2-for-1 and possibly related: Bucking and unstable/nonidle

[Ronin10]

I seem to have inadvertently solved my bucking issue. That leaking brake booster tee? Yeah, I sleeved the connection between the tee and the hose leading to the decel valve with some 1 inch heat shrink. End result? Other than my still bad idle, I had a most glorius drive into work today. I feel sorry for the short lived existence of Satchmo's Theorem/Law/Postulate, but it wasn't an electrical issue.

Interestingly, I must have disturbed the connection when fussing with CSV which exacerbated the bucking, but not realized I had.

Stay tuned, we'll see how well this band-aid survives. I wanted to hold off on a parts order until I could combine more than a single item together. Once I can get a $100 or so order together, I'll include a new tee. Does anyone know if the curved plastic tube from the tee to the decel valve is sold anywhere? Seems not based on my research. Was it originally hard or did mine simply harden with age?

[Amskeptic]

I seem to have inadvertently solved my bucking issue.
Interestingly, I must have disturbed the connection when fussing with CSV which exacerbated the bucking, but not realized I had.

Bingo. Now re-read this entire thread and look at where our communication failure points occurred.

Stay tuned, Does anyone know if the curved plastic tube from the tee to the decel valve is sold anywhere? Seems not based on my research. Was it originally hard or did mine simply harden with age?

It is a hard plastic tube from the factory . . . slips into a hose at the decel end and the top of the rubber wye at the other. What part of this tube has "failed" on you? Why would you want a new one?
Colin

[Ronin10]

Not saying it failed. More curious as I didn't know if it was age hardened or not. I just worry about it cracking or something and wanted any potential replacement parts on my radar. It's that whole be prepared thing.

[Bleyseng]

I seem to have inadvertently solved my bucking issue. That leaking brake booster tee? Yeah, I sleeved the connection between the tee and the hose leading to the decel valve with some 1 inch heat shrink. End result? Other than my still bad idle, I had a most glorius drive into work today. I feel sorry for the short lived existence of Satchmo's Theorem/Law/Postulate, but it wasn't an electrical issue.

Interestingly, I must have disturbed the connection when fussing with CSV which exacerbated the bucking, but not realized I had.

Stay tuned, we'll see how well this band-aid survives. I wanted to hold off on a parts order until I could combine more than a single item together. Once I can get a $100 or so order together, I'll include a new tee. Does anyone know if the curved plastic tube from the tee to the decel valve is sold anywhere? Seems not based on my research. Was it originally hard or did mine simply harden with age?

Call Ken@thebusco as I am sure he has a few of those plastic "S" tubes in the parts bins.

[Amskeptic]

Not saying it failed. More curious as I didn't know if it was age hardened or not. I just worry about it cracking or something and wanted any potential replacement parts on my radar. It's that whole be prepared thing.

They last the life of the Universe.
Colin

[Ronin10]

So my new injectors arrive tomorrow, but I thought I'd build a little test fixture and I got a little carried away:




Works great. The 9v baterry was just the ticket.

Incidentally, the bus has randomly been running splended lately, with respect to bucking. No idea what triggered it.

[Amskeptic]

So my new injectors arrive tomorrow, but I thought I'd build a little test fixture and I got a little carried away:
Incidentally, the bus has been running splendidly lately. No idea what triggered it.

We will need a wrap-up report so we all can make sense of this exploded confetti of random guesses sprinkled over the last several thousand posts.
Colin

(nice tester, does it have pressurized fuel?)

[Ronin10]

The test does have pressurized fuel; it come in via the overhead compressed air lines, hence the hose out of the top.

I'm going to install the new injectors tonight or tomorrow morning and will drive them for a few days since I misled myself with early impressions before. But yes, expect a report on how they shape up.

I also spoke with Michelle at German Supply. No surprise, part of my order is backordered. Frustrating. Over the last two years, I've ordered from them maybe 4 times. Each and every one of those orders has had substantial delays due to parts not being in stock, despite being listed as in stock on their website. When I first got seriously into VWs they had such a good reputation. I now avoid ordering from them unless absolutely necessary.

[Ronin10]

Back to crap running. I am now in a whirlwind of annoyance, frustration, and pessimism.

