw driver to set timming. . . .

how good a job he do on your steering parts ?

you realy need to recheck all his work or it could be a 70mph highway death machine when somthing falls off.

oh ya and what evers broken in the dist make him buy new for you.

 

[Fordum]

It may be a new dizzy, but now it may be a new FUBARed dizzy.
There is no telling what he may have done with that hammer. The cap could be lopsided on the body, he could even have cracked the housing of the dizzy, but I doubt it.

Pull the cap, take off the rotor, examine both carefully for damage. Make sure the wires are on the right sockets. Look very closely at the advance mechanism.
Sounds like he damaged something, you are just going to have to spot it.

Are you sure he did not pull the dizzy out and put it back a tooth off???

I know the lockdown screws only hook up in one place, but could he have shifted the cap on the housing by breaking the little alignment tab?

 

[diesel4me]

I've seen some later distributors have the shaft the rotor bolts onto come loose from the "main" shaft and let the rotor slip out of time---..