can yall refresh me ?

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can yall refresh me ?

Postby jethro » Fri Feb 22, 2019 12:40 am

Having really low boost---- like 3 psi at idle and about 6 to 8 max .
Do I remember that the little 2 piece steel air/vac. line that runs off the side of the intake manifold and goes into the IP ----does that line
have something to do with how much boost you get ? Or is that just a signal that goes the other way-- tells the pump how much fuel
to use based on boost (manifold) pressure ??? I think I remember that line is 2 pieces with a tiny coupling in the middle. Just trying to think if anything tiny - but loose could be killing the boost.

(H1C with new but stock injectors- fuel turned up a little--- 93 model intercooled engine. )

I am considering making a test pipe from PVC to connect the turbo output to the manifold -- just to see if I have a intercooler leak.
(plumb it for a test like a non-intercooled and see if it has any more boost...…) Would that be worth the effort ?

Tim
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Re: can yall refresh me ?

Postby Remps » Fri Feb 22, 2019 5:57 am

Your low boost is most likely a lack of fuel, not lost/wasted/leaking boost. You could pull the afc top and see if the horizontal pin is leaving a track on the vertical fuel pin. If no track mark, I'd rub a little grease on the fuel pin so you can see it's action later. If the nylon washer is still on the pin, I'd also try running without it and see if you pick up any boost. It'd also be as good of time as any to turn the fuel pin to the deep side, facing the front of the truck. Those two little mods should net you some extra fuel on the top end.
A little grease or oil wouldn't hurt to put on the rear rubber seal of the afc line going into the afc top, will reduce risk of rubber breaking up from being loosened/ tightened.
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Re: can yall refresh me ?

Postby thrashingcows » Sat Feb 23, 2019 2:28 pm

I'm no expert but my understanding is the two, boost and fuel are tied together through the AFC top. Once the boost starts to rise it pushes the diaphram down which allows the internal fuel pin to move farther out along the large fuel pin ramp and in turn increases the fuel so you can build more boost.....and a viscous cycle starts. ;)
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Re: can yall refresh me ?

Postby PToombs » Sat Feb 23, 2019 7:02 pm

Cows is correct on the operation. Where are your EGT's at? If they are way up from normal, then you have a bad IC, if low or the same, no fuel.
Check the small line to the AFC closely, if it breaks you don't get enough fuel. It's supposed to be 1 piece, so maybe yours has been repaired. Most guys tap the AFC head to 1/8 pipe thread and put a piece of 1/4" air line plastic hose to replace the metal line.
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Re: can yall refresh me ?

Postby jethro » Sat Feb 23, 2019 9:53 pm

I don't know what temp is doing--- don't have any gauges so far. Stock injectors and a BIG powerstroke intercooler. I think I will put a triple pod on it next. { next pay check :-) }
Today I raised the smoke screw about 1/2 turn. I had turned it down some several months ago to see what more fuel would do. I remember getting so much that the engine stumbled a bit when called to accelerate. I raised it back up about a full turn then. When I raised it a bit more this morning
and then drove it--- had a little more boost and the acceleration seemed a bit better--- also it seemed like idle was slightly smoother and maybe
slightly lower RPM. Should I back it off another 1/4 turn and see what happens ?
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Re: can yall refresh me ?

Postby spencerdiesel » Sun Feb 24, 2019 12:56 pm

Pre-boost/ smoke screw shouldn’t affect idle speed or quality. It only dictates the amount of “base fuel available” with ZERO boost present. It seems to me a thin/wispy haze spools my turb the quickest without smoking whoever is behind you excessively.
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Re: can yall refresh me ?

Postby PToombs » Sun Feb 24, 2019 2:15 pm

Tim, gauges are one of the first things to do so you can get a baseline and see what everything is doing. I understand putting it off because the engine is stock, but it's still a good idea, now you have a problem and gauges make trouble shooting easier.
Has it been smoking more than usual? If so I'd suspect an IC leak. Mine was bad and I didn't have a clue until I hooked up the trailer, then the EGT'S were HOT and it was smoking like a pig. I thought the boost was low with what I had done, but had nothing to compare it to. When I got it fixed I gained about 10 psi!
If it's not smoking then I would suspect fuel issues.
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