Hoping to find the tiny fuel filters in the well of the CIS dist ports

Sorry for the wide distribution, but this situation covers many models, and also many marques. In the Bosch CIS fuel system, there are 8(or 6 for V12) fuel ports that feed the metered fuel up into the lines which go out to the injector.

When the distributor is separated, and the membrane is removed, there is a spring, and a spring metering ring in the well of the top half. Within that well is also a small, tapered filter screen on a ring. There is one for each injector port on the dist.

I have searched pretty extensively and been unable to find this filter for sale. According to CIS Flowtech they have them, and can replace them. They will not sell to me, if they indeed do have them.

Places I've looked:
rockauto.com
AutohausAZ
ebay.com
boschautoparts.com
bosch.com

A few other calls with no success. If you know where to get them, or have a part number, or any specific info on these filters, please let me know. I have three ports of the dist that are not flowing and I'm ready to remove the filters and be done with them. I've removed the filters on a 928 with no ill effect, except having to adjust the pressures a bit, but I would like to retain them if it's possible.

I'm concerned that trying to clean them in a naptha or Ventil Sauber solution might damage them chemically. I will be setting one in a ultrasonic cleaner before you recommend that, but these appear to have quite a bit of varnish on them from sitting too long(my bad, get over it).

 

Being a philosopher, I love why questions. I get to defend my decisions, and my right to do whatever the hell I want. And - what I still want, and don't have are the small filters for the well of the FD.

Sure, others can do the job. Writing checks is the way people are supposed to behave. It's like - DOH!,,, I just don't understand that. Being a hard-headed doofus is in my DNA. I'm just a rube with an old, cranky, low-rent, barely a Ferrari. If I had half a brain(I don't, I'm down to about 1/8), I would just follow label directions, cuz surely - vintage 80s mechanical FI is way, way, outta my league.

 

Here ya go.
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Whew, checked this thread, almost 200 views, and hoping I was gonna get lucky. But no, more advice.

I had this whole big spiel planned, but eff it. Not worth the electrons. Obviously no one has them, or is willing to share if these are avail.

Everyone seems to be focused on the calibration aspect, 'oooohhhhhhh - you gotta know this, you gotta have that, your car won't run'. Well, as a closing comment, you may want to look up metrologist, cuz I is one, certified and everything.

buh-bye.

 

cis-jetronic | eBay

 

New? Or used? I asked, but got no reply. I will try again. Thank you.

 

Thank you. Again.

I bought a small plane a few months ago. When the PPI was done, we took up the floor in the back to inspect the cables and pulleys that move the ailerons. When we got in there, what did we find? A nice, shiny 7/16" combo wrench, conveniently left in the belly, right next to the bellcrank where if it got wedged it could do the greatest damage to the plane in flight. Looked in the logs and found: "replaced left aileron bellcrank pulley and bearing due to being froze". About 2 years back. With the signature and lic number of the PRO mechanic that did the work. :yikes:

 

Yup, I got all the bits needed, and plenty of write-ups and also some very good armchair advice(pay someone). Still no winning on those little buggers though.

 

No prob, stuff goes NLA. Thanks for checking. I'm leaving them out, and going with an added filter in the pressure line downstream from the accumulator. The 928 runs fine without them, and the Golf runs ok too. I'm betting the Ferrari will do just fine as well. Now I can finish up and start tuning.

 

Ok, sports fans thought I would close the book on this thread. Since so many were concerned about the welfare of my FD.

I finished the job a few weeks ago, and since then have tackled the job on a 928 and another car, and I'm consulting on a DeLorean(remember those? 1.21 jigawatts!).

So far, three attempts and three successes. The 928 was a bit of a pain because the FD and stuff is buried under the fancy intake but we got it done. Now for the post-mortem.

