Ok I have a 1986 N/A and it won't idle. When I start it up, it runs beautiful but once i let of the gas and it drops below 1500rpm it wants to die and then it starts to backfire once in a while( every 15 seconds ). I have check the computer for any codes and nothing has turned out. Alos when I start it up it won't backfire at all, than after about 30 seconds it will start.



I was wondering, could the car backfire if it has low compression. I know mine had compression but my friend keeps think that the engine is blown.

 

Check all the sources for a vacum leak and the plugs. Sounds like it might be running super rich or lean. If the compression is low it would not start easily. Still wouldn't hurt to check that though. You can get a tester at the parts store for like $20.

 

How would I check if it is lean or rich

 

Is the exhaust system stock? If not it will afterburn like nobody's business. Also, check your timing and TPS sensors. If either is off (particularly the TPS) then problems like these can occur.



However, one additional thing to check is to see if both rotors are getting solid spark and fuel. I had an engine running on a single rotor due to no fuel injection in the rear and it had similar problems, but it sounds like yours might actually have the opposite problem : fuel but bad spark on one rotor causing it to dump unburnt fuel in the exhaust and it goes POP back there.

 

vaccum leaks will cause it not to idle

 

The timing is good and I have to set the TPS when I get some time this weekend. I have changed both the coils from a running car, and the exhaust is also stock.

 

check the hoses to the air pump mine wouldnt run with out it it would start hit about 2000 rpms then just die unless i put my foot on the gas

 

Ok I have checked all the vacumn lines and I notice that two of my lines look like they are in the wrong places. There is one from the intake manifold that is supposed to go from the air intake into a golden pipe that then connects to the intake manifold, but instead that hose is just blocked, and the one from the air intake is going into some other pipe that goes under the intake manifold.



Also what is an air pump and where is it located.

 

Here is a picture of what is missing in my rx7. The golden pipe is not there and the hose coming out of the intake manifold is blocked off and the one from the air intake is routed somewhere under the intake manifold.



The pictures are on page 3

 

The red arrow points to your air pump. The air pump is a device that supplies the air control valve with . . . . . . .