Starting Help

[wilson234]

1983 911SC. I've encountered a new issue with getting my car to start on first crank. It feels like it starts to fire up for the first second or two then that starting feeling momentum dies out and stalls. After that it takes a second turn of the key for a few more seconds and finally it starts but having to hold the key for 3-4 seconds in cranking and nothing like the typical clean fire up.

This typically happens when i start the car in the morning and in the afternoon on my way home from work (car sits for 8 hours).

I did have a hot start issue that went away with a new Fuel Accumulator. I was thinking this had to be a fuel pressure issue as the car runs perfect. No issues outside of not have a firm clean start.

I also replaced the fuel pump check valve, thinking this was a fuel line pressure issue, but I still have the same starting issue.

Once it fires up it warms up nicely, so I don't think it's a WUR issue.

Changed sparkplugs within the last 5K miles, as well as new distributor cap and rotor.

Any feedback on what this could be? Would my next direction be a possible electrical issues?

As mentioned before, the car runs great, just trying to button down a frustrating multiple starting issue.

Appreciate any feedback.

[boyt911sc]

Wilson,

Next time you try to start car cold, do this:
1). Turn ignition switch @ ON position (not start).
2). Remove the air filter.
3). Lift up the AFS (air flow sensor) plate for 2 sec. (max.) to activate the FP and fuel injectors.
4). Try to start it this time. Do not depress the gas pedal. Put the car in neutral and reach for the ignition switch.

Let us know if the car starts using these procedures. Keep us posted.

Tony

[porwolf]

Originally Posted by boyt911sc

Wilson,

Next time you try to start car cold, do this:
1). Turn ignition switch @ ON position (not start).
2). Remove the air filter.
3). Lift up the AFS (air flow sensor) plate for 2 sec. (max.) to activate the FP and fuel injectors.
4). Try to start it this time. Do not depress the gas pedal. Put the car in neutral and reach for the ignition switch.

Let us know if the car starts using these procedures. Keep us posted.

Tony

On my '79SC I can accomplish the fuel pump running with the ignition switch in the on-position by exchanging the fuel pump relay with any black relay, like the horn relay next to it.

[stlrj]

Wilson,

I too have struggled with this same problem on my recently aquired 82 Targa. After over a month of endless adjustments to the warm up regulator and aux air regulator, I found the reason it wasn't starting right up instantly like is should was due to flooding or over rich mixture. These late CIS engines like it on the lean side to start and run right.

Easy test to determine if too rich: next time you fire it up cold, disconnect the thermo-time switch ( it's the sensor on the left cam cover that has two wires connected, just disconnect the red/bk one). Now fire it up and see if that makes a difference as far as starting much faster. If it works, you now know your idle mixture is way too rich since the combined fuel mixture from the six injectors plus the cold start mixture is causing the engine to flood.

I hope this helps,

Joe

[tirwin]

There are a few possible culprits but do what Tony said first and then report back.

[stlrj]

Originally Posted by tirwin

There are a few possible culprits but do what Tony said first and then report back.

Careful, Tony's tip could be the perfect recipe for blowing up your air box with highly explosive gas fumes lingering inside the air box plenum.

I wish you luck.

My tip, on the other hand, is much easier and fail safe at the same time (meaning you can't hurt anything even if you tried).


Cheers,

Joe

[boyt911sc]

Originally Posted by stlrj

Careful, Tony's tip could be the perfect recipe for blowing up your air box with highly explosive gas fumes lingering inside the air box plenum.

I wish you luck.

My tip, on the other hand, is much easier and fail safe at the same time (meaning you can't hurt anything even if you tried).


Cheers,

Joe

Joe,

When you get to the level of understanding how a CIS system works, I'll consider discussing the principle behind it with you. The fact that you believe a cold start requires LEAN condition in CIS means you don't know or understand how a Ketronic system. I'd safely assume that your here just to share your technical ability to diagnose a CIS problem and glad you're not my mechanic.

Tony

[stlrj]

Tony, I would not assume anything and feel safely about it either. I just feel bad about some of the armchair advice given here that could potentially do great damage.

What's so bad about playing it safe?

Just my humble opinion, and I am not claiming to be what I am not either.


Joe

[wilson234]

Appreciate the suggestions, I've been doing a bit more research and have a few more questions and open to additionall feedback.

