Few months ago i bought a little project. A Black 94 FD that was filthy but had a street port engine and a new T78 on it. The WG was missing. Just bought a Greddy 50mm WG off someone in the FS section and installed it today. Charged the battery and it started right up. No smoke, sounds great with the 3 inch DP and MP and a vibrant cat back. The car has a nice smooth idle, good oil pressure, and no overheating issues. First crack of the throttle i noticed the engine completely cuts out and a little backfire when coming back down to idle. After i let it warm up i thought since the car sat for a year and the needle is on empty i would put a full tank of fresh 93 test gas in. Didnt fix it but thought i would rule that out. Checked what engine management the has and it has the stock ECU. Revving the engine up slowly i do not notice as much of a cut out but after 2.5-3k rpms i notice a little break up/missing. My thoughts right now are a Dead 02 sensor, TPS problems, map sensor, crank sensor, or fuel delivery issues. Not so much ignition only because start up, idle, and slow revs are smooth. Please chime in with what you think this could be or where i should start to check.

 

Pull the codes, it is likely in limp mode.

Probably best it doesn't run right on the stock ecu for you. One good pull with the t78 and it's game over for your engine. Good luck

 

I had that same problem after my build, and the 2 coil pack connecters were swapped. May not be in your case since you did not touch that area, but who knows.....

 

I had a similar problem a few years ago and it turned out to be the fuel injector grommets blocking fuel delivery.

 

Wouldnt the coil pack connectors being swapped make it run poorly all the time or even run at all?

Why will one good pull with the t78 blow my engine? I have it set at 10 psi. Is it because even though the psi is the same the volume of air is a lot more?

Ill do a search for limp mode. I wonder what would put the car into limp mode, and also how would i get it out of limp mode?

Also when you found your fuel injector grommets to be stopping fuel what did the grommets look like? Was your car modded previously? Did you have fuel/injector work done? I know my fuel system is stock and the injectors have not been out.

Also no smell of fuel or signs of fuel leaks let alone any other leaks.

 

Just a an update so if someone looks at this thread they have more info. Engine runs smooth through the rpm range. Under light throttle its no different at 1k rpms than it is at 7k rpms. Checked all grounds and crank sensor connectors. cleaned battery terminals and made sure they were in good condition. Reset the computer to maybe try to get out of limp mode and no change still cuts out with a little backfire when cracking throttle or under load. Pulled codes and i got

27 28 31 32 40 42 43 44 45 46

Going to check code descriptions now. Also one last bit of info. it seems to run a little better when hot and cut out a little worse when cold. Not a big difference but it is there.

 

27 is the OMP which will cause limp mode, all the rest are emmisions, which means no resistors were installed. Honestly you need a Power FC with any single turbo conversion.

 

Bolded for truth.

Your stock ECU isn't going to run your single turbo setup.

-Geoff

 

I have about 700 i can spend right now on the car. Think i could pickup a pfc for around that? I dont need to put resistors or anything in the connectors with the pfc? will i be good to go with no limp mode?

 

You might find one used. PFC requires no resistors for the missing solenoids and has no limp mode. If your OMP is bad you need to run premix to protect your engine.

 

Thats great. Looking at one in the FS section right now. Waiting to hear back. Ok so if my oil pressure gauge on the dash is in spec per rpm range does that mean my OMP might be ok? I geuss i figured with good pressure my omp would be ok. Correct me if im wrong.

 

Having good oil pressure is not an indicator that the OMP is working correctly.

The OMP refers to 'Oil Metering Pump' though I think the official moniker from Mazda is something different. While the OMP gets oil from the motor by default, it is in itself a pump.

There is likely a test procedure in the FSM. If you have any doubts, it would be a good idea to remove the UIM and do a visual inspection and perform any test procedures. Make sure the check valves are working correctly.

I ditched the OMP a few months ago, as the check valves were not working correctly, and I was getting too much oil. One less thing to break now.

 

No.

Very no.

Your OMP and oil pump are two very different things on this vehicle.

Your standard oil pump is what moves engine oil through the engine, lubricating and cooling (yes, cooling) vital components to prevent excess damage and metal on metal wear.

Your OMP (or in mazda speak MOP, Metering Oil Pump) is a completley seperate oil pump that performs a very vital task: Apex seal lubrication.

The apex seals (the seals at each point of the triangle on each rotor within the engine) require lubrication. Due to the design of the Wankel rotary engine it is not possible for them to be lubricated by oil flow from your standard engine oil pump.

Mazda solved this problem by adding your OMP which takes crankcase engine oil and squirts it into the engine (or more specfically, squirts it at the apex seals) as your engine rotates.

Yes, this means your car is burning oil, yes this is working as Mazda intended.

If your OMP is not functioning your apex seals are not getting the vital lubrication they need and are sure to fail.

Many RX7 owners actively remove or disable their OMP's and run what we like to call "premix". Premix is when you pour 2 stroke oil into your gas tank. There are many threads on this board regarding premix and many differing opinions on exactly what to run and in what quantity.

From reading many of these threads the general consensus I feel the community has come to is that you should be running a 2 stroke oil that is of the TCW-3 standard. The generally accepted mix ratio is 1oz per gallon of gas if your OMP is disabled/not working.

-Geoff

 

No need to remove the UIM, bad oil injectors will not throw a code. Typically the OMP will throw multiple codes, 20 & 26 are for the position sensor & stepper moto, 37 is also the OMP.

Pull the codes again and verify that actually have 27, RX7 FD and Series 5 Error Codes

Then clear the codes and see if the problem goes away for a second.

 

I 100% had code 27. Not 20 or 26 and not 37. I cleared codes by disc. batt cables so when codes were not there on initial start up i did not try to give it a good rev because i did not want to damage the engine. As for clearing and see if probs go away for a second, i cannot do that because i have allready pulled my ecu out. Ordered a PFC and it should be here in a few days. Im excited. Love an FD so much more than my MKIV.