TBI 350 Running Rich

[Schurkey]

there are as many opinions of the old Frantz filters are there are motorheads... ...Is it necessary to run one of these? No. Especially on a solid lifter equipped engine.
But on a hydraulic lifter-equipped motor, I can actually see why I would want to scratch that old school itch again.

Frantz filter on my 454 boat engine. I have another on my K1500, one on my solvent tank, and a few on the shelf. I got my first two from Dear Old Dad, and all the rest from eBay.

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[scott2093]

It's been nagging at me that I had one night that I decided to change the pcv valve and hose, had some kind of weird tps issue where I pushed down on the connector and the truck idled crazy for a second, settled in and I took it for a test drive... It was all warmed up....computer had already relearned everything..hadn't unplugged battery for several days prior....
Truck felt quite different then and I could have sworn my fuel trims looked better.

The next day, I changed the pcv hose because I had it rigged up the night before and the truck went downhill again as far as fuel trims... I think that's all I changed.....
Can you see if I'm imagining things by just looking at this data from that night's test drive to a test drive yesterday? The test drive yesterday had more driving but a lot was the same route...
I just can't shake it... Driving me crazy.... fluke thing?? I do remember having to clear a TPS code after that drive the one night because of messing with the connection...Did the computer put a preset something in when that happened....idk.
Do these numbers look different enough to think I wasn't imagining things? Hard for me to tell. I'd need to search for the data....I think I erased some of it...or at least the video...maybe not....

 

[Scooterwrench]

I remember you saying you rebuilt your TB, did you ever check the fuel pressure after? I wouldn't think it would change much if you didn't change the spring but it's always good to check after opening one of those up.

 

[scott2093]

I remember you saying you rebuilt your TB, did you ever check the fuel pressure after?

I changed the diaphragm in the regulator because I saw some fuel under the weld and cleaned up the throttle body. I don't think it made any change and was in a different time frame than the scenario I mentioned above but would have to look back. Maybe it was around the same time and the reason for the tps connector weirdness that night.. Will check

I'll recheck fuel pressure//

one thing I guess I never noticed until earlier was how cold and sweaty the throttle body is...Guessing this is normal???

 

[scott2093]

check the fuel pressure

Guess it does seem on the upper end...At 14psi? could have sworn it was 13 before

But the motor is not totally stock.....I think Road Trip said it's closer to a 5.9l or something.....have the tbi spacer...fuel pod spacer...roller cam.... would this matter?
little twitchy?

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[Road Trip]

Guess it does seem on the upper end...At 14psi? could have sworn it was 13 before

Sir,

* You've cross-checked the PROMS by swapping in the original one. No change in behavior.
* Your O2 sensor seems to be as agile as the TBI computer can drive it. Your O2 feedback seems good.
* Your plugs look healthy enough. And their coloring matches what the computer is trying to correct. (infers *rational* PCM)
* I'm assuming that your lifters are back to being as quiet as possible.
* No intake manifold leaks.
* Your ECT was well within the accuracy limits that are listed in the FSM.
* You just replaced your rotor and gave the distributor cap a careful inspection.
* Obviously your fuel filter and fuel pump are working as advertised.
EDIT: * You have good compression & leak down test results. Also your oil consumption is well within reason.

****

Given all this, if you have upgraded your fuel pressure regulator to an adjustable unit,
why not reduce the pressure from 14 to 12 psi and see if your BLM numbers improve?

It would be no-cost diagnostic to see if we have the data collection resolution to discern
what a 2-psi fuel pressure adjustment would make? And I'm pretty sure that 12 psi is
still within the spec in the FSM?

Like PWTBI said earlier, we need to get your engine running as right as possible *before*
we start recalibrating your computer.

My prediction will be that dropping the fuel pressure at the injectors will improve the
Block Learn Multipliers. And this will also give us more confidence in the quality of
the live data that you are working with. (I already trust your setup, but it's always
nice to see a real-world pressure adjustment show up as anticipated in the live data. (!)

 

[scott2093]

Given all this, if you have upgraded your fuel pressure regulator to an adjustable unit,
why not reduce the pressure from 14 to 12 psi and see if your BLM numbers improve?

I have not upgraded to an adjustable type.... Would a worn out spring increase fuel pressure or decrease it?

 

[PlayingWithTBI]

Would a worn out spring increase fuel pressure or decrease it?

That will decrease it. IMO 14 PSI shouldn't make a lot of difference.

Here's a random thought - which injectors do you have? Are they the OE 5235206 61 LB/HR or something else. Here's a chart on different TBI injectors used by GM. You can look at the colors on the top or find the PN stenciled on them...

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[scott2093]

I remember looking in the past and they were the ones I was supposed to have for my truck...But can check....
FWIW I have the vortec fuel pump too.... not that it should matter....

GM 5235206

those MAP vs charts I posted earlier, do they seem like there was something different going on or am I crazy?

 

[PlayingWithTBI]

I remember looking in the past and they were the ones I was supposed to have for my truck...But can check....
FWIW I have the vortec fuel pump too.... not that it should matter....

GM 5235206

Just about everyone I know switched to the EP381 (or equivalent) pump on their TBIs.

Now that we know which injectors you have, we don't know their actual flow rates. As mentioned on my chart, fuel delivery can vary +/- 10% - a good reason to get "flow matched" injectors or at least have yours sent out, cleaned, and flow tested.