UPDATE: Removed the black/red wire (W) ground from the TTS and have been monitoring the starts over the last 2 days. NO CHANGE. Still a brief start for a second (rpms go up) then falls on its face. Second crank and it fires up, albeit not the most clean start up. I read someone elses description as a bu buu buuu slow rpm followed by steady warm up idle (this only lasts for 2-3 seconds).

So overall, I would surmise that my cold start valve is not doing it's job of injecting fuel at cold start. I'm going to measure the ohm resistance of the TTS that I found on another cold start posting, and will report back. Just curious, others have commented the TTS is a pretty failsafe unit of all the CIS items, I'm assuming the resistance test is a black and white test to determine whether the unit is still good? The reason I ask, is I would hate to go through the trouble of inspecting/replacing the CSV if the culprit is the TTS, which is easily accessable.

My last idea, I wanted to eliminate the TTS from the equation, if I ground the black/red wire at the same time I crank the engine, this would be another way to test if the TTS has failed (remains open even when cold)? Obviously, I would need two people to do this, and as soon as I crank, I would have my helper break the ground connection after 2-3 seconds, simulating a properly functioning TTS unit.

I also plan to do the plunger test over the next few days, I'm assuming if it starts right up cold with a few seconds of holding plunger in the air box this would point again to CSV not working.

Thanks everyone!

[boyt911sc]

Originally Posted by wilson234

Appreciate the suggestions, I've been doing a bit more research and have a few more questions and open to additionall feedback.

UPDATE: Removed the black/red wire (W) ground from the TTS and have been monitoring the starts over the last 2 days. NO CHANGE. Still a brief start for a second (rpms go up) then falls on its face. Second crank and it fires up, albeit not the most clean start up. I read someone elses description as a bu buu buuu slow rpm followed by steady warm up idle (this only lasts for 2-3 seconds).

So overall, I would surmise that my cold start valve is not doing it's job of injecting fuel at cold start. I'm going to measure the ohm resistance that I found on another cold start posting, and will report back. Just curious, others have commented the TTS is a pretty failsafe unit of all the CIS items, I'm assuming the resistance test is a black and white test to determine whether the unit is still good? The reason I ask, is I would hate to go through the trouble of inspecting the CSV if the culprit is the TTS.

My last idea, I wanted to eliminate the TTS from the equation, if I ground the black/red wire at the same time I crank the engine, this would be another way to test if the TTS has failed (remains open even when cold)? Obviously, I would need two people to do this, and as soon as I crank, I would have my helper break the ground connection after 2-3 seconds.

I also plan to do the plunger test over the next few days, I'm assuming if it starts right up cold with a few seconds of holding plunger in the air box this would point again to CSV not working.

Thanks everyone!

Wilson,

Check your fuel pressures (cold control, system, and residual) for starter. How many starts (attempts) before you could make the engine to run and idle? All the CIS components in your system could be bench tested by DIY'ers like you or me. You don't need any sophisticated tools or instruments to do the evaluation or testing for the part/s in question. Stop guessing and you'll locate the culprit/s.

Are you sure that you don't have any significant sources of air/vac leak in the system? Not being able to find one does not mean you don't have any. Test and confirm. Since you tend to believe someone else, PM the guy. He might have something to tell that we don't know.

BTW, TTS and CSV are some of the most reliable CIS components in your system but that does not mean they don't fail. Test and confirm. You don't need assistance to test the CSV and TTV. What you need is knowledge and understanding how the these components work. If you could find someone to assist you, please do it. Two heads are better than one.

What have you learned or achieved so far from doing the test for 2 days? Keep us posted.

Tony

[Jeff_Ragsdale]

Originally Posted by boyt911sc

Wilson,

Next time you try to start car cold, do this:
1). Turn ignition switch @ ON position (not start).
2). Remove the air filter.
3). Lift up the AFS (air flow sensor) plate for 2 sec. (max.) to activate the FP and fuel injectors.
4). Try to start it this time. Do not depress the gas pedal. Put the car in neutral and reach for the ignition switch.

Let us know if the car starts using these procedures. Keep us posted.

Tony

I have a similar problem with my '82 911SC on what I would describe as a "warm" start problem. The car starts great cold and hot. My problem is if I park it for an hour, or so, like going to dinner or in to church - come out 60 minutes later and it just cranks and cranks.

I somehow blundered into Tony's solution years ago, but it is a bit of an embarrassment to rely on it regularly. I can't find the next step of how to permanently solve this. Any help is appreciated.

Jeff