Newly Rebuilt Engine Questions 1980 Vanagon

[Amskeptic]

7) I hear a hiss from the intake, but I can't localize...will try propane today.
I'm having trouble getting a consistent ohm reading on the Temp sensor...it jumps all over the place, but seems to be low. I hope this doesn't contribute, but I installed my VDO gauge sensor under the T2S,

Hiss is normal air passing through idle screw gate, but I'd never say no to a propane leak check (with a temporarily leaned mixture so the engine will react to the propane).

I know that seemed like a neat solution, but the temp sensor should have a dedicated ground path to the head. Read up on how a single little washer was the solution for L-Jet warm-up leanness, just a little washer between the head and the sensor increased warm-up times.
You need 2500 ohms at 68*, dropping to 200-400 ohms when warm and even lower when hot.

Is your 5* ATDC reading totally separate from the 28* @3200 rpm reading by virtue of the 5* ATDC reading has to be with the vacuum retard hose on, and the 28* reading has to be with all hoses off the distributor? just checking . . .
Colin

[cegammel]

I propaned her up, with no noticible change. All the hoses are new, so it must be the air gate. I did pull hoses for the 3200 check and replace for the 900. I'll pull that temp sensor and find somewhere else to stick my vdo ring.

Tomorrow is also cv joint, rod tube, and oxs day, if you want to cruise on down to south GA...

[cegammel]

Followup...so far:

Removed VDO sender, and finangled it under spark plug...with reservations.

Temp sensor resistance immediately returned to spec, and engine seems to be better.

Also replaced OXS, whichay have contributed to better running.

As for rod tubes...is there a trick to getting the dang thing out? I managed to spin the offender, and the leak seems to have drastically slowed to an ooze. I will check again in the morning, but these fancy Viton seals may have to wait until I have more patience.

Thanks for your help; we are tripping this weekend, so I will check back if she continues acting up.

[Amskeptic]

Followup...so far:
a)Removed VDO sender, and finangled it under spark plug...with reservations.

b) Temp sensor resistance immediately returned to spec, and engine seems to be better.

c) Also replaced OXS, whichay have contributed to better running.

d) As for rod tubes...is there a trick to getting the dang things out?

a) yay!
b) yay!
c) yay!
d) small visegrips delicately grasping tube where it flutes outward, twist'n'pull towards head

Colin

[cegammel]

Van just totally crapped out...

The engine is jerking whenever it is under load, almost like a fuel filter clog. It also sounds like it is missing occasionally.

So far...I assumed the ECU was receiving bad signals from somewhere. The TSII is new, and the resistance is good. The OXS is new. I swapped in a different used ECU with no change. Fuel filter is also new, and fuel pump is about 4 years old. I have not personally changed the pump, but the problem only occurs under load, not at idle.

I have also swapped in a used AFM and fuel pump, along with a new rotor. All plug wires are within ohm range, and the plugs look normal. The van feels constipated, even when not bucking. I have no catalytic converter, so...I may try pulling off exhaust part s next...

One more variable...in checking grounds again, I found the thermotime switch unplugged... I plugged it in, and went for a test drive with no change. However, on the test drive, I stopped half out and unplugged the oxs, with the engine running. That seemed to work. She ran home with no issues.

How does the thermo-time switch work? Would it cause bucking and engine constipation?

Any other ideas?

[cegammel]

To add to my issues...With the OXS connected, I now have a very gassy sounding backfire when I punch and release the accelerator...

A buddy recommended spray checking my plug wires for worn insulation; both sets of wires I have in the shop are a little sparky, but not too bad.

So, I'm leaning toward ignition, which I will thoroughly check in the morning. So much for our week off...

[SlowLane]

Taking the time to nail down the ignition system is time well spent, IMO. My personal approach is to rule out electrical and ignition gremlins before moving on to fuel system,

You might want to take a step back at this point and assess whether you have all the right FI and ignition bits in place. From the fact that your 1980 Vanagon has an O2 sensor, I'm assuming that you have an California model (Federal models didn't have O2 sensors).

Since you are in the throes of parts-swapping, you should stop and make sure that the parts you have are all from a CA-model FI system. The ECU, AFM, FI harness and ignition system are all CA- specific, and it may be possible that you have a Federal ECU plugged into your CA harness (not even sure if that would work, but it might sort-of work).

Check ratwell's site for the correct part numbers.

The AFM actually doesn't need to be the specific part number. The AFM guts are identical between models, but they are "tuned" differently for the different applications. Since tweaking the AFM is de-rigueur here in IAC-world, you can blithely ignore the model number stamped on your AFM (but not the number of pins it has). Speaking of AFM pins, make sure yours are not receding into the connector block.

Good luck.

