Need CIS help... of course

[Schulisco]

Originally Posted by McGalliard

How does one do this? Where is the recommended access point? I don’t have a lot of vacuum components on this model. Maybe 2 lines?

Thanks

You forgot the rubber bushings on the intake runners, airbox, throttle housing, rubber boot on intake, all sealings where vacuum / air is in...there are plenty of sealings...due to the heat within the engine compartment the rubber gets harder over the decades...

https://www.youtube.com/watch?v=j80k3n_IKkQ
https://www.youtube.com/watch?v=QNdQ04halLM
https://www.youtube.com/watch?v=QtlZRlv85zY

I heavily recommend the video series from Klassikats about the 2.7 CIS 911 to inform yourself about it:
https://www.youtube.com/playlist?list=PLkWFofpgz2OgF9FdliKnlzuY0pygqRkMj

Thomas

[boyt911sc]

Lachlan,

If you could not get the fuel pressure reading correctly after almost a year of testing, something is terribly wrong. Either you lack the skill or your tools are deficient. It takes a few seconds to measure the control and system fuel pressures. And I could test the control and system pressures simultaneously easily under 5 sec. To help people like you, I offer to do the testing myself.

Last year, I offered to test them for FREE and you ignored it. But if you ever change your mind, you know where to find me. Or find someone near you to help you. Good luck.

Tony

[ahh911]

I did not realize this has been ongoing for almost a year. Sorry to hear that, sometimes I recommend saving time and money by sending every component you can remove to someone who can evaluate each part. That way you have a known starting point and some hands on help hopefully.

Phil

[McGalliard]

Originally Posted by boyt911sc

Lachlan,

If you could not get the fuel pressure reading correctly after almost a year of testing, something is terribly wrong. Either you lack the skill or your tools are deficient. It takes a few seconds to measure the control and system fuel pressures. And I could test the control and system pressures simultaneously easily under 5 sec. To help people like you, I offer to do the testing myself.

Last year, I offered to test them for FREE and you ignored it. But if you ever change your mind, you know where to find me.

Tony

While I have been working on this car over the past year, it has not nearly amounted to a year's worth of work. My time and energy are very sporadically and sparsely devoted to this car. The fact that tools could be deficient has already been discussed. You don't need to be condescending about any of this.

I have yet to hear someone say, "hey those pressures means your FD and WUR need rebuilding".

[McGalliard]

Originally Posted by Schulisco

I heavily recommend the video series from Klassikats about the 2.7 CIS 911 to inform yourself about it:
https://www.youtube.com/playlist?list=PLkWFofpgz2OgF9FdliKnlzuY0pygqRkMj

Thomas

Klassik ATS is amazing. Love his vids. I have watched many. Makes it all look so easy. I often dream about just taking the car up the Taconic Pkwy to him. But... where's the fun in that?!

[McGalliard]

Originally Posted by Schulisco

Please post a picture from the sensor plate resting position from underneath that we can see where it is sitting in the cone of the sensor plate housing.

Thomas

How are those?

[Johner]

Originally Posted by McGalliard

My 3am cogitations concluded that I MUST have an issue at the FD (to the WUR). I would bet that the CCP and WCP pressures are not absolute 0, but so low as to not register. And yes, as ahh911 points out, the car runs so sufficient pressure must reach the injectors to open. This must be true. I too have thought that the FD to WUR path might be blocked or rather markedly narrowed, but it's not at the line between the two, so possibly in the FD itself? I don't really understand how fuel is diverted and directed in the FD, especially with respect to the WUR pathway. However, I would like to think that based on a recent rebuild of the FD and a lack of change of behavior before and after FD rebuild, that a problem inside the FD is unlikely, though not entirely ruled out.

Johner, I had already read your prior threads and posts about a janky pressure gauge and quick connects being an issue. I meditated on this yesterday too. At first glance, I do not see an easy way around them. At least not with the kit as it comes. So, I guess I will have to do some plumbing to be able to use the T and valve but remove the quick connect.