The process is straightforward, I followed some online advice, some advice from the 400i website, and also some old folk lore. I replaced all my flex fuel lines with the new Cohline stuff and replaced all my injectors with new ones from some place on ebay, same part as goes in the 450SL Merc. The kit from ebay for the FD was quite well done. All the o-rings, membrane, and crush washers were in the deluxe kit, bravo. Took everything apart, clean, clean, clean, checked the system pressure relief valve and springs, replace all o-rings on the inner cylinder, cleaned the screens inside there. The little springs and the top hats were put on and adjusted for the exact height from the FD deck. I didn't go to the trouble of testing the springs for rate because I had a joker up my sleeve(later). Assemble and check the basic flow coming out the top of the FD looked ok.

Then, connected all my fuel lines, and found one that was fouled I think when I burned off the old Cohline I got a gob of goo on the end of the barb fitting. Had to redo that one. Checked my system pressure was spot on at 5.4 Bar, and control pressures were ok, but not to my satisfaction, a bit on the low side, so I took off the WUR and had a go at that as well. Wound up buying one gasket, and making another from stock material. Found some goo in the well of the fuel intake, possibly the low pressure point. Checked the resistance of the two elements, found some goo in the small vac line and cleaned it all up and assembly. Check pressures and they are right in the middle range now.

All the lines were going into home-made measure cups from old rattle can paint tops. I ran the flow test into those with the WUR disconnected(no matter, but hey) and found one cup was markedly higher than the other 7. So, I popped the little cap off that FD port and stuck my adjuster in there and then thought; 'hmmmm, which way do I go? Up or down?'. I finally got it right, and set the flow so all 8 were very close. Here's where the joker comes in...

So, we know that the air in the plenum is basically constant pressure, but all runners are not created equal. That is, some intake runners flow juuuuuuuust a bit better than others, and if the fuel is all perfectly equal, the F/A ratio is going to be slightly off for each individual bore. Added to that, not all injectors are created equal. Yes - they leave the factory with a spec but there's a tolerance of +/- some % which I am not privy to. What if - I were to get a good flowing air intake, mated to a poor flowing injector? That would be what we technical people call; A Bad Thing.

However, being the shade tree bum that I am, I figured there's a reason that little pressure adjuster is on each port of the FD. Yepper, I can match my fuel flow for my intake air volume(mass, whatev). But - the $98 question is how will I calibrate them? Hmmmm? Well, we have a vintage 80s car with a vintage 70s fuel injection so let's get in the way back machine and think like 70s people. Viola: Gunson Colortune Tuning Tool for Classic Cars | eBay Far out duuuuuude. Harsh my mellow.

Process: Get the car running ok, all jugs firing, set the mixture 3mm screw a bit too lean, and let it run a bit so we don't risk fouling a plug. Warm the car to operation temp and then pull a plug. I chose #3 on the rear to be my basis test point. Insert the Colortune, connect it up, start the car, and have a look see. Sure enough, it's a blue-white color, a bit too lean. Now with the car running about 2500 revs slowly richen the mixture screw in steps so that there's a nice blue flame. Shut down, replace the plug and from this point forward NO adjusting the main 3mm mixture screw! Our baseline is set, from here on out we will only adjust the individual port screws. Move over to #2, insert colortune, start car, check flame. This one was dead on same as #3. Move to #1, lather rinse repeat, color is good, but adjust a bit leaner, then go back a touch rich. Figure out that those port screws are super sensitive. Move on to #4, lather rinse repeat, and take a beer break.

The front bank represents a bit of a challenge because we can't adjust and see the results at the same time. I showed the adjustment process to the wife, and while I lay in the rear seat watching, had her adjust the #1 front port screw as it was definitely too rich, and now it's puuuuurfect. Finish up, clean up the mess, go for a drive, and the world is once again spinning in greased grooves.

Are my pressures exactly what is in the mfg manual? Don't know, don't care. The F/A mixture in my engine is tuned to perfection for each cylinder. Another way of doing this would be to remove the air injection ports on each jug and insert a EGT probe, then move to each jug and adjust. Yuk. I went back and checked the warm control pressure and it was a bit on the high side now. Hey, maybe my fuel consumption will be better!

YMMV, don't try this at home, pro driver close course, objects are larger than they appear, contents have settled, and may cause anal leakage.