lost fuel pressure reg under boost 2jz

[PlacentaJuan]

so while driving home from Melbourne on Thursday i was overtaking someone on the freeway and the car suddenly lost power, i was probably up to about 10-12psi at the time (mild throttle for overtaking but not full throttle)

i assumed it was one of the lines for the second turbo (i was running ttc at the time) and didn't worry that much but didn't boost the car until i could pull over and have a look.

when i had a look the turbo lines were fine but the hose had blown off the fuel pressure regulator (stock)

this hose is tee'ed off from the map sensor also, so that would be getting a dodgy signal as well.

when i stopped the car had a really rough idle like it wanted to stall and this improved slightly when i reconnected the hose but was still a worry to me.

i took it easy until i was well inside Adelaide (close to home) and the car ran find even under boost, and when i stopped at the traffic lights the idle was fine.

i assume that losing fuel pressure while under load is pretty bad is there anything i should do or check?

i didnt feel the car behave like there was a major problem, just felt like i lost boost but it made me worry when i realised it was the fuel pressure.

btw have now cable tied it on and next time i do something major i will replace all vacuum/pressure/sensor lines as they are becoming brittle and old and thats why they keep blowing off.

[thechuckster]

you would have run lean briefly - but if that had borked a piston, you would have known about it before getting home.

You could remove a few spark plugs and look for excessive pitting or metal deposition on the ceramic insulator part?

[JZA70 R]

You have nothing to worry about. When the vacuum line popped off your map sensor it would have instantly dumped a heap of fuel in which is why it was running so shitty at idle.

If the ecu detects a mismatch of manifold pressure and tps or rpm it just throws fuel in as a safety measure, its not limp mode but just as effective.

I just think your lucky your map sensor was tee'd to the same line as iirc thats not standard.

[PlacentaJuan]

You have nothing to worry about. When the vacuum line popped off your map sensor it would have instantly dumped a heap of fuel in which is why it was running so shitty at idle.

If the ecu detects a mismatch of manifold pressure and tps or rpm it just throws fuel in as a safety measure, its not limp mode but just as effective.

I just think your lucky your map sensor was tee'd to the same line as iirc thats not standard.

thats just what i wanted to hear.

yes i was wondering about the logic of teeing off the reg with map sensro but i get it now thanks mate.

[wilbo666]

JZA70 R: Factory 2JZ has tee'd boost and FPR.

Cheers
Wilbo

[PlacentaJuan]

wait how can the ecu dump extra fuel if the regulator was at its lower setting?

just open the injectors to max duration?

[JZA70 R]

just because the fpr doesnt have positive pressure on it doesnt mean there is no fuel pressure in the rail... so yes the injectors will open up and overfuel the motor...

on a 1jz the fpr gets its vacuum source from the front of the manifold and because the two map sensors (ecu and gauge) are at the back of the engine bay they get their vacuum source from the back of the manifold.

[wilbo666]

on a 1jz the fpr gets its vacuum source from the front of the manifold and because the two map sensors (ecu and gauge) are at the back of the engine bay they get their vacuum source from the back of the manifold.

That's fine, but we're talking about a 2jz, which is Tee'd like I said from factory



The ECU will detect no MAP sensor attached and it will dump in massive amounts of fuel

Cheers
Wilbo

[PlacentaJuan]

thanks guys that is some good info

[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???

[JZA70 R]

Limp mode?

[Mos]

You haven't explained how the ECU knows it should be limping - as far as its concerned it's seeing a Map signal telling it it has atmospheric pressure in the manifold...

[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.

[oldcorollas]

i concur. (but too slow )

boost at FPR = higher rail pressure = more fuel
loosing line = lower fuel pressure = less fuel under boost

boost at MAP = higher sensed load = more fuel.
loosing line = lower sensed load = less fuel under boost

both will effectiovely give you massive fuel cut under boost

BUT, both will give you more fuel at idle.

if you managed to run engine at 1atm manifold pressure (no boost, same as WOT on NA motor), then it would run just the same as normal.. but below = rich and above = lean...

[Officer Doofy]

LOL just when PJ stopped having a heart attack

Jess the motor is fucked, upgrade to a 1j