HDJ81 boost and power issues-- RePost from '80s tech'

[Munchichi]

I was told to repost this here

I'm reaching out for Tuning advice!! Something is Sapping the power in the 92 HDJ81, 1HDT
After an engine compartment strip down and cleanup, Installed the new parts:

GTurbo Grunter Extreme 2
3" Exhaust
Timing belt(all new belts and hoses)
rebuilt injectors & timed Injector pump,
Modified Anerod Pin last year-good
Boost Compensator dialed to 18 PSI
Checked Valve clearances- all good
Intercooler installed, but bypassed with stock crosstube till I figure this all out.
Also a new viscous clutch on the fan(someone mentioned it could have an affect?!)

The throttle response, in park, is dialed in to decent. Not as snappy as I like, but has very smooth ramp up.

Here is where I may have messed up: I took the WasteGate actuator off the Gturbo for paint(Okinawa rusts anything not painted). I reassembled and there was still preload pressure on the actuator.

The engine has no balls. turbo doesn't ramp up till @ 2000rpm. - it was at 1200(i think). I prefer lower end, as my foot is fuel conscious.

I saw a pic here that showed a wastegate actuator arm jammed against the hard heater line that runs between the turbo assy and the block.
Also read that I can hook up a air pump to the wastegate actuator line- to see where it activates.

I'm a newb- But is it unrealistic for the turbo to start ramp up at 1200 rpm- and still average 18psi (with an intercooler)?

Anyone's help is greatly appreciated.

I also ripped out the failing ABS system and have lots of other goodies- but only relevant stuff was listed for now.

 

[gerg]

Since you did the timing belt I'd be double checking timing. Could easily have skipped and advanced it which would destroy your low end. Can destroy other parts of your engine so I would see about that very soon.

Pressure testing your boost plumbing for leaks is another good way to gain power. Since your engine is limited by an aneroid, a boost leak means less fuel which means less boost which mean less fuel.....etc, which means unhappy you.

Hope that helps
g

 

[absalom]

Are you hitting the 18 psi? If so, by when? What does the smoke output, if any, look like?

 

[ozcrusier]

I had the pump rebuilt on my old 1hdt and it was under powered when I got the truck back. Adjusted the fuel screw and it was happy with it's power and torque.

 

[Munchichi]

Thanks everybody,.
Today I will double-check the timing, pressure test the intercooler system, check the fuel screw, AND double check my fuel lines to the pump (I may have mismatched a few during re-assembly. - after all that, I will check for my boost pressure build up.

On another note, The wastegate actuator arm is unobstructed and the actuator opens the wastegate at @ 35 psi (my bike pump gauge isn't super accurate)

As far as smoke goes- I have ZERO black smoke through all rpm -up to 2500. What little smoke it does- is gray and limited.

 

[absalom]

Are you hitting the requested boost tho? Do you have a boost gauge tee'd into your manifold? That can tell us a lot about the overall health of your setup.

 

[Tapage]

if you skip timing in your timing belt replacement process you would tell from the engine sound .. but if you mess up with timing moving the IP then you ain't gonna tell for sure .. unless you measure it by FSM ..

 

[Munchichi]

Thanks everyone for all the replies. ISSUE SOLVED (for now)
Rebuilding the Injectors + adding a much more powerful turbo = more fuel required . ADJUST THE MAIN FUEL SCREW

Warning- That fuel screw is a bugger to adjust, especially if it has the factory locking sleeve at the nut. Also, the screw is blocked by a small water hose. I had to remove the entire screw:locknut:sleeve assembly to start adjustments. Hope I didn't mess up pump internals. And I'm Not reinstalling the factory locking sleeve

Warning #2--The fuel screw is REALLY sensitive to adjustments. Mark the 12mm locknut and screw position before loosening and be sure to count half turns carefully. Two 360 turns rampd up the fuel WAY TOO MUCH!. By trial and error, the idle is now at 1100 rpm. Gonna tweak the idle screw later today and borrow a friends boost gauge for final tuning.

Last question: What connection got backwards that would cause the factory turbo light in the tachometer to illuminate in PARK but not in DRIVE ???- (during and at proper rpm of course)

 

[Tapage]

Last question: What connection got backwards that would cause the factory turbo light in the tachometer to illuminate in PARK but not in DRIVE ???- (during and at proper rpm of course)

alternator / ground related .. ( ain't the only option tho )

 

[mudgudgeon]

Warning #2--The fuel screw is REALLY sensitive to adjustments. Mark the 12mm locknut and screw position before loosening and be sure to count half turns carefully. Two 360 turns rampd up the fuel WAY TOO MUCH!. By trial and error, the idle is now at 1100 rpm. Gonna tweak the idle screw later today and borrow a friends boost gauge for final tuning.

Do you have an EGT gauge?
Two full turns on the main fuel screw is a lot. You should really check combustion temperatures as you make adjustments.

Idle speed is easily adjusted at the throttle arm on top of the IP. But check GETs before you "fix" your idle. Adjusting the idle down if the main fuel screw is set too rich could cover up a major problem