3.0 SC takes WAY too many cranks to Start When Cold
 

I searched before posting.. rule #1. but anyway...

My 78 SC 3.0 starts fine after an extended period of cranking. 5 to 10 seconds.

That seems too long. Can I fix something so it just cranks right over and starts?

I also need to work on the idle when it's cold. It surges until it gets warm.

So, hence my dilemma...

Extended cranking suggests lean mixture,, but then surging idle suggests too rich..

Or is it a combination of all?

Yikes! tear my hair out? :confused:

First, Test to see if your Cold Start Valve is working. Regardless of your fuel supply, you should get a quick firing of the engine from the injection of the CSV.

Have your fuel system pressures checked, especially your residual pressure as your symptom hints toward a bad check valve or other leak that allows the fuel to drain out of the system, in combination with an out of spec cold fuel mixture.

You are correct to think the surging is overly rich mixture--something that may show up in the fuel pressure check.

Also, check that your Auxilary Air Regulator is functioning. It should be open when the car is cold, and if not, the car will be hard to start.

hard to start does NOT mean a lean mixture . it just means conditions aren't ideal for starting .. if it surges while cold I would conclude someone thought as you did and tried richening it up to get it to start ... bad idea ..
some excellent advice above .. start with the basics , get out your bently and start checking , check the thermo time swith, cold start injector, cold system and control pressure. If your not back firing your not to lean .

Hello Scot,

The engine needs a very rich mixture to start, and a rich mixture to run at a stable cold idle. On CIS these things are handled by two different components. The Cold Start Valve supplies the fuel to fire a cold engine, and the lower control pressure from the WUR, the cold running mixture. The CSV is powered only when the key is in the start position (cranking) and is grounded only when the thermotime switch is closed. The CSV is behind the engine and hard to reach, but the TTS is on the left timing chain cover. Test that the red/black wire is grounded when cold. If not, disconnect it and attach it to ground and try a cold start. If there is no difference, you need to get at the CSV to test it.

It is very unlikely that your cold running mixture is too rich, much more likely it is too lean from a combination of possibilites, fuel pressure, lower compression, injectors, vacuum leaks. Cold engine are very comfortable with richness, and very uncomfortable with lean.

This all assumes that you have checked the ignition, that you have a good blue spark and clean plugs.

Could be a combination of things like psalt says.

Go over the cold-start wiring from Starter Solenoid-Thermo Time Switch (TTS)-Cold Start Valve (CSV)

Check the AAR located on the right side of the engine between 5-6 intake runner.
It's the item that has a small electric plug and a large vacuum hose connected to it.
Open the clamp holding the outside-hose.
Pry it off with the screwdriver just enough to get it out of the way so you can see into the opening.
Don’t worry about the Alu pipe; it’ll move enough.
With the help of a small mirror and a light, peek inside the AAR.
When COLD, you should see an opening in the slide shaped like a half-moon.
When HOT, the opening is completely closed.
If it isn't closed, the AAR is either kaput or doesn't get any power.
You can spray some WD-40 into the valve in case it is just sticky.
To check the power, carefully open the tiny clip on the plug with a very small screwdriver and pull it off.
The wire clip is tricky but necessary; don't yank it off.
Start the engine and check the plug for 12 V.
(One wire is power, the other (brown) is ground)
With power to the AAR, it should close after about 5 minutes.
If all is well, replace the hose and clamp securely.

Does the WUR get power? WUR and AAR only get power with engine running; not just ignition ON.

The WUR has a tiny screen inside the top line. Disconnect the line and clean the screen if necessary.

Be patient. SmileWavy

I disconnected the leads from the TTS and checked for 12V while cranking, but did not get consistent results, so still unsure of that.

the part in the middle of the TTS is not secure between the contacts. it moves if I wiggle it around. is that normal or is it broken? see pic attached.

Then,, If I remove the TTS., will it leak oil all over ?

