Hey guys. So I'm pretty sure I blew my motor the other day. I was pulling out of a parking lot and as i got to the main road I decided to do a little pull. 1st gear went WOT, almost hitting redline, shifted to 2nd gear foot still on the pedal then weird things ensued so I quickly let off the throttle and limped my way on a side road. During the event I notice a loss of power, a loud whining sound as I try to accelerate, and the pitch of the exhaust went off similar to an old lawnmower. When parked on side road car was shaky, little smoke, rough idle and an audible knock sound can be heard. Yup sounds like a blown motor to me. Managed to drive home and park it.

Today did a poor mans compression check, and it seems like I still have compression on both housing. I don't know if I'm hearing it wrong but the "psh" sounds even to me. I wanted to make sure, so I went and purchased a piston compression tester. Results were: hot start - front rotor housing got an overall 100PSI and hot start - rear rotor housing 115PSI; as for the bump test the rear rotor had even bounces and front is kinda hard to tell. Pretty sure front is blown. I will post some videos later on so you can get a better idea.

I just want to know what might have caused this? Its really frustrating because I spent so much money, time, and effort trying to make the best of a car - something all of us car enthusiast can relate to. I recently rebuilt the motor last year too, and it had less than 8k KM on the build.

Here's a list of mods I have: CAI + recharged filters, full 3" exhaust, wideband monitor, ECU PFC (on arghx method safer/idle base tune @ 10psi), MBC, Supra FP, Fuel Filter <2k km, cleaned&flowed stock 550cc/850cc fuel injectors, NGK sparkplug 9s T&L, NGK plug wires, coil packs. Medium streetport, all OEM Mazda seals except Goopy apex seals, and Pineapple HD water seals,thermal pallet,greddy pully, new belt, ported wastegate, stock sequential twins @10psi.

I'd also like to add during that run I saw around 10-11.50 AFR, peak boost ran was .60 kgcm2 (6~8PSI) so I know I didn't over boost, AIT 40C-45C, WT 90C-95C

 

Since the fueling system is all stock I'm gonna say it most likely was the tune. It must have been pretty off to hurt the Goopy Seals. The good news is you shouldn't have any engine damage as they should have just warped as that is what they are designed to do

thewird

 

10-11 afr is pretty lean to what I heard recently. Possible it leaned out and took the front seals? I lowered my boost down (My afr is 12-12.50) recently as this weather has not been to safe to do proper pulls.

If the rotors are showing to be having ok compression, Maybe it isn't the problem? have you checked to see if a coil pack went? How did the plugs look? Any in particular have a funky color? And if I recall, Arghx's PFC guide does not support full 3 inch with cat delete, so you should have retarded the timing or upgrade the fuel system a tad but I could be wrong.

Hope it isn't blown dude

 

check all your piping.
I don't own an FD but I keep hearing of guys blowing pipes/couplings,etc off and the engine pretty well goes flat on it's face or doesn't go into boost very well.

 

10-11 is rich...

-Geoff

 

Could perhaps having low fuel be a factor ? I did have just a little bit over the E reading on the fuel gauge- which was stupid on my part to be doing WOT runs. And shame on me if that was the determining fate of the motor lol, I'll give myself a nice tear-inducing wack if that's the case...

rota I literally swapped/tested the fuel and ignition system with new parts just few days before this happend, so it shouldn't be the problem. Idk, I'm probably gonna go over the systems again on more time. I'm hoping it's one of these as a malfunction within the system can emulate a blown motor

Heres the compression test:

Thoughts ?

 

Whopps, sorry meant rich Only makes sense as colder it is, more fuel is dumped.

Yea one of those rotors are cooked from that video it seems. Doing low fuel pulls can be very bad, I would never try imo

 

That front housing is done. A short fuel starvation isn't going to do squat to those Goopy seals. I was doing that all season on the 20b making 650 rwhp @ 13-18 psi when I'd forget to top off the gas tank and never hurt them. Your problem was a sustained issue. Either that or your diffuser broke if you reused them. Basically what I'm trying to say is stop wasting your time trying to figure it out because that motor is coming out.

thewird

 

Defiantly a blown engine...

 

I would definitely contact JDK, he knows his stuff and is the only one I trust when it comes to rebuilding my engines.

 

I am sure these guys are right but make sure the map sensor didn't come unplugged. I popped one off a while back. Scared the **** out of me because the car ran so poorly.

 

Got around to tearing down the motor on the weekend, and things were worst than i have expected. When I got to dissembling the front stack I found a mashed up needle bearing (the one under the thrust plate) and a little copper showing on the stationary gear bearing. Turned over to the rear and begin to remove tension bolts, end plates, housing, rear rotors, etc., which were in alright condition. Got to the front and it was a different story; 1 missing rubber insert, 2 stuck apex seals and a dozen of the Devils nail marks engraved on the housing, saying that i should go LSx...sike hahah.

On a side tangent, anyone have nice used condition front housing, rotor, maybe even irons, and an eccentric shaft ? May be interested in a shortblock

 

I got a shortblock.

 

I have some parts here, give me a call. I'm not soliciting a rebuild from you like others might think