How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask ironmike Your Own Question
ironmike
ironmike, ASE Master tech
Category: Chevy
Satisfied Customers: 3385
Experience:  30 years ASE Master L1 GM certified
11302663
Type Your Chevy Question Here...
ironmike is online now
A new question is answered every 9 seconds

Chevrolet 1;2 TON XXXXX 98 CHEVY ,4 WHELL DRIVE , BONE

Customer Question

98 CHEVY ,4 WHELL DRIVE , BONE STOCK , 305 VORTEC , RUNS GREAT , 63, 000 MILES ..
1ST PROBLEM -ON COLD STARTS THE ENGINE RACES UP TO 1,800 RPM FOR ABOUT 5 SECS,,,, WHAT A NASTY THING TO DO TO A POOR FROZEN ENGINE ,, WHEN ITS LIKE 0 DEGREES !!! AFTER THAT 5 SECONDS THE RPM DROPS TO 1,200 , WHERE IM SURE IT SHOULD BE..AND DROP WHEN WARMED UP ....

2ND PROBLEM -,, WHILE COLD YET,,IF YOU PUT IT IN GEAR ,,DRIVE OR REVERCEI IT DOESNT MATTER ,, THE RPMS GO UP . MAYBE TO THE SAME 1,800 , NOT SURE . BRAKE TORQUE CITY !! WITH ME HOLDING HARD ON THE BRAKES ,, AGAIN WHEN I HOLD THE BRAKE FOR 5 SECS BEFORE LETTING OFF THE BRAKE , THE MOTOR AGAIN SETTLES DOWN TO A NORMAL FAST TYPE OF IDLE, ,BUT LET OFF THE BRAKE TO SOON , HOLD ON !!..YOU CAN PUT IT BACK IN PARK OR NUTUAL WHILE ITS IN THIS CRAZY MODE , AND IDLE GOES INSTANCELY BACK TO 1200 ,,, BUT WHEN EVERY THING IS UP TO OPERATTING TEMP . NONE OF THIS HAPPENS !! SMOOTH IDLE , NO MISS , 650 RPM ON THE TAC ,, TURN THE AIR ON AND IT ADJUSTS THE IDLE TO KEEP IT AT 650 ,, GOT ANY IDEAS ? THANKS . TERRY
Submitted: 4 years ago.
Category: Chevy
Expert:  ironmike replied 4 years ago.

greetings,

let me know if the vehicle has been checked for trouble codes. If you have access to a scanner with live data let me know too. I just picked up a good one from launch for 35$, there is a bunch out there for around 50$. I would start with checking and cleaning the IAC and the throttle body bore. I use a soft pipe brush and throttle spray cleaner. Next I would check and clean the EGR, they can stick open a cause a vacuum leak. I would clean the MAF(mass air flow) sensor too, it combines the IAT(intake air temp) , if it is contaminated it could cause running issues like this.

I would like to see what the coolant temp sensor is reading. let me know what has been done as far as a tune or maintenance.

important to get the injector poppets cleaned, fuel injection service.

let me know if there are any trouble codes. Many parts stores will scan for free

lets start here

good luck