1835 German plenum FI Thing

Fuel Supply & Ignition Systems

Moderator: Tom Notch

thedrew
Posts: 83
Joined: Wed Apr 15, 2015 10:44 am
Location: Vancouver, WA

Re: 1835 German plenum FI Thing

Post by thedrew » Mon Feb 08, 2016 4:27 pm

jzsquared wrote:Had nothing to do with either one of the guesses above. The issue was with the programming. If I ever buy another VW I'll stick with carbs
thats a shame....there are people that could have helped you work through the setup/tuning part of the setup.

User avatar
woodsbuggy1
Posts: 400
Joined: Sun Feb 20, 2011 8:15 pm
Location: NE Indiana

Re: 1835 German plenum FI Thing

Post by woodsbuggy1 » Tue Feb 09, 2016 9:53 pm

So sad to here that you gave up so easily. I have had great luck with Megasquirt, most problems with installs are self inflicted, I know this from experience :oops: .
Best of Luck
Kenric
Good quality is getting harder and harder to find.

User avatar
raygreenwood
Posts: 11761
Joined: Wed Jan 22, 2003 3:01 am

Re: 1835 German plenum FI Thing

Post by raygreenwood » Sun Feb 14, 2016 11:37 am

There is no such thing with fuel injection.....especially with any central plenum system.....as it being "just the programming".....or for that matter JUST the cam.....or JUST the plenum.

I have been trying to get people ro get their head around this for years.

The plenum has specific volume and resonance. ....and turbulence. ....which affects velocity, vacuum and air distribution timing. All of this affects whatever metering device(s) you use....which affects the data that is sent to the ECU......that.....affects the programming....and the programming further affects the data by changing how the engine runs.

All of this....and the effect it can generate can be leveraged and multiped by the cam, exhaust and gearing of the transmission. So yes....of the cam is too far out in lobe centre or lift.....and disturbs vacuum signature (important with a MAP based system). ...and lift and duration will affect velocity and volume (important for mass air flow metered systems)......so yes....the cam could be a poor choice.

The type 1 beetle plenum is one of the most single purpose......set up for a very narrow range of engine volume....with a shape that had very little thought given to airflow ....plenums I have ever seen.

It worked "adequately" for the engines it came with because VW compromised everywhere else.....cam, exhaust and programming.

You cannot just program around poor intake volumetrics or poor intake vacuum signature or velocity/volume.
With aftermarket programmable systems you can tune it to a great degree....meaning you can take a crappy intake with no thought given to turbulence or volume.....and optimize it to make it run the best it is capable of.....but you cannot increase its ultimate capability through software and programming.

It was a bad combo with a poor intake design. Programming will not work around that. Ray

Steve Arndt
Posts: 7186
Joined: Sat Mar 10, 2001 3:01 am
Location: Go Boise State, ID
Contact:

Re: 1835 German plenum FI Thing

Post by Steve Arndt » Sun Feb 14, 2016 11:44 am

Cam timing and the intake were working against it. You can't program around airflow problems. I said that a year ago.

User avatar
CBDZ
Posts: 168
Joined: Mon Jun 01, 2009 11:22 am
Location: Just up-wind of all the Chino Dairies
Contact:

Re: 1835 German plenum FI Thing

Post by CBDZ » Thu May 12, 2016 2:29 pm

This is interesting...

I have a 1904 with a 110 cam, running German plenum. I have a great idle.
My Car Details:
Fiberglass Buggy on 1973 Chassis.
1904 cc
Megasquirt (MS1 with 3.57 board) Fuel Injection: German Intake Plenum, CB Performance End-Castings, Ford Escort Throttle Body with custom Adapter, MS controls Wasted Spark Coil Pack

User avatar
Jadewombat
Posts: 1245
Joined: Sat Jun 22, 2002 2:01 am
Location: Houston, TX

Re: 1835 German plenum FI Thing

Post by Jadewombat » Fri Jul 29, 2016 10:03 am

I'm currently tuning my 1588 with 9.0 to 1, 110 cam, 009 for spark, and 1.25 rockers. It's a pain in the butt so far. The idle has to be at least 900-1000 until things smooth out. Below that it just chugs and wants to die.

Steve Arndt
Posts: 7186
Joined: Sat Mar 10, 2001 3:01 am
Location: Go Boise State, ID
Contact:

Re: 1835 German plenum FI Thing

Post by Steve Arndt » Fri Jul 29, 2016 12:09 pm

What does the map sensor signal look like? What numbers and how much variation?

User avatar
Jadewombat
Posts: 1245
Joined: Sat Jun 22, 2002 2:01 am
Location: Houston, TX

Re: 1835 German plenum FI Thing

Post by Jadewombat » Mon Aug 15, 2016 8:34 pm

It jumps around about 100rpms at idle and the MAP is 50-60kpa. Attached is a log and the tune. Thanks.
You do not have the required permissions to view the files attached to this post.

Post Reply