SC / CIS Start Questions

ikarcuaso · 07:02 AM

When cold, I usually need to turn the ignition key (and crank the engine) three times before it starts (i.e. doesn't start until 3rd attempt). Unusual? Ignition/electrical or CIS/fuel issue?

Is it good/bad to press the gas pedal down (and then release) before a cold start (yes, I know the manual says this is not necessary).

Is some "instability" after a cold start (CIS) normal? Not hunting or erratic RPMs, but just very low RPMs that gradually climb and stabalize at ~900 (or wherever idle is set).

Thanks!

ikarcuaso · 07-02-2006, 07:03 AM

Pretty please...

RarlyL8 · RarlyL8's Garage

There are many things that contribute to a poor cold start. The very first thing I would do is check for vacuum leaks. If you find none check for a good spark during cold cranking. If that is OK check the cold fuel presure and compare it to the specs for your car. Also check the AAR.

Pressing the throttle peddle has no affect if your AAR is working properly. It also has no affect on STARTING the car, the AAR function is to keep the engine running once started.

Knowing no more than what you described above I would guess that your WUR pressure is on the high side when cold, causing a lean start up. A "normal" cold start would fire in a few seconds and idle at 1500+rpm for a time before settling down to ~900rpm.

Again, many things can contribute to a hard cold start and all should be considered. Pelican has a CIS troubleshooting chart in their tech section. Jim Williams over on Rennlist also has a nice compilation of articles on the subject.

Hladun · 07-02-2006, 09:39 AM

Pressing the throttle has no affect on fuel supply. But after a cold start the idle speed should be 1,500 to 2,000 rpm reducing to 1,000 as the engine warms up. It's the AAR that supplies the extra air. Try starting by holding the pedal down about 1/3 or so. Does that help? If so I'd focus on the AAR. AAR should be open when engine is cold.

What happens? Does it fire and die, does it not fire, does it backfire, what does it do the first two times?

Surging usually means a rich mixture so I don't think it's a vacuum leak.

Have you used a fuel injector cleaner recently? If not you should.

The initial start is a function of the cold start valve. It's behind the engine so it's not easy to get at. The 9,00 rpm idle after start points away from this.

My 78SC starts instantly in temperatures down to -25, so the CIS system can be made to work very well.

ikarcuaso · 07-02-2006, 10:30 AM

Thanks for the replies.

The first couple of times, the engine cranks, but doesn't start. No start up and die, no backfire. When it does start on the third attempt, the RPMs start out low, and they climbs to ~900 RPMs or so. Sometimes the rise is rather quick, other times it's a slower climb.

There are no vacuum leaks nor spark plug issues - I am certain of that. I have used fuel injector cleaner very recently.

Of course, everything if fine when the car is nice and hot. I have to get a smog check soon. Once done, I'll adjust the fuel/air mix and idle and see if that helps. But it appears the AAR could be an issue based on your input.

CliffBrown · 07-02-2006, 10:59 AM

Could be the cold start valve. A easy test of the cold start valve (when the motor is cold) is to remove the electrical connection and then see if your starting problem changes. It shouldn't effect your cold idle but it should allow an easier cold start.

It's hard to reach the connector but try using a large hand-held mirror and strong flashlight in a low-light environment to get an idea of it's location below the throttle body.

I say this because you don't seem to have a hot start problem but it could still and also be the WUR.

If yours is bad I keep a few spares in my garage.

Hladun · 07-02-2006, 12:21 PM

For cold start valve check, pull off the red/black lead on the thermo switch. The switch is at the left back of the engine, on the cam chain cover.

Don't change or touch the WUR until you have checked the fuel pressures with the proper tester. WUR's are an easy to change, but very expensive part that has gotten a reputation of being the cause of 10 out of 7 CIS problems! Most guys that change them usually have a couple and that tells you something.

911quest · 07-02-2006, 12:57 PM

next time dont crank the engine just cycle the key a few times then try to start it , this will let fuel pressure build up. It is possibly bleeding off while the car sits

Hladun · 07-02-2006, 01:23 PM

Quote:

Originally posted by 911quest
next time dont crank the engine just cycle the key a few times then try to start it , this will let fuel pressure build up. It is possibly bleeding off while the car sits

Doesn't work this way. Fuel pump does not run until the engine is CRANKING and then airflow keeps the pump running. The pump can be easily rewired to run when the key is on. (Jumper the fuel pump relay)

ikarcuaso · 07-04-2006, 09:26 AM

Great...thanks again for the help. One more - I've heard conflicting opinions on this. Any benefit to pressing the clutch while starting the car. Obviously, when starting in 1st gear there is

but otherwise while in neutral, does it make a difference? Thanks again.

hytem · 08-03-2006, 07:06 AM

I have the same problem on my SC, and I understand it's very common. Sometimes, it will catch the first cold start, other times, 2 or 3 tries. I don't drive but once a week, so that's probably a factor as well. Once it catches, warmeup to normal idle is rapid--20 seconds or so. You just have to pump the accelerator a bit AFTER it ignites, to keep it from stalling out. I'm waiting for cold weather, to see if it gets worse before I do anything. A new WUR is a last resort--it's a $500-600 item.