Bambam7

Well, I'm done with all this crap.
The car seems to have lost another front apex seal.
This is the third apex seal problem in 2 years.
1st- carbon locked engine- deformed apex seal
2nd (6 months ago) - A week after turbo install popped apex seal due to insane detonation for about 2 minutes that sounded like somebody hammering on a metal pipe(don't ask why)
So I've got 3000 km's on this newly rebuilt engine, and I'm loosing compression in the front rotor already.
The compression on this rebuild has always been pathetic, about 90 lbs. but I've got about 90/40/40 on the front now. It seems to be very slowly getting rougher and rough... like it's getting slowly worse?
I don't get it- I haven't even turned the damn boost controller up!!! I'm boosting at 6-7 psi, I have a huge intercooler, medium compression S4 NA rotors, 4x550 injectors, a walbro, and S-AFC.
I have NEVER heard any detonation at all (when my old engine puked it was LOUD detonation that you could feel through the shifter!!) That was before the walbro, and when I was got boost over 12 psi going dead lean.
I have none of those problems now.
Anyways, yesterday I was on the expressway and decided to listen very carfeully- and as soon as boost hits about 3-4psi you can hear a VERY VERY faint clicking sound, barely audible at all (I don't have a very loud exhaust) but I've never heard detonation that quiet before in my life... also- I've got tons of fuel going in, and my AF is stable at around 11.5:1
I think the sound might just be a little unevenness in the combustion cycle/revolution from the weak apex seal?? I don't know....

I don't see how in the hell I can get detonation at 4 psi, 91 octane, tons of fuel, and a huge IC.
The timing is even retarded a few degrees.

One thing- when I pulled the plugs to check compression they were CAKED (like, 1mm of buildup) with brown carbon, they are only a few months old, I know I have the car set to run rich (for anti-detonation, jees) but is it possible I just have a stuck apex seal from all the carbon? (A lot for only a few months of use)
I'll try letting it sit in ATF overnight- any other suggestions?

This car is gone.... I'm so tired of these disposable engines.

Aaron Cake

iTrader: (1)

I don't know what to say. Obviously you have made the decision to sell the car...have you considered a "proper" TII swap? Or having the engine built by someone else with many years experience? More money thrown into a car I know, but...

Anyway, excessive carbon can and does cause detonation by making hot spots which will ignite fuel before the spark occurs. Very common problem in piston engines, not so common in rotaries. But there's no technical reason why it can't happen. Plugs caked in flakey carbon can cause this because the tips of the carbon formations heat up.

If the engine always had low compression, then something else must have been wrong. Are the housings worn? Did you measure them as you assembled?

Again, sorry to hear about what happened. If you're wanting a fast and bulletproof car, look in to the Grand National.

Bambam7

Engine was built by a pro- A guy named Darryl Sendrea, who formerly owned a rotary business called Rotary Dynamics... he's now an engineer with Eibach.

Bambam7

I'm so done with this... I'll try the ATF tomorrow, if that doesn't work... I'll probably just sell it as is on Ebay.
I'm gonna buy a 325i tomorrow and stress that thing out.

RarestRX

Yo,


Go back to NA! Lose the evil snail...it only brings misery and destitution.

*grin*

Best of luck with your engine problems, I'm currently running on 16 of the 18 tension bolts...so NA might not be /that/ bulletproof.

Heh.

Kevin
1989 GTUs "Weight reduction Stage I...on the motor!"

Dvst8

iTrader: (6)

RarestRX,
Why is there only 16 tension bolts???

opps, forgot to look at your last line. =)

ERAUMAZDA

Um....could it be you were using N/A rotors?

Bambam7

Ya... but S4 N/A... there is still NO way that that should detonate at 3 psi.
There's been lots of people that have put turbo's on N/A engines, running just fine at 6psi, with only minimal fuel upgrades.

adamlewis

Timing?

I dunno...Just a shot in the dark.

87RXGhey7

since you have a safc, why dont you run it extremely rich, dont trust your narrow band o2 sensor readings, run a lot richer.

adamlewis

He said he was already running it rich.

Aaron Cake

iTrader: (1)

Timing could be an issue, but he said it was retarded by several degrees. And really, 3PSI of boost would be fine on the stock NA fuel system.

Something else is wrong....S-AFC backwards or set to the wrong AFM type? This can cause the car to lean out when you had assumed it was being richened up...of course, since you verified it on your A/F guage...was the O2 sensor in good shape?

DaleClark

iTrader: (55)

Remember, timing problems won't show up on a wideband. Something as simple as the trailing wires hooked up backwards will cause detonation problems a wideband will NEVER see.

Remember, a wideband isn't the end-all, be-all engine info display.

Dale

White_FC

Hmm very strange Bambam7....

and here I am running ~5-7 psi on my stock S4 N/A, with microtech, S6 fuel pump, stock injectors (460cc!!), exhaust/intake, FMIC but stock other than that

I actually wound the boost up to 10psi the other day
Pulled a HELL of alot harder, and didnt hint any detonation, this is with more advanced timing than stock at the moment.

I've turned the boost back down now till i get to a dyno though

inboost

I've had a similar experience. My plugs were caked, A/F's were great, and all equipment appeared to be working fine. I would get light det at stock boost levels on my bone stock (at the time) S5 turbo II. I tried fuel additives to clean the combustion chamber, and switched brands of gasoline too (FWIW: Chevron seems to burn very well in these cars, Union 76 leaves a lot of deposits). Finally it turned out that all of my oil injection nozzles were bad and drooling oil into the intake system on a car that only had 68,000 miles on it. I capped them off and went to pre-mix and never had to look back. The car still runs great to this day.

Good luck!

Bambam7

Really.. that's intersting....
Could very well have been my problem.. I know that oil reduces the octane rating of gasoline....
There is still a chance it's just a stuck seal from all the carbon... havn't atf'ed it yet.
I am burning quite a bit more oil than I should be too.....

BlackRx7

thats why you should premix as a precaution, also you can damage a motor while running too rich, but before you do anything retard the timing this will help stop detenation, do you have anything to retard your timing when you enter boost?

Bambam7

The base timing is retarded a bit from stock, but nothing for advance, execpt a homemade thing.... I have a check valve w/a relief teed off of the the N/A pressure sensor.. so it'll only detect vacuum... as soon as it hits boost, the check valve blows off, preventing a higher value from the sensor, and preventing further advancing of the timing. It doesn't retard the timing, but it should theoretcially keep it lower than if was getting a higher signal from the pressure sensor.