What causes a Chevy 350 to backfire when idle?

If a main vacuum hose such as the power brake booster feed line has broken or failing off it will cause a lean backfire due to the additional air allowed into the engine intake manifold. This problem will be accompanied by high or low engine idle and a harder to push brake pedal than normal.

What causes a car to backfire at the wrong time?

This causes an explosion of the fuel and air mixture within the intake manifold, forcing the ignited mixture to exit from the carburetor or fuel injection intake. If spark plug wires are crossed or not installed on the correct spark plugs, the plugs will fire at the wrong time.

Why does my engine backfire out the muffler?

Backfire typically occurs when the engine is decelerated rapidly. Common Causes of Backfire: Lowering engine speed too fast. Gasoline, which contains higher blends of alcohol. Carburetor adjustment set too lean. Muffler construction can induce backfire.

Why does my engine have low compression after a timing belt replacement?

If you know that you got low compression after a timing belt replacement, check the timing. Anyways, if you experience low compression on all cylinders, check the timing. These are found between the crankshaft and camshaft. Valves control the outflow of exhaust gases from the combustion chambers.

Why does my Chevy 350 Backfire at high RPM?

The 90 degree elbow in the PCV Valve hose at the base of the throttle body to the PCV valve is common to either fall off or have a hole in it. Most of the time the engine will idle at a higher RPM a suction sound can be heard.

Why does my car backfire when I open the exhaust valve?

Such a mixture could be caused by low fuel pressure due to a failing fuel pump, a clogged fuel filter or clogged fuel injectors. When a lean mixture combusts, it burns more slowly, meaning there will still be some air and fuel that isn’t used up when the exhaust valves open — leading to a backfire.

When to check engine timing for low compression?

Valve Timing. When all of the cylinders are low and inserting oil into the cylinder does not increase compression, check the engine’s valve timing. The timing belt can slip on the sprockets resulting in low compression in all of the engine’s cylinders. Before replacing the rings in this engine, check the valve timing.

What to do if your Chevy engine backfires?

You’ll want to have a Chevrolet technician take a close look at your vehicle’s fuel system if the air/fuel mixture in your engine is running lean and causing backfires.

What causes an intake back fire in an engine?

This will help locate the system that is having a problem and needs repair. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power. Every internal combustion engine runs on a mixture of 14 to 1 which is fourteen parts air to one part fuel.

What does it mean when your brakes don’t work?

Weak or Spongy Brakes Sometimes your brakes will still work, but they seem to have grown weak. It takes longer to stop, or you get less braking power when you apply the brakes suddenly. The pedal may also feel more squishy than usual:

Do you need to troubleshoot your car’s braking problem?

Seriously, brakes aren’t something to play around with. If your car is having a braking problem, whether it’s weak brakes, a mushy pedal, or grinding sounds, you need to troubleshoot and repair it as soon as possible. We’ll help you diagnose your braking problem, so you know what repairs to make.

What does it mean when your front brake is not working?

Brake Pull: Uneven braking means that you have one front brake on your Chevy that is not operating properly. Your brakes pull to the good side. This can be due to oil, grease or fluid on a pad, a caliper that is stuck, brake line blockage, or wheel bearings that are loose.

What causes an engine to backfire after shutting off?

Afterfire occurs after the engine has been shut off. Note: Backfire and afterfire through the carburetor will not harm the engine at all! Find out the most common causes and possible fixes for engine backfire and afterfire. What causes a small engine backfire & how do I fix it? Backfire typically occurs when the engine is decelerated rapidly.

How to troubleshoot an air brake system in a car?

Make sure oil return in compressor and mating engine surfaces are clear and aligned. Use caution when using gasket sealant. Check air intake to make sure air is properly fillered. Check discharge line for restriction or carbon build up. Clean or replace as necessary. Check compressor cooling system. Min. water line – 1/2″ 0.0.

What causes a misfire on a GM 3.1L V6?

The waste-spark DIS ignition system on the 3.1L is similar to that used on other GM V6 engines. It has been a fairly reliable ignition system, but at high mileage, it can develop problems like any other ignition system. Ignition misfire can be caused by worn or fouled spark plugs, bad plug wires, weak coils or faults in the ignition control module.

