I usually click on search, then advanced search and then do a title search. Choose your words well!

So after a full gasket rebuild I still had this annoying miss.
http://i237.photobucket.com/albums/f...ps0a96e268.jpg
Got my hands on a smoke machine today and I found the hole/leak!
http://i237.photobucket.com/albums/f...ps0b040318.jpg
http://i237.photobucket.com/albums/f...ps0b795aef.jpg
My friend has a 450SEL 116 Mercedes with the smiler CIS set up.
Note the gum coloured plug.
http://i237.photobucket.com/albums/f...ps3202cc71.jpg
Is there a plug that goes in this hole, I tried looking in the parts section but no luck.
I put some silicone in the hole to see if it stopped the miss, but motorway was blocked and couldn't sit on 120.
But it does feel like it has gone.

That hole is not on the vacuum side of the intake system. (Before metered air)
It is the access hole for the richness adjustment.

Did you service your injectors?

Yes injectors have been cleaned.
There are no other leaks that I can see.

One last bump before I sell intake and convert to an efi conversion kit.
Things I have done ,
All new gaskets, reconditioned injectors, o-rings new vacuum lines and has has a smoke machine air leak test.
The issues:
When it's warm it misses at constant speed and once warm when you re start it, it has a high idle 2k+ for about 5 minutes.
Are these two problems related.
I've read the bosh k-jetronic book cover to cover and It's a reasonably simple system.
So there must be a simple fix ?
Any help would be hugely appreciated.

Simplistic approach - What brand plugs are you using and have you changed the whole set, no matter how new they were? I had a similar issue with my 914-6 once; right after tune-up, an irritating miss at constant/trailing throttle. Hard acceleration, no problem; pulled great right to the limiter (7300 in this case).

Put the old plugs back in, problem gone. Threw out entire new set, installed another set, no problems.

My friend is the New Zealand importer for NGK , just called him and there are 3 listings for 911 78-83.
One plug is 3 dollars each and the other 20.
Will look into what I have in there and hopefully the end of this problem.
Also I'm running M&K shortys would not enough back pressure cause this problem?
Cheers

Test and confirm......
 

esonefoure,

If I were in your shoes, I would check the following:
1). Check the AAR and test it. It might not be closing completely when the engine is warm.
2). Check your fuel pressures (control and system pressures), both cold and warm condition.
3). Your airbox has been opened or fixed before. Look at the screws, they are not the OEM ones and you could see the glue around the perimeter. I have recently purchased several CIS air boxes sellers claimed in good working condition when removed. And they all failed the pressure test. Even a smoke machine has trouble locating the leak underside of the air box. A good way to test an air box is water immersion method.
4). Try to borrow a good CDI (Bosch or permadoom) and do a switch.
5). Inspect your ignition distributor's rotor, spark plugs, and ignition timing.
6). Inspect the fuel injectors' spray patterns.
7). Have your exhaust gas analyzed by someone with a gas analyzer.

Keep us posted.

Tony

Nice car mate, hope to see you on the streets of Auckland

http://forums.pelicanparts.com/uploa...1386279243.jpg

You will hear me before you see me.
http://i237.photobucket.com/albums/f...ps5e2b966c.jpg
Boyt911sc, thats a decent check list but so worth it if this problem is fixed.
Ill pick all the easy ones off first and go from there.
Thanks again for the input.

I also had some frustrating missing issues. They were completely cleared up by installing a set of Magnecor ignition wires. It's a pretty affordable way to rule out your wires as a source of fault. There is also a lot written about the annoying and tricky problems that can be caused by those "grounded" wires.

Before you do anything expensive... try the Magnecors. They're great, and even if you do decide to go the more extreme direction with your fix, the new wires won't work against you in any way.

Good luck. It's a great looking car and engine!

-Dan

I'm of NO help, but man, thats a nice color!

replace injector sleeves and Orings.

then i would do some injector flow and leak tests.

with each injector in its own container, power on the FP and check for leaks. then raise the sensor plate about half way and hold it. while filling the containers, check the spray pattern of the injectors. when done, compare each injectors fuel volume to each other.

