ok...here is the problem...bought a 86 FC GX N/T on Friday. Has dual custom exhaust...other than that stock but engine was completely rebuilt 15000 km ago . The car wouldn't start or idle. We fixed both of those by playing around and then putting in a fuel cut off switch. So then the car was working pretty good and felt like I hear RX-7's are supposed to, but after one night of it running good my brother was driving it and it just lost all its power and was stalling. My brother didn't push it past 7k RPMs and was going easy on it. Engine is running really rough and seems like it is flooding and not getting enough air. There is no power at all! drives like a lawn tractor. We have checked every hose and none of them have leaks. We replaced the spark plugs and wires. We checked the computer, it isn't telling us anything is wrong. We checked lots of sensors...nothing.

Mazda dealer here in regina is terrible...don't know of any good shops, could really use your guys' help. I can't afford to have it spend hours in mechanic shop. It would be awesome if you guys could help me out.

Also, I don't know if it makes a difference but on the trail spark plugs we can switch front and back and it doesn't make a difference and the engine will run without them plugged in and will also run with the lead unplugged if the trail are and it really doesn't make that much difference. Could the cats be clogged or what? I have spent hours searching and trying stuff on here but nothing yet.

any suggestions would be appreciated, thanks.

 

i dont know much, but ive been told that if removing the plugs and you hear no change in engine rpms, then one of the rotors isnt turning

 

2 words for ya: COMPRESSION TEST!

Jarrett

 

Yup, do the poor man's quick compression test. Remove 2 lower sparklugs, remove both EGI fuses in the engine bay fusebox, have a friend floor the throttle, put your fingers beside the open plugholes, and have him crank it over for 5-10 seconds at a time. Compare the pulses from both holes. It should go front-back-front-back-front-back 6 pulses in a row no skips. You'll more than likely, from your description, find that one entire rotor puts out next to no pulses, while the other does. Each pulse represents one apex seal making compression. Lack of pulses = lack of apex seals = blown motor.

Do this test first, it only takes 5 minutes to do, and no special tools. IF you pass, then you have a simpler problem, but if you dont, there is no reason to go on troubleshooting. Dont be like these other guys who deny it and refuse to do the test, and go around checking their damn oil and coolant when theyre being told they may have a blown engine.

 

ok, so we got a compression testor, started with the back one...we got even bounces at about 85 PSI then we went to the front (we were doing them in the trail) and got even bounces but only at 70 PSI...what would you suggest I do now? I read somewhere that putting ATF into your enginewill help restore pressure, but that doesn't really make sense to me but does it work? Anything else I can do to get my pressure up?

thanks guys

 

Well, 85 and 70 are by no means desireable compression numbers. Theyre usually what is seen in a rebuild before it ever gets started up, but compression in yours should have risen to at least 110 -115 by now.

THe thing should still dun with that compression if you did the test properly. Next thing I would check is spark...take an old plug, insert into the end of each of the 4 plugwires, put the 2nd EGI fuse back in (the green one), remove the dust cover from teh drivers strut tower, lay the plug near that bolt, and crank the car over watching the plug...each time you should see a whitish blue spark, adn hear it popping. Repeat and verify strong spark for each wire.

Finally we're going to try and verify fuel is getting to both rotors, but Ill wait on that explanation until you post back with results of the first.

 

oh yeah, well it was 8 o clock this morning when I did the check and forgot to warm up the engine, so I think that would make a difference, the spark plugs are all good, we just bought a timing gun and my dad did find one little air hose that was off...the engine is runnign a little better but still lacks the power and especially at 4000 rpm +, we are going to fix the timing just as soon as we eat, so catch you later

 

When you do the test, the engine should be warm, but its imperative that the throttle be open, adn that you crank the engine continuously for about 10 seconds.

I recommend using the leading holes, but trailings are ok too. As long as only one plug per rotor is removed, and both rotors have one plug removed at the same time.

 

well my dad and I didn't check the compression, but the problem is that we can't even get the car to idle at 750, it will only idle at 1200 at the lowest and it is rough there, but when we did the test this morning, the throttle was open. I am getting so annoyed though...

It cannot accelerate and is stalling very often.

we checked the timing and there are two marks but when we check both the L1 and T1 spark plugs they come up with only the same reading of the same mark and we can't adjust it because it sets both of them off.