Did you come across this thread http://forums.pelicanparts.com/porsche-911-technical-forum/838021-harbor-freight-cis-fuel-pressure-tester-review.html? This gives some clues about the issues I was having and how to fix them. If you have the same cis test kit this may help figure out if the results are real or just down to the test setup

[McGalliard]

I had not seen that thread before. I guess I need to get the valves out, although I am not using the HF system. I will remove and repeat pressure testing.

Thanks, John

[Schulisco]

Originally Posted by McGalliard

How are those?

Seems to be too low. The correct sensor plate position is cruicial for a good running CIS. It seems that someone tinkered it due to other issues. Pretty typical on a CIS without the knowledge required.
Here I linked to the basic setup procedure by Porsche for all CIS.

https://forums.pelicanparts.com/porsche-911-technical-forum/1167170-cis-hard-cold-start-idle.html#post12323466

After you adjusted it that way your car probably won't start or still have other issues. Unless they've been solved, car won't run properly. But after making the basic setup, consisting both sensor plate height together with the start of the fuel pump while being lifted by air you have not to touch this any more and instead sorting out the other issues. This is the way to do meaning going backwards through the whole system. People don't know it better and instead lower the sensor plate to enrich the mixture most likely due to vacuum leaks. But what they do in real is that they shift the working points of mixture and sensor plate out of specs which in consequence results in bad performance, bad mileage, stinky exhausts etc.

Thomas
.

[boyt911sc]

Originally Posted by McGalliard

While I have been working on this car over the past year, it has not nearly amounted to a year's worth of work. My time and energy are very sporadically and sparsely devoted to this car. The fact that tools could be deficient has already been discussed. You don't need to be condescending about any of this.

I have yet to hear someone say, "hey those pressures means your FD and WUR need rebuilding".

Lachlan,

You had PM me a lot in the last six (6) months about your current CIS woes. Asking for my opinion about the condition of your FD & WUR, and I refused to give you any answer unless you had pertinent information to share with me. The CIS pressure tests you had collected made no sense at all. So I offered to do the testing myself and get it evaluated.

You replied that you were not ready to send them to me. That’s OK but don’t expect people to give you a good feedback without testing them. All the fuel pressures data you got were questionable and unreliable.

Let someone with experience do the testing for you. You don’t have to send them to me. Find someone else. Wish you luck.

Tony

[fanaudical]

Originally Posted by McGalliard

I have yet to hear someone say, "hey those pressures means your FD and WUR need rebuilding".

My opinion: The reported test pressures are so far off from where they are supposed to be that we're all concerned about the validity of the pressure test. I brought this up in the first reply. Once we're confident the pressure test is valid then we can offer advice on the component health. All the comparisons of WUR functionality rely on meaningful pressure test results. (I'm sorry to beleaguer this point, but it's important.)

It's possible the gauge itself is not functioning properly. You can test the gauge by connecting it to another pressure source (such as compressed air) and having a second gauge connected to the same pressure source. Slowly ramp pressure from zero to ~6 bar and back see if the two gauges track. I highly recommend doing that before doing any other fuel pressure testing. I've seen gauges that were off by 1/2 the scale in industrial settings.

Everybody else is raising great points about potential seal leaks in the airbox, injector seals, etc. Those all contribute to running/drivability problems - but do NOT contribute to the fuel pressure test results.

Before tearing into everything else, I still think you want to get a valid pressure test. I would start with investigating your test gauge as described above and then repeating the system pressure test. Once you can test it and feel confident that is within a valid range then we can move on. The WUR is isolated during the system pressure test. The fuel metering operation of the FD is also isolated during the system pressure test; the only part of the FD that affects the system pressure test is the fuel regulator, and that is readily adjustable by adding/removing shims as required to get achieve the proper pressure.

Data I have for my '75 (which has the same FD and WUR as yours):

System pressure - Valid range for testing = 4.5-5.2 bar
System pressure - Set between 4.7-4.9 if adjusting the regulator shims on the FD.