Can a bad crankshaft sensor cause a cylinder to misfire?

Should you feel or hear a brief stutter in the engine, it may be a sign of misfiring cylinders from a bad crankshaft position sensor. A failing crankshaft position sensor cannot provide the right information about piston positioning in the engine, causing a cylinder to misfire.

Can a bad timing chain cause an engine to fail?

3. Engine won’t start or fails. A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won’t have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves.

Can a worn out timing belt cause a backfire?

A worn out timing belt can upset the combustion process and lead to backfires. Gasoline engines need to fire spark plugs on time to properly ignite the air-fuel mixture inside a cylinder. On time means that sometimes the spark needs to be fired ahead in advance or retarded depending on engine speed and load conditions.

What are the symptoms of a worn out timing chain?

Listed below are 5 of the symptoms of a worn out timing chain. If you notice any of these warning signs, it’s advised you contact a local mechanic as soon as possible to diagnose the exact cause and make appropriate repairs as needed. 1. Engine misfires or runs poorly There are two ways to achieve valve timing in a combustion engine.

What causes a car engine to crossfire at idle?

By design the resistance it takes to fire the coil via the spark plug is figured into the system. When this resistance becomes excessive due to severely worn spark plugs or a bad ignition coil it can cause these drivers to malfunction at which point they can crossfire into an opposing cylinder either under power or at idle.

What causes a car engine to backfire with low gas mileage?

On older engine’s ignition timing is set at a specific degree in relationship to the crankshaft. If this timing is mis-adjusted it can cause low power, poor gas mileage, engine detonation (pinging) and backfiring through the intake or exhaust system.

How to diagnose engine backfires with axleaddict?

Car owners usually forget to check the ignition system at the recommended manufacturer schedule. If necessary, consult your car owner’s manual or repair manual. Even if your Check Engine Light is not lit on your instrument panel, scan for possible pending diagnostic trouble codes that can guide you in your diagnostic. II. Injection System Problems

Why does my car backfire when I Turn on the ignition?

Engine timing is incorrect. Specifically, delayed timing causes a backfire. This is better known as retarded timing. What that means is the engine cycle of fuel-compression-ignition-exhaust in the top end (cylinder head) isn’t in sync with the bottom end(cylinder block).

Can a turbo charger cause a backfire in a car?

A backfire condition can also occur in race cars using a turbo charger which is normal because they push the fuel through the engine which is then ignited in the exhaust system. We will cover the primary occurrence of the engine under load first.

What to do when your car engine is backfiring?

Anytime you have an engine that is backfiring the first thing to look for is a check engine light. If no warning lights are on continue down this guide. If the check engine or service engine soon light in on scan the computer for trouble codes. This will help locate the system that is having a problem and needs repair.

What does side blind zone alert do on Cadillac Escalade?

Lane Change Alert with Side Blind Zone Alert can provide side-mirror alerts when a moving vehicle is detected in or rapidly approaching your side blind zone. Forward Collision Alert can alert you if it detects a front-end collision is imminent with a vehicle you are following. It also alerts you if you are following much too closely.

What’s the name of the new Cadillac Escalade?

The Next Generation 2021 Escalade raises its own high-tech standards, pushing the journey forward with innovations that don’t just enhance your driving experience—they completely revolutionize it. Certain features shown not available with all configurations.

Why did Cadillac lose its status as a car brand?

However, as the economy declined and a widespread oil crisis spread, owning giant, gas-guzzling sedans became far less convenient — and far more expensive. But more than anything, the rise of imported cars gave Cadillac some serious competition, and the brand started to lose ground as the standard of excellence in America.

How did Cadillac survive the General Motors bankruptcy?

Cadillac saw a bump in sales, a rise in popularity with the youth market thanks to the Escalade, and somehow survived General Motors’ 2009 bankruptcy that saw multiple brands dissolve.

Are there recalls on GM trucks and SUVs?

