Another misfire chasing threads (2008 express van)

Tonyv__

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Took a gamble on the PCM since the mechanic recommended that. No luck but I also did a trans flush over the weekend and either the fluid or the PCM solved the 1-2 hard shift. So that’s one thing off my list. Might just have to take it to the dealer and get the issue resolved..

Also some useful info for anyone that needs to program passlock 3. The instructions are very vague. It says insert master key turn it to on. Leave it for 10 mins. Turn off for 5 seconds then turn it back to on for 10 mins. Repeat this process 3 times…. Well I spent about 2 hours repeating this until I watched a video. They want you to turn the key all the way and attempt to start the truck then leave it on for 10 mins. 3 times in a row. Then it works
 

Rocket Man

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Took a gamble on the PCM since the mechanic recommended that. No luck but I also did a trans flush over the weekend and either the fluid or the PCM solved the 1-2 hard shift. So that’s one thing off my list. Might just have to take it to the dealer and get the issue resolved..

Also some useful info for anyone that needs to program passlock 3. The instructions are very vague. It says insert master key turn it to on. Leave it for 10 mins. Turn off for 5 seconds then turn it back to on for 10 mins. Repeat this process 3 times…. Well I spent about 2 hours repeating this until I watched a video. They want you to turn the key all the way and attempt to start the truck then leave it on for 10 mins. 3 times in a row. Then it works
Did you use a Tech2 to program the PCM?
 

Tonyv__

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Did you use a Tech2 to program the PCM?
Bought it pre programmed to my vin. I don’t have a tech 2 but I been tempted to get a knockoff one. I just really don’t understand how they work. I’m worried I’ll change or be reading stuff that I have no business messing with lol
 

Tonyv__

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Do you have an accessible place to add a tee to get a good vacuum reading you could watch driving? Old school but very accurate on a chase. Look for a 1960's vacuum diagnostics chart. Hopin for an easy fix, Good Luck!

Gave it a try. Not Sure what to make of it. It hovers in the low “normal engine” zone. Then drops when it’s misfiring Then comes back up. I’m not sure how to mess with timing. I thought that was all computer programmed now a days
 

exp500

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There are a few more things I'd like to see on vacuum tests. Try a med RPM (3000 or so)steady state run, close throttle. What is max vac? Around 28-30 and steady? Like a freeway exit ramp decel. Next is steady state cruise, Vac steady above 15? Test drive results more reliable than driveway.
Here is a quick search diagnostic link There are better old school charts but didn't take time to search.
Lastly, engine oil/carbon can cause that minor miss via intake valves(or lifters), so a can of cleaner in gas may help.Spark plugs also. NGK/AC only. Good luck.
 

Tonyv__

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There are a few more things I'd like to see on vacuum tests. Try a med RPM (3000 or so)steady state run, close throttle. What is max vac? Around 28-30 and steady? Like a freeway exit ramp decel. Next is steady state cruise, Vac steady above 15? Test drive results more reliable than driveway.
Here is a quick search diagnostic link There are better old school charts but didn't take time to search.
Lastly, engine oil/carbon can cause that minor miss via intake valves(or lifters), so a can of cleaner in gas may help.Spark plugs also. NGK/AC only. Good luck.
I was running couple bottles of cleaner earlier this year and premium gas.. I’ve been having trouble for months. Around Jan 2021 misfire in cylinder 8 and rough idle. Which is why I initially changed wires and plugs then ran cleaner in the fuel. The cylinder 8 code went away after that but the rough idle never really settled. About a month or 2 ago the frequent cylinder 7 misfire started showing on the scanner.

I’ll try to go for a ride with the vac pump hooked up

I also used ngk plugs
 

Tonyv__

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There are a few more things I'd like to see on vacuum tests. Try a med RPM (3000 or so)steady state run, close throttle. What is max vac? Around 28-30 and steady? Like a freeway exit ramp decel. Next is steady state cruise, Vac steady above 15? Test drive results more reliable than driveway.
Here is a quick search diagnostic link There are better old school charts but didn't take time to search.
Lastly, engine oil/carbon can cause that minor miss via intake valves(or lifters), so a can of cleaner in gas may help.Spark plugs also. NGK/AC only. Good luck.
Took a quick run down the road. Hope this is what you were looking for

You must be logged in to see this image or video!
a lot of the ruckus you hear banging around is equipment in the back.
 

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