Power and whine at cd unit but no spark
 

G,day all.

I have a 76 2.7 that has had a hard life before me.

The car has been completely stripped over the last couple of years and now is back together. It was running before pull down only changes new plugs, distributor cap, rotor 6500 limiter type and

I have almost completely rebuilt the engine harness except for the 2 wires from the CD unit to the distributor and the coil. Mostly because it was in a very bad way and I'm not sure the electrical connectors to the cold start, WRU ext were all connected they are now

Today hooked up a battery fuel system working.

Cd unit has a high pitched wine and I have checked all connections and continuities.

I have power at the B terminal of the cd unit but no spark at the plugs or from the coil output.

I have checked that the A terminal from the CD unit goes to the points, C terminal goes to the coil, the other side of the coil is earthed and also goes back to the earth of the CD unit. The shielding around the wire is also earthed.

I have checked the resistance across the coil at both primary and secondary the secondary .9 ohms but I have a bit of trouble reading the primary resistance the multi meter set to 20000 was reading 900 I think a bit more the the expected 650 to 750


I have a timing light a multi meter and a 12 v test light

Is there a way that a home mechanic can check a cd unit or any other advise or opinions greatly exceptedhttp://forums.pelicanparts.com/uploa...1398231543.jpg
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Please help

Regards Michael

Have you cleaned the points?
They can tarnish up when sitting for a while. Gap set correctly ?
Checked them to see they are opening and closing correctly? Checked continuity of the wires to the coil and dizzy from the CDI unit?
There was a good thread recently discussing the testing methods for a 3 pin CDI.

Plug wires oriented correctly?
Been there done that.
New rotor faulty?
Plug wires fully seated?
Think about what you have changed, it was running before you swapped out components.

G,day timmy2
 

Have checked all continuity and point gap all ok , plug leads and plugs all ok

Not getting any spark from the coil lead

Would it be fair to say that if the cd is whining then it ok?

Spent about 4 hours double checking everything I could

Do cd units fail just by sitting around for a couple of years

I pretty confident that the wiring is all ok so I guess it's either the cd unit or the coil.

Just throwing a few ideas out there!
IF the CDI whistles, I would suspect the coil - is it the right one & could you test it on another car? Are the wires to the terminals swapped?
Does the tacho needle move at all when cranking ( which might indicate a short somewhere). Do you have a "co ax" green wire on yours, as these break down a lot & the connectors into the distributor can also short.

On other Bosch equipped cars, I have experienced the rotor button metal burning out under the glue between the centre and the tip.

Looks like you are very close to running anyway - so good luck with it
Peter Melb.

G day Peter

Mine has 2 white coax type wires no blue or green

The 2 white wires come from the CD unit to the distributor at the points and the other to the coil I have double checked their orientation and continuity.

They are old and stiff but seem ok they are the original ones that were in the car prior to pull down.

I have checked the price of a new coil and I can buy a new msd and coil for about the same price (not in aus way to expensive)

I guess at least then I have new components from power to plug except leads
Regards Michael

your cables look crappy, torn... maybe one of them even broken?
what about the famous "green" wire, that connects the CDI with the dizzy head?

Ah oh, the high pitched whine of death.

As Flo suggested fix up the wires in case the current is leaking out somewhere and make sure your connectors are making good metal to metal contact.

Good luck.

Might that be the infamous (pos) Bosch silver coil in the picture? If so, it may be the source of your problems.

Check post #9: http://forums.pelicanparts.com/porsche-911-technical-forum/756231-troubleshooting-ignition-problems-but-its-all-greek-me.html#post7501161

It may contain the tests you need to narrow down the problem.

