Saturday: Me and some friends go out for a late night cruise. I get on the car a bit (around 4000 RPM in second) and suddenly the car looses power and starts running really rough. If I gave it more throttle, my boost gauge would go up, but boost never would actually kick in. I pulled over thinking maybe a intercooler hose came off or something (had a similar issue with my 180sx). As soon as I pulled over and let off the gas, the engine died and wouldn't start back up. The engine would turn over, but sounded more sluggish. I checked the fuses, vacuum lines, and intercooler piping and couldn't find anything out of the ordinary. I got some friends and we tried to push start it, but it still wouldn't start. Ended up calling roadside assistance and got towed home.

Sunday: Thinking the spark plugs may be bad, I replaced the plugs (the old ones were dark, but didn't look terrible). When I tried to start it after replacing the plugs, it sounded different. Instead of being able to hear the engine itself turning over, it sounded like the starter was just freely spinning.

Monday: I gathered some friends to help me try to push start it again. After several failed attempts, I could smell the gas knowing it was now flooded.

Tuesday: I pulled the front bumper off to get to the factory front tow hook (Mazda sure did make it a PITA to get to).

Wednesday: Got a friend to tow me with a tow rope to a self-service auto shop. I put it on a lift and pulled the starter, thinking maybe the gears were stripped. However, everything seemed to check out OK. Tried starting it normally again with the gas pedal to the floor and it sputtered a bit like it was trying to start, but still wouldn't. I did a compression test (with a regular compression tester) and got zero compression on both rotors.


My car only has just over 40,000 miles on it, and the chances of me blowing out 6 apex seals all at once at only 4000 RPM seem highly unlikely. One person at the shop suggested the gears around the center of the rotors could be stripped out; however, the engine still turned over before I replaced the plugs, so I don't think changing the spark plugs would magically strip those gears out as the car was just sitting. My car only has a pod filter, midpipe, and exhaust and is running at stock boost levels with the stock ECU. Anyone have suggestions for me to try? I've only been an RX-7 owner for about a month now and still have a lot to learn about these cars. Really hoping it's nothing too hard to fix as I have some out-of-country friends visiting and we had planned some cruises while they were here. Thanks in advance for any help!

 

Sounds like apex seals to me. But a bit strange you broke all 6.
Compression tests don't lie but maybe you are doing it wrong.
Maybe fuel pump

 

Record a video of it trying to start with a fully charged battery. Most folks here can tell if an engine is blown simply by the sound of the compression strokes.

RPM doesn't matter when it comes to popping an engine. If there were something wrong with the setup and you pushed on it....boom.

 

Put your thumb on the plug hole and feel for any pulses. They should be strong and consistent

It sounds like it's blown though

 

When you did your compression test was the elbow off and throttle fully open? I see that mistake quite often.

 

My first thought to your initial issue us the map sensor line.

The starter sounding different has me thinking it could be way flooded. I would pull all for plugs and try to turn it over by hand first. You should at least see the needle move a little bit if the engine is spinning on a comp test, doubtful you blew all 6 apex seals. Put some oil in each housing to rebuild compression and try to start again with a fresh charge on the battery.

 

Mid pipe on a stock ECU is not advisable.

Sounds like you blew it. Regardless if the throttle is open or not, the needle will still move for a compression test.

Even if the map sensor hose came off, it should still start. It will just run really really rough.

Also, you just made a thread with all this same info like 4 days ago. At least use the same thread.

Matt

 

Cmon dude, he may have just blown his engine. He's trying to find answers and rule out what could be the issue. Sometimes you may hastily post a thread and it's incomplete, or it isn't getting you the answers you need. Let the guy make a second thread if he wants huh? No big deal...

Good luck with the diagnosis OP.

Nick

 

I had pretty much the same situation happen to me. Only one set of seals broke though, not both.

 

I got zero reading on the front rotor lately. I was thinking I was doing the compression test wrong but turned out one apex seal of the rotor broke and the rotor stuck in there.

 

Throttle wasn't open, the thread I found telling how to do a compression test didn't say anything about having it open. And what elbow?

I was thinking the issue could possibly be flooded/starved engine. But that still wouldn't explain the change in the engine's sound when trying to start.

I made that other thread when the car initially broke down. Since then, I have tried several different things to fix the car and am having new issues with it. Furthermore, I wasn't getting responses on the last thread, leading me to create a new, more specific one.