[PeteKz]

Listen to fanaudical. You must verify your gauge reads correctly. Then we can move forward. Vacuum leaks and the other stuff does not cause SP and CP problems.

Furthermore, given how long you have been futzing with it, you should take up Tony on his offer to test your WUR and FD. Send them to him, you will have them back in a couple weeks, and you will KNOW whether they work correctly.

[silverlock]

“$50-$80 in return shipping costs to Tony can save months of posting.”

[McGalliard]

Alright gang, I’ve got some updates… I removed the internal valve component of the pressure gauge and now the pressures make sense. So dumb that they should be so easily fouled up. Anyway…

We are still off the charts for temp here for the next few days, but at least one problem is solved. When the weather warms up I will repeat these measurements, but for now here’s what I have (just for fun):

@4 deg C
Cold control pressure: 1.8 bar
System pressure: 4.55 bar
Warm control pressure
- 1.0 min: 2.0 bar
- 1.5 min: 2.2
- 2.0 min: 2.3
- 2.5 min: 2.4
- 3.0 min: 2.45
- 3.5 min: 2.5
- 4.0 min: 2.55
- 4.5 min: 2.6
- 5.0 min: 2.65
- 5.5 min: 2.7
- 6.0 min: 2.75
- 6.5 min: 2.8
- 7.0 min: 2.8 bar plateau…

Note: I intended to post this last night but it never uploaded.

Also, let me say that it was unclear to me that the testing of the FD and WUR offered by others was the exact CCP, SP, and WCP that we’ve been discussing. In retrospect, that seems obvious to me now, but as I’d said previously I am new to this game.

[McGalliard]

Originally Posted by Schulisco

Seems to be too low. The correct sensor plate position is cruicial for a good running CIS. It seems that someone tinkered it due to other issues. Pretty typical on a CIS without the knowledge required.
Here I linked to the basic setup procedure by Porsche for all CIS.

https://forums.pelicanparts.com/porsche-911-technical-forum/1167170-cis-hard-cold-start-idle.html#post12323466

Thomas
.

Thanks! I will read through this post

[McGalliard]

Repeat view of the plate from the top down with the trick of a light shining up from below (as seen in one of these other referenced threads). It’s not as flush as I originally thought it looked. Will measure with a feeler gauge when I get my hands on some.

[Schulisco]

Looks not too bad, BUT: The influence of the setting / rotating the mixture screw (which is basically a very precise fine tuning screw of the sensor plate height)is huge! Only turn 1/8 rotation of the mixture screw at the time on every single step.
Refer to the Porsche procedure as I referenced above! The sensor plate height must be adjusted meticously! You can easily bend the spring under the sensor plate to adjust the position. SCs have a screw there instead. This makes it more easy to adjust.

Thomas

[McGalliard]

Yes, I have read other stories on here whereby the mixture screw was likely adjusted inappropriately. Just to clarify, the mixture screw does NOT change the plate position? The plate position is changed by bending a spring underneath? Seems too imprecise to be German. Or is it that the spring is macro-adjustment and the mixture screw is micro-fine tuning? I thought the mixture screw controlled a bypass channel of some sort. I have the whole set of Porsche repair manuals and several Bosch service guides, so I guess I should find the source reference and follow the instructions.

[930cabman]

Might sound crazy, but my 1975 911S 2.7 has not run correctly since I got her back from a reputable engine rebuilder in N Ohio two years ago. Tony has reconditioned the WUR, but many parts/connections remain.

Considering ditching the CIS and going with Webers

anybody else? I have found Webers are much more simple than 50 years old FI stuff

[PeteKz]

Lachlan: good to hear you got the readings correct now.

Do not make any other changes yet! Instead, drive the car hard and put a few tanks of fresh gas through it, along with a bottle of Chevron Techron Concentrate for each tank. After you have done that, report how the car is running.