Is the Chevy TBI 454 having Idle problems?

Recently rebuilt the 454 in my 1990 TBI Burb. I am having a terrible time with getting it to idle smooth. The engine has a little over 500 miles on it. I have spent countless hours going over the engine looking for vacuum leaks and believe every thing is OK on that front.

What kind of fuel pump does a TBI 454 have?

Stock TBI 454 makes 230hp and 380tq so stock fuel pump is maxed out right off and a typical 454 will run better with a fuel pump upgrade even with stock chip. GAS MILEAGE. Always a big complaint with 454 TBI trucks. 90 and older is particularly bad and that is largely due to NO OVERDRIVE.

What is the TBI code on a 1990 Chevy truck?

Consult a service manual or see below for any check engine light code definitions. You can use a late 80’s or early 90’s GM TBI definition. If you have access to a scan tool use a hook up for a 1990 350 cu. in. 5.7L Chevrolet truck. For some scan tools enter VIN 10th“L” 3rd“C” 8th“K”.

How to troubleshoot your TBI fuel injection system?

Troubleshooting your TBI Fuel Injection System Most of the problems encountered while installing your fuel injection system or after a time of operation are very simple. If your check engine light is on you more than likely have a hard fault meaning something is grounded out, unplugged, operating out of range or has gone bad. See

When did I replace the IAC on my Chevy TBI?

I have replaced the engine temp sensor, the connections to the coil, the coil, cap, rotor, plug wires, map, checked the tps, reset the base idle, checked voltage values at the tps connection, map connection etc. The iac was replaced about 4000 mles ago. The throttle body was re-bushed about 4000 miles ago.

What to do if your Chevy 454 Idles low?

Check to see if the EGR valve is stuck open a little. If it is unable of running below 800 RPM test the fuel pressure, especially if the idle sounds weak and unstable. Is that 800 RPM, in park, or in drive?

What should the idle speed be on a TBI 350?

The IAC should NEVER get closed all the way, which would be an IAC count of zero. When everything is at its optimum, cleaned and working correctly, the idle count will be around 15-20. The IAC controls the idle speed ALL the time not only on a cold start up. Loc: Twin Cities, Minnesota, U…

Where are the fuel injectors located in a 454 engine?

The throttle portion of both the TBI units may contain ports located above, or below the throttle valve. These ports generate the vacuum signals for the exhaust gas recirculation (EGR) valve, MAP sensor and the canister purger purge system. The fuel injectors are solenoid-operated device, controlled by the ECM.

How does a MerCruiser engine work at idle?

When I start the engine from cold, I allow the engine to warm up at idle. This goes smoothly everytime. When I rev up the engine, either in neutral or under load, the engine works fine.

How is the idle speed of an engine controlled?

All engine idle speeds are controlled by the ECM through the idle air control (IAC) valve mounted on the throttle body. The ECM sends voltage pulses to the IEC motor windings causing the IAC motor shaft to move in or out a given distance a given step for each pulse often referred to as counts.

When does the 1990 c1500 TBI idle go away?

1990 C1500 TBI 5.7L Idle is surging when warm. Unplug the MAP Sensor and the problem goes away, I replaced the MAP 1990 C1500 TBI 5.7L Idle is surging..MAP Sensor..goes away..Autozone… 1990 C1500 TBI 5.7L Idle… 1990 C1500 TBI 5.7L Idle is surging when warm.

What kind of gas does a 1997 Chevy truck use?

1997 chevy c1500 WT with 4.3 . getting harder to re crank.. Only driveable with both stop revving to keep it going. And that still doesnt work well. Work ive done. New cap and rotor. Cleaned…. Exh gas.

What makes a’91 TBI 350 surging at idle?

It basically almost dies out, and then surges back to life (probably a little higher than normal idle), then repeats continuously until you apply some throttle. If I had to guess, I’d say it’s a dirty throttle body, or possibly injecters. If it is one of these, what would be the best way to clean them?

How to reset the idle speed in a GM TBI?

Unplug the IAC valve located on the passenger side, rear of the throttle body. Start the engine. Insert a T-30 size Torx driver into the Idle adjustment screw that is located behind the plug removed earlier. Turn the screw to adjust the idle speed to 650 RPM +/- 50 RPM.

What makes a 91 Chevy surging at idle?

My father in law’s ’91 Chevy was running poorly, so we put new plugs, wires, cap and rotor on it, and it’s running better, but it it still surging at idle. It basically almost dies out, and then surges back to life (probably a little higher than normal idle), then repeats continuously until you apply some throttle.

Can a bad throttle position sensor cause idle surging?

Idle surging can be caused due to other issues in the car, but if it happens in conjunction with other throttle position sensor symptoms, the culprit is often the TPS. At idle, the ECM will not get the correct information and the throttle will variate randomly causing idle surges. 3) Check Engine Light

How can I tell if my idle control valve is working?

To check if an idle control valve is working properly, start by turning on your engine and letting it run for a minute or 2. Then, when it’s at an idling speed, take note of the RPMs in your car. Next, turn the engine off and disconnect the idle control motor under your hood.

Why does the Check Engine light come on when the engine is idle?

The check engine light in your vehicle is designed to turn on if the Engine Control Unit (ECU) identifies an issues with how the engine is running. Look at your dashboard; if the check engine light is on in conjunction with idle issues, it may be because the idle control valve is malfunctioning.

Why does my Chevy Silverado not idle after a cold start?

My 89 Chevy Silverado would not idle after a cold start I took the PCV valve out and sprayed it with carburetor cleaner….no more problems!!! 5 people found this helpful. One of the MOST overlooked parts of these TBI engines is the distributor pickup coil.

What causes a Chevy C / K 1500 to drop in idle?

In order to change these, you have to completely removed the distributor and completely disassemble the distributor to get the pickup off and replace it. These components are very sensitive and when failing, will cause misfire, idle issues, and cause it to burn rich as well. 11 out of 12 issues like this are because of this pickup coil.

What causes a 1989 Chev crew cab to stall?

I have a 1989 v3500 chev crew cab with a 454. Started stumbling at low throttle, stalling when I came to a stop or any low rpm activity. Checked for vaccuum leaks, reset base idle, tested sensor components, ran Win aldl diagnostics, could not get it to run right.

Why does my Chevy truck stall at idle?

Filter is not that old, and if plugged or if pressure regulator is malfunctioning, why do I never see fuel pressure at throttle body so much as waver lower than 12psi? Also, many times the lean condition will start just off idle so bad so that truck wil fall flat on its face and stall.

Can a bad idle control valve cause stalling?

3. Engine stalling The idle control valve, also commonly referred to as the idle air control valve, is an engine management component that is found in one form or another on the majority of road going vehicles.

What causes the idle speed to go up or down?

The idle air control valve is programmed to regulate and maintain the engine idle speed at a constant rate. If the valve fails or has any issues it can cause the idle speed to be thrown off. This may result in an unusually high or low idle speed, or in some cases a surging idle speed that repeatedly climbs and falls. 2. Check Engine Light comes on

Is the Chevy TBI 454 having Idle problems?