Thanks.


So even if I did manage to blow out all six apex seals, why would the engine still have compression before I changed the plugs, then turn into a free-spinning compressionless engine after changing them out? Also, in combination with the low miles, I'd like to add that the car is super clean and not abused. Also, when apex seals go out, is it a gradual thing or no? Because the car ran perfectly fine up until it this happened. Never had an issue with overheating, cold starts (even in the snow), idling, or long drives.

 

That would make the most sense to what happened to mine right now. Possible I blew a seal on both rotors and they didn't jam it up till after I replaced the plugs and tried to start it again.

 

an engine that lost all 6 seals unlikely? where have you guys been living? it may not be common, but it does certainly happen, and a lot more regularly than people in this thread have mentioned.

additionally, i assume you used the correct plugs? in a rotary engine, it is possible to install incorrect plugs and totally destroy the engine. i have seen the electrodes hit apex seals before where incorrect plugs were installed.

chances are the engine is just toast, which is why it stalled in the first place and refused to restart.

 

Kbug, these are crucial aspects of the compression test. The elbow is the small piece of intercooler piping that joins the throttle body to the main run of pipe to the intercooler. This is the part that many replace with a Greddy elbow.

When I bought my car, I had Kilo Racing do a compression test before I purchased it and he removed the elbow before removing each spark plug. FWIW, he removed one plug at a time and did the compression test on each rotor with the other rotors plugs installed in their positions.

Merry Xmas!

Nick

 

open vs closed throttle may affect the reading to a small degree but won't give much of a result if no reasonable compression was recorded.

i prefer removing both leading plugs and leaving both out during the compression test, this allows the engine to turn faster and give a more accurate 250+ RPM cranking reading. removing the throttle elbow is a personal choice and does not affect the test whatsoever, i leave it in place, the greddy elbow is intrusive and i usually have to take those off to get to the plugs but the stock elbow leaves enough room usually.

it is possible your gauge is broken or a valve removed from the head of the gauge or leaking, you can try the test with another gauge and compare results.

 

ah shoot, sorry to hear this man hope you get it fixed up

Midpipe / open exhaust on stock ECU without ported wastegate and boost controller is risky risky business.

 

or atleast add a restrictor to the exhaust to slow the flow and not creep,

 

Just for the record, and for someone's benefit in the future who may stumble into this thread...



Nick

 

Yes, I used the correct plugs. It also had the correct ones when I took out the old ones.

Power FC is on my "want" list, but I'm still in high school and only working part time, so it's just a matter of saving up for it. Midpipe and exhaust were already on the car when I got it.


Shop is closed tomorrow, but I have a guy that's good with rotaries that is gonna come take a look and help me mess with it on Tuesday. Fingers crossed

 

Well as I feared, my engine is blown. So now I'm in a predicament. The guy that I was gonna get to help me rebuild the engine can't because of his work schedule. I don't have enough money to let a shop rebuild it, plus I want to learn how to do it on my own. So now my question is this: how hard is it to pull and rebuild a 13b? I'm not gonna lie, I've never been to a school with an automotive class and I'm the only "car person" in my family. I've never pulled an engine or really tore into one for that matter. So that being said, what do y'all think?

 

Rebuilding takes labor and materials. Even if you can figure out how to do do it, have you figured out how to source the parts? You may want to start there first

 

I'm gonna buy a complete rebuild kit. Can't remember the name, but my friend told me about a company that sells a rebuild kit that includes everything needed. As for tools, the shop has an engine hoist and everything I'd need

 

first time rebuilding a slightly modified FD while in high school as a first real car project?

i don't think you really want me to answer that. half of your engine is going to be toast, adding nearly another $1000 in parts cost unless you find a good second spare core motor for less, i dont know how much they are over there in japan. the possibility of not getting 1 in 1000 things right is also a bit higher with an FD.

 

This. It sounds like you are a bit green when it comes to cars so you may want to just save and have the professionals handle the rebuild. If you take it on yourself and miss something or screw one small thing up you will be in the same boat you are in now... just another 1500.00 down for the rebuild kit and who knows for the trashed rotors, housings, or plates needed.

Good luck.

 

Can you answer why the engine failed? If not...who says it wont happen again as soon as you go wide open throttle with the new engine...