Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
Digifant II timing issues
Forum Index -> Water-cooled VW Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
ericrb76
Samba Member


Joined: December 17, 2021
Posts: 1
Location: PA
ericrb76 is offline 

PostPosted: Fri Dec 17, 2021 4:51 am    Post subject: Digifant II timing issues Reply with quote

I have an ABA block with digifant II cylinder head and fuel management system. The cylinder head has been decked so this does create a mild offset of the CAM but I don't think that is really an issue. It ran fine before.

I've set the timing with the vehicle fully warmed up, a minimum of 2 cycles of the radiator fan and temp needle sitting just high of the red light in the center of the gauge. Next I disconnect the blue temp sensor and rev the engine up past 3,000 rpm twice to clear the "memory". The holding the engine at 2,250 RPM, with my timing gun set to 0 degrees, I rotate the distributor until the strobe light of teh timing gun matches the 6 degree BTDC mark on the flywheel.

It should be noted that after I set the timing, the drop to idle isn't strong until after I plug the blue temp sensor in. Once I do that the engine runs wonderfully and the immediate drive is great, I drive long enough in the cold weather that my temp needle drops to just below the red light in the center of the gauge. Everything is good until I start up the car a few hours later. The car starts but might stall out at idle. It does run better after it warms up but even after allowing it to fully warm up, it never runs as good as it did immediately after I set the timing. The throttle response is "lurchy" and the idle holds but spits a mild pop from the exhaust while it idles. Before it is fully warmed up it might stall out when I let the engine drop to idle.

Any ideas folks? Bad temp sensor? Bad ECU? Bad hall sender in my distributor? I'm so confused.
Back to top
View user's profile Send private message Classifieds Feedback
volkybus
Samba Member


Joined: November 03, 2013
Posts: 480
Location: CASTLETON VT USA
volkybus is offline 

PostPosted: Fri Apr 08, 2022 12:36 pm    Post subject: Re: Digifant II timing issues Reply with quote

How about your mass air flow sensor?
Back to top
View user's profile Send private message Classifieds Feedback
Buggeee
Samba Member


Joined: December 22, 2016
Posts: 4391
Location: Stuck in Ohio
Buggeee is offline 

PostPosted: Sat Apr 09, 2022 4:11 am    Post subject: Re: Digifant II timing issues Reply with quote

I start FI diagnosis with a really thorough visual for any potential source for vacuum leak. All those little cloth braided hoses, all those rubber boots.

Also with idle issues I always suspect the cold start valve. Though for me the bad ones make the idle unstable or "lurchy". Here it sounds a little different as the throttle on is lurch, but still csv is worth consideration. I forget if this has the 5th injector to enrich at start up, but if so that failure might lean it out at cold idle, making it poppy, and then the wake up on throttle might feel lurchy.
_________________
1966 Sportsmobile Camper https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
72 Super Duper http://www.thesamba.com/vw/forum/viewtopic.php?t=672387
(adopted out) 61 Turkis Pile https://www.thesamba.com/vw/forum/viewtopic.php?t=728764
SnowDaySyncro wrote:
Every setback is an opportunity to learn stuff and to buy new tools.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
volkybus
Samba Member


Joined: November 03, 2013
Posts: 480
Location: CASTLETON VT USA
volkybus is offline 

PostPosted: Tue May 17, 2022 10:38 am    Post subject: Re: Digifant II timing issues Reply with quote

Generally speaking if your engine doesn't run well till warmed up probably your cold start injector is not right. Check it's function . Back in the days before FI IT was the coke operation ..same thing basically. When it's warm enough usually the cold start valve shuts off.The same w a automatic choke.. in fact FI injectors noozels get dirty so that may be your problem
..Good Luck Bill (3 fi vws, 2 carb vws now)
Back to top
View user's profile Send private message Classifieds Feedback
VWFIXER
Banned


Joined: January 21, 2011
Posts: 411
Location: Hawaii- Rarotonga
VWFIXER is offline 

PostPosted: Tue May 17, 2022 11:11 am    Post subject: Re: Digifant II timing issues Reply with quote

It’s running rich,
Now you have to do the work.
1) Is the thermostat letting the engine get to correct operating temperature?
2) Is the compression sufficient to burn the entire combustion chamber per cycle ?
2a) is the compression strong enough to pull the vacuum so the FI functions correctly?
3) Is the ignition system operating with the correct amount of resistance?
4) Is the oil viscosity correct for the situation?
5) Does the exhaust allow the gases to escape correctly?

This is not an exhaustive list to the myriad of clues you must know before you adjust anything or try to diagnose FI on anything.
There used to be diagnostic flow charts printed in car repair manuals, but the charts became bigger than what was user friendly since the Venn diagram would overlap in so many ways it became counterproductive to even try.
When I discovered that auto dealerships we’re using new parts to diagnose cars, and they were sending stuff to me when that didn’t work. I became quite short tempered with the whole industry.
Finding that secure paid forums were leading technicians astray so they could just drive a new car instead of fixing anything over 10 years old.

Concluding the industry is shooting itself and us in the left foot, and nailing the right foot to the floor in as many ways as the above in the Venn diagram statement.
Image may have been reduced in size. Click image to view fullscreen.


Now extrapolate the above into every bit of knowledge you can think of, and it’s the same.
Computers have allowed us to collectively measure every drop of mayo anywhere and charge for it, even charge for a screenshot of a kitten with his paws in mayo.
_________________
( ) Cheap
( ) Fast
( ) Reliable

Choose 2

Over a million air cooled miles driven and 15,000+ cars serviced.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Water-cooled VW All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.