82SC Euro Cold Start Issue

[DCred911SC]

Hi Guys,

Had a few issues a few weeks back with sudden poor running, stalling, idle bounce, etc. Managed to get that sorted, but I think I still have an underlying problem with the CIS, particularly cold starts.

Prior to the latest poor running issues, the car would start more or less first click without gas. Now, it needs gas, seemingly depending upon the temperature outside. There are no issues when fully warm, only on a stone cold start. What seems to happen is that on a warm day, it will start reasonably well, idle OK (at about 1400rpm) and drive OK too (althought during warmup the idle seems to drop to about 600rpm when the engine spins down, then bounce up to 800rpm, but no stall). However on a cooler day, it splutters, and if I don't catch it right, won't start for severals cranks. When it does fire up, it is very rough, and drives rough too for about 5 mins, then seems to clear itself.

Like I said, I'd already had some poor running issues, and this is what I 've done to get it running reasonably well

- New Dist Cap and Spark Plugs
- Valve Adjust
- New WUR
- New Magnacore Leads
- Timing set
- Mixture set to 1.5%
- Checked for 12V at WUR, AAR

Some thing is not right at cold start / warm up, but not sure what it is. It runs fine when hot, hot starts are OK too. In fact, it starts fine so long as there is a little bit of warmth, even to the degree that it just takes sun on the boot lid and it will start OK.

any help would be appreciated

Thanks

David

[psalt]

David,

This is a common problem with US SC's, and the cause is usually a lean condition combined with too little ignition timing. You should not be touching the throttle on starts, it only makes things worse and can blow your airbox. CIS does not have an active idle or mixture control, so you have to find the best combination of fixed settings to tune around the problem. This requires trial and error and can take a while because you only really get one try a day. When the engine fires off the cold start injector, it must produce enough manifold vacuum to raise the air flow sensor enough to supply enough fuel to maintain a very rich mixture to keep it running. Vacuum leaks at the injectors, lower compression from wear and high cold pressure can combine to make it worse. On US models, the first thing to do is disconnect the vacuum retard, because when it kicks in on a cold start, it drops the idle timing and stalls the engine. If you do not have a vacuum retard, set the idle timing to the high end of the range. Next I would check for vacuum leaks at the injectors and if you haven't checked the cold control pressure with your new WUR check it. I have also found this problem is worse with platnium plugs and better with Bosch normal plugs. If you have no vacuum leaks, correct cold pressure and the extra timing does not help, I would bump up the mixture adjustment to 2.0% and test again. This is usually a tuning issue, not a parts swapping issue so it may take many attempts to find the correct setting for your conditions.

[Bob Kontak]

psalt - If the cold start injector system is not working can you start the car at all when cold? Could this be the problem - or at least the slow starting problem?

DCred911SC - Do not underestimate the problems that vacuum leaks can create.

[DCred911SC]

Yes, vacuum leaks seem to be the root of all CIS evils. I rebuilt the engine just less than a year ago, and gave the vacuum pipes a good going over, most of the rubber ones I replaced. It all looked in pretty good shape at the time, and it has run like a top until about 6 weeks ago.

But, that was then, and something might have loosened or cracked so I do plan to go back in and check out what I can. It's just such a PITA when the engine is in situ, but it has to be done. If it is a vac leak, I bet it's right round the back and difficult to get at !

The thermo switch and CSV intrigue me though. When the rough running began a few weeks ago, it all started with a slight hesitation between 2K - 3K during warm up. The next day, it started fine, but after driving for about 5 mins, it stalled at a junction, revs dropped so low, oscillated, then stalled. And it was a real pig to immediately start again. It would crank over and over, then eventually start, and run really lumpy. Same story at every junction till warm. Ironically, I could leave it for 3-4 hours, and it would start and run fine. Anyway, seemed to sort that out, but it's not back to where it was, something is still amiss.

[psalt]

The key thing to understand about the CSV is that it only sprays fuel when the starter is cranking. As soon as you release the key, the injectors must supply enough fuel to keep it running. A correctly tuned 82 SC should fire immediately on the first crank with your foot off the throttle, and settle at a 1500 rpm idle, and you should be able to drive off smoothly in one or two seconds. If not, something is amiss. The symptom of a failed CSV is prolonged cranking before any fire. My experience is that they spray cold and warm, and the several second safety heater is not quck enough to prevent flooding. This becomes apparent after dealing with many failed starters in different cars over the years. You can test the TTS by simply grounding the yellow wire before cranking. The CSV is out of the picture when talking about cold running issues.

