abqrx7

My recently acquired California spec full emissions (I get smog checked when I register)
1980 12A suddenly started running rough while I was driving in traffic, barely idles,
no low speed power, smooths out above ~3000 rpm, acts like its
running on one rotor. I suspected the ignition, replaced plugs, wires, rotor and
distributor cap, but no change. I don't have a shutter valve, so its not that. When I
unplug the anti-afterburn solenoid valve, it dies immediately, so that valve and the air
control valve are working at least somewhat. I do get some popping when I lift off the
gas while shifting, so I know the air control valve may be a little sick, but it doesn't
appear to be dead, so I don't want the expense of a new air control valve unless I really
need it. Any suggestions?

SoRRoW

You do any compression test latley?

How about your ignitors?Check them

pratch

Yes, pull the leading plugs and if you want, turn by hand. If you hear foomp, plat, plat, you have a dead apex seal. Everything you're describing is what I just went through. Of course, depending on how the apex seal went, you could be short a good housing as well.


I ended up getting a rebuilt engine for pretty cheap and as of today, I'm running again (tossed the apex seal 12 days ago).

Good luck!

abqrx7

I haven't checked the igniters because the Haynes manual instructions don't make sense. I have
the 1980 model, so the igniters are mounted on the left fender near the coils. But there aren't
3 quick disconnect connectors. if I take out the mounting bolts, there are two igniters on the backe,
each one has a quick disconnect with two prongs. Can I just check at those points? How do I check?
Do I put on a test light and flick the ignition on and off?

Thanks

abqrx7

I have the leading plugs out and turned it by hand. The sound is not consistent, but seems to be a gentle pop-pop periodically. What exactly should I be listening for on the bad apex seal?

Thanks

Pedestrian X

each rotor has 3 "points" and at the top of each point is the apex seal. if you loose an apex seal you loose compresion on 2 sides of one rotor. so if you have 3 good apex seals per rotor on each rotor you should hear 3 consistent *POOFS* if you lost one apex seal you wuld here only one *POOF* and two poots, check each rotor one at a time.. hope this helps..

pratch

if it were a good seal, you'd hear 1 even sound every 120 degrees of rotation. Hearing only one pop periodically means that more than likely you've got a dead apex seal. If it's just stuck, ATF might free it.

Put one of the plugs back in and if you hear 3 even pops then you know the limp rotor is in the other housing.

To check the ignitors, just get a timing light and make sure you're getting good signal. Judging from what you've mentioned though - I'd try the ATF (a few tablespoons in each chamber) let it soak overnight, then get ready to burn off a lot of ATF (took about 20 minutes for my smokescreen to clear). If it's still bad after that, get ready for a rebuild.

abqrx7

I have to quit for the night - will try again tomorrow.
Thanks for the advice.

mazdaspeedrex

Sounds like what mine did. I have no rats nest so it wasn't any of that crap. Get a standard compression tester at your local parts store. Follow the directions except for one. You need to hold in the release valve or you will just get one reading. You should get 3 similar readings as the rotor spins. If you don't, bye bye mr apex seal. Time to look at a rebuild.

Sa22c_guy

abqrx7 its a little off topic but I have the same popping sound while shifting as well, I'm looking through my haynes manual but cant find the air control valve which section is it under or is there another name for it?

abqrx7

p 86, 257,274 haynes manual on air control valve - also search the archive

abqrx7

final - it really works to pull plugs on one rotor at a time and turn it by hand. The 3 puffs/turn on the good rotor are easy to hear - the one puff/turn on the bad rotor is dramatic by contrast. This is a really handy diagnostic - but now I have to rebuild. Boo hoo.

pratch

Sorry to hear you're in my boat. If it's any consolation, the time between apex seal death and completely running well with new engine (my rotor housings were junk) was 15 days.

Sad to have been without her, but happy now that I have her back