Buy a cheap ($20-$30) VW coil at an auto parts store for just testing.
Place the coil wire going to the distributor about 10-12mm from the alternator's
metal housing while cranking. Also use a test light to make sure the points
are opening and closing properly.

if you are goning to get a coil, get the MSD.
your wires dont look that great. any wires that have the ground braid, ohm the center conductor to the braid and ground, wires that dont, ohm to ground.

just because the CD whines does not mean it is good, just means half of it is working. the large cap in there can go bad but you can check it.

open the back of the CD unit. (i am doing this from a pic, i hope yours is the same). look at the center pin on the 3 pin connector to the CD. follow that straight across the circuit board.
you will see to componets next to the coil, they are in line with each other. those are diodes. go to the end of the second one. set you meter to Ohms, probabbly a hi scale. put one lead on the far end of the second diode and one lead on pin A of the CD. the meter SHOULD start counting up or down. switch leads. it should now count the other direction. you can alsoo take a wire and short those 2 points together, then connect you meter bac k and it should count UP. that is the capacitor charging up from the battery in the metter. if it does this, the cap is good, cant remember if the caps usually short or open, but if the meter reads eirther way or just sits there, the cap is bad.
post pics of what you are doing if you need help.

you can just buy the coil and have a spare if that isnot the problem

The test mentioned above is one of many tests that will indicate whether the CDI has
a problem or not.

Bosch silver coil.... Very likely...
New rev limiter rotor, possibly opening early (or always). Try it with a non limiting rotor first.

Bosch # 0 221 122 001
 

Any developments?
Re coils; some old M Benzs (late 60's to early 70's with points ignition) have coils with the same Bosch part number: Bosch # 0 221 122 001
- they are marked "730" and "KW 12 V (yours is "460"?) It might be easier to find a MB test coil at the wreckers for next to nothing. Might even be on that era Volvo's too.

I may have one in my box of old bits if you cant find anything local

If you want to go MSD, there is a basic version called Streetfire (about $200) which a Melb. Forum member (Racetech) got for his Targa restoration & it seems to go real well.

Whining noise of the CDI indicates you are getting power (+12V and GND) to the box. Depending on the pitch it is either an internal short or the DC/DC is working normally and something else is amiss.

If the whine is higher-pitched that indicates an internal short in the CDI box where the DC/DC converter is shorted to GND and thus is frequency shifts more towards 4.5kHz range. If you remember how a normal box sounds in stand-by you can immediately.

If the whine is around 3 - 3.5 kHz that is normal - you either have no adequate trigger signal (wires, points) or a defect in the internal pulse shaping and trigger circuitry. In very rare occasions something else internally is wrong.

Ingo

You can take the points input into the CDI and short it to ground in a tapping motion to simulate the points.

Hook up something like this on the other end:

http://forums.pelicanparts.com/uploa...1398353332.jpg

you should have spark. if not you know it is the CDI or the coil

Thanks for all the input guys
 

Hope to get back to the car in the next few days and will try a few of the tests

Regards Michael

A bit of an update
 

Thanks to all for advice and offers of assistance but after more inspection there is a blown circuit that can be seen with the back off the unit.

I have a msd street fire unit and coil on the way $211 aus dollars delivered from amazon.com

My dad rigged an old coil and condenser from stuff in his shed and by passed the cd unit and the car started I guess that sorts out most things, like points, leads, power, timing ect.
So new unit should be here next week, takes a while to get stuff to Tassie from USA

But pretty sure we have it sorted now

Regards Michael

Bad Brazilian coil.

FYI you should never use an early vw or mb coil designed for Kettering ignition, the primary resistance and inductance are way too high for cdi. It might work ok but ignition power will be way down and the cdi box is not designed for it. Use a used German black 001, they are out there

No coax on a stock 76 that is not till 6 pin sc box 78-

No green coax until '78, the 2 white or grey wires from the 3 pin connector to the coil and points are actually both coax cables.


Sent from my iPhone using Tapatalk

Next phase
 

Had some trouble with the ignition system, blew up the cd unit.
So easiest option msd streetfire and master blaster 2 coil.

