First real test drive today, after V8 swap.

Schurkey · Feb 13, 2024

[Warning: Broken Record Alert]

Connect a friggin' scan tool, find out what the computer wants you to know. If your fuel pressure is low, or you have the wrong injectors, the fuel trims should be screwed-up. If the knock sensor is unhappy, the knock counts will be high. If the TPS, or the CTS or whatever is messed-up, it'll show on the data stream. This engine have an AIR pump? If it doesn't divert to the air cleaner as the engine warms-up, it'll freak-out the O2 sensor.

Make sure the EGR is plumbed and wired correctly. Did you source the correct PCV valve? But if there's a strong vacuum leak, the IAC counts will be off, and maybe the fuel trims too.

This engine is crying out for a scan tool. Get yourself signed-up for the Community MT2500 and see what it shows. Or take the money you'd have spent on rebuilding the already-rebuilt engine, and get one of your own.

DeCaff2007 · Feb 13, 2024

Schurkey said:
and get one of your own.

Any particular one you'd suggest?

L31MaxExpress · Feb 13, 2024

Road Trip said:
Thanks for the heads up. I went back and verified all that did match, fixed any discrepancies,
and documented the edits on the right hand side of the list. It's one thing to share data
from enthusiasts you don't know, another to share more accurate data from someone with a
good track record who is here to take credit for the accuracy.

The way I see it, precious few people are still interested in TBI part numbers, flow data, and
color codes, so for the good of the GMT400 TBI community we should do whatever we can
to minimize any possible confusion.

With any luck, as described by @tayto in reply #139. Looking around, folks have commented
that the color codes may or may not still be on the injectors, so you may end up having to take
a magnifying glass to them in order to see any remnants: (TBI injector identification)

Let us know what you discover.

It is no big deal. I am very familiar with the origins of that older list. It was from ~30 years ago when it was first being understood the colors even meant something at all. Something either the late Bruce Pleacan (Grumpy) or RBob put together. Then the late Mark, Eagle-Mark, later started a new list on Gearhead-EFI. Miss both Mark and Grumpy from my earlier days of tuning.

PlayingWithTBI · Feb 13, 2024

Road Trip said:
The way I see it, precious few people are still interested in TBI part numbers, flow data, and
color codes, so for the good of the GMT400 TBI community we should do whatever we can
to minimize any possible confusion.

Just an FYI - these injectors are notorious for different flow rates up to ~10% which is big when trying to fine tune an engine. There are sites on eBay, Amazon, etc. that sell cleaned and "Flow Matched" injectors.

L31MaxExpress said:
To get enough flow to feed a ~300-315 hp engine requires about 20-22 psi. 20 psi is ~ 79 lb/hr and 22 psi is 83 lb/hr. Could also swap to an 80 lb/hr 454 injector but atomization is better with smaller injectors at higher pressure and the idle will be noticeably less rich.

^^^This - I had a hard time getting the ('4304) 454 injectors (@14PSI) to idle with my build. The EBL Flash-II would shut them off completely at idle trying to reach 14.7 AFR. The 350 (61LB/Hr) ones at 20PSI ran a whole bunch better :waytogo:

YMMV

Schurkey · Feb 13, 2024

DeCaff2007 said:
Any particular one you'd suggest?

Multiple threads already covering this.

Here's two:
www.gmt400.com/threads/gmt400-community-scan-tool.60565/

GMT400 - Community Scan Tool

Truck running rough? Maybe you want to throw some parts at the 'ole girl to make it right. But which part? There are so many. Perhaps you were in the driveway with the hood open, intensely staring at the engine to telepathically coerce it into functioning again when your neighbor stops by. His...

www.gmt400.com

and

www.gmt400.com/threads/scan-tool-advice.54744/

scan tool advice

Hey all, new to the forum and a long time chevy enthusiast. My father in law recently hired me to put his 96 3500 with a 5.7 back together after he had it sitting for the last 7yrs. He had the heads gone through and just moved onto the next project. I got the truck all back together and of...

www.gmt400.com

But there's plenty more where those came from.

termite · Feb 13, 2024

Schurkey said:
Here's two

Don't hedge bets on the community scan tool. Unfortunately, it's looking like @rabbit has taken off with it.

DeCaff2007 · Feb 13, 2024

MY GAWD!@#$

I've been looking at different OBD1 scanners with live data... They are IMPOSSIBLY expensive for something I'm going to use ONCE.

@Schurkey, I'd love to plug in one of these elusive live data scanners and see what's what... but not for that price

Bosch Automotive Tools: OBD 1300 Enhanced OBD I & II Scan

OBD 1300

www.amazon.com

Then there's the GM Tech II. Seems like a great choice! Also seems like they are limited to 1991 - 2013 vehicles. What was so special in 1991 that the Tech II became the go-to diagnostic tool?

Schurkey · Feb 13, 2024

DeCaff2007 said:
I've been looking at different OBD1 scanners with live data... They are IMPOSSIBLY expensive for something I'm going to use ONCE.

As long as you own an OBD1 vehicle, you're going to use it now and then, not "once".

And if you think $250 is high, the brand-new professional-grade tools are $3000 plus, and by "plus" I mean $10K perhaps more with Bideninflation.

I paid $350 for my used Snap-On Solus Pro. Would have been ~$3000+ when new in 2008.

DeCaff2007 said:
Then there's the GM Tech II. Seems like a great choice! Also seems like they are limited to 1991 - 2013 vehicles. What was so special in 1991 that the Tech II became the go-to diagnostic tool?

I don't know. I've never seen one let alone used it. Most of 'em are Chinese clones of the genuine tool.

First Guess: On-board computers got sophisticated enough to need an updated/faster/more-powerful tool than the previous Tech 1 or...1A, maybe.

DeCaff2007 · Feb 13, 2024

Schurkey said:
I paid $350 for my used Snap-On Solus Pro

Well, that's nice I guess. "I" will NEVER buy snap on. TOOOOOO expensive for just another junk brand name.

Matter of fact, I have but ONE snap on tool in my entire collection. It's a flare fitting wrench and I couldn't even tell you what size. Used it once to try to remove a brake line steel nut. It spread apart and fell right off. Great tools, those snap on's..................

fancyTBI · Feb 13, 2024

DeCaff2007 said:
TOOOOOO expensive for just another junk brand name.

I think many people will disagree with you. One of them is me. Used snap-on tools are a great value.

There is a $250 Snappy MTG2500 on eBay right now. That is a great deal. They are normally higher than that. Any of those off-brand OBD1 scan tools are junk. They are rarely bi-directional and often don’t have graphing capabilities.

I got a Solus Pro at the recommendation of @Schurkey and it has been a great investment even for the few times I’ve used it. They aren’t cheap these days.

It’s a 35 year old truck with EFI. You shouldn’t treat it any differently than later-model engines with EFI (which are almost always hooked up to the scanner when they get to the shop).

First real test drive today, after V8 swap.

Schurkey

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DeCaff2007

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L31MaxExpress

I'm Awesome

PlayingWithTBI

2022 Truck of the Year

Schurkey

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GMT400 - Community Scan Tool

scan tool advice

termite

Definitely NOT Awesome

DeCaff2007

I'm Awesome

Bosch Automotive Tools: OBD 1300 Enhanced OBD I & II Scan

Schurkey

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DeCaff2007

I'm Awesome

fancyTBI

Some of my trucks run and drive

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