Cyclical misfire out of nowhere
#22
Registered User
Prob wouldn't hurt to check that your PCV valve still closes during idle and opens towards WOT. Just unplug the rubber hose at the valve and plug the valve with your finger to feel the lack of air flow at idle and vice versa.
PCV valve stuck closed can be associated with oil leaks. I need to check mine...
Mods...I joke. I swear I have an increase in throttle after putting a summit racing sticker one time. May have peeled off.
PCV valve stuck closed can be associated with oil leaks. I need to check mine...
Mods...I joke. I swear I have an increase in throttle after putting a summit racing sticker one time. May have peeled off.
#24
Registered User
iTrader: (-1)
The forward opening in an 22-RE series valve cover connects to a nipple on the air cleaner box. You have unmetered air entering the intake system thru the PCV lines. Also keep in mind leaks along the gasket surfaces for the top and bottom covers, IE leaking gasket flows unmetered air thru the pcv valve.
This isnt necessarily your primary issue, but it's an issue.
Fouling of the cap, rotor, sparkplug, or just a badly placed (loose, or leaking) high-tension cable. These will cause it to burble.
This isnt necessarily your primary issue, but it's an issue.
Fouling of the cap, rotor, sparkplug, or just a badly placed (loose, or leaking) high-tension cable. These will cause it to burble.
#25
Registered User
Pretty sure it connects to a nipple on the intake manifold. In the pictures he shared, he has that intake port blocked.
#26
Registered User
Make sure all the ports on the ac/power steering idle up valve are blocked. If you’re not using it at all, you can remove the whole thing with a 10mm wrench/socket and plug the port.
#27
#28
Registered User
#29
Yes, I just made that change trying to reduce the odds of vaccum leak thru the things that I just manipulated i e the valve cover. The problem was bad before that I did that as a fix. Or fact finding more so. What is on the other side of that hose on the manifold is it direct vacuum?.
#31
I have a development. So with the diagnostic port jumpered itll idle indefinitely. Still can't rev it much over 2k without the stumble. But it'll idle forever. As soon as I remove the jumper it'll stumble and die.
I put my vacuum gauge on it and it's pulling 20 lbs.
While I had a steady idle, I put a welding glove on and pulled the spark plugs 1 by 1 and all evenly made the engine almost cut off. So I have to believe they're all getting spark and fuel evenly... Or MOSTLY
More information, not closer to fixing the problem.
I put my vacuum gauge on it and it's pulling 20 lbs.
While I had a steady idle, I put a welding glove on and pulled the spark plugs 1 by 1 and all evenly made the engine almost cut off. So I have to believe they're all getting spark and fuel evenly... Or MOSTLY
More information, not closer to fixing the problem.
#32
Registered User
I have a development. So with the diagnostic port jumpered itll idle indefinitely. Still can't rev it much over 2k without the stumble. But it'll idle forever. As soon as I remove the jumper it'll stumble and die.
I put my vacuum gauge on it and it's pulling 20 lbs.
While I had a steady idle, I put a welding glove on and pulled the spark plugs 1 by 1 and all evenly made the engine almost cut off. So I have to believe they're all getting spark and fuel evenly... Or MOSTLY
More information, not closer to fixing the problem.
I put my vacuum gauge on it and it's pulling 20 lbs.
While I had a steady idle, I put a welding glove on and pulled the spark plugs 1 by 1 and all evenly made the engine almost cut off. So I have to believe they're all getting spark and fuel evenly... Or MOSTLY
More information, not closer to fixing the problem.
timing advanced too far, so with jumper in/timing retarded it idles better?
Have you checked timing?
Maybe you are having a random issue with your fuel set up and it is running lean, so with the timing jumpered/retarded it runs better.
Do you have a fuel pressure gauge?
Maybe you’ve fixed enough vacuum leaks that it’s now running rich?
Pull the efi fuse and disconnect the battery for a few minutes.
Or timing and fueling is fine and and there is still a vacuum leak evading you somewhere.
Have you checked the bottom most port on the ac/power steering idle up valve. There’s a 90* one underneath the bottom of it. This port circled in red is at the very bottom of the valve
I’m just spitballing simple quick cheap things to check out.
#33
No i really appreciate it, the reason i post in forums isnt because im looking for someone to tell me what to do but its like an idea factory.
Thats capped, I caught that a few days ago.
Fuel pressure holds 40 measured at the CSI.
I set base timing at 5* just to rule that out
I just have this feeling you're right about it being lean, that's what my feeling has been since the beginning but I can't figure out why. I'm leaning towards a computer in put is causing the lean condition but that just leads me down a terrible rabbit hole I wish I wasn't so familiar with.
Thats capped, I caught that a few days ago.
Fuel pressure holds 40 measured at the CSI.
I set base timing at 5* just to rule that out
I just have this feeling you're right about it being lean, that's what my feeling has been since the beginning but I can't figure out why. I'm leaning towards a computer in put is causing the lean condition but that just leads me down a terrible rabbit hole I wish I wasn't so familiar with.
#38
Registered User
It’s probably worth checking the resistance of the coolant temp switch and cold start timing switch too.
Heres the cold start time switch:
http://www.lcengineering.com/LCNewsl...tart_Tech.html
Here’s the ecu (thw) coolant temp sensor.
Heres the cold start time switch:
http://www.lcengineering.com/LCNewsl...tart_Tech.html
Here’s the ecu (thw) coolant temp sensor.
#40
Registered User
Also, the ac/power steering idle up screw, mine was leaking past that screw, so I just removed it and plugged it. Looks cleaner that way regardless. I found my plug on a truck with no ac/power steering from factory. The threads might be weird British pipe threads or Japanese imperial pipe threads or some such nonsense. Take the valve to the hardware store and check the brass fittings section.