Got the new bits In today pretty easy job. Started straight up after 2 1/2 years.

1 fuel leak, tighten banjo fitting fixed.

Idle around 1000 but sounded like a miss, so remove 1 plug lead at a time wierd no difference, let engine warm up checked oil level all good.

Then next start suddenly idle at 2000 I think the timing is a bit advanced but hard to check until I sort out why the high idle.

Miss seems to have gone at higher idle. Not keen to just lower idle at idle screw as car never idled this high before have retarded timing a bit but idle stays high

Tried removing 1 electrical connector at at time from the different engine cold and warm start stuff no change.

Will do a few searches but if anyone has any ideas would be glad to hear them
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Perhaps the combination of a repaired fuel leak and having re-seated all the plug wiring was enough to fix an old problem and the engine is happily running where it was set to compensate for old problems.
Throttle linkage could be binding. Or you have a new vacuum leak.
Did you run it long enough for the WUR to work and lower the rpms. May just be a real high cold idle.

If all seems normal just lower the idle and check the timing once it is at full operating temperature.

I had ignition problems that i finally traced back to a faulty low tension connection at the coil. The push on style leads are crappy at best. I cut them off, replaced with eyelets, threaded the posts coming out of the coil and all's right.
-C

All new vacuum hoses
 

G,day Dennis,

The engine was running a bit fluffy but at a good idle speed, ran for about 10 mins on and off while check individual spark to find the miss,

After checking the plug leads let it run for a while, engine at full temp.

Then shut down for a couple of minutes on restart suddenly 2000 rpm at idle and would not lower to normal .

Before engine came out it ran fine but was a bit hard to cold start.

Only change is all new vacuum hoses pretty sure no leaks there, new msd street fire and coil, but the original engine harness was shot and I don't think any of the CIS electric components were connected, I have rebuilt the harness and fitted new connectors (Thanks to your good self) just wondering if as you suggest the tune was set to compensate for all the faults that are now hopefully fixed.

Hoping to get some time on it tomorrow

Will start by double checking vacuum hoses,

Any ideas on some start up checks before the engine warms uphttp://forums.pelicanparts.com/uploa...1402185806.jpg

As far as start up checks, I would definitely install a fuel pressure gauge and make sure everything in the system is in spec. Check System, Cold start, Warm running fuel pressures to make sure the WUR is functioning correctly. (all can be checked without starting the car)

Then give it a start after checking the vacuum hoses you wanted to check.

If everything is functioning normally, then it is tuning and idle adjustments from there.

Do you have a way to check the CO levels in the exhaust? Important for checking the mixture is set correctly once you get your idle down.

Your car is looking great! The ride height looks a little high but I'm sure adding back all the missing bits will help bring it down to earth again. :)

Thanks Dennis
 

Don't have a co gauge or fuel pressure gauge but are on the list, have a few contact that may be able to help.

Car is still a long way from done, brakes are all in but not yet tested, suspension in but not adjusted, wheel alignment needed, once I get it running right and sort out a few minor wiring issues like brake and indicator lights, I will be able to drive it from one workshop to the next. At least that will be driving it instead of trailering.

Still haven't started on any interior, but have to wire in new alarm, stereo, electric door locks and a few other hidden bits just for me.

Thinking of black leather with black and white hounds tooth inserts similar to the 911 50th edition

Oh yeah and a duck tail
 

http://forums.pelicanparts.com/uploa...1402226387.jpg
Thanks to who ever owns this beauty for the picture

CIS - Return to fuel tank partially blocked??
 

I also recommend you borrow/buy a fuel pressure gauge set for testing & tuning your CIS.
I had an experience where a CIS car (not P.) sat for a while and the fuel return to the CIS tank had blocked. This caused a very high fuel pressure over the whole system which was very hard to properly diagnose without a pressure gauge.
I unblocked the return - not easy on CIS tanks :mad: !!! - and a lot of things returned to normal.