Alright, I just rebuilt the motor for my car. It is my first rotary engine so I hope I did everything right. Well I got the motor from a friend of mine and he told me that the motor had been over-heated so I went ahead and bought the gasket kit from mazda trix and only changed the coolent seals and everything else that comes with kit, I also ported the engine, street-port template also from mazda trix. Once I got everything together and went to start it, it fired right up. I noticed that it had a lobe to the idle and think it might be from the port job. Once you get on the gas the car stumbles back fires and turns off. I has no power and a miss all through the entire Rpm range. I have checked fuel pressure, timing, spark, compression. I also interchanged Parts from a running car, Map sensor, Mass airflow sensor, computer, coils with ingnters, CAS. I also tired pulling codes and no code are there? I also tried adding grounds. What else could it be? I thank you for you help.

 

This may be a crazy question, but how long has the car been sitting? Does it have fresh gas in the tank? They will run like crap on old gas.

 

Sounds exactly like a vacuum leak my friend. Triple check all hoses/gaskets/grommets all the way from the LIM to the AFM. It has to be 100% sealed from those two points in order for the engine to run right. When unmetered air gets into the intake, symptoms are just like you described.

 

Car sat with a dry tank for a month and a half when I put the engine in I went and put 5 gallons of fresh gas. All the manifold gaskets are new. Question, should there be any sealent applied to the throttlebody spacer? I will have to check the booster's vacuum line because that is the only line/hose that I have not replaced. If I can't get it resovled I am just going to have to take it to Carlos Lopez racing since they are just down the street from my house.

 

I'm having a similair issue with my engine swap. I'm leaning towards a vacuum leak. That'd be the thing to check. Maybe I'll pull my FD boost gauge to check the idle vacuum on my car.

With the FD, it idles at like 10, what should the vacuum be for and NA FC at idle?

 

A stock-port FD with good compression should idle at like, 18-20" :X

 

The easiest place to miss for vacuum leaks are usually the ones that you think are air tight for sure.

For example, I had at one point drilled out all of the vacuum hose nipples on the upper and lower intake and tapped them with threads, then sealed them with grub screws and sealant. It wasn't until much later trying to figure out why the car ran like complete ****, that it was becuase of what I did and half of them were sealed poorly.
It was the last place I suspected.

Another note, make absolutley sure that you have gotten rid of all the gasket from the old install off the mating surface, its also imperative that you do not use sandpaper. Use a pad that was designed for it, you can find gasket removal pads for dremel like tools in hardware stores that do the job good.
Finally, after the mating surface is nice and shiny, apply the new gasket with a little coating of gasket sealant. Mate the two surfaces and torque to specified torque values in the FSM in a criss cross pattern.

Doing this for all the mating surfaces will ensure that the gasket is set properly and is doing its job, preventing air from leaking.
When your done that ****, start with the vacuum hoses, search and you'll find excellent vacuum diagrams and I would recommend to always use new hose when doing and intake rebuild. If possible get the proper vacuum hose, especially if it runs through the manifolds at particular angles. Using homemade ones ends up in kinking sometimes, and nothing beats a factory pre-molded vacuum line designed for the job.

The last thing I would recommend is to get the mazda oem rubber grommets for all the fuel injectors. If the injector doesn't seal properly, air is going to leak in from there as well. Again, torque the fuel rail to factory torque spec as well.

If you do it like that, and take your time you should have an engine that has no vacuum leaks, and ontop of that will last another 20 years without leaking for sure.

good luck.

 

I thought I had read 10". crap. Well, I stand corrected. My FD had always idled around 10" though, but I did have a blown engine soon after wards. So I shoudl have said something more like "With the FD, it idles at like 10" - if your'e about to have a blown engine. what should the vacuum be for and NA FC at idle?"