hupp

My '79 seems to be running rich -- symptoms: smelly exhaust, soot on tail pipe, small "pop" in exhaust after reving. I've also pulled the plugs and they were a bit sooty but not too bad.

I've been trying to chase down the gremlins and could use a little help getting my head straight. Everything but the fuel pumps, accumulator and fuel distributer have been replaced. I put the gage on the shark over the weekend and checked the pressures. Cold control pressure was about .3 bar too high, and warn control was right at the upper tolerance of 3.8 bar. One would think the car should be running lean with high control pressures. This leads me to the following questions:

- Is it possible that adjusting the CO screw too far rich (to compensate for the high control pressures) would cause the mixture to be overly rich? OR will this adjustment even be significant since control pressure typically governs mixture. When I replaced the WUR the shark was very hard to start, so I began adjusting the CO screw to rich. I adjusted until the shark started, more until it stopped missing then finally turned a bit more to rich.

- Does tapping in the plug on the WUR lower both cold and warm control pressures by the same amount?

Dennis Wilson

Scott,

If your control pressure is good warm, then I would leave it there as the high cold pressure could be from dirty contacts or high resistance due to age of the heater. To set the air fuel mixture move the adjuster to lean until it starts to miss or idle badly. Mark that point, then move it to rich until it starts to miss/cutout. Mark that point, then move the adjuster back to lean then back to midpoint plus one or two degrees. This should put your A/F mixture just on the rich side of stroimetric (sp?). The popping on deceleration may be due to an internal leak in your deceleration valve. BTW tapping down on the WUR plug will move the valve seat closer to the seal and reduce both the hot and cold control pressures.

Dennis

jpitman2

wHICH wur PLUG ARE YOU TAPPING? the recessed small plug (~10mm dia) will lower control as it lowers the arm supporting the spring inside. Not sure if bothe cold and hot seetings will change by same amount ? Tapping the big iron thing with the pipe connections will press the valve harder on the spring and raise control. BTDT. From what I have heard the idle co screw is VERY sensitive - you need to press down to engage it, turn very slightly, relax pressure to allow it to settle, pause a bit cehck for result. Best done with a CO meter up the bahamas....
jp 83 Euro S AT 48k

hupp

pitman,

I haven't started tapping anything yet, but the small plug would be the one I go to.

Dennis,

My WUR is new. I have not adjusted one thing since installing. The cold control pressure has been a bit high from the beginning. The shark does not pop too badly when decelerating under load. The popping is more evident when reving the engine -- Vroooom....pah, Vrooom....pah

I've tweaked the CO mixture about as much as possible - using the method you refered to. I just can't seem to keep the old bugger from running rich. The exhaust smells whether adjusted to the lean or rich side - although it does smell less when adjusted lean but runs like crap.

Sean79 5spd

Carefull tapping that either plug in the WUR, pulling either back is much more involved e.g. disasembly. Check that the vacum hoses to the WUR are correly routed and not leaking and confirm mixture setting before attempting to mess with the WUR. If your WUR is new but out od spec, send it back. IF ypu follow Dennis's procedure dor setting mixture, you can get fairly close.

I have adjusted my WUR but it invloves a lot of screwing around.

Sean

hupp

Sean,

Seems as easy as hooking up the gauge then gently tapping the brass plug until desired pressure is reached. What did you find to be so tedious?

Sean79 5spd

How hard you tap is learned. I found that I ended up tapping a little too much then having to pull the WUR off the car, disassembling, knocking out the plug, reassembling, re-installing and starting again. Also, as Dennis says, you will change both hot and cold pressures when you make these adjustments.
I'm not saying don't do it, just be prepared for some iterations of the process.

Good luck
Sean

hupp

Sean,

Thanks for the info. My warm control is at the upper tolerance so I have a little room. By the way, have you ever had any problems with the exhaust smelling? Could this be because I have no cat?

Sean79 5spd

The exhaust will smell when the fuel / air mixture is too rich. This can be the result of a too rich fuel mixture or a plugged air filter. I noticed you said your pluggs were a bit sooty. I think this can also be a symptom of rich running.
Sean

jpitman2

Is your system pressure in spec, or high? Mine is right on 75psi, with hot control close to 50 after a soak - throroughly hot through - which is a tad high. My wrench adjusted mix to 1% CO, and it starts pretty well, and pulls like dynamite. If you system is high, makes sense for control to be high, which sort of evens out , except for the injectors being closer to base opening pressure all the time. If you tap the small pos inwards, do it in very small steps, and let the system stabilize before doing more. Have you tried to see what happens if you crack open the WUR return line and reduce control? Curious that you say it seems rich, when high control should give a lean mixture. Sounds like adjusting the mix at the air plate to compensate for high control is taking it right out of spec somehow, something non-linear is occurring.
jp 83 Euro S AT 48k

Dennis Wilson

A leaking injector or heaven forbid a bad o ring in the distributor would cause a rich mixture when everything else is set right. Have you looked at all of your plugs to see if one is sootier than the other? Also, are you running the correct heat range of plug? Another possibilty is low/marginal voltage to the coil. How are your resistors and connections?

Dennis

hupp

pitman,

System pressure is 5.1 (75 psi) - on spec. I have not tried cracking the return line open, but have tried depressing the sensor plate a very small amount by hand when starting cold. Result, she idles great. Let go, back to sputtering an missing when cold. I have also assumed that I have adjusted my CO screw too far rich to compensate for the poor running, but was told that the CO adjustment would not be significant enough to cause the exhaust to smell if control pressures are high.

Dennis,

The injectors are new. Regarding the o-ring, are you refering the the o-rings in the push valve assembly? The plugs are Bosch WR8DP, and they all looked the same, snd not overly sooty. I have not checked the resistors, but coil connections are good. Is there a method test the resistors/coil?

Also, for clarification. No cats on the shark and I have made the assumption that the shark is running rich based on the popping in the exhaust when rev-ing (vrooom...pah), and the strong smell. Easy to assume unburned fuel in the exhaust.

Dennis Wilson

Scott,

The o ring(s) I was referring to are small o rings at the port for each injector. They are located inside the fuel distributor and if one is bad it allows system pressure (too high) at the injector. Concerning the resistors, one is .4 ohm and the other is .6 ohm. When cranking, power to the coil will only go through one resistor (.6 ohm) and when running, the power goes through both. When running (key at on position) there should be 3 volts minimum at the 15 terminal of the coil.

Dennis

jpitman2

Scott,
Watson says to check pressure problem causes by following the line....crack open the WUR outlet - if pressure drops, WUR is NOT the problem, move to next union; if it doesnt drop, WUR is problem, or some earlier point - there is a connection en route isnt there, under the spider?. Next union is return line at distributor - crack open, check result. FInally you end up at the tank return point. If system is 75psi, main regulator is ok, so I would start following the WUR tests. Once that is right, reset the mixture adjuster.
jp 83 Euro S AT 48k