Very nice engine, K9, very nice.

I'd paint the oil cap red to match. :)

If you don't have it yet, I suggest you'll get a Bentley SC Repair Manual and check the diagram on page 970-9. The Airflow Sensor Contact is on the bottom and you can see how it is wired. It is located on the back of the CIS on the Mixture Control housing. A lot of the CIS components are in the back and hard to see or reach.

Someone may have disconnected the ASC, or made some changes that are not stock.
You want that to work for reasons mentioned.

Love that engine. :)

Not recommended. The TTS is there to prevent the CSV from squirting when the engine is hot to prevent potential flooding and/or fouling the plugs.
Band Aid Solutions generally compound problems.

I'd trace the problem and fix it. :)

A used, working TTS is much less than $200.-, leaving him some money for beer. :D

The unfortunate thing is that about half of the people asking for help never report back to tell us how they fixed the problem.

Very unfortunate. :(

Wow!!!! What a beauty you got there........
 

Todd,

That's a beautiful and clean engine!!!! Is that a modified air box? Just behind the throttle body is the AFS (air flow sensor/switch). What it does is supply ground connection to the FP relay (terminal #85). Here is a summary how the FP relay works:
Terminals #30 & # 87A........are N/C (normally closed).
Terminals #30 & #87...........are N/O (normally open).
Terminals #86 & #85...........terminals for the coil (trigger)

Terminal #30.......................FP, WUR, AAR, TTV are all connected to this terminal.

When you turned the IS (ignition SW) to ON position (not start) power is delivered to terminal #87A (FP relay). Since #86 and #87A are shunted (connected), the coil is energized provided #85 is grounded. Thus causing normally closed (#30 & #87A) to switch to OPEN. So there is no POWER going to the FP (terminal #30). So the FP should not be RUNNING at this point.

However, if you lift the sensor plate (breaking the ground contact for terminal #85) with the IS @ ON position, the coil will be de-energized causing it to switch to N/C resulting to FP running!!!!! This is one scenario where you could make the FP run during a FP test like checking the control and system pressures without running the engine. This is a well known procedure for CIS DIYers!!!!

Without knowing your current wiring set-up, I would suggest that you check your AFS's connections. This could be the reason why your FP is running when it should NOT. This anomaly will not prevent you from having a good CIS running engine except the ability to shutdown the FP when the engine stopped running. HTH.

Tony

Very pretty!!

The headers coming out of the exhaust ports aren't even blue yet !!

Good write-up about the function of the ASC, Tony, but it's located on the Mixture Control Body, not on the TB.

The ASC is green, the CSV is blue and it is possible to mix up the connections.

You're correct.......
 

Gunter,

I owe you one!!!!! I some how been calling the mixture control unit as throttle body without realizing the mistake. These are two (2) completely different CIS components. Please accept my apology for the blunder. Glad for catching and bringing it up!!!! How's the weather up there? We have been below freezing for several days now. Thanks.

Tony

Gunter and Tony

Thanks for the kind words, the exhaust headers are jet coated they have several thousand miles on them since the rebuild and have not changed colors that is pretty tough stuff, I do my own powder coating and blasting in my shop so that stuff is really cheap/easy to do have had good luck doing all kinds of stuff with it, but it can get kinda flashy I guess, hard to tell but I also did alot of black and silver as well which is not so flashy. You have to be careful to not get to much of a build up on the fan or housing or it can rub believe it or not.

Ok, back to the switch, if I am reading what you listed correctly you could actually make the pump kick on in the ignition on position by moving the throttle pedal thereby opening the plate that would make the pump come on ? This sounds crazy if it is designed to shut the pump off in the event of a wreck ?

I am going to dig out my books and look for it, can you see it if I post some of my rebuild pic's ?

Oh and the airbox cover is homemade and does not really look that good but it sounds pretty good when on throttle.

Todd

ps... I have a similar switch on a vintage race car so I do not know why I never thought of the SC having a pump that ran all the time, the whole purpose on the race car is to shut down the fuel in case of a wreck.

Reporting Back
 

Gunter.. here I am, reporting back. I just noticed my thread got revived recently.

But the report is not much. I have not tried to dig in there and find the CSV. I've just been giving it a little gas when cranking and most of the time it starts without too much fuss.

I will look deeper into this issue when it gets to be warmer weather.

To help you out, here is a pic of the Air flow switch and the cold start valve on a 79 CIS.

http://forums.pelicanparts.com/uploa...1262662879.jpg

15 minutes ago I had to leave the office at 5A.M. It was in the 50's yesterday and now it's 29 degrees. Do you think that the CIS tune could keep up with that temp swing? No.

So it finally caught after cranking for a lot longer than 60 seconds. More like full 3 min. JUst when the needles started to go wacky and the radio light beeping on and off, it started.

I had my 3mm wrench and richened it with a 16th of a turn after 2 minutes. Called the wife to come get me when that seemed to not work. Stunk of gas in the engine bay when I turned it. So it's Ignition, or wur or fuel pressure but not the yellow wire.

That Asian starter just kept on cranking. And Started the car right at the last amp! And right before the wife got in the car to come get me.

What did they do in Germany when they wanted to start a frosty car to get to work at 5a.m.? Take the beetle? Train?