Vacuum leaks are easy to find using an unlit propane torch. They can make a big difference at idle, especially cold idle, but are largely irrelevent when the throttle is open past 25%. If your injector sleeve Orings are original, they are probably leaking. The design is a weak point and my advice would be to read the archives if you want to change them. If you changed the vacuum lines, spend some time making sure they are hooked up correctly. The vacuum advance to the distributor must be from a ported source and the retard a manifold vacuum source.

[boyt911sc]

Originally Posted by DCred911SC

Hi Guys,

Had a few issues a few weeks back with sudden poor running, stalling, idle bounce, etc. Managed to get that sorted, but I think I still have an underlying problem with the CIS, particularly cold starts.

Prior to the latest poor running issues, the car would start more or less first click without gas. Now, it needs gas, seemingly depending upon the temperature outside. There are no issues when fully warm, only on a stone cold start. What seems to happen is that on a warm day, it will start reasonably well, idle OK (at about 1400rpm) and drive OK too (althought during warmup the idle seems to drop to about 600rpm when the engine spins down, then bounce up to 800rpm, but no stall). However on a cooler day, it splutters, and if I don't catch it right, won't start for severals cranks. When it does fire up, it is very rough, and drives rough too for about 5 mins, then seems to clear itself.

Like I said, I'd already had some poor running issues, and this is what I 've done to get it running reasonably well

- New Dist Cap and Spark Plugs
- Valve Adjust
- New WUR
- New Magnacore Leads
- Timing set
- Mixture set to 1.5%
- Checked for 12V at WUR, AAR

Some thing is not right at cold start / warm up, but not sure what it is. It runs fine when hot, hot starts are OK too. In fact, it starts fine so long as there is a little bit of warmth, even to the degree that it just takes sun on the boot lid and it will start OK.

any help would be appreciated

Thanks

David

David,

Verify if your CSV (cold start valve) is working plus inspect the injection patterns of the 6 other injectors. Check your control and system pressures too. A simple way to check if your system has unmetered air is to have the engine idle (fully warmed up) and remove the oil filler cap. If the engine idle speed (RPM) does not go down a bit after the removal of the oil-filler cap, you have unmetered air.

You could measure the cold and warm control pressures without even running the engine. This is a basic test for WUR. And to eliminate any quess-work about unmetered air, pressurized the system for air leak/s. Unlit propane gas works well when you know where to look for and ineffective for areas back of the engine.

Tony

[DCred911SC]

When warm, the revs drop if I take the oil cap off. Does this rule out a vacuum leak, or just make it harder to find ?

Last night, I richened up the mixture but didn't really see much cold start difference (sun was out !), but I guess I went too far (1/4 turn) because as it warmed up it would stall as the engine spins down at junctions. I didn't attach the gastester when doing the mixture because I'm not convinced it's working correctly (last time I connected it I couldn't get the meter to change irrespective of how far I turned the adjustment screw.....engine behaviour did though !). Might try and lean it out a bit tonight and try again....or did I just richen it a bit too much ?

How hard is it to start an engine with an inoperative CSV or thermo switch ? Maybe I can disconnect it and try ?

David

[DCred911SC]

forgot to add that I've also installed a 1in 2out muffler, but would that really make a difference ?

Paul, you mention that after cranking, the CSV is out of the picture with cold start issues. If the CSV didn't operate when cold, engine cranks a while, then fires up, would it run rough for 10-20secs on the throttle immediately after firing?. Where I'm coming from is that when the car is hard to start, the starter spins the engine for maybe 7-8 seconds, then tries to fire, splutters, increasing splutters, then starts very roughly. It's almost as if the speed of the cranking is actually helping it to go ! What i'm thinking is that maybe the CSV isn't working, and it's less prominent on warm days.

What do you think ?

David

[Bob Kontak]

Those were my thoughts as well DCred911.

[psalt]

No, that is not my experience.

If the engine has good compression, correct timing, correct plugs, correct fuel pressure, and a good battery, it should fire immediately when you turn the key. If it fires immediately, then stumbles, stalls or runs poorly, it is not a CSV problem. If it is not firing immediately, you need to test the CSV. The first thing to do is study the wiring diagram so you understand how the CSV is powered. It gets power only when the starter is cranking and gets ground only when the TTS is closed. It is easy to test the TTS, just ground the yellow wire with a jumper and try a cold start. If the CSV is OK electrically, you then have to remove it to test the delivery. Cold start and poor warmup are two different problems with CIS.