 

ok, so we did compression test and the car is at 80 on both the lead plugs...so I guess that is really low, but does that also tell us why the car is running really rough? also the car was fine 5 days ago and just stopped, so yeah, anything to get the compression back to normal?

 

hmm...checked the hayes manual and said normal pressure is 85 PSI so I don't know if it is too bad, but here is the thing. From checking the timing, it is showing us that both the lead and trail plugs are firing at the exact same time. that would probably cause my problem, hey? any idea how I can fix this?

 

If his wiring is getting corroded or his battery is a piece of crap it would result in low #'s as well. I wouldnt say there is necessarily a problem with the engine.

And 85psi is mazda's lowest recommendation.

Check all your vac hoses and intake pipes for leaks, spray water on the motor if you have to. Once you are sure you have no leaks then look else where.

When setting the timing, the initial set coupler has to be jumpered (green 2 pin plug at the front coil). Take a 2in long wire, crimp a 1/4in spade on each end and shove each spade into the connector. Self powered timing lights arent supposed to work properly on these cars, I havent bothered to check. Honestly dont care enough to buy one and see. Get a new set of NGK BUR7EQ and BUR9EQ's while you are doing this too (Ill explain a bit more on why later). I havent bothered to check, but I dont think you can even set the timing at 1000+ with out getting a fucked up reading, the ecu should be advancing or retarding timing at those engine speeds. Undo the mounting bolt for the cas, line up the yellow mark on the pulley, remove and align cas then reinstall. This should be almost dead on (mine was off by about 3*). Anyways, put in the new plugs and get the motor below 1000 and time L1 again. If your pulley doesnt have yellow/red markings, look for 2 dents in the pulley. The one on the right is the yellow and the one on the left is the red.

Note: my motor wouldnt idle below 900 with out wanting to die (900 was a challenge for it). I put new plugs in and it idles like a rock at 700. No BAC or anything assisting it either.

 

our timing light runs off the battery and we just got new spark plugs from mazda, but I'm not sure if they are those ones, I will check. We have checked the hoses many times, haven't found anything, but why not try again. I will try and get the idle down as low as I can.

the connectors to the battery are pretty corroded and we had to recharge the battery from before when we couldn't get it started, but it seems ok now.

I will try the CAS and pulley trick.

 

well we found that the wiring to the throttle sensor was corroded and gunked up so we cleaned it off and we can get the car to idle at around 750 rpms or even lower but it sure is rough, BUT we checked the leading coil w/ igniters and the one side is arcing really strongly and the other side is very weak and when it's idling if we disconnect the strong side, the rpms drops and it sounds like it is going to stall, but we disconnect the other side and nothing, so we are going to go get a new coil/igniter from a slavage yard.

oh yeah, we discovered this problem because our timing light wasn't getting a signal from the weak spark plug wire, but it was from all the other ones

 

my car is so weak though, we were having so much trouble getting it to 70 km/h today and I don't think it is just a coil. Would clogged cats be the problem?

 

check the e-brake =]

 

hehe....yeah...I wish

 

AHHHHH more and more problems. We got a new leading ignitor/coil and it seemed a little better but then everything went to kaput. It still won't idle and now it is backfiring and popping. There is still no power. We hooked up our timing light and it isn't self powered and we can't get a reading of T1 and L1 wires! There is plenty of spark there as we have pulled off the connectors to the coils and we get plenty of spark. any help would be appreciated!

 

ok, and to add this one in. My car won't start now...won't even try to turn over, it is just dead. We got it to start a couple times by tapping the start relay with a wrench, but that doesn't work anymore and my dad checked it and it is still good...gah...what to do?

 

ok, starting problem fixed after a very long time...just everything else...

 

hey man i had the same problem. i was driving down the freeway and then all of a sudden i lost all power too. i took it to mazda and they told me that i blew the rear rotor.everything else was fine exept for that. so i just swaped with a used engine and now everything works fine. hope this help you out. although a rebuild should be a hell of alot better than a used engine.

dom
88 rx7 se

 

When my 300ZX did this exact same thing, it was because the AFM connector slipped off. Just another suggestion...

 

oops, I just realized this thread was 8 months old...