"Pre-ignition and "dieseling" or "run on" are the same phenomenon, except in the latter case the engine continues to run after the ignition is shut off with a hot spot as an ignition source. Pre-ignition might cause rough running due to the advanced and erratic effective igniton timing and may cause noise if it leads to detonation. It may also cause "rumble" which is fast and premature but not detonating combustion."

 

Eh, I guess it's possible... I still don't see how it would do it without gas in the chamber... but what do I know.

It's also an N/A. I don't think I've ever heard of an N/A having that problem, but once again, what do I know.

My vote goes to listening to Hailers. He's never let me down.

 

I'm not saying that's what it is, I'm just saying it's a possibility! If you read what I linked it might enlighten you to how it could be possible. The only reason I mentioned it was because I had it in one of my old cars (piston) I know the disdain for piston engines so I researched it on rotarys and found the 2nd link. It's also one of the disclaimers on warranties for rebuilt rotary engines.

 

There would have to be power back feeding the electrical system or ECU or somthing to allow the injectors and coils to keep firing.

Rx7s can't really desiel since they are Fuel Injected. The injectors are supposed to be turned off and if they were firing, the ignition would have to be firing as well. Unless for some REAL bad reason your injectors leak so much even after they are off that enough fuel still gets into the chambers and is ignited by a surface hot enough. This would only cause it to run EXTREMELY rough, not smooth.

 

What RotaMan99 said... I just don't see how fuel would be in the chamber if the car was really off. No fuel, no pre-ignition or detonation.

 

The wires on the alt are crossed and its feeding back.. Pure and simple. And FCs dont diesel....

 

haha hes got it easier than i do. at least his shuts off after a few seconds. i just dropped a new motor (86') into my 88' and after i turn the key off it keeps on going.......nice and strong..... no rough idle at all.
we're thinking its related to my ecu, so we're swapping the ecu from the 86' in tomorrow, hopefully this is the problem.

pretty crazy seeing your car running strong while you're holding the keys outside the car. gotta pull that alternator wire to make it stop.

 

Not really. It's like J-RAT mentioned above, the electrical system is backfeeding. Usually it's thru the alternator wires (small plug on the back of it) being crossed.

It is odd though. Same type engine? Like both non turbo or both are turbo? IF the problem continues after swapping the ECU's, then next time try to just pull the ENGINE fuse in the interior.

Did you change the EM harness on the engine? I'm asking, is it the same harness on the engine as you had before changing engines? Make any other wiring changes?

 

i had something very similar happen but it olny happened once. my TII had a fuel cut switch wired in before i bought the car, while looknig to buy the car, I clicked the switch (to test it) off but instead of dying down like it should,the car sputtered and surged between 100-500 rpm. I never figured it out, and it never happened again.