After my car starts up it is just fine and then in a few seconds it starts backfiring like crazy. It backfires like every second all in a row bang,bang,bang,bang. It never stops, just keeps going like that. If anyonw knows what this is please tell me.
By the way I have an hks downpipe, highflow cat and apex n1 exhaust.

 

Have you done the basic checks such as checking to see if the MAP sensor (located near the master cylinder, on the firewall) vacuum line blew off? Also, are you getting any check engine lights?

A disconnected MAP can cause massive backfiring and make your car feel as if it is either blown or running extremely poor. A CEL that induces limp mode (such as a OMP going bad) can also cause these symptoms.

 

Also try reseting the ECU if your still running the stock one. I used to have that problem every now and then.

 

how do you reset the ecu???

 

there are no check engine lights at all. What is a CEL???

 

You still have not confirmed if your MAP is connected.

And to reset the ECU, you simply remove the negative terminal. With the ignition off, press the brake pedal for ~30 sec (I usually do it for at least a minute), then reconnect everything.

 

I had the same thing happen to me. Sounded like a machine gun.

I had a blown Apex seal. Engine had 88,000 miles.

Sorry to say but it doesn't look good.

Remove the radiator cap - if you have bubbles you have a blown seal.

Super77

 

I had this happen to me when I swapped ECU's and it had no base map settings whatsoever. My car was apparently running extremelly lean to the point that the manifold began glowing bright red. I doubt that's your problem if you're running stock twins though. I thought I'd mention it anyways.

 

does it idle like ****?

check the map sensor.

base map might ofn gone out of wack.

 

Just to clarify:

Blown apex seal will not make bubbles, but a leaky coolant seal sometimes does.

 

Roger that!! Thanks for the clarification!!

Bottom line: NOT GOOD!!

 

Checked the map sensor, it is all hooked up, reset the ecu, there are no bubbles in my coolant and now the battery has died. I jumped it and the car started, but still back fires

 

Have you driven it? Revved it? It sounded exactly the way you are describing it when I flooded my engine and was able to get it started... I just revved it up a little bit to clean up the plugs, and it ran fine again...

 

What is limp mode???

 

Something you may be able to get you ECU out if you reset it.

 

Do you mean bubbles jsut THERE or when you squeeze the radiator hose and see bubbles that means your got a blown seal?

 

cAN you give a better descpription of limp mode..
and if i reset my ecu is tHERe anything i should be aware of ?

 

limp mode is the safety setting that the manufacture programed in the ECU. What it does is to prevent the car/engine/cat from being damaged. What it does is limited the driver's demand and only allow the driver to drive it to a mechanic shop to have it fixed or take a look at.... Usually it can be reset by taking out the negative battery cable like some1 else suggested earlier. Step on the brake for 30-60 secs. Then re-connect the negative cable, start up the car.

Also, some1 else suggesting revving you car, you can give it a shot, just dont rev it too high, i would say the best rpm range is 2-3k. I personally do all the testing on 2500rpm. So good luck with diagnosing your car =)

 

so since I already reset the ecu, it can't be limp mode. could my plugs be shot??? their 31,000 mi. old

 

Just because you reset the ECU, it doesn't mean it's not still stuck in limp mode. I would suggest pulling codes from your ECU just to make sure nothing is afoul.

 

I was told to run the engine at idle, open the hood and open the radiator cap and look at the coolant. If you see bubbles - like small champaign bubbles or if the coolant looks like it is boiling - then you have a coolant seal leak.

This is what happend to my 93 FD a few years back. Had to get a new engine block.

 

Ha, I'd DEFINITELY change out those plugs!

 

i put new plugs in and it stopped backfiring, but it still runs like crap. low pulsating idle and running lean.