SEE ALSO: GM Issues Massive Recall for Over 1M Trucks and SUVs. Along with the buffeting, a vibration can be felt inside the cabin. According to many of those affected, the sensation gets worse when the vehicle switches into V4 mode, as these engines are equipped with cylinder deactivation.

What makes Bachman Chevrolet such a great brand?

Bachman Chevrolet is a renowned brand in the business because we believe in the age-old tradition – Customer is King. Our customer satisfaction report speaks for itself as we believe in catering to our clients with the utmost professionalism. Our GM certified technicians provide superior service for all vehicles.

Can a faulty ignition coil cause a backfire?

The same result can come from a faulty ignition coil, distributor or rotor and cause a more repetitive backfire. Car owners usually forget to check the ignition system at the recommended manufacturer schedule. If necessary, consult your car owner’s manual or repair manual.

Can a bad sensor cause an engine to backfire?

An engine sensor malfunction can also lead to backfires. Take for example a bad mass air flow (MAF) sensor. The engine computer uses this and other sensors to compute the amount of fuel to inject into the engine according to operating conditions.

Can a Haynes aftermarket manual prevent a backfire?

Yes, many backfires can be prevented with a little maintenance as suggested in your car owner’s manual or the vehicle repair manual. If you don’t have your repair manual yet, you should get one. Get an inexpensive Haynes aftermarket manual at Amazon for your particular vehicle make and model.

What causes fuel injector connectors to deteriorate?

Tips on selecting the proper type of fuel injector connector. Fuel injector connectors are susceptible to deterioration due to aging, and wear and tear. A fuel injectors location on the engine exposes them to intense heat, vibration, and chemical fumes. Over time, these will cause the connectors’ nylon body to deteriorate and eventually break.

Which is the ground wire for the fuel injector?

Minor correction, the wire to the ECU is the “ground” wire, it’s the one the ECU pulls low to fire the injector. The wire to the injector resistor pack is the power wire. Now, since it’s only the number 2 injector, it shouldn’t be the injector driver in the ecu.

How much is a blue terminal fuel injector adapter?

Blue terminal fits many ford applications. • Also known as Bosch Style EV1 Male to EV6 Female Adapter. • This adapter comes completely assembled and is ‘plug and play’ ready to use. • Only $4.50 each. • Also known as Bosch Style EV1 Female to EV6 Male Adapter. • This adapter comes completely assembled and is ‘plug and play’ ready to use.

Are there 1990 DeVille 4.5 fuel injectors on eBay?

The 2-3 big fuel injector rebuilders/resellers on eBay all have the 1990 4.5 injectors incorrectly advertised. They show that the ’90 4.5 uses the same injectors as the ’91-’95 4.9 – they don’t.

What was the problem with the 1990 Cadillac DeVille?

1990 cadillac deville 4.5l runs rough and missfires. Checked fuel pressure and for vac. leaks, both ok. have replaced plugs, wires, cap, rotor, performed injection service. no results. Hooked to scope and diag. bad distributor. repaced distributo, still have same problem.

Can a first generation Multec fuel injector fail?

First generation Multecs are relatively problematic for a fuel injector. In fact, most in the business will replace them as a set rather than just the offending injector as normally done. I have the 4.5 engine with 51,000 miles on it and have had a problem with the injectors failing.

Why do I hear a bang when my engine backfires?

First and the most common way is when the engine is running a small explosion of un-burnt fuel is ignited inside of the intake manifold creating a loud bang which is the backfire sound you hear. This explosion can bend the throttle actuator plate, push intake gaskets outward creating a vacuum leak and even blown apart a plastic intake manifold.

Why does the exhaust on my motorcycle backfire?

Shorty exhaust also has a tendency to backfire more because there’s not as much pipe length for the turbulent air to become more smooth like the motorcycle was originally designed for. Engineers put a specific length of exhaust pipes on motorcycles because that way it will get the best fuel efficiency.

Why does my car backfire when I Turn on the gas?

This is a normal event and there is no problem with this condition. On older engine’s ignition timing is set at a specific degree in relationship to the crankshaft. If this timing is mis-adjusted it can cause low power, poor gas mileage, engine detonation (pinging) and backfiring through the intake or exhaust system.

