Engine starts backfiring then dies, etc.
 

My engine has been acting up lately. On more spirited drives the issue starts to happen faster, although if I drive for more than about a half hour under normal conditions it happens just the same.

The car will start backfiring and lose a very large amount of power during more than about 50% throttle. It starts off as a little issue under heavy throttle and quickly gets more severe untill the engine simply dies and will not start again for some time. The battery will seem somewhat spent until the car cools down and then it will sometimes start up with a little coaxing. I am wondering if this is could be attributed to a major ground cable or battery wire.

Also, my tach likes to die after a bit of driving (sometimes a while, sometimes withing a block or so), at which time the CEL comes on and it might be my imagination but i notice a bit of power loss. If i just hold the clutch while driving, turn off the engine and then back on and effectively bump-start it, it works just fine for a bit (CEL goes away and as well) but then it dies again and theres the CEL again.

I just installed a new battery and alternator, and the output is reading rather low, around 12v usually, but sometimes as high as 13.5 on a good day and as low as nothing (at the cluster guage) on a bad day, however the car still runs after a bumpstart.

thanks in advance for your help.

Likely limp mode due to a failed Metering Oil Pump: http://www.johnr.com/cpucodes.html

For future threads, please list what your car is and any relevant modifcations/details. I will generally check member profiles for more information, but not everyone is going to do that. This section covers all generations of RX-7s, as well as other rotary power vehicles, and on occasion a blasphemous engine-swapped car :).

Car is a stock S5 with a manual trans, that for whatever reason had an SAFCII when I purcahsed it. I'm beginning to seriously wonder if all this could be caused by wiring, although with your experience, I will definitely check my ECU codes and keep an eye out for the MOP code/s.

Thanks for your help.

Also, if it does turn out to be the MOP, I'm not buying a new one for $1300+, and I'm not putting a used one in either if I can help it.

There are quite a few writeups that tell how to remove and block off the MOP, but nothing on making the ECU think it's still there. Anyone know how to accomplish this?

You can't rightfully remove the OMP from the electrical system as the ECU is hooked in with it..(you disconnect the OMP then the car IS in limp mode).
If you have a Working OMP and want it off the engine,then you hang it to the side of the engine,Block off the Engine with a Plate and Premix the Fuel to compensate for the internal lubing that the OMP was Designated to do.
The ONLY other way that you can get around to run the engine WITHOUT an OMP is to Go RTEK Ecu or to go standalone.
Now,IF you want to "do it on the Cheap" to Buy an OMP then Post up a "wanting to Buy" an Omp on the Sec gen For Sale Section..plenty of parts for sale..every Day.
Cheers,STYX.

Right on. Looks like if the OMP/MOP is the issue, I'll be replacing it with a used one or rebuilding the one I have.
chances are I could get the schematics and rebuild one for a far cry less than $1300. If I can build a distortion pedal for a guitar from scratch (yay studio maintenance class) , Im pretty sure this would be within my capabilities.

I just dont understand why this part is so damned expensive. Is the supply and demand really that unballanced???? :icon_tdow

If it does turn out to be throwing one of the MOP codes, you're also going to want to inspect the ECU circuit boards. A MOP failure can burn out the related part of the board.

Rtek 1.0 for $120/140: http://www.pocketlogger.com/index.ph...age=1&ecu=S5NA. This will require pre-mixing.

All RX7 electronics are expensive. Limited production parts for 20+ year old, foreign produced cars tend to be that way. Fortunately a lot of them are still working perfectly, and are available used.

perhaps check your fuel lines to ensure there are no clogs, backfiring is a result of that

thanks guys. I did also recently run a bit of seafoam through the exhaust, so there is a possibility that it knocked something loose into the lines.

RotaryRocket88- It's just funny to me because I catch myself looking at parts for my 7as if I were buying parts for my old S13, which was a year older. I have to remember the S13 really wasnt marketed the same.