blown apex seal ?
 

sooo my car is acting weird and i have a video to go with it but here is my story i was driving my car n rev matched it into 2nd all of a sudden i felt a lack of power n car will not rev past 3k also kept stalling out even with clutch in very lucky to get her home
car- 91 NA fc
mods-
ACT HD clutch kit
racing flywheel from mazdatrix
prev owner replaced stock airbox with a cone


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this video is with me holding it at around 4k with clutch in with the clutch in i can freely rev the car from 4k up once it goes under 4k it stalls also putting it into gear car stalls in this video i let off the clutch while hittin gas

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also the car shoots lots of flames when its being revd high n sparks came out the exhaust like u see from those firework sprinkler wand things



thanks for the help

the flames is due to there being un-burnt fuel left over, happens with a lot of rx7's and about the stalling, make sure everything is in place and not getting pinched, i had a vacuum leak cause almost the same problem ...

Could be an afm problem

wud that also cause the sparks? i understand the flames but the sparks came as odd to me, also i know there is a way to check for leaks with some spray i think? i tryed by hand and had no luck

do you suggest getting an afm n tps ??

Check for vacuum leaks and check the AFM to make sure the plug is on there nice and tight and making contact.

Are any of what he described symptoms of limp mode? (I've never had it, so I couldn't say if it was)

vacuum leaks dont always show up in the most convient locations, you may have to remove your Upper intake manifold. and about the sparks ... thats weird, never heard of that before..... maybe there is something loose inside a cat ( i have seen brand new cars that had stuff bang against each other in the cat )

Sparks?

I was racing some guy in my old S10 and my cat overheated, and basically did the same thing you're describing. sparks, few fireballs rolling down the road.

Pulled the cat and it had shattered into a million pieces.

Don't think that is your problem though. Could be just a problem caused by the primary problem you are having.

Check your timing and compression, too. Out of whack timing can cause fuel to burn in the exhaust, and blown apex seals can let burning gases by. Both will sound like utter crap and if you can get it to run they'll run terribly, too.

don't waste your time, i can tell by the uneven cranking pulses that you have 1 dead rotor with 0 compression. most likely the rear rotor.

yes, you need a rebuild with likely a new/used rotor and rotor housing.


if you want to verify it go get a compression tester, no need to do the fancy bounce test with the schrader valve removed. i can pretty much guarantee you one rotor is only going to read maybe 20psi max total peak compression.

sorry for the bad news but i'd rather save you the time of doing all those tests for nothing.

the flames are from unburnt fuel from the dead rotor which is being fed fuel as if it had full sealing compression which burns off in the exhaust stream rather than inside the engine. the sparks are likely debris from the metal/metal contact still going on inside the compromised rotor housing, assuming you have gutted cats(or else you wouldn't see flames or sparks, it would be collecting inside the cat and cutting it up like a ribbon).

I agree with Karack now that I re-watched the video. I'd be more detailed but he pretty much summed it up.

well to be honest this is the best news ive gotten in awhile its much better than testing everything n going through all that trouble now i just need to find a cheap motor to get to A to B to save for t2 swap one question for you guys any difficulties in putting s4 na into my s5

will require swapping the timing cover, or if you premix your fuel it isn't necessary and you can just strap the OMP out of the way while leaving it hooked up to the electrical connections. that or if you have an Rtek chipped ECU it should be a direct swap as it eliminates the limp mode.

retain everything from the S5 engine though.

just saw ur sig PM sent

I would part that thing out and buy another car. That's the easiest, cheapest solution because that engine is blown. The housing(s) are worn out and they're getting near impossible to find in decent shape.

This seems a little familiar. I think this happened to me before. Check if all your sensors and plugs are plugged in. My intake sensor was loose a little bit and caused my car to react like that.

Exactly!

This sounds like my old S4 motor that had blown both rotors and had very uneven pulses.

A botched rev match or very sudden changes in RPM (like slapping a modified clutch) is a good way to break seals.

you could always try and run it as a single rotor!:biggrin:

new clutch n lighter flywheel prob did it lol n hey maybe i could just to get from A to B before my swap :lol:

Is it still doing the same thing? I know my S4 NA engine did that alot cause the vacuum line for the pressure sensor would pop off from time to time.

i decided to swap the motor so i never resolved the issuee