BoOsTin FD

I kind of started talking about this in somebody else’s thread, but i really got nowhere.

Here is the story...

I drive the FD maybe once or twice in two weeks. I usually drive it around for like 30-40 min with like 1-2psi of boost before i even get really on it. I admit i do drive this car like i stole it. My mods are the following: Huge Street port with 4k miles on it, rebuilded with Mazda factory parts, Rebuilded stock twins with 9k miles, PFC tuned for 1 bar. PFS SMIC, Dp, Hi-flo (which I think is clogged) Catback, Supra fuel pump, 1300cc secondaries, MSD 6a going to Leading coil. Removed all emission stuff, Pulleys, some braces etc. The car ran great for a year in these 4k miles.

Saturday night, I went for a drive. I’ve been driving it for like an hour before I started boosting it. I redlined it couple of times, got 15psi everything was great. I drove it afterwards everything perfect. So later on I went on highway on my way home, I was driving it normal, then I tried to pass this truck, so I dropped it to third gear, I redlined it again and went on. 5 minutes after I came to my exit ramp, I stopped on the signal light and the engine started sounding like it’s blown.

These are the symptoms I got: Vacuum reading 10-12, Idles weird like on 1 rotor, kind of shakes, Smells like unburned fuel coming from exhaust, has no power from the start to like 3-4k. Then it pulls hard.

Things I checked so far: Compression I tested by using piston engine tester, for each rotor I got 3 even spikes of the needle in the 35-40psi range. Overall compression when I let of the bleed valve to build the reading I get on the front rotor: 89-95psi. Rear rotor: 100-105.

I bought brand new wires and spark plugs, Checked Fuel injectors, and coils… which turned out to be fine. Map sensor I replaced because I had spare and I changed the hose going to it, still the same. With it unplugged it runs even worse. Spark plugs when they were taken off, 2 were brown and the ones going through MSD were a little black like rich. There is no oil on sparks or antifreeze.

Each spark plug is getting spark, I even tried bypassing the MSD and I still got the same problem. What I did notice about the sparks is that when I unplug the L1 the engine runs the same crappy way with it or without it, I mean there is no difference. Every other one I unplug it runs even worse. T1 when I unplug the spark plug wire, the sparks start shooting at the top of the coil rather then down at the end of spark plug wire.

Now all this might have been like this forever and I the car ran great without any problems and I’m just noticing these things now. I highly doubt that even if one coil or one side of the coil is bad it would give me all symptoms of blown engine. When I tested the coils they showed everything to the spec like it says in the manual.

I really don’t know what else to do at this point… I don’t have access to Mazda Compression tester, and I’m not taking it to a dealer because they screwed my FC last time I took it there for compression test.

Anybody has any other suggestion on what I should check. If you have been at this situation and you can give me some input if it is the engine or if it’s something simpler.

Thanks a lot.

BlueTII

Sounds like you damaged it internally. Try pulling the valve out of the piston tester and test it again.

check your pulsation damper on the primary fuel rail, see if it is leaking fuel. On most of the FD's we get in that have a blown front rotor, the PD is blowing fuel out.

Montego

iTrader: (1)

check your map sensor. It sounds to like it got disconnected.

BoOsTin FD

Checked the FPR and the Map sensor. There is no fuel anywhere on the engine or around the fpr, or injectors. It's dry.

As i mentioned earlier, I swapped map sensor and i changed the hose as well. Still the same problem.

Any other suggestions?

Thanks a lot.

BOOSTD 7

Mine did almost exactly that as well. Compression was fine, but it idled like crap ... sounded like a boxer motor, and smoked. What happened was too much gunk in the motor caused a side seal and oil control ring to stick down. After tearing the motor apart I wish I had tried pouring something down into the motor to try and eat away the gunk, turning it over by hand a few times and let it sit. I was going to use some ATF or diesel fuel in the motor. Maybe you should give that a shot.

BoOsTin FD

you don't think i actually blew it then? Why would it stick all of a sudden but i could redline it and boost it and all minutes before it happend

but i will definetely try to clean it with something soon.

BOOSTD 7

Who knows, but exactly how mine went ... I was driving down the interstate, 60 mph and it just starting running rough.

zerrovalve

boOstin FD, this is what i would check: primary injector of rotor # 1. I'm also trying to learn to diagnose rotaries engine for myself and your thread is very interesting. This is what lead my conclusion to; from idlle to like 3-4k rpm your engines relies on the primary injector for fuel, so if it's not sending fuel (wheter it's pluged or have an open coil circuit) you get a missfire type sympton. as you revup above 4k rpm the secondary come on line, you get fuel and then you get some power out of the # 1 rotor so it pulls harder... another thing your coils could be reading good primary circuit but have a bad secondary ckt. it's very comon on DIS sis. (primary= low voltage sys. secondary= high voltage sys.) but as i mention i'm not a rotary expert and this just something if it can help you resolve the demon...

Herblenny

iTrader: (13)

I don't think you blew it. I've seen few blown engines (bad apex seals) and you could definitely tell its blown. You can't idle below 2.5-3k. Also, when you take the plugs out and crank it, you'll hear it skip.

I could see what Boostd 7 is talking about. Give it a try and see. Also you might have a cracked seal. Is you OMP working or are you pre mixing? Who built the motor??

BoOsTin FD

well i checked the injectors by applying 9volts to them and i can hear them opening and closing. All 3 coils seem to be fine becuase they are up to the specs like it says in the manual.

