Narrowing down common TBI problems...

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Erik the Awful

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I've been wrenching for thirty years, and I've set points once - on a two-cylinder Wisconsin engine an in Air Force NF-2 that was DRMO'd a couple months later. Unless you're digging on the old school stuff, there's no reason to know how. It's an arbitrary skill, like writing in cursive. If you have to, you can watch a quick YouTube video and understand how to set one.
 

someotherguy

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I've been wrenching for thirty years, and I've set points once - on a two-cylinder Wisconsin engine an in Air Force NF-2 that was DRMO'd a couple months later. Unless you're digging on the old school stuff, there's no reason to know how. It's an arbitrary skill, like writing in cursive. If you have to, you can watch a quick YouTube video and understand how to set one.
Simply difference of experiences - 30 years puts that around 1991, maybe a couple years less than I've been using tools to help me break things and invent new cuss words (I started on cars in 1987) - the first several dozen cars on my list of stuff I've owned were points ignition. Yeah, it's not difficult to understand how to set them, but like most things they are a mystery until explained. Also, GoToGuy's story dates back to around 1999 which predated youtube. :D

Interesting side note, even 15-16 years ago when looking for points for the 327 in my '57 Chevy 150 (swapped from a 235), the local parts house choices were slim.. with those junk clip-in terminals and overall low quality of the assembly, the dwell was changing on its own and the car would start running badly pretty quick. Had to order a set of Accels and wait a few days for 'em to come in.

Back in the 80's and early 90's, "barn finds" almost always included taking a hot battery, fresh gas, and a points file along to see if you could crank up an old engine before paying too much, and also to help get the vehicle onto your trailer or tow dolly. Sometimes those tools weren't brought out until after you paid, if the price was right. ;)

Richard
 

vr1967

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I had to go set some points the other day on a 48 Chevy 215 for an older gentleman. He’s used to the magneto on his 28 Ford.

I may possibly end up with the 48 coupe though, as he just bought a 29 Studebaker 5 window coupe
 

Bones333

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Hey all, it seems like everyone with a TBI motor is trying to fix bad idle, lack of power, and poor fuel economy, I'm no different. Common issues, but the only problem is that there is rarely ever just one magical cure-all to these issues, people think they have the answer because it worked for them, but someone else will replace that same part (say the TPS or something) on their truck and it won't make a difference. Watching posts on the internet over the last two years has taught me that as much as people like to rag on the idea of throwing parts at a car, that's really the only solution for engines like these.

My truck is a 94 with the TBI 350, rebuilt 4L60E, 4x4, extended cab, 3.73 gears and a G80 and just over 268K miles without a major rebuild, a prime candidate for the everlasting TBI issues. In the past I did plugs, wires, cap and rotor, I've replaced the fuel filter, and one of the injectors were replaced ~12 years ago. Other than that, it's all stock!

Checking the SES lights shows that I had a code for a MAP sensor and the EGR, both of which could be causing these issues. So I started there, I scraped together what leftover money I had after bills tonight and bought a new MAP and IAC (SES said an EGR, but I didn't have the money and it'll get replaced anyways.) and if replacing those two parts made a difference, it was a minimal one. Idle improved slightly, it no longer stumbles when in gear and at a stop, but it's still not as smooth as it should be. Power improved slightly as well, it lights up the rear tires at a dead stop now when the pedal meets the metal, but after takeoff and when rowing through gears, power didn't improve much. Downshifts are torquier though!

Despite my truck being an automatic, it has a tach and one thing I've noticed about the motor is that it runs out of steam at about 3800 RPM, it'll usually go to 4500 RPM before it shifts, but it just seems like the motor is spinning, but its being choked by something. I know that the exhaust and the heads are major bottlenecks on these engines, but I've driven a low mileage 95 that was equipped just like mine and it had power until about 4100 RPM, and even when it shifted at 4500 it still had more power left then mine despite them both being completely stock motors. I'm guessing my issue is more with the intake rather than the exhaust. A few thoughts I've had is that the air filter is clogged and isn't allowing the engine to breathe enough, or maybe the fuel pressure regulator isn't getting enough fuel to the engine (not sure on that one though.) Whatever it is, it's choking up the engine, and that could be the root of my problems. (lid flip just makes it louder, no power difference for me)

a bit off topic, but my 0-60 times are around the 13s range, what are everyone else's? Is 13s normal for a 200hp 4x4? I got smoked by a friends stock 99 Ram with the 5.9, 4 auto, and 4x4, and he has a 3.42ish axle ratio!

Next paycheck will most likely be vacuum lines and other rubber stuff, nothing is visibly bad, hoses still are solid, but the gasket on the stock IAC fell apart when I took it out so I know the rubber isn't in great shape. EGR will also be next since it's a known issue.

As far as other suspects go, I'd say the fuel pressure regulator and injectors, the O2 sensor, or maybe the air filter as mentioned earlier.

