CluelessInStLouis

Hello all. I've been browsing for a week or so, finding many references to idle-related problems and solutions, but have found nothing that sounds like my problem.

First of all. I have never owned a rotary. Always (since 80's) been intrigued, but opportunity never presented itself. Now I have a chance to get an 89 RX7 locally (from a private seller) for my son who will be getting a license soon. Have visited and driven the car. It's a GTUs. Looks and drives solid, with minor cancer on bottom edge of front fenders, no big deal.

My only real question about the mechanical condition is about idle. After starting (and the car had been sitting without starting for some weeks) the idle speed seemed to behave as this forum says is normal. But my concern is about an occasional "popping" sound, like a backfire in the exhaust system, every 8-10 seconds at idle. After the engine warmed up, and during the test drive it was entirely gone. After the test drive, I shut off the engine and immediately restarted it. The same "popping" was back at idle.

What could this be? It it more-or-less normal?

The car has 12X,XXX miles. Engine was rebuilt at about 80,000. I really liked the car. Seems like it'd be a fun car for a high shool kid. Just don't want to end up throwing huge $$$ at it.

My experience is more along the lines of large displacement V8's (gotta love the old Detroit muscle) and I've got quite a lot of background with building/tweaking other cars/engines. I would not be against taking up a new hobby with my son on this car, but the rotary may as well have been built on another planet as far as my knowlege goes at this point.

Thanks in advance for any/all input.

CluelessInStLouis

RX7_Racer_84

I would take a look at the TPS (throttle position sensor). Make sure that it is at 1 ohm. Use the search and you can find out how to set it. It doesnt sound like it would be too much of an issue if it runs fine while warm. Most of these cars are over 20 years old now. I hope that you do decide to buy it for your son. They are fun cars and usually very rare especially the GTUs.

veedubbed

Sounds like the ACV throwing air into the cat to heat it up, would be my guess. Oxygen + exhaust = pop

cbrinega

The popping is more or less normal. My car did that when I got it several years ago, but since then I've replaced the exhaust system (cat included) and made sure the exhaust gaskets are sealing well (makes a bigger difference than you might think). I rarely have that popping anymore.

I do know that for the first 20-30 seconds after startup the engine runs extra rich, so that probably contributes to these mini-backfires. As long as the engine has good compression and shows no issues when warm, then it probably needs a basic tune up (assuming the emissions equipment is all still in place and working).

Check out the buying guides in the FAQ. That may help. Sounds like you have found a pretty decent car.