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

How to troubleshoot an automotive engine high idle?

The troubleshooting procedure for high and low idle conditions are similar, which are included in the following: Step 1 – If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.

What are the symptoms of a bad idle control valve?

$0.00 1 Irregular idle speed One of the most common symptoms commonly associated with a problematic idle air control valve is irregular idle speed. 2 Check Engine Light comes on Another symptom of a potential issue with the idle control valve is an illuminated Check Engine Light. 3 Engine stalling

What kind of engine does a Chevrolet Lumina have?

Starting in 1990, Chevrolet offered a high performance version of the Lumina, the Lumina Z34. It came standard with the FE3 sport suspension package, the 210 hp LQ1 V6 engine shared with the Lumina Euro 3.4 (sedan), the five-speed Getrag 284 manual transmission, dual exhaust, and four-wheel anti-lock brakes.

When did Chevrolet stop using the name Lumina?

Chevrolet used the name on a sedan, a coupé and a minivan. Chevrolet Lumina is a nameplate that was used by the Chevrolet division of General Motors used from 1989 to 2001.

When did the Chevrolet Lumina start racing in NASCAR?

Chevrolet Lumina in NASCAR in 1994 In 1989, the Lumina became the nameplate under which Chevrolets were raced in NASCAR, more than a year before the model was available to the public. As a result, NASCAR received many letters complaining about the unfair advantage of Chevrolet racing an “aluminum” car.

Why does my car backfire when I let off throttle?

Backfiring happens all the time, in cars and bikes, you just don’t hear it because the muffler/exhaust. Since you’ve modified it, now you do. What it is, is incomplete combustion, fuel is left over, and shot into the exhaust pipes.

Why is my exhaust popping on deceleration backfire?

Exhaust Popping on Deceleration Deceleration backfire is caused by fuel burning in the exhaust manifold or header. Something you should understand before going any further is that a motor in perfect tune will exhibit deceleration backfiring. Just because your exhaust is popping, doesn’t mean there’s anything wrong.

What causes a Chevy 350 to backfire constantly?

The air intake boot or tube transfers air from the mass air flow sensor into the throttle actuator and then into the engine. If there is a problem with these parts such as a tear or rip it will allow un-metered air into the engine which the computer will see via the oxygen sensor which in turn will deliver less fuel creating a lean condition.

What causes an engine to backfire after a compression stroke?

On the other hand, retarding the spark too much after the cylinder compression stroke will not only cause engine to lose power and waste fuel, but can also lead to exhaust backfire (aka afterfire). This is because flames from the combustion can jump through an open exhaust valve and cause unburned fuel to explode in the exhaust system.

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

Why does my Jeep backfire through the intake?

My jeep is fine as long as i just give it about half throttle. But if i really get on it then it just cracks and pops and backfires through the intake. The engine doesn’t stall nor miss when it”s ideling. Does anyone have any idea whats wrong. As I stated it just started this morning.

What causes a Backfiring in a 4 stroke engine?

That’s a 4 stroke engine. IMO, It is likely you have a chain that is out of time or stretched (which would be exacerbated at higher RPM), but it could very well be a burnt valve, although neither of these can really be described as intermittent typically.

Can a Dist cause an intake to backfire?

A dist can’t cause backfiring by not firing, and as they have mechanical contacts, there really can’t be an electrical backfire other than water in the dist – not to my knowledge anyway. Intake valves are almost always burnt if getting intake firing, but more than likely it’s out of time (and isn’t starting) if youre getting intake firing.

How to fix an engine backfire in 15 minutes?

– YouTube HOW TO FIX AN ENGINE BACKFIRE IN 15 MINUTES! If playback doesn’t begin shortly, try restarting your device. Videos you watch may be added to the TV’s watch history and influence TV recommendations. To avoid this, cancel and sign in to YouTube on your computer.

What causes engine to shut off and then start back up?

No warning lights come on and all the gauges are normal. I got the garage to scan computer and they said no codes were coming up. So the blazer starts fine and runs fine just shuts off whenever it feels like without warning. Any suggestions? Answer: This could be a problem of a failing fuel pump. This is pretty common on this truck.

