And can I remove it? It appears to be something added when the car was Federalized. Both shops that have worked on the car have said so. Must be some sort of smog device? I've seen pictures of other 400i's without it, just the two regulators hooked together. It just seems to be one more point of failure that I can do without. It came adrift (actually, never secured after maintenance) and ended up near the alt belt which wore a hole thru the hose, leading to a large fuel leak. Happily we were able to repair it on the side of the road. (I now carry a fire extinguisher). And it has wires connected to it, what do they do? Where can I get the fuel line? It appears to be a HP double hose with hard plastic one the outside. What size and specification is it? TIA Image Unavailable, Please Login Image Unavailable, Please Login
It's an added frequency valve that gives a crude "with Lambda" functionality to the stock 400i K-Jet without Lambda system. If you replace the lines going between the WURs with the stock single continuous hose, you will have to readjust the mixture settings if the added aftermarket ECU is still operating that added frequency valve. If the added aftermarket ECU has been disconnected (and the mixtures were adjusted with it disconnected), I believe you could go to the stock single continuous hose between the WURs with no readjustment needed. The stock single hose (113925 Bridge Hose) is still available from Maranello Classic Parts -- item 9 here: https://www.ferrariparts.co.uk/diagram/ferrari/400i/010-fuel-injection-system-fuel-distributors--lines Or Larry Fletcher at CISFlowTech or Verell Boaen at UnobtaniumSupply could probably make one up for you (but you might need to send them your old assembly to get the end fittings and length right).
OK, that makes sense. Is this what the aftermarket ECU looks like? We determined I don't have one (this picture is of another car). Is there a way to check if there is voltage coming or going to the valve, i.e., what am I looking for for voltage if it's still connected? Also, doesn't it need info from the exhaust to function as a Lambda function? Image Unavailable, Please Login Image Unavailable, Please Login
Wow. It's scary what we used to do to modify fuel injection systems. The "frequency valve" is really a fuel injector with the pintle cap modified to accept a banjo valve. This means atomized fuel is running though that rubber hose. Even more scary is that K-jet fuel pressures (probably 70psi?) are running through those hoses that are supplying the injector that are secured by cable ties and Oetiker clamps. It's a fire waiting to happen. The grey plastic box and gold power resistor next to it power the "frequency valve". I would remove everything and return it to stock asap.
Yes. I have/had saved that same photo, and the file name I used says that that's the DC Johnson brand FAC-1 Lambda aftermarket ECU -- here shot of what the other white side looks like with the label: Image Unavailable, Please Login There is also a Neutronics brand Lambda aftermarket ECU from the same era that looks like this: Image Unavailable, Please Login Have you tried following the two wires connected to that added frequency valve to see where they go? The voltage between the two wires at the added frequency valve, I believe, would be going fairly rapidly between 0V to 12V DC if it was operating. It's an on-off valve device so they change the "on" time vs the "off" time to get a variable flow rate. You could also try measuring the AC voltage between the two wires as that would also sort of give an "average" result of a signal rapidly switching from 0V to 12V DC. Yes, to have the real Lambda operation you'd need an O2 sensor in the exhaust stream, but sometimes these ECU are designed to default to an "average" setting of on time vs off time if the signal from the O2 sensor is missing or if the system thinks the O2 sensor is not hot enough to give a valid signal (there is often a water temperature thermoswitch added to "tell" the ECU either: "I'm too cold so just ignore the O2 sensor signal and use the default values" or "OK, I'm hot so go ahead and use the O2 sensor signal to control the duty cycle of the signal going to the frequency valve"). I forgot to add that if you do remove the system and replace it with the Bridge Hose, you'll need to remove/block the return line from the frequency valve (it's the hose leaving the frequency valve on the right side in your photo and going off to the upper right corner of your photo). It probably also goes to a longer, double-stacked Banjo bolt so you'd need to get a shorter single-fitting Banjo bolt. Can you post a pic of where the other end of that return hose is connected?
A way to check it is to listen to its noise: under normal operation it does make an audible "buzz". If it's perfectly quiet, then chances are that the frequency valve is not operating. The idea was nice, too bad they did not make a proper enclosure/plumbing for these. As a side note it seems that on the OP setup, there is only one frequency valve? I though these modules were normally working as pair, one for each bank with independent control loops. This being said I like better, the idea to balance the control pressure with a common frequency valve.
Having the two WUR control pressures connected together (with the Bridge Hose) gives the same average control pressure to each bank, and a place where a single added frequency valve can alter that average control pressure going to both banks. If the two banks are left independent, you could you use two frequency valves (one for each bank), but that's just more complexity and needs two added ECUs. Adding the Bridge Hose between the two WURs on two bank systems (even when completely stock K-Jet without Lambda) was/is a good idea and should be done to all 400i and BB512i if they don't have it (and was included from the start on the early euro K-Jet without Lambda TR).
I've ordered the original fuel line, thanks for the link! I can't see where the red and blue wires go, they go up under the battery so I assume they end up someplace near the fuse box. No picture, sorry. A little more disassembly than I want to do right now. I checked the valve with the engine running but could not hear/feel any kind of noise or buzz (screwdriver in the ear high-tech method ) Will I be able to tell by something as simple as "driveability" if I unplug the valve and it feels like nothing changes? Or possibly plugs getting blacker because it's too rich (I'm assuming too rich, not too lean) I'll have to read up on adjusting the K-Jet system, don't you adjust the mixture by adjusting the fuel pressure or some such? My O2 guy is far away and now I want to get rid of the multiple points of failure of the fuel piping.
Does anybody have a picture of where fuel pressure gauges might be installed to check fuel pressure? Might be a custom look too, I've seen a lot of hot rods with these under the hood. Answered my own question. Looks like a lot of this has been covered, just hard to search for https://www.ferrarichat.com/forum/threads/checking-system-and-control-pressure-on-k-jetronic.373121/#post-141549790
Certainly no harm in trying that. Your report that the FV isn't buzzing/vibrating is a strong clue that it isn't operating (if you did this with a warm engine), and you can always plug it back in if it causes an obvious bad change.
Having a tough time finding the stock fuel hose and banjo bolts, all NLA. I can probably use most any HP fuel line. Does anybody know what the ID of the hose is? P/N 113664 & 113925
www.Belmetric.com has the banjo fittings, banjo bolts, and the (stock) black Polyamid Cohline hose if you want to make your own. For example: https://belmetric.com/rubber-hose-fitting-banjo-eye-single-cohline-series-8081/ The ID of the Polyamid Cohline hose isn't critical (the amount of flow is very low) -- 4mm ID would probably work, but 5mm or 6mm ID is probably the stock size: https://belmetric.com/hose/gasoline/?sort=featured&page=1 (at the bottom of page 1 and top of page 2) Can be a bit of a challenge pressing the barbed fitting into the hose needing some tooling to clamp/hold the hose just below where the barbs will expand the hose. I use a couple pieces of wood clamped together, then drill a hole a little smaller than the OD of the tubing all the way thru on the joint between them, then counterbore/counterdrill that hole with a slightly larger diameter a little deeper than the barb length ot allow for the expansion.
For a fairly reasonable price, Verell at unobtainuim supplies the polyamide hose and has made a special tool for fitting the hose to the banjo and fuel line fittings. There’s a bunch of posts if you dig into the 308 section of the forum. There’s enough hose supplied for you to screw up once or twice as well doing a couple of practices Sent from my iPad using FerrariChat.com mobile app
