i recently bought a 93 mazda rx7 fd3s. i am having a weird problems it stops suddenly with a check engine light and the rpms also fall rapidly. i took it to aamco to get the check engine light code but when i turned it back the check engine light is gone and aamco guys did not find any error code. So i am confused now and dont know what the problem is. It happens every once in a while. but when turn it off and turn it on again its back to normal. So can any body help me with this, how can i get rid of this issue?

 

the CEL is useless on this car. do not let anyone but a rotary shop touch it. In maryland, ma-motorsports or PFS can take a look at the car

 

Internet diagnosis is usually worth what you paid for it. But if I had to guess.....you have a transient CEL. That CEL is putting the car into limp mode and that's what your experiencing as "stopping" and "rpms fall rapidly". In fact, limp mode is simply the car's engine computer cutting fuel and refusing to advance timing whenever the intake manifold doesn't see vacuum. And that happens any time the engine is put under load. It would be easy to confirm. Next time it happens see if the car will start, idle and slowly rev normally while parked. If it does, it's almost certainly limp mode.

The next question is "why". Not every CEL causes limp. Again just a guess, but probably the most frequent cause is one of three different CELs associated with the oil metering pump (OMP). And intially they can be transient... i.e. reset themselves. But eventually it will come on and stay on.



Run, don't walk from AAMCO. In a world of great pizza restaurants, those guys would be the cheap tomstones you nuke at the QUICKIE MART. I agree with Vosko. Take it to either of those two shops. It'll be cheaper in the long run.

 

i made an appointment with the pfs for a compression test on the engine.



What does a Limp MODE means? My oil preesure gauge is not working, could this be a problem too?

 

Limp Mode is really a safety feature for your engine. There is a computer that controls your engine parameters...timing, fuel delivery etc. If it senses something critical on the engine is malfunctioning, the CHECK ENGINE LIGHT comes on a it puts the car into "limp mode" to reduce the risk of more serious damage if the owner continued to drive it.

As I said above, when in limp mode the engine computer will cut timing advance and fuel if it doesn't sense vacuum at the intake manifold. This means that while it will idle normally, you won't have any power and only able to accelerate VERY very slowly. If you try to go too fast it will cut fuel and timing will be retarded. Basically it would feel alot like you described in your original post.



As for the oil pressure gauge, that's a common problem on these cars. It's likely just a dirty contact but the sender sometimes goes bad too. Regardless, it wouldn't have anything to do with your engine running badly.

 

thanks signal 2. That was very help full.