Non existent idle after FI install

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Amskeptic
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Re: Non existent idle after FI install

Post by Amskeptic » Sun Jan 19, 2014 7:10 am

SlowLane wrote:Let's rewind

There are a lot of variables here.
Good points . . .
What size are the valves?
150psi is 15 higher than the top of the factory recommended range.
What is the design compression ratio of this build?
Wer might need to consider the effects of substantial valve overlap, like a typical Raby engine with inadequate air flow at idle and better breathing higher up.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Sun Jan 19, 2014 10:56 am

SlowLane: no skin off my nose, I just realized what I wrote may come across poorly and wanted to make sure I wasn't giving offense.

An update and than I'll answer some of the outstanding questions. First and foremost, after some contortionist maneuvers to get the can of carb cleaner positioned at the correct angle, I found the vacuum leak at the underneath side of the cold start valve. That lower screw wasn't fully cinched down from when I replaced the prior leaky cold start valve in situ. I remember having great difficulty getting my stubby screwdriver into the small area, but thought I had gotten it correct. I pulled the screws and replaced them with 6mm hex head bolts so any future replacements will be easier to accomplish.

So after doing that, idle smoothed out and responds to the idle screw. I made some adjustments to the wiper arm and black cog to get the response from the wiper arm as described in the AFM tuning guide and then took it for the same test drive as before. Accelerating through 1st and 2nd remained indiscernible from the previous run, 3rd and 4th both seemed stronger, but definitely rough, especially 4th. I was able to accelerate up to freeway speed a little better and hold it better, but I'm still definitely not finished yet.

One minor issue was when I exited the freeway to turn around. It didn't return to idle and died at the stop light at the end of the off ramp. Turns out the wiper arm had stuck open. So like the other AFM, this one needs some lubrication as well. That's on the ticket for today. Another test I'm planning on running today, now that the vacuum leak has been eliminated, is to put my original AFM back on see what the response is on my test drive route. With my current AFM, I've changed my minimum setting via the wiper arm adjustments as well as the slope of my fuel curve; I'd like to understand how the original VW configuration behaves.

Okay, onto your questions: Compression ratio remains stock. Intake valve is 42mm, exhaust is 36mm. The Webcam 107i has a 255 duration, 0.430" lift.

Anything I miss?
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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SlowLane
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Re: Non existent idle after FI install

Post by SlowLane » Sun Jan 19, 2014 12:24 pm

I found the vacuum leak at the underneath side of the cold start valve. That lower screw wasn't fully cinched down from when I replaced the prior leaky cold start valve in situ.
Hey, nice find. :cheers: That lower screw can be a bugger to get to, especially with the distributor in the way.
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Sun Jan 19, 2014 12:36 pm

Yeah, I'm glad I found it. Both myself and the mechanic had been over that area a few times. It wasn't until I was really going for absurd angles with the carb cleaner that I had any clue. The hex head bolts I replaced it with are much easier to get in and out as my 1/4" ratchet and a deep socket fit into that gap between the CSV and the distributor perfectly. I'm sure I'll get into another rebuild at some point down the road so that will be incorporated into the next build and any advice I give out later.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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SlowLane
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Re: Non existent idle after FI install

Post by SlowLane » Mon Jan 20, 2014 4:27 pm

Depending on how snugly the CSV gasket fits around the bolt threads, you may still have a low-grade vacuum leak around the threads themselves. The welded nuts in the air plenum are open to the plenum, so there is a tiny path for air to get through around the threads. I'm pretty sure the original screws in that location had sealing washers (copper?) to block off that winding path.

Of course, LocTite would fix that problem pretty well, too.
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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Amskeptic
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Re: Non existent idle after FI install

Post by Amskeptic » Mon Jan 20, 2014 8:45 pm

SlowLane wrote:Depending on how snugly the CSV gasket fits around the bolt threads, you may still have a low-grade vacuum leak around the threads themselves. The welded nuts in the air plenum are open to the plenum, so there is a tiny path for air to get through around the threads. I'm pretty sure the original screws in that location had sealing washers (copper?) to block off that winding path.

Of course, LocTite would fix that problem pretty well, too.
Not an issue with the original gasket. It seals the plate fully and covers the threads. Any fuel resistant gasket stock can be easily punched and cut to size.
o
O
o
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Mon Jan 20, 2014 10:34 pm

Okay, here's where I'm at and I need some guidance to know which way to go from here. I can get the idle RPM response the way it should be: a 1/4 in nudge CCW and the RPMs rise solidly, but not outrageously so, a 1/4 inch nudge CW and the engine falls off, nearly dying. At speed, give it a CCW nudge and the engine RPMs will rise a bit, CW and it drops off smoothly. Basically, as described in the guide. But when I go to drive it, I can accelerate through 1st and 2nd comfortably, 3rd accelerates...okay, but maybe a bit underpower, 4th is terrible: very weak and rough acceleration, it's smooth at very light throttle, but once I put it down accelerated meaningfully, there's a mild shake in the pedal and seat of my pants. I can coax it up to freeway speeds, but only on level ground. When going up inclines, the speed falls off.

Without a air/fuel ratio meter, how do I sort this out. Is there something else at play?
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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SlowLane
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Re: Non existent idle after FI install

Post by SlowLane » Thu Jan 23, 2014 10:12 pm

Ronin10 wrote:When going up inclines, the speed falls off.
Yes. :wink:
Is this your first VW bus? :flower:
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Fri Jan 24, 2014 7:54 am

Ha! How about this correction: When going up inclines, the speed falls off more than previously.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Gypsie
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Re: Non existent idle after FI install

Post by Gypsie » Fri Jan 24, 2014 11:43 am

I know I am late in the conversation but.... I think I see a major contributor right here:
Camshaft is a Webcam 107i the correct, corresponding Webcam hydraulic lifters. Yes, I know it's not stock for a 1976, but I'm confident it was running correctly since it was in good order on while running with carbs.