And.. my bently says to check the current at the CSV to check if the TTS is working correctly.

But how do I get to the CSV? There is a pic in the Bently, but it doesn't show where it is or how to get to it to check the voltage..

I will work on checking the other things, too, but where is that CSV?



http://forums.pelicanparts.com/uploa...1256509213.jpg

I checked the AAR, as Gunter suggested, and I saw the little half moon shape just fine. While I had it open, I tooted a little WD-40 in there just in case...

Is it this dealie-bobber? Is this the CSV? It is located between the 1 & 2 intake runners..


http://forums.pelicanparts.com/uploa...1256511713.jpg

Hello Scot,

That is the WUR, the CSV is on the other side of the engine in the middle of the airbox. You need to remove the heater blower and use a mirror to see it. The TTS is the ground for the CSV. Do you understand how it works ? There are two terminals, one is the ground for the CSV, when you turn the key on a cold engine, power goes to the CSV and it sprays. It is dumb, so it will continue to spray fuel into the engine if the engine does not start and you keep cranking. To prevent damage from flooding, the other terminal is for a heater, the same yellow wire that powers the CSV powers the heater to disconnect the ground connection if the engine does not start in around 7 seconds. Yes, a broken TTS insulator can be a problem. The test you want to do is disconnect both leads, tape off the yellow wire, ground the red/black with a test lead and try a cold start. Forget about the AAR it has nothing to do with this issue.

I will try a test start in the morning as wired up with a test lead.

I looked up a new thermo time switch from Pelican and it is genuine Porsche and almost $200.00. Mine might be broken, because the middle part moves/wiggles.

The picture of the new one makes it look like that center section is insulation, and I guess that might be important.....

TTS test .......
 

Scot,

Follow the above instructions. And if you want to test the TTS check the following:
1). The large terminal (for red/blk wire) is the ground contact for the CSV. It is grounded to the body (TTS) when cold. The internal contact switch inside the TTS will open after a few seconds when energized (cold) due to the built-in heater or will stay open when TTS body is warm (due to engine temp).
2). The smaller terminal (for yellow wire) is the power supply line for the heater. Depending on what type of wiring set-up and starter you have, the heater is energized either directly from the ignition switch ('76-'77) or via the starter solenoid (SC's).
3). Check the heater resistance between the two (2) terminals at cold condition.

In summary, the TTS serves as ground source for CSV. When the red/black wire is grounded, the CSV will inject fuel when energized. But with an open ground (red/black), CSV will be dormant.

Inspite of the above suggestions, a sure way to verify the condition of the CSV's is to physically inspect it when energized (FP running). Removing and installing the CSV is very cumbersome with engine in place. But once you're able to dismount the CSV, the tests are easy. If you decide to follow this route, I still have the fuel hose and electrical socket used to do this test. PM me.

Tony

All good stuff, scotricker.

Glad the AAR checked out, it doesn't hurt to check everything to do with cold-start. :)

Your picture shows the WUR. I would check the tiny screen in the line because when it is clogged, it can screw up your fuel pressures.
Checking is easy. Use 2 open end wrenches: One to counter-hold the fitting, and one to open the cap-nut. You'll see the screen inside.

Getting to the CSV and removing it is such a PITA that I would first check the wiring and power going to it before proceeding.

The CSV has a seal that can be damaged; PITA, is held in by 2 screws; PITA, has a large hose attached to it with a clamp; PITA, has an electrical plug secured with a tiny wire clip that you cannot see; PITA, and everything is very hard to reach.
The electrical plug cannot be disconnected unless you remove the tiny wire clip; PITA. :(

You can get a used one here on Pelican.

