Archangels

basically long story short, i installed my BNR3 turbo and went on the dyno, first few pulls were pig rich but resulted in 260rwhp on a mustang dyno, not bad i thought, so on the 4th or 5th pull it had a massive lean spike out of absolutely nowhere, i was running 10psi and i believe it hit 12.7psi for a second, but at 5500rpm the AFR went to 13.5:1 and my car detonated, very badly, it was clear as day it was so bad....

needless to say, my car idles alright but when i go to revv it it stumbles a little and revvs slowly, you can hear it almost "miss" when you revv it, but at higher RPM it sounds perfectly fine, the car still feels like it has power and boosts alright, i havent pinned it since but what do you guys think might have gone wrong?...

i'm running 720cc secondaries and 550cc primaries, the AFR's were perfectly fine but the one run it decided to go lean, bad....

i did another pull and the power resulted the same after it detonated, it was at 10psi and everything....

i pulled the plugs and did a "poor mans" compression test, all rotor faces are exactly the same, front and back, but it sounds.... maybe a little weaker?, the rear starts off with a weak pssh then goes louder the second one and so forth, i put my hand infront of each plug hole and the air coming out is strong....

any idea's guys?, could i have cooked an injector?, although it's probably obvious my motor's done, but WHY would it suddenly have a lean spot?...



i should mention the previous dyno run before the lean spot there was an apparent "pop" i was told....

plus you can hear the "miss" in the idle....

imloggedin

do a compression test if youre concerned. you said you did another pull and it was the same HP... what are you worried about? you said theres some stumbling.. be more specific. is it a certain rpm? is it immediately when you stomp the gas?

woundup7

iTrader: (1)

Mostly likely toast. Buy a compression guage and check it. What are you running for fuel mangement.? 720 and 550 are only going to get you to 290 flywheel horsepower at 80% percent duty cycle.

I just popped mine, ran great above three grand, like a dog under that. Boost makes up for some of it. I boost spiked to 13psi with a bad tps. Not enough injector pulse for all that boost. BTW I run 750's and 1000's you should definately get more injector.

Sound like your injectors maxed out on duty cycle and that why you went lean very quickly. Sorry. I know the feeling.

Smoken'

iTrader: (1)

Yeap, do a compression test bro...

imloggedin

so quick to call it lol. didnt u see he said he ran the same numbers on the dyno after he detonated?

RETed

Do you have an aftermarket boost gauge installed?
Is the vacuum readings at idle the same?


-Ted

Archangels

the car runs fine, just seems sluggish at lower RPM's....

i'll try a compression test, but it's weird to have the same compression on all face's of the rotors?...

i did 5+ good runs then a quick lean one when i didnt really change anything....

and yes, it made the same PSI the last run as it did when it detonated, and the same power it made before....

there was something else i was going to say, but i dont remember, the engine sounds done but it drive's perfectly fine, i cleaned the plugs, checked for spark, i dont know....

havent checked but it idle's fine....

i'll check tommorow after work when i get home....

oh right, i dont remember completely if i did or not, but the turbo only boosted to around 10psi the final run and fell off to about 7-8psi, i dont think i touched the boost at all, but could the turbo be junk now too?...

ok, so i checked it just now because i ran home, and the vac is basically at 0 at idle, it's not sitting around it's happy 10vac anymore, and it barely idles, if i take my foot off the gas it wont stay idling like it would before it just idle's at 500rpm then dies, mind you it's not warmed up fully yet....

regardless, the vac at "idle" is very low, basically at 0....

RETed

10?
10 mmHg?
Or 1.0?

Even for a street ported motor, it's kinda low.
Sounds like a hose blew off or was loose from before?


-Ted

Archangels

i think it's 10mmhg?, i'm not sure, on my profecB specII it rear -59 psi, on my autometer guage it rear 10vac (-10), and now it reads 0....

does that help?...

Spectator

iTrader: (1)

Are you sure a vac line didnèt pop-off during the detonation? For you to lose all your vac, I dont see how else that could be, I mean, the engine still runs. And it would explain the rough idle and keeping it alive with the gas pedal.

coxxoc

iTrader: (3)

I cracked a rear apex seal doing this on a new engine before. Check your compression; my car ran fine in boost but poor out of boost as you were saying yours does.

Josh

Archangels

did all the rotor face's seem to have the same compression like mine though?...

Archangels

i should mention, NOW my profecB reads -19 and my aftermarket autometer reads 0....

classicauto

iTrader: (3)

There's a reason they call that the poor man's compression test. Throw it on an actual compression tester before ruling out compression numbers.

Odd's are if the vac is that low (and there's no vac leaks) that the engine is pooched.

Archangels

but what are the chances of it affecting all three apex seals?...

ericgrau

iTrader: (1)

About the same chance as you misreading your "poor man's compression test" and merely thinking that the 3 pulses are even. Just do the actual compression test and find out for sure.

re-rx7

iTrader: (3)

I love it when everyone says it's a apex seal....ari yallon still tells me to rule out all other possibilitys before assuming the worst. Now is their any problem with hot starting cold starting??? Any vaccum leaks??? Could be a number of things.

Archangels

i havent touched the car since, actually, i did however start the car last night to warm it up and check the vac. reading, it wouldnt idle unless my foot was on the gas, and when it was kold it needed a little gas to start but it revved alright and all....

the vac. read 0 and barely moved when revved a little bit....

dean23

one det. couldnt blow all the seals and make each face give equal numbers. maybe a few dets, but not just one. like every says, get a real comp tester..

and whats it sound like at idle? i DESTROYED an apex seal on my rear rotor and the car would still idle, but my whole car would shake like an overloaded washing machine and sounded like a harley with straight pipes.....

chances are a vac seal blew off. especially if you car was making the same numbers befre AND after the det.

Archangels

i'll definitly check it out, i dont know what could have happened, but even if it checks out OK, i couldnt imagine the damage the one massive ping did on my engine, it was the loudest one i have ever heard....

it idle's alright but you can hear something's wrong, it sounds like an inline6 runing on only 5cyls....

when you revv. it you can notice it if you put your ear by the engine, but above 3000rpm it sounds primo....

re-rx7

iTrader: (3)

^^^^+1 i agree mine did 2. It will shake violently you will know trust me. To check for vacuum leaks find some starting fluid spray around the injectors and thrittlebody anywhere their could be a possible leak. If their is the car will surge up and down.

re-rx7

iTrader: (3)

You also pull the plugs could be fouled ive seen it happen, if all else fails take off the exhaust manifold and stick your finger in their and feel for scarring.

dean23

the 3000 rpm thing is odd too... especially since thats where the secondaries normally kick on......

woundup7

iTrader: (1)

For the love of god, throw a compression tester on there and be done with it. Whys that so hard. My car was running exactly as you describe yours, and guess what it had a grenaded rear apex seal.

Heres probably what happened, you pinged it, shattered the apex seal, it stayed somewhat intact for the next dyno pull, made good numbers again, then on the way home it fell out into a pile of pieces, hence your new problems. I can go out to my car and pulled of the remaining vacuum lines, and all it does is step up the idle a couple hundred rpm's, doesn't shake or cause a low vacuum reading.

Also what are you running for fuel mangement. Check the fuel calc out for your injectors. 260 at the wheels is about 300 at the flywheel, which takes your duty cylce up to 82%. The reason I am asking is because iirc stock ecu is only good to 58-65% duty cycle.

RXJIM

iTrader: (3)

I have to agree with woundup. I have the same story but diffrent version. I chased my tail for two weeks looking for something other than a blown engine.