How does TBI fuel injection work? TBI is a type of fuel injection system that has one or two fuel injectors mounted in a throttle body. The injectors deliver fuel into the air above the throttle plates. From there, the air-fuel mixture enters the intake manifold, where it is distributed to the engine’s individual cylinders.
How do you test a TBI fuel injector?
0:071:07How to test your TBI Injectors - YouTubeYouTubeStart of suggested clipEnd of suggested clipThat's where power and ground would to go to and the easiest way to test for this is to actually getMoreThat's where power and ground would to go to and the easiest way to test for this is to actually get a 9-volt battery like that and just kind of go touching on the terminals.
How does a throttle body injection system work?
1:3411:09How Throttle Body Injection ( TBI ) Works by HowstuffinmycarworksYouTubeStart of suggested clipEnd of suggested clipThe filters the impurities from the temp. As the pump is energized filled travels through the supplyMoreThe filters the impurities from the temp. As the pump is energized filled travels through the supply line it exits the fill pump module enters the filter. And it travels and it goes to the throttle
What is TBI injectors?
Throttle Body Injection or TBI, uses one or two injectors mounted directly in the throttle body which spray fuel into the intake manifold.
How long do TBI injectors last?
The fuel injectors on your car will typically last between 50,000 and 100,000 miles.
What controls the injectors on a TBI?
The vehicle's fuel pump moves fuel from the gas tank to the throttle body assembly. Then a computer, often referred to as the powertrain control module (PCM), activates the TBI injectors. The injectors spray fuel into the throttle body bore, right above the throttle plates.
What sensor tells injectors to fire?
Electronic Control Unit (ECU) It does this by telling the fuel injectors when and how long to fire. The ECU often controls other functions like the fuel pump and ignition timing.
How much HP can a stock TBI handle?
around 275 hpStock small-block throttle bodies only flow around 500 cfm (compared with a stock Q-jet that flows 750 cfm). It's possible to make around 275 hp with a stock TBI unit, so rather than go nuts on a heavily modified TBI, I'd suggest you start by making sure the existing TBI unit and injectors are in good shape.
Does a TBI have a fuel pressure regulator?
Second only to the stock TBI ECM, the stock TBI fuel delivery system leaves a lot to be desired. Starting at the tank the fuel pump is a turbine pump. Quiet and long lasting, but weak fuel delivery. The fuel pressure regulator is set for approximately 12 psi (30 psi on '94 & '95 BBC trucks).
Can TBI injectors clean?
Cleaning fuel injectors is generally not a do-it-yourself project, but you can clean the throttle body on your vehicle with common tools and specialized spray cleaners. While throttle-body cleaning is good preventative car maintenance, it should also help engine drivability.
Is it better to clean or replace fuel injectors?
Fuel injectors should be cleaned at least once every 36 months, or 45,000 miles. Replacing weak or worn-out engine parts without improving performance is not a good idea in general. However, cleaning out dirty injectors may gain a different perspective on engine health.
What does a leaking injector sound like?
I would describe the sound of a bad injector as more like a rattle or tapping sound. A bad injector would also leak excess fuel which could be seen or smelled in the exhaust. It would also be likely to result in a code from the oxygen sensor.
Can fuel injectors give too much fuel?
A bad fuel injector can cause too much or not enough fuel to be delivered into the engine – this will cause the Check Engine light on the car to turn on, indicating an issue.
What is the advantage of throttle body injection?
Improves performance and fuel economy TBI easily yields higher output in the form of more horsepower, without having the need of complete servicing of the engine.
How much fuel pressure does a throttle body injection need?
The fuel pressure regulator is set for approximately 12 psi (30 psi on '94 & '95 BBC trucks). With a service range of 9 to 13 psi being considered good.
What is the difference between throttle body and fuel injection?
The injectors are mounted at each of the intake ports so fuel can be sprayed directly into the ports. A single throttle body meters the amount of air entering the intake manifold so the amount of fuel delivered can be matched to the engine's needs.
What is the difference between TBI and EFI?
ALL fuel injection can be classified as Electronic Fuel Injection (EFI). TBI is an EFI setup that utilizes Throttle Body Injection (looks like a carburetor). The TBI units have two injectors that meter the fuel for all the clyinders at once (again, similiar to a carburetor).
How much fuel pressure is needed for a TBI injector?
The big variable is fuel pressure. These late-'80s and early-'90s TBI injectors are intended to run at between 11 and 13 psi, although it's typical to see the pressure down around 10 psi. Generally, a 1-psi change in fuel pressure—from 11 to 12 psi, for example—can be worth roughly an additional 4 percent fuel flow. That doesn't sound like much, but going from 50 to 52 lb/hr can be enough fuel to make another 8 to 10 hp.
What is a TBI?
The GM TBI is a speed-density system, which assumes the engine ingests a given amount of air at wide-open throttle (WOT). Mass airflow systems measure the air entering the engine, but speed density systems like those used on these TBI engines do not.