So a small update,
Pulled the plugs out and they looked ok, but got some iridium to replace them.
http://i237.photobucket.com/albums/f...ps4tjacogk.jpg
http://i237.photobucket.com/albums/f...psgkofh2yo.jpg
New plugs look space age apart.
http://i237.photobucket.com/albums/f...ps1mcgenvk.jpg
http://i237.photobucket.com/albums/f...psj5z5jwsw.jpg
This didn't fix the problem but I guess im getting through the list.
Also ran some race gas left over from the drag car,
Smells so good.
http://i237.photobucket.com/albums/f...psymyxskjc.jpg
Been to a well recommend auto sparky shop and they think it's in the permadoom unit.
So might throw a msd kit at it and go from there.
Also these are definitely going to make any problem go away.
http://i237.photobucket.com/albums/f...sptm1vyiw.jpeg

Back on track to finding the air leak/electronic miss.
Bought a MSD blaster coil, rotor and cap.
Had it installed buy a autosparky friend of mine.
http://i237.photobucket.com/albums/f...psqg37chjo.jpg
It sounded so much more crisp and clean but still high idle and not running right.
So some new leads were the next on the list, as I found some that just fell out of the lead.
still running ruff and my patience was wearing thin, so I found a bumper to finish my clone.
http://i237.photobucket.com/albums/f...psbkoejvv0.jpg
My dad was down for the day to collect his drag car, We went over the electronic system started with
finding TDC with a paint brush in number one and for some reason the cap location was out.
Pulled dizzy out and made TDC right with number one and the mark on dizzy.
It started and for once I could see the timing marks with the timing light but still way out 10-11 o'clock.
Begining to get very frustrating and started to google EFI conversions.
Started to look into the MSD and Coil green wire, found a page on Pelican were someone was having issues "Green to Green and Purple to outer wire.
Dun Dun Duunnnn !
http://i237.photobucket.com/albums/f...pslsxcqiac.jpg
Temporarily wired it up, and it started no high idle TDC and 5deg were bang on never been happier and 2 days on still smiling, so happy I have this monkey off my back.
http://i237.photobucket.com/albums/f...psjuhxqebr.jpg

That was a bit fast.

What is the green to purple and outer wire problem?

Bad connection? crossed wires?

Glad to see those issues are over.

Green wire from dizzy goes to green wire on msd and the outer sheath? to purple.
There is no real clear instructions on this, unless I missed it in everything I read.
Was the permdoom unit wired in wrong, or was it just so faulty that a wired incorrectly msd preformed the same.
It's been a long road but fixing everything contributed to the making the issue disappear.

MSD calls the Violet + and the green -. on the porsche, the inner green wire is considered + and the outer braid is -. so you would think violet would go to the center or green conductor but it is wrong. here is why.
MSD wants a neg to pos signal. the bosch unit uses a pos to neg signal. normally the output of the dist has a slow rise to pos then a very sharp drop to neg. this transition is what triggers the MSD or bosch unit. the difference is bosch wants a pos to neg transistion and MSD wants a neg to pos transition. dont think of the signal like battery voltage were you have pos and ground, its more like AC in your house.
the problem with leaving it connected wrong is that due to the shape of the wave form, the slow rise to pos will trigger the MSD BUT, it will also advance the timing at idle AND as RPM's go up. i image there are a lot of people out there that just pulled the dist, like i amost dod, and just re-time the ignition. this is very bad due the the advance that is added in.

as RPM's go up, the voltage out of the dist goes up. as it does, that slooow rise of the "up side down" side happens sooner and sooner thus advancing the timing.

this is hard to explain typing, hope it helped.

Wonder if permadoom use the same pickups.
That made sense as to why a sparky can get it wrong.
Just over the moon it's sorted, need to get some k's (miles)on this thing.