Anyways, anyone have any thoughts or wanna add anything to this?
Hey all, it seems like everyone with a TBI motor is trying to fix bad idle, lack of power, and poor fuel economy, I'm no different. Common issues, but the only problem is that there is rarely ever just one magical cure-all to these issues, people think they have the answer because it worked for them, but someone else will replace that same part (say the TPS or something) on their truck and it won't make a difference. Watching posts on the internet over the last two years has taught me that as much as people like to rag on the idea of throwing parts at a car, that's really the only solution for engines like these.

My truck is a 94 with the TBI 350, rebuilt 4L60E, 4x4, extended cab, 3.73 gears and a G80 and just over 268K miles without a major rebuild, a prime candidate for the everlasting TBI issues. In the past I did plugs, wires, cap and rotor, I've replaced the fuel filter, and one of the injectors were replaced ~12 years ago. Other than that, it's all stock!

Checking the SES lights shows that I had a code for a MAP sensor and the EGR, both of which could be causing these issues. So I started there, I scraped together what leftover money I had after bills tonight and bought a new MAP and IAC (SES said an EGR, but I didn't have the money and it'll get replaced anyways.) and if replacing those two parts made a difference, it was a minimal one. Idle improved slightly, it no longer stumbles when in gear and at a stop, but it's still not as smooth as it should be. Power improved slightly as well, it lights up the rear tires at a dead stop now when the pedal meets the metal, but after takeoff and when rowing through gears, power didn't improve much. Downshifts are torquier though!

Despite my truck being an automatic, it has a tach and one thing I've noticed about the motor is that it runs out of steam at about 3800 RPM, it'll usually go to 4500 RPM before it shifts, but it just seems like the motor is spinning, but its being choked by something. I know that the exhaust and the heads are major bottlenecks on these engines, but I've driven a low mileage 95 that was equipped just like mine and it had power until about 4100 RPM, and even when it shifted at 4500 it still had more power left then mine despite them both being completely stock motors. I'm guessing my issue is more with the intake rather than the exhaust. A few thoughts I've had is that the air filter is clogged and isn't allowing the engine to breathe enough, or maybe the fuel pressure regulator isn't getting enough fuel to the engine (not sure on that one though.) Whatever it is, it's choking up the engine, and that could be the root of my problems. (lid flip just makes it louder, no power difference for me)

a bit off topic, but my 0-60 times are around the 13s range, what are everyone else's? Is 13s normal for a 200hp 4x4? I got smoked by a friends stock 99 Ram with the 5.9, 4 auto, and 4x4, and he has a 3.42ish axle ratio!

Next paycheck will most likely be vacuum lines and other rubber stuff, nothing is visibly bad, hoses still are solid, but the gasket on the stock IAC fell apart when I took it out so I know the rubber isn't in great shape. EGR will also be next since it's a known issue.

As far as other suspects go, I'd say the fuel pressure regulator and injectors, the O2 sensor, or maybe the air filter as mentioned earlier.

Anyways, anyone have any thoughts or wanna add anything to this?
Had the exact problems you’re having. I rebuilt the throttle body and added a 14 psi fuel pressure spring and it’s back running like it should be. Rebuild kit is only $40 or less and the spring was $20 off Amazon. Most of the idling problems come from the base gasket between throttle body and intake collapsing into the air passages. The pile of dust is the gasket material that I removed when I rebuilt it. Since then I’ve added the injector pod spacer, added the power charger bowl and done the ultimate throttle body modifications.
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GoToGuy

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I had to go set some points the other day on a 48 Chevy 215 for an older gentleman. He’s used to the magneto on his 28 Ford.

I may possibly end up with the 48 coupe though, as he just bought a 29 Studebaker 5 window coupe
Allright, yes I'm now getting to be an old dog. And yes alot memories and experiences. Highschool sophmore 1974, ya see it, all those cool 60's, 70's factory hot rods, muscle cars are the normal driving around vehicles. Me and school classmates. Our high school parking looked like a muscle car party show. One guy his dad owned the local Datsun (Nissan) dealership. He drove this box sedan 510, that full of Datsun race goodies. And yeah joe average won't know all types of ignition service, points single, dual, magneto, hall effect, digital etc. The exception if your in a professional position, you should have knowlege, not service, but " oh yeah points, gotta look that up". History does matter, it got you here. Oh well i got a Bendix magneto to inspect and install.
 

Schurkey

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The only time I dicked with a magneto, was when I was fixing my friend's tractor. What was IHC before it was IHC? McCormack-Deering? Pretty sure it was a M-D, four-popper gasoline tractor. Wouldn't run, no spark.

The magneto has a bigass clock-spring inside. The engine turns one end of the spring, when it gets wound tight enough, it snap-unwinds, turning the magneto guts and makes a spark. Repeat for each of the four cylinders. The spring was broken. I pulled the spring out, overlapped the broken pieces, and brazed 'em together.

Tractor ran afterwards. It was in overall poor condition, but it had been in his family from new. Several generations had learned to drive a tractor (and manual transmission) on that unit.

He had plans to fix it up...arranged for it to be stored at the farmstead of a friend-of-a-friend-of-a-friend; someone died, and "his" tractor got sold with the rest of the farmstead at the auction. He found out after it happened, and he's never seen it since. Family history g-o-n-e, because he wasn't keeping tabs on the folks on the farmstead that had "his" tractor, and no written storage contract.
 
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