lost fuel pressure reg under boost 2jz

**oldcorollas** · 14-10-2008, 03:46 AM

losing so much fuel pressure under load = fuel cut = maybe nothing bad happened

(ie, say 10psi boost = 0.68bar.. losing hose = reduce fuel from 1.68's worth, to 1..
ie, onyl 60% of the fuel needed.
also, FPR, if 40psi is base, and you needed 40+10psi.. you only have 40/50 = 80% worth of fuel..
so 80% of 60% = 48% of fuel needed...
ie, you would be lucky if the thing fired at all... even tho the timing was advanced from loss of load sensing)

keeping it offboost = smart and probably saved motor from a "lean but running" condition which coulda farked it nicely.

as long as you haven't smashed rings or ringlands.. she'll be roight... compression/leak down test to be sure maybe?

**wilbo666** · 14-10-2008, 09:52 AM

Originally Posted by Mos

Huh???
Can you guys explain your logic?
Map sensor OR FPR with vac lines open to atmosphere simulate conditions of ATMOSPHERE, not shitloads of boost, so where is the ECU finding out about all this extra fuel it's supposed to dump in???

I believe that there is a weak pull up resistor inside the engine ECU on the MAP sensor line that pulls it to a state that the ECU can detect as being unplugged...

But that is silly,

My mind was thinking the plug came out, not the hose duh

Cheers
Wilbo

**PlacentaJuan** · 14-10-2008, 10:32 AM

yea looks like i might do some testing on it after all.

the thing is that when the line first blew i thought it was the compressor output for the second turbo, which means all boost output would be restricted to the bypass valve (which is what happened at the drags you just get less power than normal) and while driving i tried boosting it, but once boost came on i felt loss of power and boost would not go above 3-5psi, but only did that once.

once i realised it was the fpr i kind of freaked out and thought shit.

**thechuckster** · 14-10-2008, 10:41 AM

it would be worth covering your bases by pulling a few plugs - that fact that you tried to boost it and it refused to generate enough exhaust gas for >3-5psi suggests that it ran quite lean briefly.

... having said that, while tuning the 18rte, i ran it thru situations of very lean and very rich conditions and all it did was produce some impressive anti-lag-like popping when the fuel came back on much to the consternation of other drivers around me at the time

**JZA70 R** · 14-10-2008, 07:57 PM

Originally Posted by MWP

Mos is correct (of course).

What you guys said about going always rich would apply for a NA engine, but not a turbo.

At idle the engine would have been running rich, but under boost it would have been running lean.

I retract my statement and replace it with this one

...sorry PlacentaJuan if i caused you any confusion, hey i think i learnt something out of this!

Hope the motor is ok, you would think that losing that extra rail pressure would cause it to hesitate or stall underboost, i hope what pressure was left wasnt enough to cause a lean burn and fry stuff or cause it to ping...

Good luck.

**PlacentaJuan** · 15-10-2008, 04:43 AM

yea maybe next time i have a quiet day at work, ill take it into the hangar and do a boro through the spark plug holes

still goes like stink though

**limbo** · 17-10-2008, 01:01 PM

lean on a boosted car is likely to get you a piston thru the block, best have it checked out.

**oldcorollas** · 17-10-2008, 01:41 PM

Originally Posted by PlacentaJuan

yea maybe next time i have a quiet day at work, ill take it into the hangar and do a boro through the spark plug holes

sounds like a great idea

mmm perks of work equipment....

**Mos** · 18-10-2008, 04:34 PM

Originally Posted by limbo

lean on a boosted car is likely to get you a piston thru the block, best have it checked out.

Are you suggesting that people capable of doing an engine swap (ie doing all the bolty bolty stuff themselves) are not able to tell when a piston (or more correctly, a rod) has gone through the block and they should seek professional guidance?