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Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 23590
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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I have a 1997 chevy 1 ton 5.7 It will not start unless you

Customer Question

I have a 1997 chevy 1 ton 5.7 It will not start unless you put the pedal to the floor. It idles fine once it starts but when you put it in gear it stalls. I replaced the EGR valve but that did not fix the problem.
Submitted: 1 year ago.
Category: Chevy
Expert:  Dan replied 1 year ago.

Hello, my name is***** it rev up fine or act like it has a rpm limiter? Is check engine light on?

Customer: replied 1 year ago.
Revs up fine. no check engine light
Expert:  Dan replied 1 year ago.

I'd start by cleaning throttle body and checking air filter. You can get throttle body cleaner from parts store and use that with a rag to clean out throttle body. At the same time you can clean out idle air control valve which is supposed to maintain idle. Let me know if you would like diagram to help locate idle air control valve or if you have other questions. Thanks.

Customer: replied 1 year ago.
I have cleaned both. what is the best way to check the idle air control valve to see if it is working right.
Expert:  Dan replied 1 year ago.

The iac gets power/ground in pulsations as needed so no way to test without scan tool. You can check resistance on 4 pins to verify 2 pins have about the same resistance. You can also unplug mass airflow sensor to see if that helps if so then clean/replace. Let me know how it goes or if you have more questions. Thanks.

Customer: replied 1 year ago.
what does unplugging the MAF do?
Expert:  Dan replied 1 year ago.

It makes computer run in default setting since it cannot use sensor.

Customer: replied 1 year ago.
I unplugged the maf and that did not help. When the motor is warmed up and you shut it off I have to push the pedal to the floor and it starts right up. Otherwise it will crank and crank and not start. The idle then goes to 1700 for about 4 sec then drops down to 1200 and idles fine until I put it in gear and then it stalls out. Without the pedal to the floor it will not start. It will however start with no pedal when it is cold.
Expert:  Dan replied 1 year ago.
Does the coolant temp gauge ever move off the cold?
Customer: replied 1 year ago.
it goes about half way
Expert:  Dan replied 1 year ago.

This is definitely a strange problem. Unplug front oxygen sensors and let me know if that changes anything. I'm about to come to a dead end but I can always open up question to see if someone else has some other ideas. Let me know, thanks.

Customer: replied 1 year ago.
Once I'm able to get the truck moving it's fine. There's no stalling there's no hesitation. If I stop at a red light there is no problems. It's just that first time I put it in gear that it wants to stall out on me and I have to keep pumping the gas to keep it running . Then it may stall out on me three or four Times before I can get the truck moving.
Expert:  Dan replied 1 year ago.

Does holding down gas while shifting into gear help? Did problem come out of no where or slowly get worse?

Customer: replied 1 year ago.
It does help to press on the gas but that doesn't always work either . Sometimes it takes a couple tries to get it moving. Yes it came on all of a sudden just one day it wouldn't start . I figured with fuel injection you didn't have to hold it to the floor like a carbureted Engine but when ahead and tried it and it started up .
Expert:  Dan replied 1 year ago.

Holding the throttle opens allows more air into engine, so this points toward a problem with air being let into system. If throttle bore is clean then I'd replace the idle air control valve. Let me know how it goes or if you have more questions. Thanks.