What causes the Check Engine light to turn red?

The unburned fuel enters the catalytic converter, causing it to overheat and turn cherry red. Over a short time this will cause the converter to fail. Additionally, the vehicle’s computer, sensing a rich mixture in the exhaust, will set a code for the oxygen sensor that will often appear as a “Check Engine” light.

What causes black smoke in the combustion chamber?

Piston Rings are designed to prevent the infiltration of engine oil inside the combustion chamber. If there is any problem with the piston rings, the engine oil starts flowing into the combustion chamber. The combustion of the mixture of this engine oil and the fuel delivers black smoke. 6. Engine Deposits

Why does my car have black smoke coming from the tailpipe?

Engine deposits are another reason causing black smoke from tailpipe. When the engine is new, it will run fluently without any problems. But after a long period of use, the engine conditions get worse and worse and this consists of getting accumulations of combustion product in important areas like combustion chambers and injectors.

When to run at 2800 rpm for camshaft break in?

Heat cycles help. The least amount of recorded break-in wear occurred when the engine was run at 2800 rpm for ten minutes, allowed to cool, and ran again for another ten minutes. This is now recommended for all camshafts – bushing and needle bearing lifters, or flat tappets.

Why does a cam lobe miss at high RPM?

So a miss from a single, slightly flattened cam lobe will often start to go away as engine rpm rises and the lifter pumps up, but will probably reappear at very high rpm as the cylinder begins to once again starve for airflow. Engines with solid lifters may or may not experience low-rpm or idle problems.

When does a miss on a camshaft go away?

How can I tell if my engine is having a backfire?

Valve issues may also involve poor fuel economy, rough idle, stalling, high oil consumption, hard starting, and exhaust smoke. Valve problems of these type tend to create a more consistent backfire condition. You may diagnose valve problems at home with the use of a compression gauge or a vacuum gauge.

Why does my GM V8 engine misfire when cold?

Because, GM V8 engines are very prone to a rough idle and engine misfire when cold. The check engine light may also come on, with codes P0300, P0171 and PO174. But, as the engine warms up, the engine misfire or rough idle tends to go away; which seems confusing.

What causes rough engine idle or TDC code?

So, should the engine misfire, rough engine idle or (TDC) code; point to an air leak in the intake manifold gasket, following the below directions. A very common cause of a leaking intake manifold is the gaskets and bolts used from the factory.

What causes an intake back fire in a car?

If the check engine or service engine soon light in on scan the computer for trouble codes. This will help locate the system that is having a problem and needs repair. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power.

What causes an exhaust tail pipe to backfire?

An exhaust tail pipe backfire is caused by an excessive amount of un-burnt fuel remaining in the exhaust system or fresh air being allowed to enter the system which ignites a small amount of un-burnt fuel. If fresh air is allowed to leak into the exhaust system it will ignite the un-burnt fuel inside the system creating a popping noise.

Where are the freeze plugs on a 2000 Chevy Blazer?

You can’t post conmments that contain an email address. where are the freeze plugs located on a 2000 Chevy blazer. HOW can i hook my phone to my 2000 chevy blazer radio to play my music .

How can I tell if my Blazer cylinder is dead?

If the cylinder is NOT ‘dead’, then this will have a negative effect on engine idle since it will get worse. Repeat this test on the remaining 4 spark plug wires (testing 2 at a time). The result? The result of the cylinder balance test was that cylinder #1, on my neighbor’s Blazer, was dead!

What do you need to know about Backblaze Storage?

As a highly open company, Backblaze publishes detailed information on the Storage Pod hardware, the Vault software, and the reliability statistics behind the hard drives it uses.

What is the difference between backfire and afterfire?

What are backfire and afterfire? Backfire is a condition described as a loud bang, poof, explosion, etc., while the engine is running or while shutting down. Afterfire occurs after the engine has been shut off. Note: Backfire and afterfire through the carburetor will not harm the engine at all!

What’s the misfire code on a 1998 Vortec?

