1999 Chevy Silverado engine misses once warm and under load

Tiny
JJROBJOHN
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 186,000 MILES
I have a 4.3 l and all of a sudden it has a miss when it is warm. It idles excellent but once it warms up it misses like crazy. I changed the plugs, cleaned EGR valve, wires are good but still has a miss when warm. When cold in the morning it runs excellent with lots of power.
Please help with any solutions
Tuesday, May 5th, 2009 AT 2:38 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Did you check for vacuum leaks? Also, has the check engine light come on? Also, have you checked fuel pump pressure?
Was this
answer
helpful?
Yes
No
Tuesday, May 5th, 2009 AT 7:51 PM
Tiny
JJROBJOHN
  • MEMBER
  • 3 POSTS
I have no vacuum leaks and I did have my check engine light on. The code was 4020 which was left side catalyst problem
Was this
answer
helpful?
Yes
No
Saturday, May 9th, 2009 AT 6:54 PM
Tiny
JJROBJOHN
  • MEMBER
  • 3 POSTS
I am wondering if I have a problem with my pre converter oxygen sensor. I tried unplugging it but I don't know if that would do anything.
Was this
answer
helpful?
Yes
No
Saturday, May 9th, 2009 AT 6:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
It should set the check engine light.
Was this
answer
helpful?
Yes
No
Saturday, May 9th, 2009 AT 8:03 PM
Tiny
JJROBJOHN
  • MEMBER
  • 3 POSTS
I unplugged the oxygen sensor and drove around for about 15 minutes. I did not get the check engine light on and once the truck warmed up just under half on the temperature gauge the rpm tach started to go from 2000 to 5-6000 constantly. (Fluttering)When this happens if you give it hard throttle it starts to hesitate and miss. But when it is cold in the morning the truck works excellent.
Was this
answer
helpful?
Yes
No
Sunday, May 10th, 2009 AT 6:29 AM

Please login or register to post a reply.

Sponsored links