Ive searched but nothing seems to match what is happening with a car im looking to buy.

I went over there today and the owner said it does run but wont hold an idle. He thinks it was spark plugs because the car has been sitting for a year and hasent been driven in a while, just startups to make sure thigns are ok. He said when he parked it he was useing it as a DD.

we started it up and the car would start but as soon as RPMs went below 2k it would stumble and stall. If held above 2k it would run fine, even redline no problem. I did a quick poor man compression test on both rotors and they had stround sounding and feeling pulses. The plugs looked fine when we pulled them.

what could this be? I love the car but dont want to buy a lemon that will be too expensive to get running.

 

It's been sitting for a year?
http://www.aaroncake.net/rx-7/unstore.htm

By just starting it up and running it around, you've probably spread trash throughout the fuel system.

As for the problem, it could be due to a lot of things. The most common causes are vacuum leaks. If it is "just" the spark plugs, then why was the car parked? It is possible that the plugs are so hammered that they don't fire properly down low but I doubt it.

 

we drained old fuel, and put new in. there wasent any jelly or powder in there. we just ran it didnt really drive it.

it turned into his project car that was quickly replaced by a transam he got for graduateing college. nothing malicious about why it was parked.

spark plug was just his uneducated guess. I guess the question is with a good compression its it worth it to take a gamble and buy it and just pray that its a large vacuum leak? I dont want to discover it is somthing different. any other way to narrow this down?

 

Doing lots of searching I think the problem is one of these:

Vacuum leak (large) – we briefly looked but couldn’t find a significant leak
TPS, Idle adjustment, ect – perhaps a solenoid died, but I’m not sure it would completely remove my idle
Stuck injector – running rich while in closed loop during idle causing stall and stumble, but not a problem during higher RPM; however the engine isn’t flooded after setting so not sure that makes sense either.
Coil/spark problem – maybe one rotor isn’t firing or something similar, although I would imagine this would be more of an issue at redline than down low without load.
Fuel problem – maybe old fuel went bad, clogged filter or something but I’m not sure how it would have trouble at low RPM but be fine at high.

I really can’t think of any other problem. Does anyone more knowledgeable be able to narrow this list down for me? I plan on going to do a real compression test next time I see the car to make sure, but is there any quick way to figure this out? I’ll take a light tester for the tps too. Basically if I can narrow this down to a relative quick fix (replace injector, vacuum hose, or fuel filter) I would buy the car as is and fix it after I get it home. But if it is more serious (engine rebuild, expensive replacement parts) then I rather not buy it since this is just a side project and I am on a budget.

So should I just buy it, do an intake teardown (http://howto.globalvicinity.com/gv_w...i=55&co=1&vi=1) and drive off happy, or do I need to investigate further or avoid the car altogether. PLEASE HELP!!!

 

There is a lot of mixed up information here...

Closed loop does not happen at idle. At idle, the A/F ratio is set by the mixture screw on the passenger shock tower.

The TPS really doesn't have anything to do with any of the solenoids and they won't greatly effect the idle. The only exception is the BAC valve. If the TPS is out of adjustment, the ECU has no way of knowing the car is at idle so BAC operation will be all wonky.

It is impossible for one "side" of the leading coil to fire and the other side to not fire. The leading plugs are two sides of the same coil. So either one fires, or they both don't. However if the plugs are hammered with fuel and gunk, and the engine has been flooded, then it is possible for to run like absolute crap down low yet still run reasonably well up top. The cure is to swap the plugs out and then just run the engine around 3K until it clears up.

There are about a million places vacuum leaks can occur. A brief look won't uncover them. You need to spray something like water around the engine bay and see if the engine sucks it in. For example, if there is a big crack in the underside of the black intake duct, it will cause these exact symptoms.

 

thanks. I guess I am used to my RX8 on alot of technical issues....

I was pretty sure that the 89 does not use the mixture screw but it wouldent be the first time i was wrong (see above)

And plugs look good, hell they look better than my RX8 plugs with only 20k on them.