This right here can be giving you quite a little runaround.

This cam has given me some issues, 'specially at idle, if there is any substantial altitude, when cold, or very hot...

The advice you have received so far, IMHO, is spot on.

Assuring that your 'foundation' is solid: Timing, advance, vac integrity, valve adj., spark, fuel pressure, etc are all needing to be right where they need to be, otherwise any fuel delivery adjustments will be set with wonky parameters.

Making adjustments to Fuel delivery with injection is a very nerve wracking proposition....at first.

Yes you can blowtorch valves in a short time by setting things improperly. Or you can foul plugs quickly and create poor performance that can lead you astray. ("I just changed those plugs, it can't be them". Who wants to keep pulling plugs to see if they are fouled...)

Sing it with me..."The mix bone connected to the time bone, the time bone connected to the flow bone..."

Anyway, I digress..

Familiarizing yourself with the afm adjustments will go a long way to a volken mind meld...

Where the manual's "one cog" adjustment is playing it safe, Colin's 6 cogs speaks with a loud clear voice, and is intended to speak to your understanding of what is happening in the works.

Make the adjustment, do some diagnostics, take it for a drive, think on it a bit.

Let it cool, check some parameters, lather,rinse, repeat.

You have given this machine a heart transplant, and you have a heart you can pretty much play around with.

I am curious to know if you have confirmed that both vac and centrifugal advance are doing what they should be doing. advancing to the right spot at the right rpms and then returning to the right spot after?

also..
Is your timing set using high rpms or at idle?

Just curious.
So it all started when I wanted to get better gas mileage....

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Fri Jan 24, 2014 12:04 pm

Timing was set using high rpms, with full advance bang on at 28 degrees, consistent and reliable return to idle timing.

My conclusion at this point is that between the cam and the larger valves, I've tweaked the airflow sufficiently to get it outside L-Jets adaptability. I have sourced an air/flow meter so that will allow me to correlate changes in driveability to changes in air/fuel ratio. It'll also allow me to do more than guess at the difference in the behavior I'm witness with and without a load on the engine.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Gypsie
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Re: Non existent idle after FI install

Post by Gypsie » Fri Jan 24, 2014 1:56 pm

:thumbleft:

"Timing was set using high rpms, with full advance bang on at 28 degrees, consistent and reliable return to idle timing."

This is centrifugal advance only (no vac hooked up)? With vac it will be more advanced than *28 at high rpms. We want both advance mechanisms doing their part and both should be tested. Not saying you haven't just haven't seen it in the thread.


Also, that you have confirmed that the vac routing is all correct (I have seen several set ups that have switched FPR and Dizzy Vac. connections during some project or another along the way. It's easy to miss this error.)

I have installed the 107i (w/corresponding lifters) in my '80 vanagon and after many tribulations continue to have troubles when cold at altitude, throw on top of that an auto tranny that gives a bit of idle load when in D, have found comfort keeping the idle speed bumped up a bit.

Sounds like your on the right track.
So it all started when I wanted to get better gas mileage....

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Ronin10
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Re: Non existent idle after FI install

Post by Ronin10 » Fri Jan 24, 2014 2:17 pm

Vacuum and centrifugal advance. Set at high RPM with the vacuum hose disconnected. I'm confident my vacuum lines are correctly hooked up. That was one of the problems with my old system - everything was switch about - so I did a lot of research to ensure I had it correctly hooked up.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Amskeptic
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Re: Non existent idle after FI install

Post by Amskeptic » Sat Jan 25, 2014 12:15 pm

Ronin10 wrote:Vacuum and centrifugal advance. Set at high RPM with the vacuum hose disconnected. I'm confident my vacuum lines are correctly hooked up. That was one of the problems with my old system - everything was switch about - so I did a lot of research to ensure I had it correctly hooked up.
If heavy acceleration is the only time that your engine behaves badly and your timing is correct (28* @ 3,400, no hose)(38-40* BTDC with hose), then I am most interested to see what your AF ratio is under acceleration.

Please help me find the baseline performance parameters by doing the following air/fuel ratio measurements.

Full Throttle 4th Gear
read at:
45mph 55mph 70mph

Cruise 4th Gear
45/55/70

Full Decel
start at 50, read at 45
start at 60, read at 55

Thanking You In Advance
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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SlowLane
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Re: Non existent idle after FI install

Post by SlowLane » Sat Jan 25, 2014 12:33 pm

Ronin10 wrote:consistent and reliable return to idle timing.
That's very good, but there's one more possible wrinkle here that I just noticed: I see you're using a Pertronix.

I know that a lot of folks have had good success with the Pertronix. My own experience with the unit is that I was unable to pack the thick wires and insulation into the distributor body in such a way that they didn't interfere with smooth operation of the vacuum advance. Regardless of which routing I tried, the wires imposed some resistance to the movement of the vacuum advance plate, enough that I decided to abandon the Pertronix. Instead, I went with a Crane Cams XR700, which has much finer wires that could be routed to my satisfaction. This setup served me well for more than a decade. Currently i'm using a modified CA-spec factory electronic ignition that has been retrofitted with the springs, weights and vacuum can from my original Federal-spec distributor. Works wonderfully.

Good luck. Sounds like you're making great strides.
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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