cair0

I couldnt really find anything about this by searching, so im gonna post it here, i went out and looked at an rx7 today, i forgot how many miles it has, but all the electrical stuff seemed to work just fine, but it had some problems with the engine, and i didnt get to test drive it, so i dont know about the transmission.

anyways, upon startup, the idle was jumping back and forth between 1k to 1.5 k, kind of sounding like it was gonna die or something.


when i revved it and held it, it seemed to miss about every second or so...


anyone know what might be the problem...?

cair0

its a s4 87 coupe, by the way, and the speedo was in km/h

Josepi

Idle roaming is either an intake leak or a misadjusted/bad throttle position sensor.

KM/H? Eh? hint...Eh EH!

Most likely it was sold in Canada and came down into the states sometime. Keep in mind that the mileage is going to be reported in KM as well. Unless that is, someone went and swapped in a Canadian/Japanese gauge cluster which isn't as likely. Do you have a VIN# for it?

cair0

dont have a VIN for it, but would it even work on carfax since its from canada?


anyways, i dont think roming is the right adjective to use, to would go down to 1000, then kick up to 1500, then sound like it was gonna die, and go down to 1000 again, and repeat this cycle about every second...


how much would this cost to fix, assuming i had a mechanic do it?

Josepi

Answer these...

Did it ever drop below 1000?
About how long did it take to start (counting in misissippi)?
Did you let it completely warm up?
Was it doing this when warm or while warming up from cold?

One thing to keep in mind is, have someone check the compression. The real way is to (the only time you ever should) goto a mazda dealership. They have compression testers built specially for rotary engines. Typical costs is around 50-75 dollars for a test.

Depends on the mechanic. If he replaced any parts with stock parts from the dealership, it could get around 3-400 w/labor. That is presuming that it is only something like the TPS or an intake leak.

If you do buy the car, try HARD to find a mechanic that KNOWS THE INTERNALS OF A ROTARY ENGINE. Don't let some grease monkey fool you. Same goes with the dealership.

cair0

yes, after i let off the gas after revving it, it would go to like 500-700, but then shoot right back up and do the 1000 rpm dance

took about 2 or 3 mississippi to start

i dont know, the longest i ran it for was like 30 seconds, so, probably not.

i had just started it, and it was doing it.





ok i know a really good rotary mechanic i can go to, but your saying that if the compression looks good, then its the TPS or an intake leak?

Josepi

92% sure!

You really should never cut it off after so short of time. Doing so can result in flooding the engine.

Did it smoke AT ALL when starting and initially running? If so what color? If not, GOOD!

I'm done on the forum tonight, but i'll check this thread tommorow, or maybe someone will take over for me.

cair0

no smoke at all, but it did smell like gas when i was revving the engine...

cbrinega

The bouncing idle was probably caused by the car not being warmed up fully. The car should rev to 3k RPMs on start and gradually work its way down to a 750 RPM idle. Sometimes if it is warm outside the ECU will bounce the idle, because it tries to go into a normal idle state too soon.

cair0

how long does it take for it to get "warmed up"?

rx_7_driver

about 10 min



-Shawn (thats how long it takes for mine)

Josepi

If your TPS is in good working order, it won't bounce whatsoever. It'll be a gradual decline from 2K (if you start it in first, then take it out of gear...if it's a manual!)...