Still more problems - CIS?

[Scott R]

Well I am at wits end, and I am really just trying to get my SC into storage at this point, but here is the deal:

Replaced-
Injectors and seals (had a bent injector of all things)
Air boot between throttle body and sensor plate
Intake boots
Intake runner gaskets
Cold start valve (was inop)
Timing/frequency valve (caught fire)
WUR (no change in cold control pressure when hooked up)
Coil wire (had a crack in the metal anode at the coil side)
Cap and rotor

So now I have a new issue, I suppose... When I start the car it's hard to start, you have to crank it a while, then it backfires a bit through the air box and then catches.

It runs after this, clean and smooth as the idle stays up over 1000k for about three or for min, then the idle drops. It drops to around 950 and starts to miss-fire through out the range, I shut it down and wait about 5 min then it starts up strong again and then drops and misses.

I really want to try and figure this out, I spent a combined $700 now on three mechanics that can't get a handle on this, seems like CIS is getting rare and so are the experts.

[Yellowbird RS]

regap your points and look for an air leak

[vash]

what are the various CIS pressures? looks like someone measured the cold control press. what was it, and the ambient temp?

[boyt911sc]

Scott,

Trouble shooting CIS problems could be both frustrating and expensive if you don't know how to check these compoments, WUR, AAV, AAR, FP, injectors, CSV. TTS, etc.

But I find the most challenging is locating a vacuum leak in a CIS system. This system is reliable and will last for a long long time if properly maintained.

Tony

[bigchillcar]

ditto with yellowbird..check points..old or dirty ones will cause backfiring. also, check timing..make sure that this is set correctly. in other words, baseline your ignition by starting with ignition basics: points set correctly, timing set correctly..then start looking for air leaks if still experiencing problems by spraying a little carb cleaner around the intake and airbox areas. good luck!
ryan

[Scott R]

Ok, well this is just great, I lost my notebook with my pressures, however I remember that cold control was 35 or so PSI and warm was 53 IIRC.

Now I went out to the grage and I have tremendous arcing between the coil posts, in fact I have a continous ZAP between the two terminals, and little blips of spark all over the braided grounds!

Has the coil failed? My multimeter stopped working the other day so I can't yet check resistance on the coil, but why would it do this?

EDIT: It's an 80 so no points, I wish at did at this point, (no pun intended)

Also on the airbox leaks it was removed and checked a few weeks ago, it appeared sound on all sides.

[Tex3]

Originally posted by bigchillcar
ditto with yellowbird..check points..old or dirty ones will cause backfiring. also, check timing..make sure that this is set correctly. in other words, baseline your ignition by starting with ignition basics: points set correctly, timing set correctly..then start looking for air leaks if still experiencing problems by spraying a little carb cleaner around the intake and airbox areas. good luck!
ryan

wow , assuming that Scott R's is a 80sc . I didnt know that they had points in them i guess you learn somthing new everyday

[ianc]

Scott, I'll take a crack.

You say that the car is hard to start. Is this a cold or warm start condition or both? Approximately how many secs of cranking does it take to start and what is the ambient temperature?

Have you measured the warm and cold control pressures and system pressures? What were they and what was the temp they were measured at? What is the part # on your WUR?

After replacing all this gear, have you had the mixture checked on an EGA, or tried playing with it?

You describe a couple of problems that to me would point to different causes. The hard cold start is usually unrelated to poor cold running; a poor warm start can also have different causes. The fact that the car runs OK upon finally initially starting but then drops after a bit leads me to believe that the WUR is still not operating correctly, as enrichment from the WUR would be responsible for ensuring a smooth transition from the cold to warm regimes.

Any change if the O2 sensor is disconnected? Do you have a popoff valve and is it seating properly on its gasket?

ianc

[Scott R]

Originally posted by ianc
Scott, I'll take a crack.

You say that the car is hard to start. Is this a cold or warm start condition or both? Approximately how many secs of cranking does it take to start and what is the ambient temperature?

Both cold and warm are hard starts, about 60 seconds of cranking on cold, it catches right away on warm but dies until you hold the gas for a while

Have you measured the warm and cold control pressures and system pressures? What were they and what was the temp they were measured at? What is the part # on your WUR?

I'll get the part number when it gets light out again, however I have two, one is the original (came with the care) and the other is an adjustable from an 82. I will recheck pressures in the AM when it's cold again. However I think it was 35~37 cold and 53~55 hot last time.

After replacing all this gear, have you had the mixture checked on an EGA, or tried playing with it?

Yes it costs me $20 per trip and I had it done last week, it was set to 3.1 IIRC.

