Carb SBC vs TBI SBC vs Gen 3 LS reliability

[slow_c1500]

One thing I have heard about the TBI is that the computers aren’t as sensitive to problems compared to OBDII, so there could be something wrong and it wouldn’t throw a code. Is this because of how little sensors it has? Or the computer itself?

Has that been a problem for any TBI owners?

 

[PlayingWithTBI]

Has that been a problem for any TBI owners?

Yes, the OBDI TBI is a little dumbed down compared to OBDII. Another way to look at it is the TBI doesn't have as much to go wrong with it. One O2 Sensor compared to 3 or 4, Speed Density (MAP) compared to MAF and MAP. It won't tell you if you have misfires but, by process of elimination, you can figure it out with other troubleshooting methodology. The later PCMs, like the 16197427 are faster, with expanded tables and, can control E Trans. I ran my 88 5.7L Mr Goodwrench long block for ~17 years (it was 2 years old when I bought it) without any issues other than a water pump, until it blew a head gasket. Same old sensors, Throttle Body, Starter, EGR valve, A.I.R. Pump (It was a CA truck), 700R4 Trans, 10 Bolt Rear End, etc. Batteries lasted ~4 years in the heat. It wasn't fast but dependable, it never failed to start and run. Now I'm having fun pumping it up with go fast parts

 

[slow_c1500]

Yes, the OBDI TBI is a little dumbed down compared to OBDII. Another way to look at it is the TBI doesn't have as much to go wrong with it. One O2 Sensor compared to 3 or 4, Speed Density (MAP) compared to MAF and MAP. It won't tell you if you have misfires but, by process of elimination, you can figure it out with other troubleshooting methodology. The later PCMs, like the 16197427 are faster, with expanded tables and, can control E Trans. I ran my 88 5.7L Mr Goodwrench long block for ~17 years (it was 2 years old when I bought it) without any issues other than a water pump, until it blew a head gasket. Same old sensors, Throttle Body, Starter, EGR valve, A.I.R. Pump (It was a CA truck), 700R4 Trans, 10 Bolt Rear End, etc. Batteries lasted ~4 years in the heat. It wasn't fast but dependable, it never failed to start and run. Now I'm having fun pumping it up with go fast parts

The tbi is sounding like a great option to me in terms of reliability, and I don’t need it to be crazy fast. I got a couple more questions tho:

What ways could you find misfires if it didn’t throw a code and tell you what cylinder?

How much mpg would I be losing with TBI compared to a vortec? (Assuming the displacement is the same)

 

[618 Syndicate]

With apologies to the Mopar 318, but none to the LS motors, the TBI motors may be the longest lived cast iron V8's ever devised by humankind......

Donning my flameproof suit........
It's simple, the TBI's operate at lower RPM's. Less RPMs for every mile driven translates into less wear. LS motors have higher HP potential, lower emissions potential, all in a slightly smaller package, albeit at higher RPM's than the TBI or 1st Gen Vortec.

The Vortec V-8's fall somewhere in-between.

The SBC have 45 years of R&D, and the Vortecs are the culmination of that. Particularly reliability. I"m old enough to remember when any engine was "wore out" when it crossed over 100k.

I know I'll catch flak, but.....all things being equal, the Gen 3 LS motors do NOT last longer than the TBI's or the Vortecs--notably dependent on level of maintenance and how it's driven.

I've owned all three of these engines, and I've owned 2 of them when relatively new and I know the provenence of ALL four of my pickups noted in my sig and am/was the second owner of all four. They all were fairly well maintained and driven fairly sane. Importantly "well maintained" also means keeping the truck relatively clean beyond the interior and the shiny side. It also means keeping the chassis and engine bay clean. I see photos on here all the time of filthy engine bays and rusty trucks. Plastic and rubber doesn't like to be covered in grease and road grime. Road salt and mag chloride love to rust metal.