The new injectors seem to spray in a more focused cone than my old ones, but while there was the usual, seemingly positive bump after I change some variable, inevitably things returned to not-so-well. I am still waiting on my German Supply order to even ship (which adds to the frustration...going direct to Scott momentarily) so I haven't had a chance to put in the EGR block off kit or brake booster tee. I did spend a good hour, give or take, trying to find vacuum leaks again, but still can't identify anything more.

At a loss.

[Amskeptic]

Back to crap running. I am now in a whirlwind of annoyance, frustration, and pessimism.

The new injectors seem to spray in a more focused cone than my old ones, but while there was the usual, seemingly positive bump after I change some variable, inevitably things returned to not-so-well. I am still waiting on my German Supply order to even ship (which adds to the frustration...going direct to Scott momentarily) so I haven't had a chance to put in the EGR block off kit or brake booster tee. I did spend a good hour, give or take, trying to find vacuum leaks again, but still can't identify anything more.

At a loss.

The worst part of it is that is so likely to be some stupid thing that will become part of your ingrained technical knowledge base once you have solved it.

My most difficult fuel injection diagnosis turned out to be a little terminal finger in the ECU plug had been shoved back due to misalignment when somebody plugged it in with a little too much force and a little too little finesse. This killed the ground signal from the coil #1 to the injectors. My customer had spent seven months replacing pretty much almost everything and still - no start. Your bus is running, which means you do not have as neat of a diagnostic track, but you still have to be very focused and very scientific in your variables reduction, and very observant. Good luck.
August is just around the corner . . .

[Ronin10]

So had a get together with the local Seattle Bus owners this weekend and was crying in my beer about my idle issues which led to one of the guys taking a peak at my engine. We went down the discussion path of valve adjustments, timing, vacuum leaks, etc. that we've been worked through here. One thing he did notice was that my AFM wiper was sticky. So on Sunday, I took it out, sprayed a little lubricant in there and worked the wiper a bit. The wiper moved better, but still not as smooth as it should, but I progressed anyway. Reinstallation led to more AFM tuning and lo' and behold, I was able to get a warm idle. It's still pretty lean (17-18 A/F ratio) and the higher RPM run too rich (11.5-13, give or take), but it'll idle warm.

Starting it this morning was a bit rough, but it did barely idle while running cold. After 10 minutes or so of driving (AAR closing, I would think) it would idle fine around 900-1000 RPM. More to do to improve the tune of the AFM and I suspect I'm masking something, but progress nonetheless. Colin, we'll definitely have to go over this when you're out in June-ish.

[Ronin10]

Decided to take a few steps back...so I checked my timing and dwell tonight. My dwell was at 52 degrees on new-ish points so I pulled my distributor and re-gapped the points. 0.016" produced a dwell of 42 degrees so I went through a few iterations playing with it a bit to get the dwell within spec (44-50 deg). It was tedious and took a few tries but finally got it set at 48 degrees using my 0.013' feeler gauge. Retimed my engine to 30 degrees with hoses off. Short drive around the neighborhood didn't produce any real different behavior.

[Ronin10]

After a day of rough running, I checked my timing again. Full mechanical advance was actually at 32 degrees and had considerable scatter above 3400 rpms. With vacuum advance included, it was well above 40 degrees which is where my timing scale ends. My idle ended up around 2-4 degrees BTDC which seems to be much too late and could explain my idle is so lean (i.e. incomplete combustion).

With this in mind, I did some research on the Webcam site and notes some differences which are pertinent to my vehicle...

Here's the specs for the 107i, the cam I'm currently running. Intake is listed first, exhaust second...
Lift: 0.430"/0.430"
Advertised Duration: 255 deg / 255 deg
Duration @ 0.050": 225 deg / 225 deg
Lobe Center: 108 deg
Intake opens: 4.5 deg Before TDC
Intake closes: 40.5 deg After BDC
Exhaust opens: 40.5 deg Before BDC
Exhaust closes: 4.5 deg After TDC

The stock cam hydraulic camshaft (per Webcam) has the following specs:
Lift: 0.329"/0.303"
Advertised Duration: 223 deg / 229 deg
Duration @ 0.050": 192 deg / 195 deg
Lobe Center: 108 deg
Intake opens: -12 deg Before TDC (I guess that means 12 deg ATDC)
Intake closes: 24 deg After BDC
Exhaust opens: 25.5 deg Before BDC
Exhaust closes: -10.5 deg After TDC (also, I take this to mean 10.5 BTDC)

So with these specs in minds and given the poor idle/running I'm having, is there any recommendations for the ignition timing and valve adjustments?

