hyperRx7

When i start my 7 it sounds like a big block V8 with a race cam and sputters when i gas it, it doesnt rev past 5,000rpm.
I pulled the rear rotor plug wires off and there was no difference, the motor has 20,000 mileson it and mazda installed it about a year ad a half ago, i didnt do anything abnormal to cause this.
What could be wong?

skibum9199

Are the spark plugs for the rear rotor getting power? You can check this by taking off the wires of the plugs(rear only) and inserting a screwdriver into the boot. then just lay the screwdriver so that the shaft can ground out on the frame. You ought to see sparking there... The other thing to check would be your injectors.. the secondaries(the ones visable on top, i think) come on at 3500 rpm, and can supposedly be heard clicking if they are working. Maybe try disconnecting the power to them and see if it makes a difference. Is your car a turbo 2, an na, and what year is it?



~Jesse

hyperRx7

Oh yeah i forgot, its a 87' NA and yes the rear plugs are getting spark so ill check the injectors.

hypntyz7

It's toast dude, no compression on one rotor. IF it starts and runs like a briggs and stratton 3.5 hp lawnmower motor, that is. Go to autozone, invest in the $25 compression tester. Put it on your lower plug hole of the rotor in question, and have a friend crank. By holding in the pin valve, you can see each seal's compression(or lack therof), youre looking for 3 close to even bounces. Then release the pin adn watch for max compression. Should have a minimum of 85. This is not the most acurate way, but it will tell you if there is nothing, or something.

hyperRx7

what would have cause my rear rotor to lose compression i didnt do anything abnormal?

hypntyz7

They can go at any time for any reason. Are you sure the mileage was accurate? Usually you should get 40K out of a rebuild at least. One thing that does hurt the, sitting undriven is hard on the rotary. Sorry for your loss.

zyounker

WIthout doing a compression check you do not know if the engine is toast.. .DO A COMPRESSION TEST! Or at leas pull 1 of the rear rotors spark plugs out & turn the engine over.. Then do the same with the front rotor.. You should hear compressed air escaping the housing.. the sound should be even... & it should sound about the same as the front rotor..


BTW has the car sat for a long period of time? or where you just driving one day & pop the engine started running bad?

-Zach

hyperRx7

mazda installed a rebuilt engine alittle over a yar ago and ive been driving it every day, but now that i remember it sounded and acted the same about a month ago while i was driving. But i havent had any problems for about a month.
p.s. the compression sounds strong and the same for the front and back rotors but thats just using my ear , im gonna go pick up a tester.
Where can i get a new block?

zyounker

If the compression is good you don't need another block..


it could be a couple things.. First are you getting any error codes? is the car beeping when you go to turn it on???


It could be one of the following:

Fuel filter
Fuel pump
injectors
Mass Airflow sensor.
Plugs

Those are some ideas off the top of my head.. if the Mass airflow sensor is the problem you WILL be getting error codes.. You might want to take it to a mechanic & have them tell you what the codes are/mean....You can pick up a re-manufactured one for about $200.... (The dealer will try to charge you like $1000)....



-Zach

rx7_ragtop

Ok, if it SOUNDS the same on front and rear, 3 even whooshes... then it is probably (95% sure) not blown. Sounds like either a fuel problem or an ignition problem. Check out your injectors, and re- check the spark, ESPECIALLY leading.

Brad

skibum9199

Maybe one of your sensors gave the computer an error code ~a month ago, causing it to go into safe mode. I've heard that this can cause your 7 to run like a lawnmower also. Take off the neg. battery cable and hold the brake pedal for 30 seconds, then reattach and start her up. Might work, mine ran much better after i did this. Good luck!


~Jesse