Can someone please help with what I should check next, I have a 1998 Chevy K1500 5.7 Vortec with a misfire, P0300 code for 3 months. runs a little rough, while driving under normal conditions it sputters, hesitates, and also will backfire, under heavy acceleration no noticeable skip, no sputters, and does not hesitate or backfire.

How does an engine misfire feel to the driver?

An engine misfire will be recognizable to the driver because their engine will feel like its stumbling for a few seconds and then regain its pace again. The number of times this happens will depend on the seriousness of the misfire. If at least one spark plug is not firing correctly then it will cause the engine to malfunction and run terribly.

What causes an engine to miss at high RPM?

Any type of constant engine miss that resembles a dead cylinder, can point to a faulty HEI plug wire that has a corroded connection or too much resistance. Plug wires that measure 15 to 25 inches in length, normally carry 400 ohm resistance at low engine rpm, and 15,000 ohms resistance at high engine rpm.

Why does my car idle at high RPM?

It only happens when i hit the gas hard, it idles and cruises like a kitten. The first thing i though was the plugs, as the new plugs i put in were rated a bit colder than my old plugs, so i switched the plugs back out for the old ones, and it didn’t change anything.

What makes a rough idle a misfire condition?

What complicates a rough idle/misfire condition is having the PCM not register any specific misfire codes. In my neighbor’s Blazer, the PCM wasn’t even registering a P0300, but it was obviously running very rough (at idle that is).

What are the most common signs of engine misfires?

The most common situation to notice misfires is on high gears, low RPM, and the accelerator to the floor. Rough acceleration is a typical sign that your engine is misfiring.

What causes engine to misfiring at high RPM?

Engine misfiring at high RPM. Discussion in ‘ Troubleshooting & Diagnosis ‘ started by Andelin74, Mar 29, 2011 . Ok so i have my car tuned up pretty well, ignition timing at about 12 degrees, brand new plugs and wires.

What are the most common problems with a Chevy Impala?

Chevy Impala: The Most Common Problems You Should Know About. 1 Gas cap problems. A car’s check engine light can come on for multiple reasons, some more severe than others. Many drivers of Impalas from every model 2 Faulty instrument panel gauges. 3 Jolting. 4 Shifter malfunction. 5 Bad transmission pressure control solenoid.

What causes hard shifting on a Chevy Impala?

Some drivers never got a solution for the Impala’s hard shifting. However, some mechanics found that the cause was a failed transmission pressure control solenoid. To fix the problem, partial disassembly of the transmission was the only option. On average, this repair can cost around $1,000.

What makes a GM 4.8l engine misfire?

Now that we’re aware of the core essentials that each engine cylinder needs to run at a 100% power output.. in the next sections I’ll explore some of the specific components that fail and cause a misfire and misfire codes.

Where does the fuel come from in an engine backfire?

As oxygen content increases, it causes partially burn or unburned fuel entering the system to ignite loudly. The extra oxygen may come through a leak in the exhaust manifold gasket, an exhaust pipe sealing ring, or a damaged pipe.

How does the EGR work on an engine backfire?

Backfire is one of them. The EGR system is designed to reintroduced a measured amount of exhaust gases back into the cylinders for reburn. This reduces combustion temperatures and dangerous emissions like NOx (oxides of nitrogen). The EGR valve opens when engine speed increases and closes when engine is resting at idle.

What should I do if my GM 454 backfires?

That is the system with the 2 springs one on each side are good and that the arms the springs are connected to mover freely in one direction and back again when released. A drop of oil at each pivot point is good job while the rotor is off.

Where is the idle button on a GM TBI?

The “A” and “B” terminals are located on the top right of the connector. 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.

How do you change the idle speed on a T-30?

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. Turn off the engine and disconnect the negative battery terminal from the battery using a wrench. Reconnect the IAC valve.

Why is the EGR valve at idle not working?

This could be caused by one of two possibilities… either the EGR solenoid is defective or the vacuum hose is attached to the wrong port on the EGR solenoid. Resolving this ‘continuous vacuum to the EGR valve at idle’ problem will solve the EGR valve and rough idle issue.

What’s the minimum idle speed for a 1988 350?

