Hey guys,

Just took the rx7 out for a drive today and came across an odd issue. I had 0 issues with it last time I drove it, however, I had a guy come and pull a dent out of the car yesterday. He had to remove the taillight assembly to get access to push the dent out which was located by the gas cap. I have no idea if the issue popping up today is coincidental or if it may have been caused by the dent pulling.

Basically what is happening is at 2k rpm the car starts shuttering violently, almost like the fuel is cutting out, and backfiring like crazy. I don't have a boost gauge in the vehicle so I can't tell if it's boosting at all or not. But it seems to happen whenever the car hits 2k. It drove perfectly fine a week ago. The car is a 2002. Any ideas what I should be looking for? The engine mods on the car are intake, exhaust, SMIC, but stock ecu. The mods were all on the car when I purchased it and the car has been running perfectly up until today

 

No one has any thoughts? I can't seem to find anything with the search

 

I would guess most of us here arent familiar with a late series FD. Does it have a check engine light, or a way to pull the codes? Maybe in limp mode? I'd also check the vacuum line to the MAP sensor on the firewall.

 

Since its JDM, there's no CEL. There is a way to check engine codes, but its very... interesting. You have to open up a diagnostics box and bridge 2 connections and attach it to an LED light, then the car basically says the engine codes in morse code I checked around the engine bay and everything looks to be fine.

Weird thing is, I started her up today and took her around the block so I could record a video of the problem, but the problem went away on its own. I'll need to take it out tomorrow and let it get a little hot to see if it's gone for sure. Super confused at what it could be

 

That's basically how you read the stock USDM codes, except there's a CEL to let you know a code has been thrown. Do you know the JDM codes and have check them?

Generally backfiring is a timing problem. Two things to potentially check are your CAS and MAP sensor, both of which affect timing. Or it's getting too much fuel (open injectors). I doubt a closed injector would cause backfiring, but it may cause stumbling, especially when it's called for more fuel. When was the fuel filter last replaced?

 

Could also be ignition problem. I have had fouled plugs cause unburned fuel to exit engine and ignite/backfire in exhaust.

Replace plugs to rule those out because it's easy to do, wires too. Could also be the coils flaking out. The wasted spark coil does double duty, so it would prob go first.