[Bob Kontak]

I think he is only talking about cold start here. Not anything past several (10-20) seconds after start up without the CSV working.

Can you even start an SC CIS engine with an inoperative CSV?

[boyt911sc]

Originally Posted by Bob Kontak

I think he is only talking about cold start here. Not anything past several (10-20) seconds after start up without the CSV working.

Can you even start an SC CIS engine with an inoperative CSV?

You need the CSV to inject fuel when the engine temperature is cold for CIS. The cold start valve will only work (cold weather) when the TTS is grounded. Otherwise the circuit is open. You could test the CSV like a WUR without running or starting the engine.


Pull out the CSV from the engine:
a). Place the CSV in a glass container and have an assistant crank the starter. The CSV should inject a uniform spray (mist like) pattern. Observe closely for the amount of fuel sprayed and the spray pattern (this is critical).
b). Since I don't usually have somebody around when I'm troubleshooting, I use a 12-volt power to inergize the CSV. But the FP has to be running when doing this test.

When Paul mentioned that the CSV does not come into play for cold start, I thought that was a typo!!!! CSV stands for cold start valve.........needed only when engine is cold. I find CIS troubleshooting easy and fun!!!!

Tony

[boyt911sc]

Originally Posted by DCred911SC

When warm, the revs drop if I take the oil cap off. Does this rule out a vacuum leak, or just make it harder to find ?

Last night, I richened up the mixture but didn't really see much cold start difference (sun was out !), but I guess I went too far (1/4 turn) because as it warmed up it would stall as the engine spins down at junctions. I didn't attach the gastester when doing the mixture because I'm not convinced it's working correctly (last time I connected it I couldn't get the meter to change irrespective of how far I turned the adjustment screw.....engine behaviour did though !). Might try and lean it out a bit tonight and try again....or did I just richen it a bit too much ?

How hard is it to start an engine with an inoperative CSV or thermo switch ? Maybe I can disconnect it and try ?

David

David,

What was the engine rpm when you removed the oil filler cap? Data or numbers are easy to analyze. At any rate it looks like you don't have a significant vacuum leak by the reduction of the engine speed during the test. But this does not completely tell you about the integrity of your vacuum system. If the engine RPM did not change when you removed the cap, a significant amount of unmetered air is going into the system.

While smoke machine is not readily available in most maintenance shops, pressurizing the system is another method I use at home for locating air leaks. The simple test will tell you whether there is air leak/s in your engine or not. No guessing game is involve for detecting vacuum leak in a CIS engine.

Lastly, I try not to touch the air-mixture screw during troubleshooting. It will add more variable in the problem unless the setting is way off the chart. Adjusting the mixture screw is for tuning purposes. The CIS engine will run if you have ignition (spark), compression, pressurized fuel (control and system), and the right amount of air for combustion.

Tony

[DCred911SC]

More info,

Over the weekend, thought I'd try to isolate the CSV to see if the car would start without it operating. Not sure if its correct, but I disconnected the red wire from the thermo switch (this is the one which the CSV uses as ground when the switch is closed). The temp outside was about 18-20C. Guess what.....

Car started like it has done for the last couple of weeks. cranked over a few times and started to go, then went.

So, does this mean anything or nothing ? how cold before the CSV is needed, I thought it stopped working at about 35C but maybe not. I think a deeper investigation may be need like what you guys have already mentioned.

David

[psalt]

David,

Not much.

If you ground the wire and try the test again after the car cools overnight, and it fires immediately, the problem is the TTS. Test the TTS red wire terminal for continuity to ground when cold.

[DCred911SC]

I'll check for continuity tonight, and ground the wire for tomorrows cold start.

Paul, do you think the CSV should be operating at an ambient temp of 20C or thereabouts ?

Thanks

David

[psalt]

My experience is the CSV always sprays on a cold engine (overnight).

[DCred911SC]

Grounded the CSV for this morning's start (cooler today too!), and still didn't start....more or less the same as before. Looks like I need to take out the CSV and watch it while cranking. Is there enough slack on the wires and pipes to be able to do that in-situ ? I bet it's fun removing it with everything still on.

David