thought i blew my motor on thursday, car lost almost all power and the engine shaked really bad. i got a mazda compression tester, front rotor pulled all number's in the 9's, rear rotor was not so lucky.

when we pulled out the trailing plugs to do the test, the plug in the rear rotor was soaked in fuel. when cranking for the compression test a strange noise came from the engine and lots of air pressure came out of front rotor plug hole. tester showed 0 compression in all 3 chambers and 0 for the crank speed, almost as if the tester couldnt pick up any results.

it clearly shows that something is terribly wrong but i want to confirm this, has anyone had these same results? My conculsion would be that there is nothing external besides the battery and the starter that would cause a change in the results. I would assume rear rotor is blown and doesnt move when cranking, but front rotor pushes it along when car is struggling to run.

also, I live in Prince Edward Island Canada, would anyone know of a place in atlantic canada that would rebuild a rotory, or what would you suggest be my best option in getting a good block in my car? thanks

 

First, I'm not an expert, but... just to let you know that in the FSM it states that if all 3 chambers are below 290 kPa ( in the 3's, or 43 psi) the mazda tester will show zero for all three, and also zero for the cranking speed. If thats what you're getting then yes, the tester is operating properly and that is likely a blown rear rotor. As for where to go for a rebuild, check the regional forum section, they will probably be able to help more. Good luck!

 

thanks. i guess i gotta find the best option from here. im debating purchasing a used engine/tranny and the whole works for $1500 vs a rebuild around the same price...

 

Whatever you do...fix the issue that caused the engine to blow BEFORE you get it running again. Motors don't fail for no reason.

 

my understanding is that they will just blow over time... 94 with 72,000kms. the only thing i noticed was a little boost spike to 12 after the second turbo came into play. i just thought this was the nature of the beast and wasn't to detrimental to the longevity of my motor.

 

Typically it is fuel starvation of some sort. Clogged fuel filter, injectors not flowing full rate, tired fuel pump, etc.

Stock boost is 10-8-10, spike to 12 typically would not cause a blown engine but if there is a fuel issue it can take out an engine.

J-specs should still be rebuilt considering that they are just used engines. If you blew the rear apex seals the engine is going to require additional parts that are going to drive the rebuild cost up since you will need a rotor and housing. Also keep in mind that your turbos will most likely be damaged as well from debris passing through them.

 

That's very wrong and only perpetuates misinformation about rotary engines. The engine experienced detonation for whatever reason. Was a wideband installed on the car?

 

i have a wideband but didnt get around to getting a bung welded and it is not installed. i will make sure that it is installed asap when the car gets running. would an intake cause me to possibly run more lean that i want? car is basically stock

 

An Intake will not cause a lean situation.

From what I remember you had a problem earlier with your car shutting off while driving.

I believe the consensus was in that thread that you may have a bad fuel pump. A failing pump can easily cause a lean AFR.

-Geoff

 

issue was not fuel related. ended up being ignitor troubles. borrowed a friends ignitor which caused the same issue, turns out he had a bad ignitor too.. :S got er fixed only to have the motor blow a week later :S

I will keep an eye on the fuel situation in future tho with the wideband. I see what you mean tho, running lean would def cause a blow.

 

yes this is very wrong, they may slowly loose compression over time as seals and housings wear down, and springs weaken (leading to a usually fairly cheap rebuild) - but zero psi. i.e a blown rotor is a catastrophic failure and dosent "just happen" because the engine has a few k's on it.

 

How do you figure that these ignitors are bad? I have never heard of one going bad, ever.

 

I'm reading this as:

"I think my ignitor is bad, so I put in a different ignitor and the problem stayed, therefore both ignitors are bad"

If that's the case, I'd have to say that the ignitor isn't the problem.

If I'm not reading this right, please clarify.

-Geoff

 

the car i borrowed the first igniter off of didnt run. i then borrowed a second igniter from a 100% working vehicle and it cured the problem. i probs shouldnt have even tried borrowing parts of a car that wasnt running but it was an easy grab at the time to test it out.

i will check over everything when motor is rebuilt. running lean would def cause a motor to blow, i understand that, but do you not think if the vehicle was sitting around before i purchased it or the apex seals didnt just break down over time and not be as durable to handle the load under acceleration?

I did a compression test in the fall and both rotors had excellent compression. but my understanding is that there is no way to tell the condition of the apex seals without tearing the block apart.

 

No.


Something caused detonation, that's the only way to break apex seals besides debris being ingested into the engine.

Detonation could have been caused by: too lean fuel mixture, ignition timing too advanced, intake air temps too high, boost spike, map sensor line fell off, dirty injectors, restrictive fuel filter.....the list goes on and on. The point is that engines don't just fail. It's the parts attached to them that causes the failure, either from lack of proper maintenance or operator error. SO OFTEN is the case that someone will pop a motor, spend thousands on a really nice rebuilt motor....only to blow it up because of the exact same reason...then they start bad mouthing rotaries and put an LS1 in their car.

 

i will make sure spark and fuel are operating exactly as they should when motor is back in place. I will have my wideband installed and keep an eye on it.

 

Also a good idea to have your injectors cleaned and flow tested. Inspect/replace/remove your injector diffusors as well.

 

ok. i have not heard of that before but i will look it up to see what to do. I have replaced thermostat, fuel filter, cleaned intake, new plugs just to make sure everything is flowing as its supposed to... but since she blew you guys got me doubting my little beast!

 

update:

i ended up ordering a used jdm engine because it was going to take too long to do a rebuild and i havent had the car for that long and i want to enjoy it for the summer.

the swap was alot more work than I was expecting because the mailed me a 96 or newer engine that had a 16 bit computer and had to replace that wire harness with my 94. car mechanically runs great so far, only had it up and running for a few days now. few electrical issues that i need to sort out then ill be sailing!

ordered a new igniter and new coils came with the engine so no more ignition issue which is a blessing.

thanks for the help guys!

 

Hey just wondering what kind of electrical issues you are having because i was in the same boat as you a while ago. I got a used motor came with a 96+ ecu and i as well swapped the harness, now im having some electrical issues.

 

I was messing around with the electric motor for the pop up head lights and ended up having all my lights come on in my dash (add coolant, low oil, battery, and abs light). I searched into it and it ended up being the alternator. I had a spare and swapped it last night and now im good to go.

I have only had the car running again for 5 days so its hard to say if issues will come up in the future but all looks to be good as of now.

What type of electrical issues are you having? My car is a 94 JDM and it plugged in perfect with the 96+ JDM harness, what year is your car and is it JDM or Canadian spec?

 

my car is 92 jdm i had to swap the engine harness with my 92 harness so that it would plug into my ecu. My brake warning light is on constantly and i was just wondering if it had to do with me swaping the harness cause ive checked everything else

 

I am not too sure what that would be... if you are talking about your e-brake light, the workshop manual says you could be low in brake fluid or you have a bad parking brake switch or damaged wiring harness to that unit.

id try checking those things out if ya can. how did the swap go for you?

 

yeah im stumped because i have checked everything all the switches and sensors, brake fuild is full, so i dont know i think im just gunna take out the bulb so i can get it safetied and on the road then figure it out after . Also the swap went alright, took me a while cause i had to figure out where everything went and i also had to swap over alot of the old parts off my other motor for it to work, but it looks like everything worked fine in the end