Engine misfire
- Thread starter jhurst10
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
fyremanpat
Fyremanpat
Check your wires and plug. Its possible they are defective.
ryank99
Member
i just went thru a similiar problem with my '99, except it was cylinder #4. anyway, it seemed like i had a valve sticking. i would suggest using seafoam spray (they have special instructions for the vortecs on their website)
its a $10 fix if thats your problem, that seafoam stuff fixed me up, worth the 10 bucks
its a $10 fix if thats your problem, that seafoam stuff fixed me up, worth the 10 bucks
BattelWagun
Full Access Member
Ahhh the dreaded P0305 code....
I agree, check your plugs and wires again for defective ones, and if they're all ok, seafoam it.
I agree, check your plugs and wires again for defective ones, and if they're all ok, seafoam it.
ryank99
Member
FYI: heres cut and paste instructions from seafoams website.
(http://www.seafoamsales.com/how-to-use-sea-foam-spray.html)
i've read alot about people pouring the bottle version into the brake booster vacuum line, this method does not work on the vortec engines because ther is no vacuum line that feeds all cylinders equally.
*NOTE – THIS OPERATION ONLY PERTAINS TO 1993 – 2000 4.3 LITER, 5.0 LITER and 5.7 LITER VORTEC ENGINES*
With the engine warm and turned off. Remove the air intake boot and open the throttle plate. Attach Sea Foam® Spray’s 30” induction cleaning tube to the Sea Foam® Spray can and feed the tube into the air intake until it reaches the plenum. The 30” induction cleaning tube has a 360 degree spray pattern so the Sea Foam® Spray will distribute to all cylinders evenly. Spray for thirty seconds while slowly removing the 30” induction cleaning tube. Reconnect the air intake boot and allow at least 10 minutes for Sea Foam® Spray to re-liquefy fuel varnish deposits that hold carbon together. Start the engine in a well ventilated area as exhaust will be extreme for a short period of time. Drive the vehicle aggressively for approximately four miles or until the heavy exhaust clears. Repeat this treatment process as necessary.
Sea Foam® has introduced a convenient new long-reach straw for performing an engine treatment in special situations like Vortec engines and Subaru’s H style engines, where there is no single vacuum line for all cylinders. These situations require spraying of Sea Foam® Spray directly into the throttle body. The long-reach straw is uniquely designed to spray 360 degrees through 4 holes in the side of the straw, to help in evenly distributing the spray to all cylinders and throughout the inside of throttle bodies.
Begin by removing the air intake boot from the throttle body
With the throttle body now exposed, it will be easy to see the built-up varnish and fuel residue on the butterfly valve.
Feed the 30” straw into the throat of the throttle body until it reaches the plenum.
Start the engine, ensuring you have very good ventilation. A large amount of white exhaust smoke will be generated for a few minutes. Drive the car aggressively for about 5 minutes to aid in expelling the varnish and gum deposits liquefied by Sea Foam® Spray.
(http://www.seafoamsales.com/how-to-use-sea-foam-spray.html)
i've read alot about people pouring the bottle version into the brake booster vacuum line, this method does not work on the vortec engines because ther is no vacuum line that feeds all cylinders equally.
*NOTE – THIS OPERATION ONLY PERTAINS TO 1993 – 2000 4.3 LITER, 5.0 LITER and 5.7 LITER VORTEC ENGINES*
With the engine warm and turned off. Remove the air intake boot and open the throttle plate. Attach Sea Foam® Spray’s 30” induction cleaning tube to the Sea Foam® Spray can and feed the tube into the air intake until it reaches the plenum. The 30” induction cleaning tube has a 360 degree spray pattern so the Sea Foam® Spray will distribute to all cylinders evenly. Spray for thirty seconds while slowly removing the 30” induction cleaning tube. Reconnect the air intake boot and allow at least 10 minutes for Sea Foam® Spray to re-liquefy fuel varnish deposits that hold carbon together. Start the engine in a well ventilated area as exhaust will be extreme for a short period of time. Drive the vehicle aggressively for approximately four miles or until the heavy exhaust clears. Repeat this treatment process as necessary.
Sea Foam® has introduced a convenient new long-reach straw for performing an engine treatment in special situations like Vortec engines and Subaru’s H style engines, where there is no single vacuum line for all cylinders. These situations require spraying of Sea Foam® Spray directly into the throttle body. The long-reach straw is uniquely designed to spray 360 degrees through 4 holes in the side of the straw, to help in evenly distributing the spray to all cylinders and throughout the inside of throttle bodies.
Begin by removing the air intake boot from the throttle body
With the throttle body now exposed, it will be easy to see the built-up varnish and fuel residue on the butterfly valve.
Feed the 30” straw into the throat of the throttle body until it reaches the plenum.
Start the engine, ensuring you have very good ventilation. A large amount of white exhaust smoke will be generated for a few minutes. Drive the car aggressively for about 5 minutes to aid in expelling the varnish and gum deposits liquefied by Sea Foam® Spray.
Last edited:
Ironman1979
Full Access Member
could also be the spider leaking.. as the cfm increases with increased rpms the miss would be less noticeable as the fuel is sucked into the cylinder and would be more noticeable at idle and throw a code as the fuel is puddling in the intake
Firechief70
TYF Newbie
- Joined
- Jan 23, 2012
- Posts
- 4
- Reaction score
- 0
Ok on that note....I have a misfire on #4and#6 no compression on 6 and not even 20 psi. On 4 and loud ping/knock....any ideas?
