CIS fuel pressure test - correct values?

I have the Mondial service manual with the fuel pressure check procedures. It says it can be used with the 308/328 with the appropriate supplement. The supplement has no reference to Section D (the fuel section), so I am working under the assumption that the information given in the Mondial manual is correct for the 308/328.

The cold pressure for a U.S. spec car should be between 1.6 and 2.0 bar at 10 degrees Celsius. Warm pressure should be between 3.3 and 3.7 bar. Note that this is with 550 millibar of vacuum applied to the WUR. The manual doesn't give cold values without vacuum, but the hot value drops to between 2.5 and 2.9 bar without vacuum.

If you aren't applying vacuum to the WUR, it looks like your pressures are pretty good.

See the attached pages from the manual.
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Hi Mr. Gigante,

I can't seem to find it at the moment, but Ferrari released a "K/KE-Jetronic" separate service manual of about 50 pages dedicated to the Bosch FI systems (Ferrari Bosch KE3-Jetronic 3.2 Mondial/328 factory manual #539/89) that may be where I copied the values from. In the Probst book, page #18-19 of "continuous injection - troubleshooting and service" the WUR cold pressure is listed from 1.4-1.8 bar (22-26 psi) and warm 3.4-3.8 bar (49-55 psi). On my testing (cold with engine off, warm with engine running/vacuum connected) I saw 20psi/51psi.

Hope this helps,

Carl

 

You need to get your WUR Bosch number. I am not certain what would be on a euro spec car, but my guess would be 0 438 140 116. The number is on the top across from the plug. The first 7 numbers are raised in the casting and will be 0 438 140 the next 3 numbers are stamped into the casting. Let me know when you get the number and I can get all the test specs to you.

Larry

 

OK the pdf file that Bandit posted has your info in it. Your WUR is the one in the center of the page. If you test with the engine off and fuel pump running, unplug the WUR and use a hand pump to pull a vaccume on it. You want to pull the vaccume on the small nipple on the lower part of the WUR not the one on the top. The 550 mbar pressure is an absolute pressure number, any thing over 200 mm or 10 inches will be fine. Once you find cold pressure on the graph and check it, plug the WUR up and it should reach warm pressure in about 2 to 3 min. Then dump the vaccume and see how much it drops.

Larry Fletcher

 

Coincidentally, I've just check my pressures on my 85 308 USA QV last night and ran into almost the same issue. All pressures were within allowable ranges printed in specs except when I applied "warm" vacuum to WUR, where my control pressure shot up to 71psi at 510mbar and 74 at 550mbar.

I have a few questions myserlf that seem perfect for this thread. I was hoping someone could explain what this vaccum connection is supposed to be accomplishing....In other words, what load/operating conditions will put sufficient vacuum on this port, and wont an increase of control pressure lean the mixture out? Why do some cars use TWO vacuum connections from the WUR (one in front of throttle plate and one in rear), and on cars like mine that have a single vac connection on top of WUR, and most importantly, is it supposed to be connected in front of(engine side) or behind(fuel distributor side) the throttle plate?

 

When you lift off the throttle at high RPM and the RPM is falling -- no need to run at a low A/F ratio.

Don't know this for sure, but this can be related to the designers just getting smarter with experience -- e.g., realizing that using some other pressure difference in the system is better for controlling the control pressure. This is where the diagrams in the SPC and the OM (for your exact model/version/year) can be invaluable (to make sure what you have is "original" and hooked up correctly). I do know that the K-Jet WUR plumbing is different on different models/versions/years as you've noted (hence the gaggle of different WUR part numbers), and, since some WURs are no longer available, there's been a fair amount of mis-substitution. If you can post OM or SPC illustrations of the K-Jet systems that you are interested in, that show the connections, I'd be glad to comment.

 

Full-load enrichment Engines operated in the part-load range with a very lean mixture require an enrichment during full-load operation, inaddition to the mixture adaptation resulting from the shape of the air funnel. This extra enrichment is carried out by a specially designed warm-up regulator. This regulates the control pressure depending upon the manifold pressure. This model of the warm-up regulator uses two valve springs instead of one. The outer of the two springs is supported
on the housing as in the case with the normal-model warm-up regulator. The inner spring however is supported on a diaphragm which divides the regulator
into an upper and a lower chamber. The manifold pressure which is tapped via a hose connection from the intake manifold downstream of the throttle valve acts in
the upper chamber. Depending upon the model, the lower chamber is subjected to atmospheric pressure either directly or by means of a second hose leading to the
air filter.
Due to the low manifold pressure in the idle and part-load ranges, which is also present in the upper chamber, the diaphragm lifts to its upper stop. The inner
spring is then at maximum pretension.
The pretension of both springs, as a result, determines the particular control pressure for these two ranges. When the throttle valve is opened further at full
load, the pressure in the intake manifold increases, the diaphragm leaves the upper stops and is pressed against the
lower stops.
The inner spring is relieved of tension and the control pressure reduced by the specified amount as a result. This results in mixture enrichment.

