1989 bad misfire/stumble
10-04-2018, 01:32 PM
#1
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1989 bad misfire/stumble
i have a 1989 with a 5.0 and have had a bad misfire for about a month now and connot figure out cause, just installed new
rotor
dist. cap
spark plugs
spark plug wires
has 3 codes,
25 no knock sensed during dynamic test
31 PFE or EVP below minimum voltage of 0.24 V
45 thermactor secondary air is misdirected
checked all vacuum lines for leaks
the EGR has been disconnected for months and i disconnected the entire thermactor system and plugged the vacuum line
rotor
dist. cap
spark plugs
spark plug wires
has 3 codes,
25 no knock sensed during dynamic test
31 PFE or EVP below minimum voltage of 0.24 V
45 thermactor secondary air is misdirected
checked all vacuum lines for leaks
the EGR has been disconnected for months and i disconnected the entire thermactor system and plugged the vacuum line
10-05-2018, 10:30 AM
#2
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Join Date: Jan 2018
Location: Memphis, TN, Earth, Milky Way
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It will run better if you keep all the systems working properly.
What gap did you set the plugs to? What plugs (brand, PN, source) did you install? Same for each other new part. Did you test the plug wires? Are they routed exactly as this diagram shows?
(phone app link)
(phone app link)
How old is the filter? What happened just before this symptom appeared - did you fill up at a different gas station than usual? Crawl under the truck & unplug the fuel pump inside the driver's frame rail, under the driver's seat. Then jumper the DLC as shown here for the fuel pump, turn the key to RUN, listen to the selected gas tank, then switch & listen to the other:
(phone app link)
Can you hear EACH in-tank pump running? Plug the frame pump back in - does it run? What is the fuel pressure?
(phone app link)
Click this, read the caption, and fill in your signature:
(phone app link)
What gap did you set the plugs to? What plugs (brand, PN, source) did you install? Same for each other new part. Did you test the plug wires? Are they routed exactly as this diagram shows?
(phone app link)
(phone app link)
How old is the filter? What happened just before this symptom appeared - did you fill up at a different gas station than usual? Crawl under the truck & unplug the fuel pump inside the driver's frame rail, under the driver's seat. Then jumper the DLC as shown here for the fuel pump, turn the key to RUN, listen to the selected gas tank, then switch & listen to the other:
(phone app link)
Can you hear EACH in-tank pump running? Plug the frame pump back in - does it run? What is the fuel pressure?
(phone app link)
Click this, read the caption, and fill in your signature:
(phone app link)
Last edited by Steve83; 10-05-2018 at 10:32 AM.