I'll take a look at mine later to see how loose the center is. SmileWavy

I found the center of the TTS is solid. :)

As I understand the original problem, he's having difficulty starting. Otherwise performance is okay. I suggest that you simply ground the red/black wire from the Thermoswitch. This completes the Cold Start Valve's circuit by providing a constant ground. Power to the CSV is provided by the ignition key on the crank position only. This means the CSV will squirt every time you hit the starter, regardless of engine temp. If this solves your problem, spend the $200 TTS replacement cost on beer and drive on. If you find a tendancy to flood on warn or hot starts, then replace the TTS.

Larry
'79 911 SC

Listen don't do this simple test first because my car must be messed up from what people are telling me.

(1) get in car
(2) put key in ignition
(3) turn key to "on" position
(4) listen for fuel pump to run (I can hear mine it is loud!)
(5) look at watch or clock on wall (must have second hand)
(6) sit and watch clock
(7) when sixty (60) seconds or one (1) minute which ever comes first goes by then proceed
(8) turn ignition to strart position and release when your car starts

I know it sounds simple but give it a try, if this fails see below.

(1) replace WUR
(2) Follow directions above for a great running car.

Todd :)

"(4) listen for fuel pump to run (I can hear mine it is loud!)"

Unless this car is a 73.5 T or an early mid-year model this means the air flow safety switch is bad or has been disconnected. From '76 on, the fuel pump should only run when air is being inducted into the engine: i.e. during starter cranking or when the engine is running.

Hi Jim

I have owned my car (79 ROW) for years and I have always been able to hear the fuel pump on the car, it is quite loud from inside the car (unless the engine is running then you cant hear it). I use the above method to start my car which sometimes sits for several weeks between starts and have never had a problem

Todd

Not applicable to SC cars........
 

Todd,

Fuel pumps for '76-'83 (911) CIS cars do not run when your turn the ignition switch to ON position. Unless it is wired incorrectly or have a defective AFS switch. However, for earlier CIS like '73.5-'75, FP does run at 'ON' position. And never replace a CIS component unless verified defective.

Tony

K9Torro,

The air flow safety switch was installed to stop fuel flow into the engine in the event of a rollover or other incident that jams the the air flow meter plate open. It also prevents filling a cylinder with gasoline due to a leaking CIS fuel injector. There were instances with the early CIS cars without this safety switch that resulted in raw gasoline filling a cylinder and then proceeding through the exhaust all the way to the tail pipe! The '79 ROW had such an air flow safety switch. Yours may be disconnected; this was sometimes done to mask a problem with a fuel pump check valve or the accumulator instead of actually fixing the problem. A noisy fuel pump can mean the pump is near the end of its life or that the fuel pump rubber mounting bushings have failed or become excessively hard.


Jim

CIS troubleshooting.........
 

Todd,

If your '79SC (RoW) exhibits what you described above, the AFS (safety device) is probably not working as Jim Sims mentioned or worse, incorrectly wired. Unless you know and understand the wiring set-ups for '76-'83 CIS cars, having a FP running @ ON position is an anomaly. BTW, are you familiar with AFS (air flow sensor/switch) in your car? HTH.

Tony

Tony

I have never even heard of an AFS until now, as I stated above I have owned the car for years and the fuel pump has always turned on with the ignition in the on position. As this was the first air cooled 911 I owned I always thought that it was normal and never mentioned it or asked about it before.

I have replaced the WUR at one point several years ago when I could not get the car to stay running when the engine was cold, this has been the only CIS component that has ever been changed on the car.

I think I will check the rubber bushings to see what they look like on the fuel pump, I had never actually thought about doing that to see what they look like, if they are still in decent shape I guess I will wait until the pump fails before replacing it if it is the pump itself making the noise.

Where is the AFS located and how should it be wired ?

Here is a couple of pic's of my engine bay if that will help,

Todd :confused:

http://forums.pelicanparts.com/uploa...1262586998.jpg
http://forums.pelicanparts.com/uploa...1262587122.jpg
http://forums.pelicanparts.com/uploa...1262587140.jpg
http://forums.pelicanparts.com/uploa...1262587168.jpg

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