Ignition condensor

[Martyn]

I have a 1985 Spider Europa. I am troubleshooting an electrical no start issue. Coil is OK and it could be the condensor or control unit. But is the condensor necessary? Some earlier posts suggest it isnt???? If it is, what is generic spec so I can get a replacement is Spain.

Thanks

[BwBrown]

Short answer - YES it is necessary.

As the points open and close, the condenser charges, then releases/discharges the stored energy out through the rotor/cap to the plugs.

If the condenser is faulty (either shorted or open) - or missing, there will be no spark.

[Nut124]

BwBrown, where do you get this? Have you tested this?

I was told by an "expert" that the condenser has little function in a car w electronic ignition, and even then, only to reduce radio noise.

OP, I would disconnect the condenser and replace the ICM module first.

[Martyn]

Hi Guys,

Thanks for the responses. The two views summarise my confusion.

The ICM is diffciult to source in Spain but I guess the condenser is more widely available if I can get one with the right spec.

Totally selfish reason to try condensor first is that theres a rally here on Sunday and good go if condensor's the problem, but not if I have to wait for ICM.

Any ideas on spec? The one I have has 0.5 (mu)F 360VI (as best I can tell) stamped on it. Does this mean anything? Anyone with right specs so I can ask at aprts place?

[spider2081]

I think both replays are correct. A condenser servers the purpose of reducing ignition point arching and increasing spark when the ignition system is mechanical points.
The condenser used n later spiders with electronic ignition systems is more of a radio noise filter than anything else. A 1985 Spider should have an electronic ignition system and could be run with out the condenser with out hurting anything or effecting engine performance.
Have you removed the distributor cap and inspected the pick-up inside ? pay special attention to the wires. Sometimes the insulation breaks down from oil and heat leaving bare spots on the wires.
Also there is a ground wire that connects the back of the exhaust cam box cover to the coil pack mounting plate.
Also loose or corroded connections on the coil cause intermittent issues.
The coil pack housing is the heat sink for the coil. So all the physical mounting points should be clean and tight for maximum heat transfer. The ICM is heat sensitive and a heat transfer grease is used between it and the heat sink. This grease dries out over time and looses its effectiveness. Any grease is better than no grease for heat transfer

[Nut124]

eBay UK: "Ignition Module Fits Fiat 124 Peugeot 505 & Renault R18i"

1979-1983 Fiat 124 Ignition Control Unit AC Delco 86728JX

https://www.ebay.co.uk/itm/353386419056 ... SwuPpgeJ9v

[18Fiatsandcounting]

Any ideas on spec? The one I have has 0.5 (mu)F 360VI (as best I can tell) stamped on it. Does this mean anything? Anyone with right specs so I can ask at aprts place?

Martyn, I'll see if I can find a spec, but basically the one you have is 0.5 microFarads, which is abbreviated as uF, where the "u" is actually the Greek micro symbol. My vague recollection is that 0.5 to 1 microFarads is in the ballpark. It doesn't need to be exact.

The 360 VI is likely the breakdown voltage, that is, if you go over this voltage the capacitor will "short"' and be destroyed, which obviously isn't good. I would think 600 Volts would be better, but maybe 360 is OK. You only have a 12V system, but it's the very high transient spikes that you need to worry about.

As far as I can tell, automotive ignition condensers are just like capacitors in your radio or TV except that they are more robust to be able to last in an environment of heat/cold, vibration, oil/grease, voltage spikes, etc.

If I find a spec, I'll post again. My sneaking suspicion is that the microFarad value doesn't need to be exact, but you want a high enough voltage spec so you don't fry your capacitor (condenser).

-Bryan

[davidbruce]

As stated by Nut124 and Spider 2081, in an electronic ignition set up the condensers job is to filter out radio interference. My service manual doesn't even include it in the ignition system diagram. I suppose if it were internally shorted to ground that could cause issues. I doubt this is the case but you could disconnect it from the coil and see if it makes a difference. To test the pick up coil. Disconnect it from the icm, probe both sides of the connector and you should get 700-800 ohms. Remove one probe and connect that probe to the distributor body. You should get infinity. If it is out of spec it is faulty. I would still check the wires. Especially the white one to the distributor as they can fall on the exhaust and burn. If it tests OK you can check the icm. With everything connected. Remove the high voltage wire from the centre terminal on the distributor. While holding the end with a pair of insulated pliers. Hold it about 5mm from a clean area on the engine and have someone crank the key and check for spark. If no spark jumps the gap replace icm. These are tests straight from my IAP workshop manual reprint. Those 4 pin icm''s were used in thousands of vehicles. I suspect if you give a parts man AC Delco number 19180771 or even take the icm to them they will be able to cross it to something readily available. There are tests for the coil itself but I think one of the other 2 is the culprit. I have personally only seen 2 coils that had aile. Both had developed leaks and lost their inulating oil. Good luck.

[18Fiatsandcounting]

For what it's worth, the only info I could find on the condenser was 0.20 to 0.25 uF up to 1978. After that, no condenser is listed, although one may have been installed to cut down on radio interference (if the car had a dealer-installed radio). For 1978 and before, the condenser was there to reduce the arcing across the points and thus prolong their life. And for reducing radio interference as noted.

Since non-precision capacitors only have an accuracy to 20% or so, and sometimes as much as 0.5X or 2X, I'm thinking anything in the 0.25 to 0.5 microFarad region would be fine. Appropriate voltage rating of course, and higher is always better although capacitors with higher voltage ratings are more expensive.

-Bryan

[Martyn]

Thanks to everyone.

I get no spark from wire going to distributor so my guess it is the ICM. But now everything cleaned of 35 years of crud and wiring looks good. So off to get a new icm and possibly a new condensor.

Ill post again when all running as it should

[spider2081]

I get no spark from wire going to distributor so my guess it is the ICM

Have you tested the pink wire for battery voltage when the key is in the run position?? Then test it again with the key in the "start" position for the coil pack to make a spark battery voltage must be present on the pink wire.

The ICM needs more than 10 volts in order to operate properly. This is measured at the pink wire connection on the coil with the engine cranking.

[Martyn]

Hi Spider2081,

I get 12.5 volts with ignition on and voltage drops to about 10 volts (or a little over) when engine cranked.

It is unlikely now that I will be able to sort this problem out until possibly next year!. I will be leaving Spain for UK in two weeks and due to holidays the only European supplier of the ICM I can find cannot guarantee delivery. So why next year you ask? Because due to BREXIT I cannot return for at least 90 days .

Thanks everyone for ideas help etc.