FIRE out the exhaust during hard accel

[datsunmotorsports]

I have a stock RB25DET in my 260z.

The timing is at 10*. I installed a larger intercooler. The exhaust is basically 3" stainless mandrel bent exhaust with a pre muffler and a GReddy muffler nothing else not even the cat, and everything else is pretty much a stock configuration. Even the fuel pump is the OE R33 pump.

So I was told today that while entering the freeway I was shooting fire out my tail pipe. I laughed for a moment cause that just sounds funny and then I joked how it was my "after burner". But on a more serious note I want to know what is going on. This sounds like unburnt fuel in the exhaust that is burning. I have good cylinders so its not like one of the cylinders is just dumping fuel.

Thanks

Ray

[Largekid]

yes, its probably unburnt fuel in the exhaust igniting from the exhaust. I dont know about during accel though...but I shoot flames occasionally under shifting or decel after WOT. Not a big deal

[neonbomb]

You dont have a cat so thats not totally unusual.

[Joe]

your timing is at 10 degrees?

of course you are shooting fire. your timing is wrong.

[Nissan2367]

Mine does the same thing... on stock timing. Its normal from what i have read on RB's

[eh?]

Mine does the same thing... on stock timing. Its normal from what i have read on RB's

Do you have any mods at all?

The timing is at 10*.

You need to be at 15° btdc

[Cjmartz2k]

15 degrees for sure. It's NOT normal to shoot fire balls under acceleration. Maybe a little when you lift, but not under accel.

[Darius]

What do you mean by having "good cylinders"? The engine doesn't miss, correct?

I find it hard to believe that retarding the base timing 5* from spec would result in fireballs from the exhaust during acceleration. Are you sure the fire balls weren't seen popping out during shift points on the on ramp? Do you have the BOV vented to atmosphere?

[Nissan2367]

I miss understood mine do it when i let up off the gas after wot. Mods:Greddy Intake90mm Q45 TBGreddy Front Mount2.75" Intercooler PipeGreddy Type RZ BOV (not recirculated)Apexi Suction Intake3" DP3.5" HKS Hyper ExhaustAeromotive FPRWalbro 255lph Fuel Pump

[Darius]

I miss understood mine do it when i let up off the gas after wot. Mods:Greddy Type RZ BOV (not recirculated)

^^ Exactly what I was getting at ^^

[Nissan2367]

Hahaha yeah i know thats why it does it! I use to be in love with hearing the bov go off and now i think i am growing out of it... that and the RZ is so loud! Ill be recirculating it again!

[S14-NEO]

hehe only 10 degrees of timing, man is he in for a treat when he corrects his timing to 15 degrees...yeah FREE HP....woot

[Nissan2367]

wow i need to set my timing! Mine is dead center with no timing ether way!

[datsunmotorsports]

Initially I was able to set the timing on my motor with a ETHOS scanner, but when I tried to set it at 15* with a Modus Scanner the computer just self corrected my timing adjustments and would not show me the actual timing just the corrected timing.

I have a 94 S2 RB25DET and it doesnt have the TPS switch at all just the TPS potentiometer. So unless I can get my hands on another Ethos scanner or a normal inductive timing light I am stuck at 10*.

Basically everything about my engine is OE with the exception of the mods listed in my original post.

I dont know the timing of the fireball event exactly. I need to find someone I trust to drive my car while I follow it to see if I can pinpoint the timing of this event.

As far as good cylinders I mean that I have good compression across the board. I just replaced the bad coils last week thanks to Raw Brokerage. So I no longer have any misses. So my coils and compression are good.

Id toss the car onto a dyno and check it out, but the first time it went off like that I have a feeling they would pull the car off the dyno.

[l0nestar]

wow i need to set my timing! Mine is dead center with no timing ether way!

[Nissan2367]

^^Haha nice and slightly impressive...

[datsunmotorsports]

hehe only 10 degrees of timing, man is he in for a treat when he corrects his timing to 15 degrees...yeah FREE HP....woot

Yeah like I need the extra HP... Its a RB25DET in a Datsun 260z and I already have mad traction issues with drag radials...

however, Id like to get the timing corrected just to be in spec and safe.

Ray

[Cjmartz2k]

I had a HKS SSQV (super sucky queer valve) on for about one week way back in the day. It leaked at anything over .7 bar real bad. It would do that, my MAF would see a BUNCH of air coming through it, and dump a LOT of fuel on the motor. Result was 4 foot flame thrower coming out of my tail pipe anytime I got on it. I thought it was funny until I realized what I was doing. Chucked the HKS crap, got a real BOV, no more problem. Check for leaks.

[eh?]

Initially I was able to set the timing on my motor with a ETHOS scanner, but when I tried to set it at 15* with a Modus Scanner the computer just self corrected my timing adjustments and would not show me the actual timing just the corrected timing.

Make sure your CAS is in the middle. That will be ~15 on a stock motor.

[S14-NEO]

im sorry but i have to say that is one awesome a** response...WELL DONE!!!

[l0nestar]

I don't remember where I found it at, but I loved it. .. and I didn't even need to say a word.

[datsunmotorsports]

hehe only 10 degrees of timing, man is he in for a treat when he corrects his timing to 15 degrees...yeah FREE HP....woot

Fixed my timing. Tossed a random wire I had around for the old L28 on the #1 coil and plug and timed it correctly. There is a notable difference in power. Its not huge but you do notice the difference. The powerband is smoother with the correct timing.

I have no idea if its still spitting. I will have some free dyno time coming up here in the next month where I can dial it all in. I asked and they said they will put it up on the dyno as is.

Ray

[meet07]

my cas isnt set in the middle and dead on base timing. I as well shoot about 2-3 fireballs a day. I see most of them in the morning. Other times I hear it. I have a safc to correct the maf signal with the atmospheric bov.

[eh?]

my cas isnt set in the middle and dead on base timing. I as well shoot about 2-3 fireballs a day. I see most of them in the morning. Other times I hear it. I have a safc to correct the maf signal with the atmospheric bov.

How far off is it from the middle? A lot of timing guns have problems reading the nissan DI.

[Joe]

my cas isnt set in the middle and dead on base timing. I as well shoot about 2-3 fireballs a day. I see most of them in the morning. Other times I hear it. I have a safc to correct the maf signal with the atmospheric bov.

you are using an atmospheric bov

of course it shoots fire. SAFC (GARBAGE) or not.

i cant believe you people think this is a bad thing? i CANT make my engine shoot fire. consider yourselves lucky.