My hunch is to adjust my valves to a "warm zero" rather than "cold and preloaded by 1.5 turns" to offset the earlier opening of the valves. I wouldn't expect the ignition timing to need to change, but am interested in your thoughts.

EDIT: after posting this, I went and decided to experiment a bit to see what would happen if I adjusted my timing for idle rather than full advance. So 7.5 degrees at ~1,000 rpm. Full mechanical advance ended up around 35-36 degrees. Turns out, it was crap pretty much all around. Idle wasn't sufficiently better (although that could be an AFM or vacuum leak effect) and the pull on my acceleration was well off, not feeling really strong until above 3400 rpm or so, just about when I'm ready to shift. My view on this seems to be that the mechanical advance curve is well off, i.e. the advance springs are too soft. Apparently, my rebuild skills are poor or I need to source a spring set and try again.

[Amskeptic]

107i cam I'm currently running
Lift: 0.430"/0.430"
Duration: 255 deg / 255 deg
Intake opens: 4.5 deg Before TDC
Exhaust closes: 4.5 deg After TDC

The stock cam
Lift: 0.329"/0.303"
Duration: 223 deg
Intake opens: -12 deg Before TDC (I guess that means 12 deg ATDC)
Exhaust closes: -10.5 deg After TDC (also, I take this to mean 10.5 BTDC)

So with these specs in minds and given the poor idle/running I'm having, is there any recommendations for the ignition timing and valve adjustments?

My hunch is to adjust my valves to a "warm zero" rather than "cold and preloaded by 1.5 turns" to offset the earlier opening of the valves. I wouldn't expect the ignition timing to need to change, but am interested in your thoughts.

EDIT: after posting this, I went and decided to experiment a bit to see what would happen if I adjusted my timing for idle rather than full advance. So 7.5 degrees at ~1,000 rpm. Full mechanical advance ended up around 35-36 degrees. Turns out, it was crap pretty much all around. Idle wasn't sufficiently better (although that could be an AFM or vacuum leak effect) and the pull on my acceleration was well off, not feeling really strong until above 3400 rpm or so, just about when I'm ready to shift. My view on this seems to be that the mechanical advance curve is well off, i.e. the advance springs are too soft. Apparently, my rebuild skills are poor or I need to source a spring set and try again.

The numbers up there are utterly senseless. I know of no camshaft with no overlap. When you run into BTDC, that means before TDC. ATDC means after. There has to be overlap.
Exhaust valves close After TDC.
Intake valves open Before TDC.
This is called overlap.

Your numbers up there are senseless. The stock cam does not have 22* of overlap.

You bring up an interesting point, however. Performance cams do not play nicely with L-Jet fuel injection, there is nowhere near enough intake vacuum. When you get your tangled numbers straightened out, I think we will find that you have **too much overlap** with the Web cam. Friggen aftermarket performance purveyors never tell you the consequences, do they?
Colin

(p.s. do NOT run your hydraulic lifters at "0". That is a recipe for blowing the circlips out of their grooves)

[Ronin10]

Haven't had a chance to straighten out my numbers yet (busy weekend), but did have the opportunity to play with different spring combinations in my 205P distributor, trying to make sure I have a centrifugal advance curve that makes sense. I never achieved spec (7.5 deg @ idle, 8-13 deg @ 1,600 and 20.5 - 24.5 deg @ 3,400 rpm - as given by OldVolksHome), but here's what my curve looks like: 8 deg @ idle; 8 deg @ 1,000 RPM; 16 deg @ 1,600; 18 deg @ 2,000; 20 deg @ 2,500; 24 deg @ 3,000; and 33 deg @ 3,400 RPM.

EDIT: I also received my shipment from German Supply so I removed my EGR and used the block off plate and swapped in the new brake booster tee. Morning drive in was pretty uneven. When the engine pulled smoothly it was really strong, but frequently it was interrupted with misfires either out the tailpipe or simple gaps in then engine pull. Will double check my valves as soon as I'm able.