Thank You.

If you have a vac gauge, hook it to intake vac source .
As you increase the rpm , you will see more vac ... hold the throttle at 2500 and watch gauge ... if it drops off [ less vac.],
the cat is not allowing passage..-[ engine can not breath, restricting amount of intake air needed ]

Check your ignition coil while you're at it.

I disconnected the pipes at the exhaust manifold. Now the car still is very rough when stepped on, with no power, but now is back firing. What do you think?

I'm thinking possibly the cam has jumped timing.

Gilly

Wouldnt it do that with the pipes still attached?

Yeah, but you might not hear it very well.


Gilly

just so you get the whole picture. Idles fine, when stepped on slowly exhelerates smoothly, when stepped on hard anytime, hesitates then runs very rough attempting to gain speed, ( kicks in to lower gear fine). If backed off a little during accel engine smooths out. Since exhaust manifold seperated can hear backfires when pedal backed off. What am i missing?

levi

OH! THAT'S what it's doing, Oh, OK.

Gilly

Correction Engine backfiring during acceleration and deceleration.

Backfiring through either the exhaust (which I assume is where yours is backfiring from) or through the intake is an strong indicator of either the cam timing or ignition timing being incorrect. I still think it's very possibly that the timing has changed, like a jumped timing chain.

Gilly

Thank you.

levi

Before I tear into the timing chain, I was wondering why it wouldnt back fire during easy acceleration. What advances the timing during heavy accel? I know that you can adjust the distributor back and forth and it makes no change. Is that controlled by the computer? Do you think it is a vaccuum problem, if so where would be the first place to check?


levi