Idle surging up and down 99c1500

[Cprevo]

99gmc c1500...engine replaced with only 2000 miles now...when at a red light with vehicle
in drive and brake depressed the idle starts to surge to 600 or 700**rpm from 400 rpm,**this
will go up then down and keeps fluctuating till the brake pedal is released.**Once brake is
released the idle goes to normal.**If I shift to park or neutral the idle stays at 400 which is
normal.
Had throttle body clnd professionally, replaced idle air control mtr, rplcd an oxygen sensor
that reported failed,cleaned mass air flow sensor,**flushed fuel injectors.**Also had throttle
position sensor replaced. This last part helped but the problem still occurs.**The
improvement is the surge seems slower to occur.**Anyone ever run across this type of
behavior?

 

[Molson02536]

99gmc c1500...engine replaced with only 2000 miles now...when at a red light with vehicle
in drive and brake depressed the idle starts to surge to 600 or 700**rpm from 400 rpm,**this
will go up then down and keeps fluctuating till the brake pedal is released.**Once brake is
released the idle goes to normal.**If I shift to park or neutral the idle stays at 400 which is
normal.
Had throttle body clnd professionally, replaced idle air control mtr, rplcd an oxygen sensor
that reported failed,cleaned mass air flow sensor,**flushed fuel injectors.**Also had throttle
position sensor replaced. This last part helped but the problem still occurs.**The
improvement is the surge seems slower to occur.**Anyone ever run across this type of
behavior?

Here is a TSB that addresses what seems to be your problem.
1.) TSB #01470 -- ERRATIC IDLE, IDLE SURGE, ROUGH RUN, OR NEAR STALL. *TT (NHTSA ID #10004413, JANUARY 01 2000)

Have you also cleaned and inspected your EGR valve?? Post me back and start with that and also post back your fuel pressure and inspect your fuel pressure regulator for any signs of leak.

 

[Cprevo]

Will start with egr valve
[/LIST]rg...
How do I access a tsb? Pardon my ignorance

 

[Molson02536]

Will start with egr valve
[/LIST]rg...
How do I access a tsb? Pardon my ignorance

Since you have a 99, have the Dealer look up any updated TSB for your Suburban and give them the TSB number i gave you. TSB (technical service bulletins). Here is also a link that can help you. http://www.alldatadiy.com/recalls/

Good luck, keep us posted and feel free to ask any more questions you may have.

 

[ISLANDER914]

I had my engine replaced and that same day it was doing the same thing to my wife, then a few days later to me. I am taking it back some time this week. Let me know what you come with, if not I will let you know hopfully by the end of the week. It doesn't happen all the time to me it is hit or miss. I am hoping it happens when I am close to the mechanic so he can fix it.