Author |
Message |
chris30559 Samba Member
Joined: May 20, 2018 Posts: 3
|
Posted: Sun May 20, 2018 4:45 pm Post subject: Random misfire?? Help! |
|
|
Hi Everyone,
I am have a troubling issue with my 71 standard, which is my Daily driver, first a little background info to fill you in to what I've done so far. about 3 days ago, i had fuel delivery issues turned out to be a dirty jet in carb. cleaned that up, then had some fouled plugs, possibly due to trying to run it with the fuel issues.. so all in all i now have a clean carb, new fuel filter, new NGK BR6HS plugs, and new points. Ran Great for 2 days didn't skip a beat.. Still does 90% of the time..starting today it randomly misfires. it idles fine, no issue, revs fine. just misfires out of nowhere, for example, waiting at red light running fine, start taking off in 1st and at around 15-20mph it skips a beat for about 5-10 seconds then clears up... or could be cruising along in 3rd and skips again about 5-10 seconds. never dies and seems to clear up when i rev it a tad. its truly random, sometimes starting out at lights its fine, during a 20 minute drive, it happened maybe 10 times..
any ideas. i am totally lost.
Thanks Everyone!
Chris |
|
Back to top |
|
|
joey1320 Samba Member
Joined: September 12, 2006 Posts: 2325 Location: Cleveland, OH
|
Posted: Sun May 20, 2018 6:30 pm Post subject: Re: Random misfire?? Help! |
|
|
Can you post pictures of the engine?
How dirty was the carburetor? Could something else had gotten stuck somewhere?
Checked timing, valve clearance, fuel pressure? _________________ **1971 Super Project
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0 |
|
Back to top |
|
|
chris30559 Samba Member
Joined: May 20, 2018 Posts: 3
|
Posted: Sun May 20, 2018 6:59 pm Post subject: Re: Random misfire?? Help! |
|
|
Its to dark to take a picture now, but it's stock 1600 dual port. I can post one in the morning. Oh its also got the vacuumless distributer. As far as the carb, id say very dirty, bottom of float bowl had tons of crud..metal? Dirt? Who knows. Took all parts off except acl pump and blasted carb cleaner through all passageways. All should be clear. I guess it's possible there is still something in carb but I'd be surprised. Do you think this symptom could still be fuel related.
Have not checked fuel pressure, or timing. I adjust and check vales every oil change and just did one about 400 miles ago, roughly 2 monthe ago. |
|
Back to top |
|
|
chris30559 Samba Member
Joined: May 20, 2018 Posts: 3
|
Posted: Mon May 21, 2018 7:54 am Post subject: Re: Random misfire?? Help! |
|
|
Here is a couple photos of my engine. Now I am confused, as well. I just noticed it has the AB prefix, I was told this was a 1600 dual port. Now I am wondering if it is a 1300 per the AB prefix? Anyhow the misfire is worse now. Even at idle.
|
|
Back to top |
|
|
ashman40 Samba Member
Joined: February 16, 2007 Posts: 15982 Location: North Florida, USA
|
Posted: Mon May 21, 2018 12:31 pm Post subject: Re: Random misfire?? Help! |
|
|
chris30559 wrote: |
As far as the carb, id say very dirty, bottom of float bowl had tons of crud..metal? Dirt? Who knows. Took all parts off except acl pump and blasted carb cleaner through all passageways. All should be clear. I guess it's possible there is still something in carb but I'd be surprised. Do you think this symptom could still be fuel related. |
You mention above that you replaced the fuel filter and here you mention there was crud at the bottom of the fuel bowl. This means the crud passed the old fuel filter and made its way into the carb. I notice your filter is between the pump and the carb. Did you flush the rubber hoses when you replaced the filter? If not, there could have been crud in the hose between the filter and carb? Remove the top of the carb and peek down into the bottom of the fuel bowl. If you flushed it out it should still be pristine w/o any sediment.
Also, knowing that there was dirt in the carb bowl means there could be dirt in the small passages of the carb. Using spray carb cleaner alone cannot clean those passages. You need to soak the carb body overnight in a can of carb cleaner (the type with a basket) and then blow all the passages clear with high pressure air from a compressor (90+psi). This will blow out all the small passages. The pressure from aerosol carb cleaner isn't enough to clean these very small passages.
