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

Tiny
DOUBLE B
  • MEMBER
  • 1990 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Installed an engine from a 1988 Chevy Scottsdale 1500. It starts good, but it has sluggish idle and will not idle in gear. The truck I installed it in is a 2500.
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Monday, September 3rd, 2018 AT 4:55 AM

34 Replies

Tiny
ASEMASTER6371
  • EXPERT
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
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Monday, September 3rd, 2018 AT 5:02 AM
Tiny
WA
  • MEMBER
  • 1990 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
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.
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
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
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
WA
  • MEMBER
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!
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
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

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+6
Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
WA
  • MEMBER
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!
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
SILVERADO88RED
  • MEMBER
Thankyou!
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
JUNERIVERA
  • MEMBER
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.
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
KEN
  • ADMIN
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
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
KEN
  • ADMIN
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
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
JUANANDRES LOZANO
  • MEMBER
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.
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
KEN
  • ADMIN
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

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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
NPG316
  • MEMBER
  • 1989 CHEVROLET SILVERADO
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!
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
JACK42
  • EXPERT
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
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
JASON SCARBROUGH
  • MEMBER
  • 1989 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 98,000 MILES
My truck has a 350 with throttle body injection. It was running fine now it won't idle. Could the fuel filter cause this
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
MERLIN2021
  • EXPERT
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...


https://www.2carpros.com/forum/automotive_pictures/62217_95_OlderGM_2.jpg


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...
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Thursday, February 18th, 2021 AT 1:02 PM (Merged)
Tiny
ALLEN134
  • MEMBER
  • 1987 CHEVROLET SILVERADO
  • 2.0L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 20 MILES
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
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Thursday, February 18th, 2021 AT 1:03 PM (Merged)
Tiny
HMAC300
  • EXPERT
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.
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Thursday, February 18th, 2021 AT 1:03 PM (Merged)
Tiny
JOSH71411
  • MEMBER
  • CHEVROLET SILVERADO
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
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Thursday, February 18th, 2021 AT 1:04 PM (Merged)
Tiny
BMRFIXIT
  • EXPERT
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
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Thursday, February 18th, 2021 AT 1:04 PM (Merged)

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