Mr. Vapor

So im dropping off my GF, and im leaving her house. i get on teh on ramp and give the litttle turbo everything shes got..full 7psi, WOT, redline, i shift to third and BOOM, nothing, engine dies.

I pull over
i panic
i search the eingine, wont start. turns over, but no start
then i see gas on the ground. so i start to check my fuel lines, and sure enough i blew the one from my airtex pump to my fuel rail. so i put it back on and away i go. yippee im happy! then it blows again, and continues to blow off every 2 miles for the next 25 miles (a 20 minute trip took 1 hour 30 mins) i lost the hose clamp that held it on.

its all back to normal now, but did i harm my engine blowing the fuel line at WOT? please, im having trouble sleeping!

rjardy

no your good, just cutting fuel is no problem. you run into problems when you cut ignition at high rpm and fuel puddles in the cumbustion chamber. but yeah sleep good dude your allright and so is your b16

Giuseppe

cant help u on the motor issue,

but it wasnt safe to be leaving a trail of gasoline
from the freeway to your house..
if u know what i mean..


[Modified by Giuseppe, 8:50 AM 3/4/2002]

dustin

Hmm, well it was definately pinging some when the line blew off... fuel was still being injected but not a whole lot of it..!

I'm sure it is fine, just don't do it again =P

Dustin

JM Performance

??? one day I hear fuel cut is bad, get a spark cut, then I hear this.....sheesh

rjardy

yeah im almost sure that fuel cut is better than ignition cut due to just backfireing alone. you lose ignition the fuel is not getting burnt, so it doesnt leave the cumbustion chamber like it would if it were burnt, so you then throw spark back into a puddle of fuel and it detonates. at least thats how i understand it...sorry if i cunfuzed you 00silverls but damn !!!!! no im curios and not sure DAMNIT you got me thinking!!!! does any one know for sure????? GRRR

Mr. Vapor

thanks, i think im ok, once i got it clamped on, it drove ok home. i didnt boost it though, i was to scared. but can anyone give me a definate?

bigTom

i dont know this out of experience... but this is how i see it... its better to cut spark then fuel anyday.... when u cut fuel u continute to ignite in the cylinder with the fuel thats there even though there is very little of it and u run extreme lean which is what actually blows motors... the fact that it goes lean... when u cut spark... yes the fuel double basically in the combustion chamber but then u run extremey rich... i dont know about u guys but i would much rather run extremely rich for a split second or two then run extremely lean as i have seen what running lean does to motors/pistons/etc... i am not saying it does not happen... but i have not yet seen a blown motor from a ignition cut...

falcongsr

keep thinking.

lets see...cut spark... fuel goes into combustion chamber and doesnt ignite. nothing happens.

cut fuel... fuel pressure drops, engine goes lean PING PONG DETONATE BAD BAD BAD BAD BAD

got it?

Mr. Vapor

im getting more and more nervous............

what are the tell tale signs of a detonated engine?

Phantom

Im not convinced. First, I don't think your fuel pressure drops, I think the injectors are just closed. If the injectors are closed, you are getting NO fuel into the combustion chamber. No fuel = NO chance for combustion. If you cut spark, you CAN detonate. Ever heard of preignition?

I have seen at least one person at the track who launches by holding the revs at the rev limiter and dropping the clutch. This guy drag raced the car ALL the time and had no problems. How is this possible if he is running so lean every time fuel is cut? When I began autocrossing I smacked the rev limiter frequently, never had any problems.

If cutting spark is so much better, why didn't honda do it in the first place? It couldn't be any more difficult to cut spark than fuel?

97integraLST

Same thing happend to me last week. I was on the parkway (NJ) I am from Ext 164 and I was down by 118. Anyways, it was open road so i decided to gun it. I did and pulled hard. Then 1 min later I was switching lanes then car just dies. I press on the Gas and Nothing! I see Red lights, i was like of POOP! So i pull over to the E lane. Luckily someone saw what happend. The dude behind me said I blew a fuel line. Gas everywhere. I look under the car and Gas dripping like a faucet.

Got it fixed but Noticed my car not boosting properly. Checked all lines an all ok.
I look under my Intercooler and I see a hole about half an inch wide. Then another part where the bottom part of the intercooler got caught on somthing and ripped it.
Damaged 3-4 rows

Mr. Vapor

so was there any correlation between the blown fuel line and damaged intercooler?

