My stepson has a Firebird that I like to call a FrankenBird thanks to the PO.
It is an '85 'bird with a 350 Mr Goodwrench longblock ... and the intake and engine mangment of a late '80's camaro TPI.
the engine wiring harness runs down the passenger side of the car and the original FB runs down the drivers side. WHEEE.

Well the boy and I have been trying to figure out what's been going on with the engine and I'm almost out of ideas. He was driving , lets just say agressively, ok,ok he was racing ! Well something happened to the engine and he didn't tell me and kept driving it. It still runs but rough.
we found that all plugs on the passenger side bank are black with carbon. The drvrs side bank all plugs look good light tan to white.
I had him replace all plugs and wires.
For some bonehead reason he drove it to his girlfriends and back and it ran so bad that he has left it sitting now for months (I'm not fixing the car without him there doing most of the work).
We pulled the plugs to do a compression check. the plugs on the pass. side are carboned over again(dry), the drvrs side look brand new. the compression looked good, a low of 130 psi to a high of 140.
I'm lost. why one bank would run so rich ???? leaking injectors? restriction in the exhaust ? it does have a heat riser flapper in the exaust on the pass.side so tonight (hopefully) we/he are going to pull the y pipe and check that the flapper isn't stuck in the closed position.

ANY help would be apreciated (and sorry for the book that I just wrote)

Tony

 

The 85 Firebirds also had the TPI systems in them, and on my 83, the wiring harness goes in on the passenger side. The only real difference usually with the birds and camaros was the sheet metal. It may have a vacuum leak, or you may well be on the right track, You should be able to move it on the outside without having to drop the y-pipe, those manifold bolts have a nasty habit of snapping off.

 

Thanks for the response. the PO's father is the one that told us the routing of the wiring and what was done to it. You are right about the TPI in '85 (but it was the 305 not a 350)

 

there were a few 350's, but not many. The system trades off ok though, they are close enough in cubes the computer isn't affected. Sounds like the PO's father doesn't know as much as he thought... for reference, I had 2 T/A's, one crossfire injection, one feed back carb, both ran the engine harness on the pass. side, where the computer is pretty much always located. Stepson had an 83 Camaro, feedback carb, wiring on pass. side. Friend has a couple Camaro's, feedback carbs, pass side wiring. Wouldn't make a lot of sense to run the wiring in on the driver's side when the computer is on the pass. side. Part of the harness may go there, but not all of it.The harness spilts in half on the driver's side, half going to the engine for guages and such, the other half going to the headlights and other lights. The engine control harness will still run on the pass side, through to the computer.

 

First thing I would do would be to pull codes. If you're concerned about the valve in the y-pipe, you can inspect that without the hassle of dropping the pipe. Just reach down there and rotate it with your hand.

 

My biggest issue with the valve in the y- pipe is that it is vacuum operated and I haven't been able to locate a vacuum source for it.
I wasn't sure if it is normally open but we found out yesterday that it is normally open... not an issue. now we are carefully pulling out vacuum lines and are going to remove the plenum to check for disconnected wires vacuum lines or holes in hoses...exc.
Thanks for the responses guys!
Tony