*** Restricting New Posts to SD Premium Members ONLY *** (09 May 2025)

Just made a new account? Can't post? Click above.

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!

99 Chevy Astro 4.3 P0303

  • Redwolfauto
  • Redwolfauto's Avatar Topic Author
  • Offline
  • New Member
  • New Member
More
2 days 11 hours ago #92343 by Redwolfauto
99 Chevy Astro 4.3 P0303 was created by Redwolfauto
I have a 1999 4.3 p0303 I can’t get rid of. Been a while sense I messed with it but here’s what I’ve checked
Swapped plugs, checked cap, new distributor (old one had worn gear) compression tested, new crank sensor (for different reason, intermittent no start) fuel pressure and and injector test (all fuel pressure drops identical). Fuel trims are a lil off don’t remember what they were. The misfire counter will count on 3 and move to the next cylinder in the firing order at higher rpm, probably normal. I’ve also swapped around o2 sensors just to see if it would affect the trim numbers, it didn’t. I don’t have a lab scope or id look at some secondary ignition wave forms to try and determine what’s going on. Also, not a dead miss, dropping that cylinder is still plenty noticeable. But you can also feel a slight miss at idle. I’ll attach freeze frame
Attachments:

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

  • Noah
  • Noah's Avatar
  • Offline
  • Moderator
  • Moderator
  • Give code definitions with numbers!
More
1 day 8 hours ago #92347 by Noah
Replied by Noah on topic 99 Chevy Astro 4.3 P0303
This looks like the freeze frame data for the crank sensor code. Is that code still returning?
Did you perform the crank sensor variation relearn?
You said fuel trim was " a lil off". -17% on B2 is more than what I would call a lil.
You said you tested fuel pressure and compression, but didn't offer any values.
Checked cap and rotor, how exactly? I'm sure you know these caps are failure prone.
Swapped plugs, what about the condition of the plugs and the wires?

"Ground cannot be checked with a 10mm socket"

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

Time to create page: 0.248 seconds