For the car we are using (1988 350 AT), the minimum air or idle speed should be a 400 RPM. I highlighted the needle on the RPM gauge as well as marked what the goal for this vehicle should be at (400 RPM). If the speed is off, there is a torx screw on the side of the throttle body on the driver’s side.

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.

How does idle air control work in a GM TBI?

The air gap between the throttle body and the throttle plate is calibrated to allow enough air to pass by it for the engine to run at base idle speed. The IAC (Idle Air Control) valve utilizes the on-board computer to fine tune the idle speed according to engine conditions.

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?

Why does my Chevy truck sputter when I accelerate?

The engine starts and runs fine, when I leave for or from work. But when I accelerate out of the parking lot it hesitates and really sputters. If you try to accelerate more it backfires a few times and then takes off like there’s nothing wrong.

Can a Chevy C / K 1500 run at idle?

There is often a backfire or two when this happens. Pumping the gas does not help. I basically have to crawl through any intersection until it picks up a bit of speed from idle. The truck idles smoothly, and it runs fine once it’s above about 5-10mph or so. If moving at a picking up the speed.

What causes a Chevy C / K 1500 to bog down?

My truck bogs down (and tries to die) when I give it gas to accelerate off of a stop. There is often a backfire or two when this happens. Pumping the gas does not help. I basically have to crawl through any intersection until it picks up a bit of speed from idle. The truck idles smoothly, and it runs fine once it’s above about 5-10mph or so.

What causes an engine to stall at idle?

If the ISC valve is gummed up with fuel varnish or dirt, it may stick, preventing the engine from maintaining the proper idle speed when the throttle closes. A faulty idle speed control circuit may also allow the engine to stall when idling if it fails to compensate for idle loads placed on the engine by the charging system or A/C compressor.

What’s the knocking noise coming from MY Suburban?

I recently ran into this same knocking/ ticking issue coming from my 2005 Suburban, 5.3 Vortec. After countless hours of research, multiple engine flushes, oil change, air filter, valve adjustment…etc etc etc…my solution and problem were relatively simple.

Why does my Chevy 350 backfire under load?

When high performance turbo engines are under load they use an excessive amount of fuel which then is transferred into the exhaust system once the throttle is let up on and the engine is de-accelerating. This is a normal event and there is no problem with this condition.

What causes a car engine to backfire at idle?

Using a smoke machine or carburetor cleaner you can check for a vacuum leak and repair it to fix the problem. A repetitive backfires are generated when the engine is simply running at idle or at cruising speed and can be inline with the engine RPM. A rhythmic popping sound which is not as prominent as lean under power backfires.

Why does my Chevy Truck start and idle?

Not sure why this test caused a better and longer gas flow than the above test of just putting the ignition in the ON position and seeing how much gas comes out of the line before the fuel filter. Last test says to start the vehicle and remove the relay.

Why does my GMC Sierra 1500 run rough at idle?

The spray smoothing out the rough rpm is an indication of the engine running lean, could be low fuel pressure, could be a vacuum leak. With it running rough at an idle and smoothing out at a higher rpm is a general sign of a vacuum leak.

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.

Why does my Chevy k1500 stall when gas is released?

I have been working on our 89 Chevy K1500 and am still having an idle issue. The truck idle drops and lopes and occasionally completely stalls. This usually happens when driving slow in town… backing out of parking space, letting off gas when coming to a stop sign or to park etc. It does fine to start and accelerate.

What should the idle rate be on a 1997 GMC Truck?

Underdog, I don’t know the 1997 5.7, but 1000rpm sounds like a high idle, not where it should “bottom out”. A V8 should idle at 500rpm. GoNDown, did you recently disconnect your battery? After I left mine dead in the yard for a while and didn’t charge it, when I started it up it ran like you describe for a few days and then it was fine.

Why is my Chevy truck bucking at idle?

During idle it would sound as if it were about to shut off but it wouldn’t. Rough idle and hesitation sounded like a vacuum problem, so I checked the TBI. The EGR valve was faulty so I replaced it. That fixed the rough idle and it drove fine for a day or two. But then yesterday and today, my truck began to buck pretty hard.