Car is idling rough, but in the right area ~720-750rpm. Boost is normal, and all vacuum lines are good. Idle adjust screw does nothing, ECU does not put out error codes. Should I get a compression test at a Mazda Dealership to see if the seals or bad or if the engine is blown? I mean.. if I Had a blown engine, wouldn't I have a lot more problems then just straight idle? Engine runs nice with a lot of power as long as it isn't idling. I've thought it might be Fuel Injectors, Fuel Filter, Apex Seals (anyone have a guide on replacing these?), or a blown rotor. What should I Do?? ANyone in Arizona want to give me a hand, please lemme know!

-Darren-

 

have you checked your MAP sensor? It gives the same symptoms as a dying engine.

 

YEs MAp sensor is connected properly. HAd that problem before, engine doesn't bottom out.. just idles really rough.

 

Do you have a boost gauge? If so, what is your vacuum reading at idle?

 

Oh boy. Look in your engine bay while the car is idling--does your Upper Intake Manifold shake violently? Also, as Mahjik said, if you have a boost gauge, check your vacuum at idle. How many inches or mm of vacuum are you pulling? Does the needle oscillate back and forth? Also, when pulling away from a stop, does the car feel weak below, say, 2000 rpms?

 

Seems like lots of idle problems lately, i've got it to.
Hunting idle, low vacume, loping at idle. The Gotham boys tested my compression in the mid 6's. Car still runs fine like yours. (for now) Just not as much power as it should have.

 

If you have power, you *probably* don't have a blown engine. When mine went, I could hardly accelerate at anywhere under 4k rpms. I could build no boost, and vac was at like 5-6 in hg. Idle was non-existent, I had to hold the throttle to get it to "idle" otherwise it just died. And I could not, for the life of me, get it moving past about 40mph. So, it probably isn't the engine.

 

The Vacuum moves around 12-14inhg it won't stay at a solid 15inhg. It has power below 2000rpm, but not as much as it should have... so yes... a bit weak. DOes the upper intake manifold shake violently? Well.. depends on what you call violently... it does shake a bit... not really violent... but it does shake a small amount... noticable if you look at it.

 

Doesn't sound good, my man. Does the vacuum oscillate when the rpms at idle are constant? You might have just chipped a seal. If that's the case, it could be a cheap rebuild, relatively speaking.

I'd recommend that you drive the car as little as possible and definitely don't boost it.

I had similar symptoms once, and one seal on the front rotor was cracked in half (although it held in together) and another seal had a chip off of the tip. The good news was that all the housings and both rotors were ok.

 

Yes, the car will be at a constant idle. BUt the vacuum will oscillate around 12-14inhg rapidly. It's a small movement, but it won't stay at a solid 15inhg. Cheap rebuild...? I have a hoist... I'd rather save the money... how difficult and how much will this cost me to do on my own, compared to taking it to a shop?

 

https://www.rx7club.com/forum/showth...hreadid=187791

 

NO power below 2000rpm, over 2000rpm it's fine... sound like an apex seal?

 

Again, take "internet motor health diagnoses" with a grain of salt, but.....

 

I'm going to throw in the throttle position sensor and related attepts by the ECU to regulate idle using the ISC which will give fluctuations in the vacuum signal.

It's an easy check before going the compression check route, which is also an easy check.

 

Forgive me for being a dumbass...ECU using ISC? What is an ISC, and how do remedy this problem? I am doign the comp later this afternoon, what should I check before that?

 

ISC = Idle Speed Controller

Check this thread:
https://www.rx7club.com/forum/showth...hreadid=196607

 

Wasn't the plugs... next.. the fuel filter... then the injectors... ;p

Oh what fun!