Cyclical misfire out of nowhere
Jul 25, 2018 | 04:40 PM
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Cyclical misfire out of nowhere
Oil pan was leaking pretty bad so I decided to finally fix it. Started the engine and ran it for a minute to get the oil warm so it'll drain faster. Ran great. Dropped the pan and found pieces of a timing chain. So obviously I pulled the valve cover to inspect... All there, must have been from a previous repair. Get it all back together and it runs terrible
I have a cyclical miss every 3 or so second.... like hums hums hums stumble... Hum hum hum stumble and doesn't go away with RPM.
I figure it has to be vacuum related sincw that's really all I messed with to pull the valve cover. But I've ran through everything. I have an EGR delete so there's not really that many hoses.
whats that's large hose thats the same size as the PCV but on the front?
Any ideas? I'm stumped
I have a cyclical miss every 3 or so second.... like hums hums hums stumble... Hum hum hum stumble and doesn't go away with RPM.
I figure it has to be vacuum related sincw that's really all I messed with to pull the valve cover. But I've ran through everything. I have an EGR delete so there's not really that many hoses.
whats that's large hose thats the same size as the PCV but on the front?
Any ideas? I'm stumped
Last edited by tgell001; Jul 25, 2018 at 05:15 PM.
Jul 26, 2018 | 03:00 AM
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Jul 26, 2018 | 06:05 PM
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Video of me reving it
https://photos.app.goo.gl/Hpo6Jab6TqZUzqCd6
Vacuum line pics (I'm not going to lie to lost track of where the pressure regular went)
https://photos.app.goo.gl/V8LQ99UmWskYBu9W6
https://photos.app.goo.gl/hfyX8dExCte4qp9k7
So when I first started it up today it ran great but after like 2 mins it started acting like crap again. I'm assuming that's because the cold start injector closed
I'm pretty sure I'm chasing a lean condition, but all I did was remove the oil pan and valve cover
https://photos.app.goo.gl/Hpo6Jab6TqZUzqCd6
Vacuum line pics (I'm not going to lie to lost track of where the pressure regular went)
https://photos.app.goo.gl/V8LQ99UmWskYBu9W6
https://photos.app.goo.gl/hfyX8dExCte4qp9k7
So when I first started it up today it ran great but after like 2 mins it started acting like crap again. I'm assuming that's because the cold start injector closed
I'm pretty sure I'm chasing a lean condition, but all I did was remove the oil pan and valve cover
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Jul 27, 2018 | 05:04 AM
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Ha! I just realized this looking at your other pics. Similar noises are complained about and they are usually coming from the evap canister. Might still be fuel bleeding back into the tank. What’s up with the fuel lines, pump, filter, fuel cell situation?
Last edited by RASALIBRE; Jul 27, 2018 at 05:06 AM.
Jul 27, 2018 | 05:07 AM
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Stuck an inline pump between the cell and the other end into the factory fuel line. Wired the pump to the factory wiring. Return is tied into the factory return and goes back to the cell. Was actually a really simple mod
Jul 27, 2018 | 05:15 AM
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Hmmm, well not trying to send you down any rabbit holes. You removed the oil pan and valve cover and all this started to occur.... hmmm Was that filter already on the front pcv port on the valve cover before all this, or is that new?
Jul 27, 2018 | 05:20 AM
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The problem was present before I did that. I did that yesterday to eliminate one more possible vacuum leak because I capped the other end. Symptoms unchanged
Jul 27, 2018 | 05:34 AM
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There maybe potential for that filter on the pcv port to still be causing a vacuum leak past leaking bad valve stem seals, or it may be sucking air in and trapping it, exacerbating positive crank case pressure. I’d hook it back up to stock configuration to rule it out.
In my head the frog noise is likely air trapped somewhere could be fuel lines, or some weird pcv situation. You opened the crankcase when fixing the oil pan leak, so I’d start there.
How old old is the fuel filter? Is all the new fuel system easy to get to and check?
In my head the frog noise is likely air trapped somewhere could be fuel lines, or some weird pcv situation. You opened the crankcase when fixing the oil pan leak, so I’d start there.
How old old is the fuel filter? Is all the new fuel system easy to get to and check?
Jul 27, 2018 | 05:44 AM
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About two months ago I had a very similar issue and it ended up being a torn intake boot and a broken fuel injector plug. But in resolving those issues I did
cap/rotor, coil, tpa, tested AFM, new injectors, new fuel filter, O2 sensor, set timing, and replaced intake boot, and checked compression. The compression wasn't great, but ran fine after so it's not the issue.
Ran like a top after than and enjoyed a great weekend. Pulled it in the garage and left it for like a month stepping out to tinker here and there and it ran great. Ran great when I ran it up to temp before draining the oil out to repair the pan seal.
It's got to be something stupid. I can't even focus at work because all I can think about is things around the valve cover that could have dislodged or broken.
cap/rotor, coil, tpa, tested AFM, new injectors, new fuel filter, O2 sensor, set timing, and replaced intake boot, and checked compression. The compression wasn't great, but ran fine after so it's not the issue.
Ran like a top after than and enjoyed a great weekend. Pulled it in the garage and left it for like a month stepping out to tinker here and there and it ran great. Ran great when I ran it up to temp before draining the oil out to repair the pan seal.
It's got to be something stupid. I can't even focus at work because all I can think about is things around the valve cover that could have dislodged or broken.
Last edited by tgell001; Jul 27, 2018 at 05:47 AM.
Jul 27, 2018 | 06:25 AM
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I’d replumb that front pcv port back to stock configuration. If you have the hose it’s free, if you have to buy one it’s cheap enough. It also falls under the “things around the valve cover that could have dislodged or broken.” and it’s quick/simple to do. You say the compression check wasn’t the best, so you’d want the closed system/extra vacuum there.
Jul 27, 2018 | 06:29 AM
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I’d replumb that front pcv port back to stock configuration. If you have the hose it’s free, if you have to buy one it’s cheap enough. It also falls under the “things around the valve cover that could have dislodged or broken.” and it’s quick/simple to do. You say the compression check wasn’t the best, so you’d want the closed system/extra vacuum there.
Jul 27, 2018 | 06:32 AM
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I just read your comment on opening the crank case, I didn't touch anything while I had the pan off. And it idles decently whwn cold, so see no way it could be in the rotating assembly.
That being said, is there anything in the area of the oil pan that's sensative or could be causing a lean condition?
That being said, is there anything in the area of the oil pan that's sensative or could be causing a lean condition?
Jul 27, 2018 | 07:26 AM
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The pcv (positive crank case ventilation) system works when the engine is completely sealed and under proper compression readings. All I was getting at was by removing the oil pan you’ve opened it up. You also opened it up by removing the valve cover. If there are no oil leaks from the oil pan or valve cover it’s safe to assume they’re sealed.
Jul 27, 2018 | 07:29 AM
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