You describe a couple of problems that to me would point to different causes. The hard cold start is usually unrelated to poor cold running; a poor warm start can also have different causes. The fact that the car runs OK upon finally initially starting but then drops after a bit leads me to believe that the WUR is still not operating correctly, as enrichment from the WUR would be responsible for ensuring a smooth transition from the cold to warm regimes.

I will check the pressures again in the AM and post them.

Any change if the O2 sensor is disconnected? Do you have a popoff valve and is it seating properly on its gasket?

Will check the O2 sensor in the AM as well, I am pretty sure it's plugged in however you never know. I will check the pop off valve as well, it was pretty well secured when we checked the air box, but it never hurts to check again.

ianc

[ianc]

Both cold and warm are hard starts, about 60 seconds of cranking on cold, it catches right away on warm but dies until you hold the gas for a while

So which is it: warm starts are hard, or it catches right away when warm? If cold start is your only trouble, then I would immediately look at your cold start valve installation. Are the wires put on the thermotime switch correctly? Switch is in the LH chain cover and it does make a difference which way they're installed. Try reversing them and see if that makes a difference.

If you have an adjustable WUR, then you should be able to set your control pressures very accurately if you have a pressure gauge and know what temp your checking at. The ambient temp is very important. Let me know your pressures and temp and I'll look them up in the factory workshop manual to see if you're in spec. Making sure control pressures are in spec is the absolute first step in diagnosing a problem like this.

ianc

[Scott R]

Will do on the pressures, and it's cold starts crank for sixty seconds then catch, idle is low then idles up and runs well until warm.

Hot starts are about 30~60 seconds cranking and I can't keep it running at all unless I have my foot on the gas.

As far as the thermotime wires are concerned I think they only fit one direction, red IIRC is on top and the white is on the bottom.

[ianc]

OK, so it sounds like you're having both cold and hot start problems. Hot starts problems have different causes than cold start. Most likely culprits for hot start are the fuel pump check valve and the fuel accumulator.

Cold start issues are usually the cold start valve. The wires on the thermotime switch can be put on either way. I have an 80 also, and the wires are red\black and yellow. The switch is at the far left of the top of the driver's side chain cover.

ianc

[LFogelson]

Maybe your CDI is bad. I was having issues of my car running very irregular and backfiring until it completely stopped running. Switched to an MSD ignition and this solved my problem.

[Scott R]

You know it would not suprise me, I don't appear to have consistant spark when I disconnect a plug wire and watch it. Anyway to test a CDI?

[LFogelson]

Easiest way is to swap with a known working one.... if you can find someone to lend you one.

[Scott R]

I am going to borrow one from my mechanic today, he has a few spares so he says.

[Jim Williams]

Scott,

Reference your remark early in this tread about the arcing between coil posts: This is a symptom of no ground at the coil. You might double check this. Trouble shooting CIS is a real problem when the spark is not reliable.

You might find some help with CIS by looking here:

<http://members.rennlist.com/jimwms/CIS/CIShome.html>

[Scott R]

Originally posted by Jim Williams
Scott,

Reference your remark early in this tread about the arcing between coil posts: This is a symptom of no ground at the coil. You might double check this. Trouble shooting CIS is a real problem when the spark is not reliable.

You might find some help with CIS by looking here:

<http://members.rennlist.com/jimwms/CIS/CIShome.html>

OK thanks, does the coil go right to ground from one of the two posts? I will pull the wiring diagrams up and try and make sense of it.

Also I brought home a loaner CDI unit tonight, and it was the wrong one, I have a six pin and I brought home a three pin.

Anyway here is an update on other things, I went out just now and started it up, it stumbled a bit then picked up right away to about 1500RPM, then as it warmed up over say three minuets the idle droppped down to 950 and then it started to arc and miss again. It does not arc until after the warmup part is done.

I will try and borrow a six pin CDI tomorrow, but I am still very stumped, and I had no time to check fuel pressures.

[tdatk]

Originally posted by Scott R
Ok, well this is just great, I lost my notebook with my pressures, however I remember that cold control was 35 or so PSI and warm was 53 IIRC.

Now I went out to the grage and I have tremendous arcing between the coil posts, in fact I have a continous ZAP between the two terminals, and little blips of spark all over the braided grounds!

Has the coil failed? My multimeter stopped working the other day so I can't yet check resistance on the coil, but why would it do this?

EDIT: It's an 80 so no points, I wish at did at this point, (no pun intended)

Also on the airbox leaks it was removed and checked a few weeks ago, it appeared sound on all sides.

Scott,
I see you replaced the coil wire. Good, I believe that the rest of your plug wires are shot. If they are arching to the braided sleeve, they are probly cracked. Most likely all the spark thats supposed to go to your plugs is shorting to the braids. Try new wires.

Tim

[Scott R]

Ok, plug wires it is. Now do I go with braided? Or not?