It backfires through the intake, then it revs real high on it's own, then it goes back ot normal.

New plugs
Wires
Distributor cap
Rotor button
Coil
all that stuff plus more.
Tpis/IAC all set to perfect specs

Can't figure it out and want to drive the damn thing. Getting more impatient and loosing interest in it. Timing is fine to.....

Help me please before I pull what little bit of hair I have out. :D

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I would suspect either of these two somehow being the problem, even though you've spec'd them both.

Either that or you have a massive vacuum leak?

Luck, man.

Backfire through the intake is generally timing related. Double check everything with the distributor. Did you remove it and reinstall it? Could be a tooth off. Check everything inside. When you reset the timing did you disconnect the EST wire? How is your harmonic balancer? Worn? Are you sure you have TDC?

High idle can be a vacuum leak, IAC, work TB shafts, multiple things.

Matthew

I agree; it sounds like a timing problem.

High idle can even be caused by a timing problem... keep that in mind.

There is no way to check the distributor; if it had been removed, it's time to do it again.

Make damned sure that #1 cylinder as at TDC - remove the plug, and bump the starter until it is there (or REAL CLOSE) to being there. Then install the distributor, with the rotor installed, and pointed at the general area of #1 plug wire. Put a mark on the distributor body (sharpie?) to indicate where the rotor must be once the distributor is fully seated. If the distributor is off, you could technically compensate for it, but that would mean that 6* BTDC could now be too advanced to too retarded, depending on which direction the gear is off.

The reason it's idling high after a backfire is because the MAP sensor goes haywire with all that positive pressure it's seeing.... takes a second for the computer to clear that stuff out then adjust the IAC motor.

Backfires mostly happen because of low extremely low timing or burned or miss adjusted (too tight) intake valve(s).

Easiest way to narrow it down is tell us what you've been working on.
Will

Will - don't ask - he has been working on pretty much everything.

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This may help

http://www.corvetteguruforum.com/modu ... id=191911#forumpost191911

Got it, thanks Tommy!

Kid-
1. Double check the firing order. 1-8-4-3-6-5-7-2

2. Double check that all the plug wires are seated on the cap and the plug.

3. If those fail, I'd start checking for fire at the plugs... if you find a dead one, ohm the wire, check the terminal on the cap and replace the plug.

One other thing.... A long time ago (1992) one of our race engine customers put a new cap, rotor, wires, plugs ect on his Hobby Stock car (HEI dizzy). It was backfiring and busting up like crazy... took me a few mins of trouble shooting to find he had left the rotor button screws loose.... So check that.

Will