With thanks to Mike Blount and the Bosch technical manual for the foregoing. Russ

 

Kevin,

Check your WUR number, it should be and probably is 0 438 140 132. If so this is a altitude compensating WUR and the above info does not apply. When you put vaccume on it it reacted like being on a very high mountain. I don't have a way to upload the spec sheet here, so call me and I can fax it to you.

Larry
251-929-3771

 

Larry is absolutely and 100 percent correct here about the altitude-compensating WUR. I have found that owning a 1985 308 poses an extra challenge because of the lack of doccumentation for this model year. I have figured out that since this was the last year for the 308, and the first for the 328, several "improvements" and changes that were designed into the 3.2 motor were also implemented on the 85 308 motor, but was never properly documented.

The 1985 WUR seems to be one of these things, and does anyone have the correct warm and cold control pressures for this model (ending in 132)? This also beggs the question......how then does this car provide accelleration and high-load enrichment, if there is no vac feedback? What about leaning the motor out upon decelleration, does this happen? At first I thought these are being be done by the lambda system, but it just does not seem possible that this system can "react" quick enough when you punch the throttle. The throttle microswitch can detect fully-closed and wide-open throttle states, but the lambda computer considers anywhere in between these extreemes as the same state. When I punch-it, rarely do I mash the accewllerator to the floor. Do I need to adjust my driving style to get full power on accelleration? Does anyone else have a 308 equipped with a lambda system and a vacuum enriching WUR (top and bottom hoses, ending in 040)? I would really like to understrand what is going on here.

 

Your question implies that, since the WUR is altitude-compensated, it must do nothing to the control pressure during a warm-running throttle blip or warm-running moderate throttle (i.e., during low manifold pressure) -- I don't think that that can be directly concluded (but don't have any documentation, and with the FerrariUK parts site down can't access the US 308QV SPC figures -- can anyone post?).

I do think it is true that: 1) if the WOT switch is not closed during acceleration, the duty cycle supplied to the FV is not changed so no extra enrichment is added, but, 2) if the WOT switch is closed during acceleration, the duty cycle supplied to the FV is changed by some sort of offset value to add enrichment. If you measure the duty cycle (or maybe the voltage) across the FV terminals during warm-running acceleration with the WOT switch both open and closed, you should detect this difference.

Good luck with your quest -- and post what you find!

 

Ahh, the plot thickens! And this is one I really want to understand. Since the only vacuum signal to the 132 regulator is just a connection to "atmosphere" (behind the throttle plate, this area will never give the WUR a signal beyond the static air pressure. For example, If I was racing my car up pikes peak, the WUR would lean out as I ascended based on the lower air density to keep the air/fuel ratio the same. If I was coming out of a corner and hit the throttle from near idle up to about 70%, you would think the motor should get a slightly enriched "burst" to help the motor accellerate (like a carb might spray fuel into the throat). My car does not seem to have any type of mechanism to do this.

Where it really gets strange is when I found this Q&A item on the net somewhere (sorry so loing):

IMPULSE SWITCH????? Never heard that before and I know that my car does not have one under the coolant tank. I only have the IAC valve and Air Injection solonoid valve under there. This post is supposedly regarding the same car as mine, and although it is a little more comforting knowing I am not the only one looking to address this issue, why is this guy having to jimmy-rig something to provide enrichment under accelleration and high load?

 

Can't really respond well here without the SPC figures from the FerrariUK parts site. IIRC, on all '80-'88 US version 308/328 K-Jet there is at least 1 coolant-based thermoswitch used for detecting and/or differing cold-running vs hot-running functions -- so, if yours is a US version, it should have one somewhere; if euro/standard version then not.

I can't recall exactly where the WUR vacuum connections are, but I don't recall any with none, and I believe you are mis-describing that 132 set-up bit. On the early set-up, the pressure difference is between a port on the downstream side of the throttle plate (which will be less than atmosphere at idle) and the "open" atmosphere port. When you open the throttle, the pressure on the downstream side of the throttle plate rises so the difference to atmosphere is now less -- and this lower pressure differences causes the mechanism inside the WUR to reduce the control pressure which allows the FD plunger to move further for the same inlet airflow (i.e., adding enrichment when under high load). The later configuration compares the pressure difference between the port on the downstream side of the throttle plate and a port on the downstream side of the airflow metering plate. If we ever get access to those US version SPC, maybe we can have a better discussion.

That "fix" isn't so great IMO -- by always holding the WOT switch closed, the system will always run as an overrich "dumb" K-Jet without Lambda. He's just masking the real problem and wasting fuel out the tailpipe (which is sort of how carburettors work ). You could probably get the same result by just unplugging the O2 sensor and tweaking the mixture screw to "very rich". Wouldn't help the life of a working catalytic converter.