308 QV WUR Issue/Odd problem?

Perusing the US QV diagram looking for WUR and related info-
Voltage to the fuel pump also goes to the protection relay, and warm up regulator, and supplementary Air Valve.

The coolant tank switch goes to the ECU's Electrovalve relay and controls several other things.

Cold Injector is relay controlled with voltage from the fuel pump relay which is controlled by the Air Flow Metering Switch. Cold Injector voltage goes through the Termp-Time Switch.

It's been my experience (when my temp-time switch was bad) that pulling the connector off the cold start injector solved my warm start problems.

I just compared the US QV and Euro QV diagrams and, golly gee moses, you fellows with the Euro QVs are so fortunate not to have the extra engine garbage the US models have.

I believe the WUR is a fancy air/vacuum switch with electrovalve. There was a thread earlier this year with great pictures of the WUR and servicing it. Sounds like yours need some attention. Believe in cold conditions it allows extra air into the plenum which is what many of us plug off to reduce the 3k idle to reasonable speed like 1.2k.

_________________________
http://www.ferrari308gtbi.com/

 

Mark,

I'm experiencing the exact same issues; please let me know what your findings are.

Cheers,

Warren,.

 

Are you sure you have your terminology correct?

The WUR is a rectangular-ish box with a round bit that has two fuel lines going to it. It also has an electric connection and one or two vacuum lines. It is usually mounted to the block or in some place where it will get warm with the engine.

The Auxilary Air Valve has an electric connection to it and an approx 1/2" hose goes through it. The hose goes from before the throttle to after the throttle. It has a big round disc part right in the middle.

The Cold Start Injector is mounted on the side of the plenum. It has a fuel line and an electrical connector going to it.

If you did disconnect the WUR, what did you disconnect? Vacuum? Fuel? Electric? All of it? Unplugging the electrical connection should actually have virtually no effect on the operation of the WUR or the car. The WUR has a little heating element in it, but in normal operation that heater is swamped by the engine's heat. Often the WUR is mounted to the engine block to get it good and hot and get an accurate indication of how hot the engine is.

(First pic is my WUR. Second pic is the PO's engine compartment with the three components circled. Your components will look the same even if they might be in slightly different locations. In fact, these components look the same across all the CIS cars from VW and Volvo to Jag and Ferrari.)
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Here is some good information on the WUR
http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1372083-warm-up-regulator-wur-calibration.html

"So the Warm Up Regulator is the element which sets the control pressure, and, when the engine is cold, lowers it, so the mixture is richer."

 

My 84 GTB QV acted the same way until I replaced the WUR. Bought a new one from Lyle Tanner Ent. before he went out of business. cost me $575.00. I would think if you did some searching you could still find one.

 

The WUR actually increases the control pressure when the car is cold. This increases the rate of flow of fuel, richening the mixture (correct for a cold engine).

As the engine and the WUR warm up the bimetalic spring acts to lower the control pressure thus leaning out the mixture (again, correct for a warm engine).

 

I'd call Larry Fletcher. He is the ultimate CIS Guru!

Larry Fletcher
CIS Flow Tech, Llc
19225 County Road 13
Fairhope, AL 36532
251-929-3771

 

My Bosch book says you have it backwards. From Gasoline Fuel Injection System K-Jetronic Technical Instruction Edition 2001, page 20: "When starting the cold engine, the control pressure is about 0.5 bar. As the engine warms up, the warm-up regulator increases the control pressure to about 3.7 bar (figure 26)."

But I don't think he disconnected the WUR anyway. If he unplugged an electrical connector and it made any difference, it wasn't the WUR or there are major issues not WUR related. If he disconnected the WUR fuel lines then the car wouldn't run.

 

Interesting thread.

My car behaves as it pleases.

It always cranks right up, then usually idles at 800 for a couple minutes, gradually rising to 1000.

I wait for the temperature light to go off and the water to move off the peg, then get underway.

Occasionally, idle speed will gradually rise to 2000, then drop down to around 1000, simultaneously with the temp light going off.

Engine runs perfect and smooth after that.

It's not an annoyance, but maybe I ought to look into the WUR?

 

Yep it's inversely proportional. I spent the last 2 hours reading K-Jet Tech Instruction, learned so much about WUR, FR, 50% duty cycles,..

I recommend CIS newbie to read it too, it will help you troubleshoot your problem, otherwise it's like swinging a bat in the dark.

Wish I can get my hands on the official Ferrari 328 K-Jet manual!

