Itinerant Air-Cooled

Amskeptic wrote: ↑

Sat Jun 24, 2017 6:47 pm

SlowLane wrote: ↑

Sat Jun 24, 2017 10:02 am

the OXS relay 3000 RPM threshold where the problem manifests.

Have fun figuring out this puzzle, guys.

Yes, you and I had a front row seat to the mixture shift, it was fascinating. I think it was on gauge 3MNR mid-level on the secondary pod. Or was it on the sub-mezzanine display cluster?

This is a Federal Vanagon with a full throttle switch, but these symptoms occur underneath full throttle as well as at full-throttle. Keep the ideas coming, maybe we have a CA ECU?
Colin

TrollFromDownBelow wrote: ↑

Mon Jun 26, 2017 7:42 pm

Okay, I will be the one to post the stupid questions, just to get the obvious out of the way....I'm sure you tested for all of this, but it will help level set everyone else's brains....

- good compression on all 4 cylinders (good enough, I don't remember the numbers)
- good fuel pressure both at idle and under load ( 28-36 )
- good vacuum as tested with a vacuum gauge ( 18-20 overrun damn close to 0 on acceleration )
- proper valve lash ( hydraulic, preload set at 1 1/2 )
- air filter that isn't plugged ( NOOOO )
- coil that is pumping out proper voltage ( good 5/16" purplish spark )
- valve timing that looked heuristically correct from watching them open and close ( didn't check on account of the good idle )
- Temp sensor 2 that tested okay ( didn't test )
- AFM mixture settings good ( it liked to be left alone )
- strong battery ( eventually, yes )
- oil that isn't pure sludge
- plugs/cap/rotor in good working order ( yes )
- timing and dwell set correctly ( why, yes, yes, of course )
- dizzy that advances correctly ( good behavior down low, weak upper end, 40* BTDC vacuum and 28* centrifugal )
- good gas ( I think so )
- AFM wiper (not sure of correct terminology) that isn't worn out ( check and symptoms were same with different unit )
- S boot in good condition (eg no funky cracks that may be partially sealed at idle, but may open up with some harmonic vibration at higher RPM's ( did not check )
- exhaust that is not restricted (although from the post sounds like you tested this) (oh, we TESTED IT )

TrollFromDownBelow wrote: ↑

Wed Jun 28, 2017 6:39 pm

Thanks for the response Colin...now we need more subjective clues, like:

- how consistent was the lack of power...was it always abt 3k rpm,
- was the 3k bog consistent in all gears?

Amskeptic wrote: ↑

Wed Jun 21, 2017 6:56 pm

It is about concrete in Motor City, concrete:

Amskeptic wrote: ↑

Wed Jun 28, 2017 8:10 pm

TrollFromDownBelow wrote: ↑

Wed Jun 28, 2017 6:39 pm

Thanks for the response Colin...now we need more subjective clues, like:

- how consistent was the lack of power...was it always abt 3k rpm,
- was the 3k bog consistent in all gears?

Very consistent.
Colin

hippiewannabe wrote: ↑

Thu Jun 29, 2017 7:53 pm

Amskeptic wrote: ↑

Wed Jun 28, 2017 8:10 pm

TrollFromDownBelow wrote: ↑

Wed Jun 28, 2017 6:39 pm

Thanks for the response Colin...now we need more subjective clues, like:

- how consistent was the lack of power...was it always abt 3k rpm,
- was the 3k bog consistent in all gears?

Very consistent.
Colin

I think this is key. If it depended on load, and RPM was incidental, air or fuel would be suspected. If it is only RPM, irrespective of load, must be ignition or something else that only knows RPM, like valve train. .

asiab3 wrote: ↑

Thu Jun 29, 2017 11:46 pm

Any noticeable hesitations when revved in neutral? Any interesting diagnostic readings in neutral? (Timing light flashing irregularly, dwell angle changing, fuel pressure reading?)

Or is the problem only replicable under load?
Robbie

Amskeptic wrote:Fuel pressure gauge needle danced horrendously.

Amskeptic wrote: ↑

Fri Jun 30, 2017 3:54 pm

Fuel pressure gauge needle danced horrendously.

SlowLane wrote: ↑

Sun Jul 02, 2017 12:32 am

Amskeptic wrote: ↑

Fri Jun 30, 2017 3:54 pm

Fuel pressure gauge needle danced horrendously.

Fuel pressure dance; symptom or cause?
Symptom: Is the fuel pressure dance being caused by fluctuating manifold vacuum (caused by something else?)
Cause: Is the fuel pump not able to provide sufficient capacity for stable fuel delivery at high RPM under load? Are the fuel injectors (one or more) not able to maintain the higher duty cycles required for loaded operation? Are the injectors the correct ones?