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Hi,
To answer this, “I had ac replaced This backfiring started after new ac
Would compressorhave anything to do with it,” I will have to say no!
The A/C is a separate system altogether ... Especially, if it’s off. If it’s on you just have extra loading that needs more power so more fuel.
Backfire can be a slipped timing belt but hard starting goes with that. You said nothing about it.
What could and most likely happen is the accordion hose behind the AMM could have been damaged. You have done a lot of work in that area.
The number one first cause of Back Firing is usually a result of too lean of mixtures or too much air to the amount fuel.
From looking over what you have done to the car it seems you were chasing another issue and it has gotten worse or for sure is still there.
Upon acceleration or punching the gas pedal a lot of things have to happen in sequence but more or less all at once.
The throttle switch is first to tell the ECU we are wanting to power up so it says we are going off idle right now.
While idling the AMM is already changing its signal from a correct one, we hope, but only if the accordion hose is good! If not, that there could be part of the problem. Low power can be a malfunctioning AMM but always save that for last!
You say you were cleaning it. That you have to be careful in doing that.
A direct blast going down the throat through the screen should be done from a little distance.
On some AMM’s there is a very fine wire strung around inside these units. It’s the only thing that senses the air mass from temperature changes. No moving parts to get gummed up like vane type AMMS.
The next thing is when the pedal is punched down more is the vacuum drops and goes to more atmospheric pressure. There is a vacuum line that goes to the FPR. The lack of vacuum releases the diaphragm inside to close down the fuel going back to the tank. This raises the pressure on the injector rail and therefore increases the amount of fuel available for each of the pluses that also get made longer in duration by the ECU.
The ECU is working from the AMM, Oxygen sensor, Engine Coolant sensor, and if necessary the knock sensor to move the timing to advance it along a program built in.
The ECU is another “last to blame” for wrong doing!
So you question, what is causing this? You have to look all around where the air is coming in and know that things are setup right and hoses air tight. The AMM cannot look backwards and the ECU can only work with what it’s told!
The program in the ECU was written for an engine that has its incoming air inside those perimeters.
A proper thermostat and the ECT telling it if it’s cold, warming up and up to operating temperature.
If the temperature gets too high, the ECU has a protocol for that too!
Don’t go blaming fuel management devices, AMM or ECU, until you know what is bogus elsewhere or not!
The 1986 is pretty bulletproof except in the engine wiring harness area or tailgate hinges.
The ignition system is the same as always on any car, keep the components fresh!
I hope this helps put the A/C “cool” as not the problem. (:)
Phil
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