 

Terminology issues aside, the cold idle through the initial warm up cycle is control by the AAV (Auxilary Air Valve). When the engine is cold, this device creates a "control vacuum leak" from one side of the throttle plate to the other.

So...simply stated, if the AAV is not functioning properly, either mechanically or electrically, the fast idle when the engine is cold will not be correct. Another factor that can have advese effects on the cold idle is the "base setting" on the throttle plate angle.

If the WUR (Warm up regulator) is not functioning correctly, the mixture curve from cold to hot, will be incorrect. The base mixture setting is adjusted by the screw in the Fuel Distributor housing. To verify that the WUR is fuctioning correctly, several methods can be employed.

Set the base mixture with an exhast gas analyzer.
(If the engine has a frequncy valve/Oxygen sensor, a duty cycle reading will suffice.)
With the engine fully warmed to temperature, verify the AFR/Lambda (pre-cat, if applicable with a external wideband 02 sensor. Lambda should be steady from idle on up, if all is "in specs". Depending on the "preferred set-up", AFR could range from .97-1.02...

WUR functionality, cold and hot, can be verified as well with a fuel pressure gauge. If the OP did "disconnect" the electrical plug on the WUR, the idle speed may, or may not change..However, the mixture level will be richer than it needs to be during the inital warm-up period. As Mr. Harper stated, most of the heat "going into the WUR" comes from the engine...

It is the combination of the WUR richness curve and the controlled vacuum leak caused by the AAV that gives the engine the correct AFR and idle speed when cold and during the initial warm up cycle.

Best,
David

 

To further add to the confusion...

Ferrari uses on some models a WUR which utilizes a vacuum port. This vacuum port senses atomspheric pressure and adjusts the mixture (finely), accordingly. For those who are familiar with the Porsche 944 Turbo cars, Porsche used a similar WUR to adjust the fuel pressure under "boost conditions" to ensure that the mixture didn't lean out "under pressure", despite a "fully warmed up" engine condition.

Best,
David

 

I did a search & didn't find it. Can you post the link?
thx.

 

I had a similar problem, when cold, car starts great, idles at about 1500rpm for a minute or 2 then runs rich(stinks) and idle slows to 600-700rpm or so until warmed up, then idles perfectly at 1000rpm.
*My theory, the AAV heating coil is closing off the air valve(flapper) in the AAV too soon, thereby shutting off the extra air needed for warm-up, causing the car to run too rich. My fix(still testing) was to add a 3 or 4 ohm 3 watt resistor in series with the AAV connector, to slow down the closing of the AAV air intake, thereby allowing more air for a longer time. So far it's working perfectly but I won't know for sure, until colder weather hits. (the problem was the worst during cold-50-60 degrees or below, my last test was at 61degrees outside but near 70 in the garage).
When I confirm my theory, I'll do a complete write-up on the subject. It's a common 308 problem and this would be a cheap and simple fix.

 

I have the Bosch K-jet Instruction, PM me your email address if you want the file

 

They probably are connected, but they both are just heating elements, no switches or logic or anything like that. They shouldn't know or care what else is connected.

Yes, both the AAV and WUR have simple heating elements and that is all. And both heaters should be completely overcome by engine heat at operating temperatures.

I would check the AAV. Remove it and put it in the fridge for 30 mins. Look through the hole and you should be able to see right through it. Warm it up - leave it on you daily driver's hot engine for 10 minutes or be careful with a torch or heat gun. You should be able to see the shutter close off the hole as it warms. If you now have low idle I suspect the shutter won't open when it is cold.

You might also have an additional throttle bypass device that is vacuum operated through an electric soleniod that is activated by a thermo switch in the coolant. I don't know what, if any, Ferraris were equipped with this. Most CIS cars just have an AAV, but this additional device pops up here and there.

Never a bad thing! The official Bosch book is good and so is Probst's How to Tune and Modify Bosch Fuel Injection book.

 

Ask and ye shall receive
http://www.ferrarichat.com/forum/showthread.php?t=106594&highlight=WUR

And don't give me any flack about the 2006 date please...I'm still living in 1967

 

Thanks Brian, yes, you're absolutely correct. Perhaps it's more terminology than anything else. Functionally, basic element is that the WUR bimetallic spring acts to cause more fuel to be pumped through the CIS fuel distributor (richening the mixture) by way of fuel pressure.

 

Thank you very much.

 

Sounds like the AAV is closing off the fast idle air source, too soon, causing the engine to run rich. If you unplug the AAV heater connector, it will idle fast and not rich at all.(plenty of air)
*See my solution in the post above.
(I tried cleaning-testing the AAV but it made no improvement on my car-so I had to dig deeper)