My 96 and 97 ECSB's have no rust in the corners of the x-cab. Why? Because I and the previous owners washed the underside of the truck often. Even though I own pressure washers I still hit the carwash (especially during the winter) often. I almost always spend more time (and money) washing underneath and the engine bay than I do the paint.

Reliability and longevity are not the same thing, but I get your point. I too am old enough to remember 100k being "worn out", and I think that it comes down to personal choice.

 

[PlayingWithTBI]

What ways could you find misfires if it didn’t throw a code and tell you what cylinder?

If you're getting a misfire, you may feel it and/or your O2 feedback will go Lean, throwing a code. Then you can put an IR gun on the exhaust manifolds, look at the spark plugs and test them with an HEI plug tester, do a cylinder balance test, Ohm out the plug wires, check cap and rotor, etc. Pretty much what you'd do when you get a cylinder misfire code but, you'd be looking at all of them instead.

There are scanners and computer programs that will tell you just about everything going on with your engine and controls too. Here's a couple examples;

TunerPro RT on an 88 1227747 ECM...

You must be registered for see images attach

EBL FLash-II WUD (What's U[ Display) on my 88, running Hiway Lean Cruise (for better mileage) note SA and AFR.

You must be registered for see images attach

The ODBI TBI ECM/PCMs aren't totally dumb, just didn't move on to Graduate School. Plus, you can Data Log (and play back) for as long as you want until you see what's going on when your issue occurs. Then you'll have an idea where to start.

 

[fancyTBI]

I like the TBI. I don’t get into the tuning side as much as others here (like the fella above me) but I can diagnose them with a scanner and feel comfortable working on them. All three of my trucks are TBI 5.7s. They don’t ask for much besides basic maintenance and quality parts. I will always opt for OEM or equivalent parts when replacing something engine wise. I’ve never owned a Vortec but am not opposed to them.

 

[slow_c1500]

You guys are really making me want a TBI truck. I also prefer the pre 95 interior too, so that would be a plus.
For me, there wouldn’t really be many downsides to trading mine for a TBI OBS. Really the only thing is that I’d be losing 45hp and around 1 mpg, but the benefits are worth it for me.
I still plan on fixing my vortec though.

 

[Schurkey]

If you're getting a misfire, you may feel it and/or your O2 feedback will go LEAN, throwing a code.

FIFY.

 

[1990Z71Swede]

If you're getting a misfire, you may feel it and/or your O2 feedback will go rich, throwing a code. Then you can put an IR gun on the exhaust manifolds, look at the spark plugs and test them with an HEI plug tester, do a cylinder balance test, Ohm out the plug wires, check cap and rotor, etc. Pretty much what you'd do when you get a cylinder misfire code but, you'd be looking at all of them instead.

There are scanners and computer programs that will tell you just about everything going on with your engine and controls too. Here's a couple examples;

TunerPro RT on an 88 1227747 ECM...

You must be registered for see images attach

EBL FLash-II WUD (What's U[ Display) on my 88, running Hiway Lean Cruise (for better mileage) note SA and AFR.

You must be registered for see images attach

The ODBI TBI ECM/PCMs aren't totally dumb, just didn't move on to Graduate School. Plus, you can Data Log (and play back) for as long as you want until you see what's going on when your issue occurs. Then you'll have an idea where to start.

How much does your lean cruise impact MPG compared too running 14.7 cruise? Just wondering if it is worth it considering it supposedly will greatly increase NOx emissions .
And also just out of curiosity really, what gearing? 60mph 2000+ Rpm with locked TC seems highish for 3.73 but low for 4.10.

 

[PlayingWithTBI]

Just wondering if it is worth it considering it supposedly will greatly increase NOx emissions .

It may but, I have a new style 3-way Cat which cuts NOx over the old pellet style that came with these trucks.

And also just out of curiosity really, what gearing? 60mph 2000+ Rpm with locked TC seems highish for 3.73 but low for 4.10.

700R4 trans .70:1 in 4th, "4.11" gears with 275/60-R15s