Replaced engine now it does not idle - stalls in gear?

Good morning.

Since this is a throttle body unit, the base idle needs to be set at 500 rpm. Then the idle air control motor takes over and works with the ECM to adjust the idle speed according to load.

I would clean the throttle body real good and make sure there is no carbon build up on the plates or any of the passages.

Roy

https://www.2carpros.com/articles/throttle-actuator-service

https://www.2carpros.com/articles/how-a-throttle-body-works

Truck stalls when I put it in gear. I have changed the TPS sensor, injectors, fuel regulator, plugs, wires, cap, rotor, coil, runs/idles strong but when I put into gear it stalls out. Any ideas would be great thanks. 350 V8 5.0L engine.

You may have a bad IAC (idle air control). Try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carburetor cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.

Here is the part you need.

https://www.amazon.com/gp/product/B01N9WAML5/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&tag=2carprcom-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B01N9WAML5&linkId=91f0b5473b67dc2adf2955aa21c6dfa9

Please let us know what happens.

Cheers

The IAC was it. I bought it took five minutes to install it and it fired right up and did not stall when I put it in gear. Thanks for the answers!

This site rocks!

You should still clean the throttle body to prevent further problems.

Here is a guide to help you

https://www.2carpros.com/articles/throttle-actuator-service

This was a friend of mines truck broken down at my house so I did not know this truck well. It had several things wrong with it and has over 200,000 miles on it. I was working with their low budget so I had limited funds available. It needed lots of repairs (fuel injectors, throttle position sensor, fuel pressure regulator, IAC, distributor cap/rotor/plugs/wires, starter, tune up items, etc) all because it was not well maintained. Along with the other things I replaced when I replaced the IAC valve I replaced the fuel pressure regulator at the same time and inside the spring was broken, rusted and corroded. When I replaced them together it helped until operating temperature kicked in but in the end I still had the stalling problem. What wound up really finally fixing it was the coolant temperature sensor. What I read at the library was when the truck first starts it runs on the main computer using those settings, but when it gets to operating temperature it goes off of it. It took me a while of checking everything I had repaired over and over and then I replaced the coolant temperature sensor and it ran good after that. I do not think that part was too expensive either. like $15.00 to $20.00. Hope all that helps you!

Thankyou!

Hello. I am new to this page and I need some help. My friend has a 1991 Chevrolet Silverado pickup truck V8 c1500 5.7L. She is currently having the same stalling issues. It idles fine when parked but then stalls when put into drive or reverse. The idle drops quickly. Before this issue started happening, she had the truck sitting in her friend's drive way for over a year. About two weeks ago I replaced her battery since it was drained flat and I changed the engine oil. Everything was fine with the truck until it started stalling a week later. Went out to check the truck today and cleaned the throttle body with carburetor cleaner, removed all the nasty carbon from all passages and replaced the IAC valve. It is still stalling in drive. The only way I was able to keep the truck from stalling was by putting a hard plastic piece on a small threaded stud on the throttle body that makes contact with the throttle lever when closed. This is keeping the idle at high and somewhat decent while it is in drive. Now it is only stalling when the steering wheel is turned all the way to the looking position, plus it tends to hesitate when accelerated. Any help or ideas will be helpful and appreciated. Thanks.

Hey JUNERIVERA,

This problem sounds like the EGR valve is hang open a little causing a vacuum leak. Can you remove it and check it for leaks?

Here is a guide and the part (below) to confirm the problem and get you back on the road.

https://youtu.be/DqUCbbKdWf4

and

https://www.amazon.com/gp/product/B0019ILKVA/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&tag=2carprcom-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B0019ILKVA&linkId=216e7105e978e12cd9cbca15d597a0a9

Please let us know happens so it will help others.

Best, Ken

It sounds like it may be a vacuum leak, here is a guide that will help you find the problem:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please run this test and get back to us so we can continue helping you.

Best, Ken

I have a 1996 Chevrolet Silverado 5.7 with 184k miles, I have hesitation on first start up when in drive with light acceleration, and also the truck dies when I put
it in reverse. I have replaced the fuel filter, spider injectors, distributor,
cap and rotor, crank and camshaft position sensor, ignition control
module and coil, spark plugs and wires, map sensor, egr valve, mass air
flow, idle air control valve, pcv valve, iat sensor, throttle position sensor,
and an air filter. And yet the truck still hesitates, and now it dies in gear.
It throws code p1351 I have changed all parts known to fail with that
code and yet the truck still runs rough. And on cold start the truck will
only turn on with starting fluid. I'm not sure what's wrong with it, anyone have an idea.

Hello,

This post is for a 1990 chevy pick up yours is a 1996

Please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken

I have a 1989 chevy silverado with a 305, and when it is idleing it trys to die out and then picks back up again, although when I added fuel injector cleaner to the carb it ran fine for a few minutes then did the same thing again? Any help on what the problem could be would be appreciated!

Could be the Idle Speed Control Motor. Located on the pass sdie of the TBI unit, it has a square 4 wire connector. Remove it (1 1/4 wrench) and clean it with carb cleaner and see if it helps, if not it may need replacing

my truck has a 350 with throttle body injection. it was running fine now it won't idle. could the fuel filter cause this

Is the SES light on? If yes pull the codes, but check the EGR for sticking open, and the Idle air control, it's bolted to the side of the throttlebody. A badly clogged filter might cause it...

Check codes this way, jump these two connections at the ADL, turn the key to "ON" then count the flashes. a 22 will count as 2 flashes a short pause the 2 flashes, if more than one code is stored, the pause is noticably longer between codes! The codes will flash 3 times! Write them down and post them here...