[cegammel]

Thanks. On the upside, I have spare parts...except for a coil, which is where I am at now. The ignition system checks out, mostly. The throttle speed switch is a little iffy, and the coil primary resistance is a tad too high.

This problem started as a couple of minor hiccups, which I assumed to be the fuel filter, since I had just removed the tank. Two hundred miles later, it started jerking like crazy. Now, it is way under powered on take off, jerks at mid range in each gear, and it feels the wheels cannot keep up with the engine. I also rebled my clutch, just to make sure.

So, I have not changed the coil or wires, and the resistance a tad off on both. I ordered new ones, so hopefully that will do it.

If anyone can explain why my full throttle switch failed the bentley test at 3000 rpms...I would like to know...

Also, the engine runs better with the fuel pressure regulator unplugged, and the vacuum line plugged. The regulator is new, and I do not have a pressure gauge.

Thanks for your help.

[cegammel]

So...here's a dumb question...does my aircooled 1980 vanagon have a throttle position switch?

[SlowLane]

So...here's a dumb question...does my aircooled 1980 vanagon have a throttle position switch?

Not as such. Just the Wide-Open-Throttle (WOT) switch that you've been messing with.

The switch is just a dumb reed switch, but the 3000 RPM business is down to the "OXS relay", which should be a black cube mounted on the left side of your engine bay, aft of the ignition amplifier and idle stabilizer boxes. If you don't have those items, then you may not have the full CA ignition setup.

The OXS relay basically just sits in series with your WOT-switch and monitors the spark frequency (via a tap from the coil). When engine speed exceeds 3000 RPM, the circuit closes and you get your full-throttle enrichment. The whole point of this was to prevent the catalytic converter from getting flooded with uber-rich mixtures and unburned gasoline at lower engine RPMs. Since you don't have a cat, you needn't worry about this too much.

You should really not run with the pressure regulator disconnected from the manifold. It's there to ensure that there is a consistent pressure differential between the input and the output of the fuel injectors. The ECU makes its injector timing calculations based on that assumption. As a diagnostic, however, the observation that the van runs better with the FPR disconnected suggests that you may be running lean, but I wouldn't take that to the bank, what with everything else that seems to be going on with your engine.

Done a valve adjustment recently?

[cegammel]

No valve adjustment yet...with the hydraulics, I assumed I would be good for a few thousand miles. The funny thing here is the engine ran great for 700 miles, then started this nonsense. I will check the valves out tomorrow. Thanks for the advice. I do have the full CA setup, and the speed limit switch checks out ok. The FPR was disconnected only as a diagnostic and to check that line for vacuum leaks.

[Amskeptic]

No valve adjustment yet...with the hydraulics, I assumed I would be good for a few thousand miles. The funny thing here is the engine ran great for 700 miles, then started this nonsense. I will check the valves out tomorrow. Thanks for the advice. I do have the full CA setup, and the speed limit switch checks out ok. The FPR was disconnected only as a diagnostic and to check that line for vacuum leaks.

Breathe. Ponder . . .

Engine runs better with oxygen sensor wire disconnected.
Engine runs better with fuel pressure regulator disconnected.
Problem developed over time.

All point to lean mixture.

Check ALL vacuum hoses (the little guys, remove and pinch, if you see splits on the ends, replace.
Check S-boot for crack in a pleat.
Check brake booster and breather and dipstick and oil filler, all can lean out the mixture..
Seems dumb, but if you have been fooling around back there, you can inadvertently annoy a hose that was perfect yesterday and leaking today.
Colin

[SlowLane]

Check ALL vacuum hoses (the little guys, remove and pinch, if you see splits on the ends, replace.
Check S-boot for crack in a pleat.
Check brake booster and breather and dipstick and oil filler, all can lean out the mixture..

And be sure to check the AAR elbow. Remove it from the car and give it a good once-over in good light. They frequently crack/split underneath where you can't see just by looking from the top. Carry a few spares of these, the cheap aftermarket ones are abysmally bad and can fail again in amazingly short time.

Buy OEM if you can. I can't vouch for this one from Airhead Parts, but they seem to be in the business of selling quality reproduction rubber parts. I can vouch that the same part from CIP is pure garbage (but that's a statement that one can generally apply to most of CIP's offerings).

[cegammel]

Vacuum is where I started this quest turnes crusade...I visually checked, pulled and checked, propaned, brake cleanered, and replaced every line. I have not replaced the throttle body to intake, but hosing it with brake cleaner did not affect engine speed. The brake booster made a nice pop when I pulled it, so it must be air tight.

I adjusted valves today, also no effect. They were still right where I left them. I di find that I put the dang catalytic converter on upside down...makes removing the valve covers a bit tricky...

[cegammel]

I hate to ask...but how would a leak between the head and cylinder behave? I have this annoying oil drop clinging to my lower baffle...and it frightens me...