Arturbo

You should be ok. I was helping a friend program his profec a and he had just installed a new inline fuel pump. We went on the highway to program it and at 15psi the fuel line popped off and it felt like we ran into a wall!! We pulled over, put it back on and it has been running for two years no problem.

I wouldnt worry too much..

art

falcongsr

good points phantom. when i said cut fuel, i was referring to losing a fuel line. were you autocrossing with turbo? i dont think the fuel cutoff is that bad on a stock motor. obviously its better to cut fuel than spark because you dont want to douse the engine in fuel (from the manufacturers standpoint, drag racing is another story)

cutting out fuel in a turbocharged engine while boosting is a bad scenario in any case. i dont think the injectors just close and you go to zero fuel instantly. i have heard too many cases of people losing a line or hitting the limiter under boost and HEARING the engine detonate.

i should have differentiated between the different scenarios. good discussion!

blah i have to do some work now. h-t is more fun tho!

Phantom

I've autocrossed once since I put the turbo on. I was running street tires as well, so it was definately a learning experience - lotsa fun though. This season I will be doing a bunch with the turbo, we'll see how competitive the setup is in SM.

Xerxes

That's the theory, BUT it's quite possible (especially when running a very dense air/fuel mixture) that you won't completely burn up your air/fuel mixture during the combustion process, so then you can have some fuel remaining in the cylinder during the next cycle. If there's enough fuel left in there, then it can ignite and burn quite quickly when the spark lights off, causing detonation and possible engine damage.
One guy with a greddy kit on a civic Si blew his engine basically by bouncing off the rev limiter too much -- he was running stock boost and had the fuel management working correctly, so it's quite unlikely that anything BUT bouncing off the rev limiter caused him to bust his ring landings.


turbo car? n/a? If he has full combustion and burns up ALL the fuel then he won't be causing any damage. Or if he's not turbo, then there's not enough pressure in the chamber to cause a problem. Basically honda did the fuel cut because it's simpler (if you cut the icm signal from the ecu then the tach goes crazy, so basically it's simpler to cut the fuel from the ECU); for a naturally aspirated or stock car, the engine usually does a good job of burning up all the fuel.

-Xerxes

2000_Civic_Si

Your good! But now, this should tell you something. You got alot of fuel pressure goin through those lines. It's time to upgrade to Stainless Steel lines with Earls fittings. Then you won't have to worry about the fuel lines blowing off.

rjardy

falcon gsr, you confuze me you contradict yourself in your two posts, first you say that it is better any day to cut spark than fuel, then you say its not, isnt that how the factory limits your RPM? by cutting fuel? so what im getting out of all this is that its cool to cut fuel to an N/A engine but not one thats seeing boost, is this correct? someone help i can feel myself getting stupider!!!!<----see i dont think i evan spelled that correct HELP!!! ARGH

dbman96

I think he got a FULL fuel cut when that line blew off - think about it: fuel line blows off the pump; fuel pressure immediately goes to ZERO. Manifold pressure is still at 7-8 psi since he was at full boost. Even if the injectors open, the pressure would be pushing air back into the fuel rail, not pushing fuel into the intake manifold. And if he wasn't making boost, then he has no worries about detonation. I can see it being a problem if an FMU breaks and drops you from 100 psi down to 50 psi fuel pressure under boost, but with the input to the rail completely disconnected he wasn't getting ANY more fuel into the manifold.

falcongsr

that is my opinion. take it for what its worth (not a whole lot! )

Bunyfofu

OK, Tell me how cutting spark is worse then cutting Fuel? 2 Step rev-limiters.....launch
rev limiters...all cut spark at a desired RPM. When I had a MSD Digital 6, I used the 2 Step Launch Rev limit every time I went drag racing. MSD makes somthing called a
SOFT TOUCH REV LIMITER!!!!!!!!! SO YOU WONT HIT THE FUEL CUT OFF!!!!! SHEESH.

DeeJay

Do a compression test.

Mr. Vapor

im scared hhahah

rjardy

Allright boys and girls here it is stright from msd them self. (this is in summit catolog add for soft touch) There are 2 ways to limit your rpms. The rough way wich simply cuts off the fuel wich CAN CAUSE BACKFIRING AND EXTREME ENGINE ROUGHNESS AND POSSIBLE ENGINE DAMAGE. Then the soft touch way/.....yada yada yada on and on about the soft touch. So i gues the soft touch does it with spark but only drops one cylinder at a time so its not so rough. So take this as you will, me personaly i prefer fuel. thanks for playing guys and gals.