I'm actually trying to relocate them, and am also working on taking the twins off so i can pour some atf in the engine and try to clean the seals... if in fact all 6 of them are there.

Amel

Herblenny

iTrader: (13)

I forgot to ask you.. Are you running seq turbo system??

BoOsTin FD

I am using the omp and yes i'm still on the seq turbo system.

The motor was built by my buddy Justin and me. We used all Mazda parts and i'm pretty happy with the outcome.

SLOW 7

You said you checked the ignition system right? If IGN is OK, I am thinkin' its probably a side seal.

Definatly try to throw ATF or something down its throat and hope for the best.

BoOsTin FD

I just doubt the seal would be stuck for no reason, but i'll do that.

Thanks

Howard Coleman

iTrader: (6)

i think your shortblock is o k as you would notice during your compression test that you had an uneven pulse (sideseal) or 2 uneven pulses (apex seal). you didn't get that because you had the fuel injectors turned off.... result, even pulses

the most probable suspect is the primary injector for the front rotor. you say your exhaust smells of unburned fuel. if the injector is sticking the additional fuel will dampen the spark and wash the walls causing a loss of compression similar to worn apex/side seals.

your motor runs o k once the secondaries kick in.

while your at it... you mentioned that when you had a plug wire disconnected you noticed spark jumping thru the boot at the coil. you need to look very carefully at your plug wires especially the boots at the coil. if you have primary ignition leakage it initially occurs from maximum torque to redline. in other words checking for leaks at idle w no load on the engine doesn't quite cut it.

i suggest you remove and replace your front primary injector.

btw, you will significantly extend your engine life if you add .4 oz/gal of any TCW3 2 cycle oil to your gas in addition to the OMP.

good luck and keep us posted,

howard coleman

BOOSTD 7

Super rich tuning can do it, too much carbon buildup will stick seals ...

BoOsTin FD

Well about injectors, they were cleaned by RC when i replaced the engine, so that would be 4k miles ago. I checked them by applying 9 volt battery to them and i can hear them click open and close.

I do add .4 oz marvel mystery oil every fill up.

See, when i first noticed that spark coming from the top of the coil, i tood the spark plug wire off and it has a small crack on it. I immediately both all new wires and replaced them... That didn't do anything.

When that spark starts coming up at the top, it's only when i disconnect it from the spark plug, so i really don't know what's up with that.

I am in the market of getting 2 550'cc injectors just for testing purposes.

Thanks for your reply.

BoOsTin FD

Ryan, I know for a fact that lately, like for the past month, the car has been running rich for some reason. When i took of the spark plugs, the Trailing ones were rich a little but the leading ones, (they are going through MSD 6a) they were pig rich. Plus the car is only being driven like 4 times per month.

I'm trying to take the twins off and make sure that i have all 6 seals then i'll be for sure that engine is fine.

How do i tell if the seals are stuck? Do they look pulled in or something?

Thanks a lot.

Amel

BOOSTD 7

The rich running, and letting it sit could certainly do it. Now if you could just source out some smart nanobots to fly inside the motor and look if the seals are stuck or not Other than that, only way to know is take the motor apart.

I'm going to call THE MAN when it comes to rotaries, Rick Engman. Ask him what he thinks about sticking seals, and how to unstick them without tearing down the motor. I'll post back later today!

Jason

iTrader: (5)

With a piston compression tester you should be seeing about 80-90 PSI on each side. That is with the pin pulled.

Jason

BoOsTin FD

on this site at the tech section says it should be in the 30-35 psi range....

http://rotaryresurrection.com/ Also many other threads i've searched said it should be in that range.

BoOsTin FD

Cool. Thanks a lot.

There was a thread a while back, that someone cleaned the seals by taking the twins off and putting some injector cleaner on them.

BoOsTin FD

Well, tonight i decided to take a close look and use a mirror to see through leading plug holes if i can even see apex seals there. The good news i guess is that all 6 seals are there and shiny. As i was turning the crankshaft manually the rear rotor gave out 3 loud swooshes every time....

The front rotor gave out 1 loud swooshes and 2 kind of low ones. So the problem is with the front rotor. So i put back the rear spark plug so i could just focus on the first one.

I used a no2 pencil with the rubber eraser in the hole pointing toward apex seal to see if i can push them in and if they'll come back... it seems they do. All three of them seem to move back and forth. Now what bugs me is when i did the compression test couple of days ago, i could hear loud swooshes every time, but turning it slowely i only heard 1 loud and 2 low.

So what do you guys make of this? Corner seal maybe? I can't see if it has corner seals anyway. Or could they still be stuck. I noticed as i was turning it actually spiled out some fuel out and you can see the rotor sides to be really black with what it looks like some black film on it.

Suggestions, comments?

BOOSTD 7

Spoke with Rick Engman ... obviously the assumption here is that something is stuck, which he says is possible describing the symptoms. He said in that case he's pour a full cup or two of diesel fuel in each chamber and crank it a full revolution or two by hand. Let it sit for a couple days and crank by hand again. After another day or two of sitting pull the plugs obviously and get the crap out. Then either try and start it, or if you're persistent put one more flush of fuel in.

Keep your fingers crossed during this whole period

Mine did exactly as you describe, again. When I pulled my motor and cranked it by hand, the chamber with the stuck seal belched a big glob of fuel and carbon filled fluid, and everything in the motor was REALLY black and carboned up.

BoOsTin FD

I'll definetely try that. I have all the time i need. It can sit for a day or two it's not a problem.

Thanks a lot man.