'88 'Burban Update...

'88 Suburban, 350 TBI/TH700, 4x4...
I replaced the IAC valve and the oxygen sensor and rebuilt the FPR...Previous replacement of the base gasket and cleaning of the TBI

EVERYTHING is better(not perfect), Idle quality, throttle crispness, over all power, and starting! I still have a slightly higher idle(1100RPM) unless I crack the throttle. I still have a stumble about 1300RPM that clears up with slightly more throttle or with getting off the throttle all together. I think it might be the pintle adjustment on the IAC valve...
How do I get the proper setting on the IAC valve pintle?
I noticed that spring tension can be adjusted on the FPR with it disassembled, would it help if I monkeyed with it a little?
Could I have warn or faulty injectors?
Any other ideas anyone wants to throw into the mix???
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Look at the EGR valve:
Sounds a bit like tip in hesitation. Can you tell the difference from a stumble to a hesitation?
A stumble the engine almost dies, then jumps like a bat out of hell, a hesitation slows, then gradually picks up.
If it's injector related. You'd have more of a stumble condition from the rich mixture.
The injectors are best checked with a residual pressure test, after the key is off, there should be a negligible pressure drop, and it shouldn't drop for days.
I hope this helps?
Refinish King

FPR...Previous replacement of the base

over all power, and starting! I still

have a stumble about 1300RPM that

together. I think it might be the

disassembled, would it help if I monkeyed

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If I keep the throttle at that RPM she will die!
| > '88 Suburban, 350 TBI/TH700, 4x4... | > | > | > I replaced the IAC valve and the oxygen sensor and rebuilt the | FPR...Previous replacement of the base | > gasket and cleaning of the TBI | > | > | > EVERYTHING is better(not perfect), Idle quality, throttle crispness, | over all power, and starting! I still | > have a slightly higher idle(1100RPM) unless I crack the throttle. I still | have a stumble about 1300RPM that | > clears up with slightly more throttle or with getting off the throttle all | together. I think it might be the | > pintle adjustment on the IAC valve... | > | > How do I get the proper setting on the IAC valve pintle? | > | > I noticed that spring tension can be adjusted on the FPR with it | disassembled, would it help if I monkeyed | > with it a little? | > | > Could I have warn or faulty injectors? | > | > Any other ideas anyone wants to throw into the mix??? | > | > | | |
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Either fuel pressure:
Fuel on the rich side, or maybe a long shot. But, a distributor pick up coil.
The best I can do with a seat of the pants diagnosis, without more symptoms. When it dies, does it stumble on, or just die flat?
Refinish King

crispness,
still
all
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She will stumble down until she dies if I hold the throttle in the stumbling RPM range. She will fire right back up though with no problems.
| > | > '88 Suburban, 350 TBI/TH700, 4x4... | > | > | > | > | > | > I replaced the IAC valve and the oxygen sensor and rebuilt the | > | FPR...Previous replacement of the base | > | > gasket and cleaning of the TBI | > | > | > | > | > | > EVERYTHING is better(not perfect), Idle quality, throttle | crispness, | > | over all power, and starting! I still | > | > have a slightly higher idle(1100RPM) unless I crack the throttle. I | still | > | have a stumble about 1300RPM that | > | > clears up with slightly more throttle or with getting off the throttle | all | > | together. I think it might be the | > | > pintle adjustment on the IAC valve... | > | > | > | > How do I get the proper setting on the IAC valve pintle? | > | > | > | > I noticed that spring tension can be adjusted on the FPR with it | > | disassembled, would it help if I monkeyed | > | > with it a little? | > | > | > | > Could I have warn or faulty injectors? | > | > | > | > Any other ideas anyone wants to throw into the mix??? | > | > | > | > | > | | > | | > | | > | > | | |
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Take a look at your TPS voltage at idle position:
Then do a TPS sweep with an analog meter, to see if there any missing spots on the carbon rheostat, best checked with a square wave meter. Like a lab scope or a cheap square wave counter for a VOM.
Also, have you ever checked the plugs, wires, cap and rotor?
Refinish King

I
throttle
it
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the
throttle.
with
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key
The TBI systems have an "autobleed" feature where they bleed off pressure when the pump ain't running. Takes anywhere from 1-3 hours for the pressure to completely bleed off. This is why it isn't necessary to relieve system pressure on the TBI trucks before cracking a line if they've been sitting a few hours. CPI and MPFI systems on the other hand should hold the pressure indefinitely.
Doc
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Thanks for that note Doc!
I haven't done a long term pressure test on a TBI, remember the fixture I told you I made. Just done some quick checks and got the hell out of there!
LOL
Refinish King

the
drop
pressure
a
pressure
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a
the
pressure
system
sitting
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That's what I did!
That's why I use it and get the hell out of there, and it's also great for running an injector cleaning cycle, in a jury rigged kind of way. (Racist word omitted, to be politically correct)
LOL
Thanks again Doc!
Sincerely,
Refinish King
PS How about some Melingianna? I'm sure you know that means eggplant?

from
a
from
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Inline.................

hell,
after
shouldn't
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Actually:
I used a new filter, I was to chicken shit to use a used one, so I used a new Wix and a 1/8" pipe to flare fitting.
It was easy.
Refinish King

the
relieve
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Too bad:
I'm really sorry to hear that, maybe gardening would help my nerves?
Farmer Bundy!
LOL Sincerely,
Refinish King

the
relieve
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difference
condition
been
the
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Ever try lady bugs? Gasoline would have killed it all (you, the eggplant, the bugs, the grass, etc..)
~KJ/TLGM

the
relieve
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difference
condition
been
the
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I understand that they eat other bugs that move, or don't move, or haven't previously been eaten....
~KJ/TLGM

of
test,
off
for
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