85 308 GTS Euro: Throttle Body Vacuum Port Identification

On an unmodified euro 308QV, that hose port would be connected to the top port on the WUR -- hose #50 here (and the lower port on the WUR would be connected to the port upstream of the throttle plate):

https://www.ferrariparts.co.uk/diagram/ferrari/308-quattrovalvole/010-fuel-injection-system-fuel-distributors--lines (They mangled this drawing a little.)

On a euro 308 QV modified for the US that hose port would be blocked, and the top port on the WUR would be left open to atmosphere or (better) connected to somewhere upstream of the throttle plate.

In no case should that hose port be just left open to atmosphere (as that would be a vacuum leak downstream of the throttle plate). What is the Bosch part number on your WUR? Does your WUR have a lower port.

 

You are missing few numbers there (there should be three more numbers following the ...140) that might be stamped in and not cast upward) -- and the lower port, if present, is at the other end of the WUR.

PS (I edited my post so please reread).

 

That is hitting my often-wrong memory as an unusual (non-Ferrari) WUR number. Having no port on the top (pointing upward) is also very non-Ferrari. Will post picture later to clarify (but a WUR with no ports at all would only compensate for temperature).

 

Well, when you buy a euro version in the US there is some risk since it gets modified and then, usually, unmodified (often poorly) later . A search on that Bosch PN comes back as a BMW or MB WUR, and it might be quasi-appropriate IF the "with Lambda" modifications are still present. However, if the "with Lambda" stuff has been removed, or is disabled, it would be necessary to get the correct "without Lambda" WUR (as that's what adds enrichment during acceleration when "without Lambda"). Do you (still) have a frequency valve added into the CIS plumbing? If you can post a pic or 2 of your engine bay I'd be glad to give it a look over.

 

No, I would say that if it was ever modified to be "with Lambda", it's been removed. Here's a picture of a typical addition of a frequency valve to the 2-valve V8, and one of the banjo bolts at the WUR will be a longer one with two banjo fittings stacked on top of each other:

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If you do want to get back to stock euro operation, I believe the correct WUR for a euro 308QV is either 0438140078 for up to engine SN 728 and 0438140116 for engine SNs after 728 (but either would work OKish I think). Note the two hose ports -- one on top pointing up, and one at bottom pointing out to the side:

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Agreed, my very late 1984 Euro QV has a WUR number ending in 116, and has the port on top that is missing on the OP's WUR.
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SeattleM5 rebuilt it for me 5 years ago, along with the fuel distributor - it turned out that the WUR was near perfect, except that the bimetallic strip was broken... and Bosch doesn't sell a replacement bimetallic strip for the 116. They offer 69 variations of WURs, according to Special T Auto , and the -116 version isn't available as a rebuilt WUR either. SeattleM5 was able to use a replacement bimetallic strip from a WUR -013, which was only ever used on the 1978-79 SAAB 99

The WUR is a critical part of the K-Jet fuel injection system, and Bosch fine-tuned the WUR cold and warm fuel pressure maps for each version, so they're not readily interchangeable. For example, here are the fuel pressure maps for the -033 WUR for a Euro 2 valve 308 engine alongside the -116 map for the Euro 4 valve engine - those ranges are so different that even with adjusting a -033 WUR you couldn't get it within the operating window of a -116 WUR. You can find WUR fuel pressure maps on the internet (here's a good link about how WURs work: https://www.ferrarichat.com/forum/threads/wur-rebuild.547525/
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When we were researching for my WUR -116 bimetallic strip issue, I browsed Bosch WUR Cold Control Pressure charts on the internet and found that the -045 WUR in the 1978-79 Porsche 911 SC has almost the same control pressure ranges, close enough so that a -045 WUR could be adjusted to give control pressures within the 308's -116 WUR range. So, that's a backup plan for the future (and while the -116 is unobtainable because of the bimetal strip not being available, a rebuilt -045 WUR could be found for $270 USD, at least in 2018)

This was my -116 WUR test report from SeattleM5 after he installed and setup the -013 bimetallic strip:
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Gordon

 

The WUR is not a plug-n-play replaceable item as they have a large tolerance. The typical diagnostic procedure would be:

1. Confirm the regulated supply pressure is in spec.
2. Measure the WUR cold control pressure and the warm control pressure both with and without vacuum.
If something in step 2 is not in spec = bad WUR = return to Seller.
If all in step 2 is in spec = the mixture screw is tweaked at warm idle to give the correct air-fuel ratio.

 

The Bosch K-Jet without Lambda system (how Ferrari implemented it on 308 and Mondial) is in the Mondial8/QV WSM 281/83 Chapter D (specifically pages D37-D41 for the pressure measurements):

https://www.dropbox.com/s/z99soo68ny9n2qa/Mondial8qv_workshop_281-83.pdf?dl=0

but you should read the whole chapter D. It isn't necessary to have that exact test tool, but you might need to get some banjo bolts/other fittings to tap into the right places. Go to Youtube as well -- I'm sure people have posted videos about how to measure things like control pressure on a Bosch K-Jet system.

 

I agree with Steve, the next most appropriate step is to check CCP and WCP with and without vacuum to determine of the WUR is calibrated appropriately. Many years ago one of our Fchat members, Carl Rose, put together a testing protocol with photos: Ferrari 328 CIS Fuel Pressure Check (b2resource.com) . This is for a 328 but the process would be very similar for your 308. If you have any difficulties with the fuel pressure testing let me know, I have a fuel distributor/WUR testing rig and I'd be happy to test the WUR for you. Happy to do if for you for free if you want to cover the shipping costs.

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