Hi Im 15 and just bought a 87 rx7 for $600 with 94,000 original miles and im wondering how many more miles the engine has left before it needs a rebuild so that way I can go ahead and rebuild the engine before I get a job. The car has sat for around 17 yrs and just got it running again starts right up first time idles perfect and has a lot of power the only problem is that it sounds like it has a slow rev limiter and backfires alot when I hit 3800 rpm (wont let me go past 4000rpm) wondering what this could be too just replaced fuel tank, fuel filter, spark plugs, and fuel pump im thinking I need to clean the injectors but not sure.

 

Kevin of Rotary Resurrection has a wealth of information on his website under the Tech section. Regarding engine longevity, here's Kevin's thoughts: https://www.rotaryresurrection.com/2...longevity.html

 

Could be a secondary injector issue. 3800rpm is where the secondary injectors come on.

My T2 did this when one of the primary injectors died on me and I moved the dead injector into a secondary position so I can get the car home.

 

Okay so now I think it has to do with the transmission because when its in neutral it will rev past 3800 no problem it only does the hesitation thing when its in gear.What could be the cause of this

 

Oh man.
Step one, replace all fuel lines and vacuum lines.
Step two, get new fuel pump and filter
Step three, get a fire extinguisher.
Step four, 20W 50. not 10 w 30
Step five, Premix 2 oz per gallon of gas.

step six - enjoy the car. dont be an idiot and mod it. its an old car. things will break. keep up the reliability on it with new things periodically.

 

If you have not, drain and refill the rank with fresh gas and replace the fuel filter. Replace the spark plugs and wires, air filter, inspect and replace vacuum lines as needed, replace the drive belts, remove the injectors and have them professionally cleaned and flow tested (you will need a new gasket that goes between the upper and lower intake manifold), and change the oil and coolant at a minimum. Inspect the hoses for weakness and degradation while you're in there. You will likely need new tires and brakes as well if the car has sat for 17 years. Inspect the bulbs and check the suspension for any rotten bushings and leaking struts.

If the car has stock catalytic converter, do not premix 2 ounces of premix per gallon of gas. This can cause catalytic converter failure. The oil injection system on the these engines is decent for street driving. 1/2 ounce of premix per gallon of gas at the most for street driving if you are dead set on it.

If the engine is maintained, 150k miles is easily reached. Many members have gone over 200k miles before a rebuild was needed. You will want to perform a proper rotary compression test with a rotary compression tester to verify engine condition. There's more than likely no need to remove the engine and tear it down.

 

ive all ready done every thing except for a true rotary compression tester i have installed a new gas tank new lines a fuel filter a fuel pump and changed oil also the car looks like it was serviced by mazda judging by the mazda dealer sticker on the side for when the car need to some back. Car also looks brand new under it it almost looks like it has sat in a garage or on a concrete pad because there is no rot in lines and everything seemed perfect on the the condition of the car except for belts i still need to replace those. Suprisingly i have put almost 100 miles on the car with no problems it runs amazing doesnt sputter and injectors are fine its something to do with the throttle stuff on the engine its causing the trans to somin weird but now i can get above 5000 rpm without a problem

 

Does the car have a manual or automatic transmission?

 

automatic

 

prob would be a good idea to get your injectors cleaned as well as replace fuel filter and possibly pump. good luck with your car.

edit- nevermind just saw your post above.