Thanks for the help, I guess at this time my only option is to wait for some fairly warm weather and test out the compression.

If my car does need a rebuild.... Is $9000 a lot for an rx7 with a rebuild? what would avg value be? I tried looking but everywhere is different. Seems like what ever a specific buyer is willing to pay.

Thanks

 

You won't be able to sell that car with a blown motor for $9000. If you try to sell it now (and the motor is toast), you will loose money.

 

thats what i figured....

 

Anyone interested in an RX7 for $9000? hahah....

If it does need a rebuild... I think I will have to empty my pockets... even though I have had nothing but problems with this car.... and the older rx7 convertable I had a few years back.... It's gunna be hard to get rid of this car...

 

try posting in the local section and see if there is someone close to you that will do the rebuilt for you with you paying him of course.

and you just have to get a basic rebuilt kit.

 

That may not be the case. Without examining the housings and rotors, you have no idea if they can be used at this point (as well as the rest of the components). In most cases, unless you know the engine failed from a coolant seal, you can bet that there is either rotor and/or housing damage.

 

You should, as everyone says, get the compression checked to determine the basic condition of the engine. However, I have some other thoughts on the backfiring scenario:
1. The backfiring increased gradually, it didn't start all at once. That, IMO, is not what usually happens when you blow an apex seal.
2. Backfiring and flames, as I think you're describing, are not usually the sign of a blown engine. They ARE a sign of un-burned fuel in the exhaust, which can have several causes.

These causes can be:
1. Ignition problem - bad plugs, bad HT wires, bad coils, bad primary wiring, bad components elsewhere in the electrical or ignition system.
2. Fuel problems - water in the fuel, bad fuel pump, clogged fuel filter, frozen-up fuel lines, sticking injector, iced up throttle plates, vacuum leak, etc. Either too rich or too lean to burn properly can cause misfiring/backfiring.
3. Other things I haven't thought of or mentioned here.

Therefore, although you MAY have blown the engine (compression test will confirm or rebut that), don't give up hope yet. It could be something simple and inexpensive. However, you may have to take it to a shop that knows FD engines to get the true problem diagnosed.

Good luck,

Dave

 

yea my bad

didnt think about that.

 

Does anyone know of anyone close by that is an expert(or half expert around IOWA? Im in the middle of Iowa. The best I found is a mazda dealer about an hour and a half away.

 

Unless that dealer has a FD-knowledgeable mechanic (quite rare), I wouldn't trust them. You need someone who knows our cars!

Hopefully someone from IA can help. Have you tried posting on the regional forum from your area?

Midwest Forum: https://www.rx7club.com/midwest-rx-7-forum-32/

Dave

 

https://www.rx7club.com/midwest-rx-7-forum-32/hey-iowa-571995/

 

Avoid Mazda like the plague.

 

My guess is that the car was overboosting due to the extremely cold temps we have been having. FD's are not great northern winter cars. Most likely it was detonating, not backfiring. Of course this is just a guess based off the info given in this thread. A compression test will tell the story.

 

Maybe, but detonation doesn't often throw flames...

Dave

 

Well, just like i was saying before, if you paid under 10K and assuming everything else on the car is very good, ie paint, interior, electrical, transmission, clutch and so forth, you didn't get totally reamed. For around $6000 or so more you might actually have a car that is close to worth what you will have paid, and that is rare on these cars.

 

Replace the plugs I had a cracked one once and did the exact same thing. It would barely idle and would surge really bad shooting flames out the back 10' or more with full exhaust. Five so called experts said I needed a new motor and the sixth person sent me home with a strong car for $60. If your lucky it's the same problem.

 

Poor man's compression test:

1. Take the rear rotor plug off
2. Crank the engine, listen to the sound, is it constant or does it have faster paces
3. Install the plug back
4. Take the front rotor plug off
5. Repeat step 2 .

So if you had constant paces in both chambers then propably? not blown. I did this prodecure and determined that my rear rotor apex seal went BOOM as it was.

 

I have already tried changing the plugs... helped... but still problems with starting and running...

As far as the cold issue... It was when we were having the records warm temps... This happened back around november. The car has been sitting since then, Ive tried to start it a few times ehre and there but no luck.

 

Check again the boost sensor hose, BOTH ends! My engine was running like crap and I unplugged the sensor hose, it ran worse so I ASSUMED the hose wasn't the problem. I adjusted TPS, plugs etc and it still ran like crap, then I noticed this small hissing noise coming somewhere from UIM, played with the hoses for a while and noticed that the UIM-end of the boost sensor hose was split in half, still tight enugh to give some readings to the sensor but loose enough to run like crap.

 

HMmmmm ... OK , make sure the MAP Sensor line IS connected 1st ... then Clean plugs well (are they Fuel-Fouled??) ... disconnect ignitor , and then pull REAR Trailing plug out and crank the engine over a few times to blow out the Rotor Housings of any excess Fuel or whatever ... then quickly reinstall plug , wires and ignitor and then try to start , you may have a bad(leaky) injector ??? this is just something I went through awhile back ... I installed a bunch of new parts and it STILL wouldn't run right , turns out it was a leaky injector

 

TPS = ?
UIM = ?

I was looking through my repair manual last night and found that it could possibly be, Fuel Injector, Fuel Filter, or Fuel Pump. So maybe your right on that one.

 

Throttle Position Sensor (rear driver's side corner of UIM), Upper Intake Manifold (big thing with 4 fingers sitting on top of your motor)

 

Big thing with four fingers... I know where thats at lol

 

lmao

 

TPS = Throttle positioning sensor
UIM = Upper Intake Manifold