So these cars take some cranking, I guess, when It's not orange county weather :)

Blueye,

What they do in Germany, or anywhere else, is to troubleshoot the CIS and trace the problem in the cold-start circuit. :)

Bosch CIS is extremely reliable and durable and used in very cold climates like Sweden and Canada. I remember many minus-40-mornings with the engine coming to live after 2 cranks. :cool:

Enriching the mixture is obviously not the way to fix CIS-problems. With the right tools and knowledge, the CIS is fairly easy to maintain. But, if you don't understand how the CIS and its various components work, find a shop that does.

I suspect that your cold-start problem is an easy fix for an experienced mechanic.

Considering that CIS runs on Millions of cars is comforting. SmileWavy

Can you take a picture of the back and post? SmileWavy

You've slightly misunderstood Tony's explanation. The plate is moved by vacuum from a running engine, not by the gas pedal. The test he was referring to requires lifting the plate by hand with the air cleaner removed, thus tripping the switch as if the car was running, kicking on the fuel pump.

edit: Gunter already posted the correction while this was typed, so two versions.

W.C. Fields would have called it "A pardonable error". :D

It's easily done, they both have a round plate inside. :)

Since CIS-issues come up so often, a write-up on the sequence might not be a bad idea. Like describing what happens electrically and within CIS when the key is turned to Start. Then one could just have it saved in "My Documents" and copy/past it when the questions come up.

You're da man for CIS.

Very mild so far here meaning: Climate Change is real. :eek:

CIS troubleshooting........
 

oneblueyedog,

One criteria I required on my CIS engines is to be able to start them in dead winter the very first try. Maybe a quick second try if you have not run the motor for more than a week. A well maintained CIS car should have no problem starting anytime of the year!!!! Whether dead winter or the middle of summer. And for those of you who likes to adjust the mixture screw to correct starting problem/issue is making the situation worse. The mixture set screw should only be adjusted when the engine is fully warmed up (operating temp) for calibration purposes only!!!. The main reasons for the change in air-to-fuel mixture are either caused by the fuel pressure change or unmetered air going into the system (vacuum leak).

To demonstrate my concept, I went outside (25°F) to start Tom C's engine that has been sitting in my carport for several months now. First try, it cranked and stumbled. Second try it comes ALIVE and roaring!!!!. Maintaining a CIS engine to reliably run anytime of the year is not that difficult!!!! All you need is stop guessing. Every individual CIS components could be bench tested without running the motor. As long as you maintain the specs close to the designed CIS values, your engine will perfomed well.

Tom C.
If you happen to read this post, sorry for running your engine when the temp. is well below freezing without getting it to operating temperature. Next time it will run would be after installation in your car.

Tony

I think I'll start at the start, and read all these posts again. I want mine to start in two cranks, too!

CIS troubleshooting.........
 

Scot,

There is nothing secret about I do!!!! I'm no CIS expert that's why I try to avoid guess work and keep things under control (if I could). It's all about fuel pressure and vacuum. And add ignition with a decent compression, your engine will ROAR to life on demand!!!!

You should be able to run your engine anytime on the first try!!! If it does not, there is reason/cause why it's not starting. There are only a few things that could affect a no-start. So sorting which of these probable cause/s is your next move.

Tony

+100! Well spoken Tony.

Wanted to share what I found with my car.

I checked out my WUR for a cold pressure test. Bosch number ending at 089. I viewed my chart. At 6.111°C the pressure should be 1.1bar. Hooked up the gauge and disconnected the plug to the WUR, jumped the fuel pump terminals and put the key in the ignition– 1.8bar. No wonder it was lean starting at below freezing.

Tapped the WUR plug down to read 1.1bar.

Removed the test equipment and hooked up the fuel lines, checked for leaks. Hooked the relay back up and it started right up. It began hunting, but roared right up.

I tried lift plate tuning after warming it up, and have discovered that I cannot get my idle down to 950 (or kill the engine with the idle adjust screw). I got some starting fluid with an extender pipette and squirted the intake manifolds to head joins first. The bank of 6,5,4 each made the revs increase pretty dramatically.

I have some work to do. I must not have correctly reinstalled the intake manifolds when I replaced the injector sleeves last winter. I just happen to have 3 intake gaskets in my parts stash. Hmmmm?

So, thanks to the level headed people on this post for the sober advice, to not be brash about CIS.

Another thing you might consider is to take the battery inside at night keep it at 75 or 80 degrees overnight and in the morning and the car starts on the first try at 26 degrees. Along with a trickle charge, this has been helpful for getting old fussy cars cranked over on cold AM's.
It works well for a stored car in mid-winter (only if the roads are dry and salt free)
My daily driver, a 200,000 mile '86 VW appreciates this kind of thing, it hates the cold.

BTW your engine is absolutely blinging! I have to say, I am kind of envious, I would do it all black and silver, it looks unreal like its from a museum display or something... good work.

In the diagnostics for high idle-False Air
Removed the CIS this morning and found another good reason for hard starting resulting from improper mixture. #5 intake runner boot. So this cold start lesson revealed a lot of trouble.<br>http://forums.pelicanparts.com/uploa...1263158331.jpg