When was the last time this carb was fully rebuilt? Many of the original Solex carbs have so many years on them that the throttle bores are worn. You cleanup of the carb could have washed away crud that was minimizing the vacuum leaking past the throttle bores. After a cleaning MORE air may be leaking thru causing an occasional lean condition.
One last thing... how have you set your ignition timing? That 009 distributor you have should be set at max total timing to make sure it does not exceed 28-32BTDC @3800rpm when all timing is in. A common mistake is to set timing to the original 5ATDC or TDC @idle which was correct for a DVDA distributor but NOT correct for the 009. _________________ AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
|
Back to top |
|
|
74 Thing Samba Member
Joined: September 02, 2004 Posts: 7389
|
Posted: Mon May 21, 2018 1:20 pm Post subject: Re: Random misfire?? Help! |
|
|
Pull the carb and clean and blow it out. Probably a plugged idle jet on the side of that carb. |
|
Back to top |
|
|
74 Thing Samba Member
Joined: September 02, 2004 Posts: 7389
|
Posted: Mon May 21, 2018 1:20 pm Post subject: Re: Random misfire?? Help! |
|
|
Pull the carb and clean and blow it out. Probably a plugged idle jet on the side of that carb. |
|
Back to top |
|
|
Starbucket Samba Member
Joined: April 30, 2007 Posts: 4023 Location: WA
|
Posted: Mon May 21, 2018 2:14 pm Post subject: Re: Random misfire?? Help! |
|
|
How old are your plug wires? You might have a bad wire after pulling them off and replacing them. Did it ever have this problem before your carb problem and replacing the plugs? You might have gotten a bad plug as they are all made in China now. You could take a plug wrench and drive somewhere you can switch off the motor when it starts to miss and pull and look at each plug and look for a wet one = bad plug or wire. |
|
Back to top |
|
|
joey1320 Samba Member
Joined: September 12, 2006 Posts: 2325 Location: Cleveland, OH
|
|
Back to top |
|
|
scrivyscriv Samba Electrician
Joined: October 04, 2011 Posts: 2922 Location: Memphis
|
Posted: Mon May 21, 2018 3:10 pm Post subject: Re: Random misfire?? Help! |
|
|
Hey man random misfires are usually ignition related in my experience. Since you had your carb lid off, it would be good to measure and set your fuel height in the bowl if it's off.. if the fuel height is off, you'll run rich or lean. Rich will foul your plugs and wash oil off the cylinders; lean will make hot CHTs and cause misfires. Rich will misfire too but if you're rich enough for a misfire, your exhaust will be sooty black and it your pants will STINK after working on the engine.
Maybe this is just information bias but I've been seeing a lot of guys posting here lately with ignition problems that end up being bad condensers. So.. in this order..
check your valve clearance, set them all to .006" (unless you have an aftermarket cam with a different spec)
check the cap & rotor for carbon tracks or cracks.
check your points gap.. I believe spec is about .048-.052"?
check your timing - at full advance you want around 32º on your particular distributor.
check your fuel bowl height. it is very easy to measure or set wrong.
If adjusting those doesn't help, swap in a replacement condenser.
You can check coil resistance and engine running input voltage too before replacing the condenser. _________________ Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help. |
|
Back to top |
|
|
ricaroo Samba Member
Joined: July 06, 2016 Posts: 662 Location: 603
|
Posted: Mon May 21, 2018 3:30 pm Post subject: Re: Random misfire?? Help! |
|
|
I believe the points are set at .016 thousands with a feeler gauge, with a meter 052
Just saying
Rick _________________ 1971 Standard Beetle 2 dr Sedan 1600dp |
|
Back to top |
|
|
scrivyscriv Samba Electrician
Joined: October 04, 2011 Posts: 2922 Location: Memphis
|
Posted: Mon May 21, 2018 3:32 pm Post subject: Re: Random misfire?? Help! |
|
|
ricaroo wrote: |
I believe the points are set at .016 thousands with a feeler gauge, with a meter 052
Just saying
Rick |
Lol, I knew there was a 52 there. Ever since I got a dwell meter I haven't put a feeler gauge on my points _________________ Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help. |
|
Back to top |
|
|
|