Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

5.7 vortec

More
3 years 8 months ago #42806 by DiamondDave
5.7 vortec was created by DiamondDave
1999 Chevy 4x4 5.7 vortec.
Engine runs,idle varies and when the throttle is snapped it stumbles.
Unplugged MAF,no change. Fuel pressure test 56# key on,50-52 running at idle.
Replaced pump and filter. 60# key on 54# at idle.
Still idle varies up and down. Snap throttle and it dies off.
Unplugged MAF and runs great in limp.
Now what?

Please Log in or Create an account to join the conversation.

More
3 years 8 months ago #42811 by Chad
Replied by Chad on topic 5.7 vortec
Have you checked the Throttle Position Sensor?
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right. :-)

Please Log in or Create an account to join the conversation.

More
3 years 8 months ago #42815 by Tyler
Replied by Tyler on topic 5.7 vortec
Scan data and fuel trims would definitely be the next step. Short and long term trims with the MAF plugged in and unplugged, preferably.

Also look at the CMP Retard PID. Should be zero +/- 2.
The following user(s) said Thank You: Chad, DiamondDave

Please Log in or Create an account to join the conversation.

Time to create page: 0.202 seconds