How much horsepower can a TBI make?
Stock small-block throttle bodies only flow around 500 cfm (compared with a stock Q-jet that flows 750 cfm). It's possible to make around 275 hp with a stock TBI unit, so rather than go nuts on a heavily modified TBI, I'd suggest you start by making sure the existing TBI unit and injectors are in good shape. The actual throttle plate diameters for the 4.3/5.0/5.7L TBI units are all the same at 111/16 inches (big-block TBIs are 2 inches). The difference is the injector flow rates. The 5.0L injectors flow 40 to 45 lb/hr, the 5.7 ones are 50 to 55 lb/hr, and the big-block injectors flow around 75 lb/hr. We would suggest sticking with the stock 5.7L injectors to begin your testing.
How to increase fuel flow?
One of the easiest ways to increase fuel flow is with an adjustable fuel pressure regulator. Companies such as JET, Turbo City, and CFM Technologies sell adjustable pressure regulators. The price hovers around $90 depending on the source. The approach is to first measure the existing fuel pressure. If the pump in your truck is already delivering 13 psi at the TBI, consider yourself lucky and don't bother with the adjustable piece. More likely, the fuel pressure will read 10 to 11 psi. Mount the new regulator and bump the pressure to 13 psi. You won't be able to go much higher because stock pumps generally can't generate more than 14 or 15 psi. Keep in mind that raising the fuel pressure increases fuel delivery across the entire engine operating range. At part throttle, this additional fuel isn't needed, but the oxygen sensor should sense a rich mixture and reduce the injector on time (pulse width), which will lean the mixture back to the ideal 14.7:1 air/fuel ratio. At wide-open throttle, the computer switches to its base fuel map and the additional fuel pressure will increase fuel flow and (assuming the engine needs the additional fuel) will increase power. You should test any fuel pressure change with a WOT acceleration run in Second gear from about 30 to 60 mph. If the truck accelerates to 60 in less time, the engine is making more power.
How fast does a wide open throttle increase fuel pressure?
You should test any fuel pressure change with a WOT acceleration run in Second gear from about 30 to 60 mph.
Why add a longer camshaft?
Adding a longer-duration camshaft with more lift will drastically improve airflow and increase power at a higher engine speed. The problem is that it will require additional fuel that will mean changes to the base fuel map in the computer. We'll get to that in a moment.
How fast does a TBI injector run?
TBI....errr, rather TPI..... injectors tend to run around 19 to 30ish pound per minute. But they have to come on faster, run for a shorter time and operate under higher pressure. So they appear to be oversized in terms of flow because of the way they cycle they need more instant flow and when the engineering design for that gets tested the standard way for electronic injectors, they end up looking too big or conversly the TBIs look too small. But it all works for the applications they're intended for.
How to get more flow without changing to a higher flow injector?
There are two tricks to getting more flow without changing to a higher flow injector, the first is the afore-mentioned increase in pressure. The second is to reprogram the computer for a longer open/on period . Typically injectors are flow rated at 80% duty cycle. The off time used for solenoid cooling.
Is a 4.3 a stock power?
If your seeking stock power numbers simply use the stock equipment. If you can not find the correct equipment the 4.3 was put into several things. Several forklifts used the 4.3 as a power source. The forklift 4.3 is similar enough to the road 4.3 to be a great source for parts.
Can you run a 7.4 injector on a 4.3?
Keep in mind that when hot rodding these things it's better to use a too high of a flow injector and run the computer chip to select a shorter on time, than it is to run too small and injector that has the computer programmed for more on time, with-in reason. You don't want to run a 7.4 injector on a 4.3 with a real short on time as that provides a crummy spray pattern.
Which valve functions better with the lower vacuum signal of a performance engine?
This PCV valve functions better with the lower vacuum signal of a performance engine using a camshaft with more duration and overlap.
How much pressure do you need to bump fuel pressure on 454?
From 370-440hp you need to bump the fuel pressure up on the 454 injectors to the 15-18psi to increase their flow rate to 100lb/hr.
Does TBI do 5k RPMs?
TBI computer does not do well past 5k rpms so some of the cam choices have been adjusted.
Does a camshaft have a vacuum?
A performance camshaft will typically produce a lower vacuum signal than the stock engine/camshaft, and the stock PCV valve may not close enough at idle, which can cause an irregular and/or high idle, or otherwise not function efficiently throughout the operating range of the engine.
Can you use a flat tappet cam in a new engine?
So I really never recommend a flat tappet cam in a new engine build. Its ok to toss one in a motor with some mileage on it but with a new engine. GO ROLLER. 1987-93 blocks have all the roller cam provisions. 1994-95 GM did stop drilling and tapping those provisions so I typically wont rebuild one of those motors. I will search craigslist or car-part.com for a different year block. 1996+ vortec all came with a roller cam. all the roller cam hardware needed is here.