My Chevy truck is a 1987 model its fuel injected and when I crank it it wont idle and if u come to a comeplete stop it will shutoff what is wrong with it can u help im sick of not knowing what to do

scan for codes and have fuel pressure checked first. then spray choke cleaner around tbi unit and see if there is leak under it. that is a common problem as well as soft hoses leading to map sensor an dpcv.

with the a/c on and in gear and i turn the wheel my truck wants to stall it doesnt die but almost does then the rpms will pick back up until the wheel is turned again i have tried everything i think if anyone has some help i would really appreciate it

the rpm drop not being compensated for by the idle air control
check it and check the air way for it make sure its clean and free of carbon
good luck
let us know

i have already replace the idle air control valve and no improvement

[quote:120f80004c="josh71411"]i have already replace the idle air control valve and no improvement[/quote:120f80004c]
try cleaning the throttle body and spraying a good carbon cleaner in the throttle body with the enging running. I would recommend "sea foam" or "GM top engine cleaner".

i have already cleaned the throttle body for about an hour still no improvement any more suggestions

i seriously need help on this problem its driving me crazy i dont know what it is i think i have replaced just about everything it only wants to drop idle when the wheel is turned with the air on and in gear if truck is in park its not as bad but still stalls when the wheel is turned so i dont think it is a torque converter problem i have replaced the idle air control valve so i think it maybe a power steering pump of steering gear please help !!!!!!!!!!

Let’s start fresh
Running ok steering fine put AC on wants to stalls when steering
Rpm ok @ idle and in drive engine running strong
AC on wants to stall when turning
Here what I m thinking?
Check the AC pressure hi side

Good luck

ok so i need to ask a few questions before i do this i believe u know something i dont but what would the high side have to do with the problem and how would i check the high side i have a set of manifold gauges but im new at a/c and also what would i be looking for

You did just about every thing else
Just another idea
hook the gauges up and read the high and the low side s
If the high is too high that may be putting drag on the engine

what should the high side pressure be

I don’t have the spec on that but I would say no more than 260

Thank you fisherman
Another carpros tech
He came with this
hope that can help

(the IAC valve its not adjusted right! the ECU should take care of the "load" of the A/C and power steering!

Here a text about IAC Valve:

Basically, as we already know, the IACV regulates idle speed, raising and lowering it as needed. It does this by opening and closing a "trim" valve to allow more or less airflow into the intake manifold when the throttle is closed.

The adjustment we make on the IACV is for setting the "base idle". By unplugging the TPS (and the IACV in some cases) we tell the ECU to completely close the trim valve in the IACV. When this happens, the idle airflow comes completely from a needle valve - the very one we are adjusting when we turn the screw on the IACV body.

If everything in the fuel and intake system is operating properly, the idle speed will not be able to drop below this setting. A few things can cause the base idle speed to go out of adjustment.

First, the needle valve can become clogged with dirt or carbon, reducing or completely blocking off airflow through the needle valve. This would reduce the airflow through the needle valve and cause the ECU to rely partially or fully on the opening of the trim valve in the IACV to maintain target idle. This would mean that the idle could possibly fall below 750 before the ECU could intervene.

Second, the trim valve within the IACV could be rendered partially or totally inoperable, either through blockage or failure. If this valve is blocked open, idle speed would be high unless the needle valve's opening was reduced to compensate. The result of this may be the inability for the ECU to compensate for all idle conditions - base idle would be set for Y percent trim valve opening, leaving only X-Y percent of the operating range of the trim valve for ECU adjustment. If the trim valve is not blocked open but the passage to this valve is partially clogged, it would require the ECU to open the valve farther than normal to allow a given amount of airflow to pass. This would also reduce the amount of compensation the ECU can apply to idle speed.

To sum it up, there are two idle speed adjustments to control idle on our cars. First is the manually adjusted base idle setting, which determines the minimum airflow through the IACV (and minimum warm-idle speed). Second is the ECU's control over the "trim" valve within the IACV, which compensates for hot and cold idle and engine loading (power steering and A/C operation).

ok well i see i need to get a different iac i bought an idle air control valve from oreillys that has only been in the truck a few weeks but right after i put it in there were still no improvements what name brand iac should i get and again tell me how to set it once i get one also i want to tell u exactly what its doing. In the morning or after the truck has been sitting a while i go to crank it up and it does not idle rough as long as the motors cool even if the air is on and its in gear and you turn the wheels there is no stuble and no rough idle once the motor heats up to normal operating temp the truck starts to idle rough sitting still at a light and if u slightly turn the wheel the idle drops and the truck trys to stall and shakes real bad then after the idle drops it will surge up and then back down to a rough idle it also makes the motor feel like it is missing but its not a miss because i have changed all of the igniton components so thats exactly what it does its the most aggrivating problem i have ever run across please reply back

i appreciate the pic but i kinda cant see it all is there anyway for me to see the other half thanks

good news i fixed the missing problem and most of the stalling problem when the wheel is turned i took the iac out which was factory preset and screwed the valve in which immediately fixed the problem when i started it back up and let it warm up but i still have the steering problem but i think it is in the actual power steering here is what it does if your in park with air on and u turn the wheel without foot on the brake its usually fine if its in gear its usually also fine but if the brake is applied and u turn the wheel the wheel wants to lock and u have to let off of the brake for it to unlock but the power steering is NOT in full lock position therefore i have reason to believe it might be the power steering pump getting weak or the steering gear locking up when the wheel is turned but i dont see what that has to do with the brakes thanks for helping fix one problem just one more left =)