need help want to shoot myself

check ure vaccum lines, a broke or open one can cause it to backfire

Check for codes. My guess is the module or the pick-up in the dizzy

First I will suggest something stupid, did you put the diode back in by the distributer? Ya know the one you pull to set timing. Now the not so stupid thing. AOD Foxes have more agressive timing in the computer than sticks so you may need to pull a little timing out of it

LaserSVT said:

First I will suggest something stupid, did you put the diode back in by the distributer? Ya know the one you pull to set timing. Now the not so stupid thing. AOD Foxes have more agressive timing in the computer than sticks so you may need to pull a little timing out of it

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AHA! That might explain why Frankenstang's '89 notch doesn't take well to timing advances of 14* or more in the summer.

Another kinda stupid suggestion: Your car has been sitting since august? What about your gas? Is it 5 month old gas you're running through it? Just a thought.

I try to think of stupid simple things first, as I've gotten tired of spending tons of money replacing parts only to find something as simple as a stupid vacuum line broken.

Did you put the ground wire back on the bellhousing bolt? Put in some fresh fuel and a couple bottles of dry gas or a bottle of Seafoam and try that.

Try the TFI module, contrary to popular belief I learned that they can gradually go bad. When I did my AOD to T5 / engine swap a couple of months ago, my car would buck at low rpm's (a load on the engine). Then after a while it started dying at idle, I kept suspecting the TFI so I took it off and tested at Autozone 20 or 30 times straight so it would get hot. It passed every time. So I went to the JY and got a TFI, put it on and the car worked! So I ended up getting a new one and havent had a problen since.

LiquidGT said:

Try the TFI module, contrary to popular belief I learned that they can gradually go bad. When I did my AOD to T5 / engine swap a couple of months ago, my car would buck at low rpm's (a load on the engine). Then after a while it started dying at idle, I kept suspecting the TFI so I took it off and tested at Autozone 20 or 30 times straight so it would get hot. It passed every time. So I went to the JY and got a TFI, put it on and the car worked! So I ended up getting a new one and havent had a problen since.

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I had them test my old tfi twice and it Failed twice so I bought a new one and I didn't feel a difference but anyway, check out your cap and rotor for moisture....I found moisture in my friends cap and it stumbled and missed under any Load.....worth a shot, let us know what you find out.

What comes to mind:

A) Vacuum
B) Fuel Pressure
C) Distributor


Which of those have you touched, cause like someone here told me, when you work on a car and you find a new problem you need to retrace your steps because it doesn't magically appear out of no where.

My guess is that tranny install has 100% to do with it.

Once you have followed all the advice about looking for vacuum leaks and other similar problems, do this cheklist.

Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, or misconnected. Check the line for the vapor recirculation system – it is easy to knock loose and not see it when you connect the air pump plumbing. If the vacuum line for the EGR valve and the air pump are cross connected, some very strange things can happen. Check the mass air flow electrical connection and see that it is tight, the same goes for the fuel injection wiring harness connectors up on top of the manifold near the firewall.

Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches.

Lean fuel mixture breaks out into several sub categories:
A.). Vacuum leaks
B.) Air entering the intake without passing through the MAF.
C.) Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D.) Leaking exhaust gases from EGR valve at WOT or EGR opening when it should not be open.
E.) Poor fuel delivery due to bad fuel pump, clogged filter or bad fuel pump wiring. Look for low pressure or fluctuating pressure. Standard injector pressure is 39 PSI at idle, with the vacuum line disconnected from the regulator and capped.
F.) Clogged fuel injectors.- see the cylinder balance test below
H.) Fuel injector wiring problems causing injector not to deliver rated flow.
I.) Computer problems: (computer problems are not common like sensor problems)
J.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
K.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one. Use a noid test light to test the injector wiring & injector drivers,
L.) MAF calibration off or mismatched to injectors.
M.) ACT or ECT bad. Sometimes the sensors will be off calibration, but not bad enough to set a code. If they falsely read too high a temp, the engine will back off fuel delivery.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure