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NEED HELP! No spark. 8V -CIS

3K views 18 replies 3 participants last post by  newvwdude777 
#1 · (Edited)
Need your help folks.
car is a 87 golf GT (gti engine and trans) CIS car.
lost all engine power cruising down highway. then would not start at all. fuel pump fuse OK.
towed home. engine cranks but no spark. fuel pump humming. i can smell fuel b/c i tried cranking alot. so i dont think fuel related. went through bentley procedures. checked following:
LED test light to center pin of distributor hall harness to positive of batt. flickers OK while cranking. i think that rules out hall effect in distributor.
touched ground with center pin and voltage jumps as per bently to 2-3V. checks OK.
coil resistance on pri and secondary OK within range. but I have only 0.8V to coil pri while cranking. wiring looks ok.

can i connect 12V straight from batt to coil primary? or will that cause harm?

figured ICU is hosed b/c no voltage was going to coil primary. changed it with Meyle unit from FCP euro. still nothing. have another one on order original VW german unit. but not new.
ICU is getting voltage to pins.
i dont think ignition switch related since i was cruising down highway and lost power at that time. but who knows?

any other ideas? love my MK2. it had no problems starting before this. i maintain the car and wires, plugs , dist cap, rotor, and other stuff is in very good condition. i want to keep the car as long as i can.
appreciate any specific detailed help. :peace:
 
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#2 ·
I like using a test light to test the coil. Hook up one end of the light to the neg side and touch the other end of the to the pos side of the coil. When the engine is cranking, the test light should flicker. If it does not, use your test light to determine if there is power to the pos side [key on of course]. If there is, then take the light and test the neg side. If the engine is not cranking [key on] the test light should also come on [slightly dimmer]. If it does not, the control module may be shorted. The module should not provide ground when the key is on, engine off. If it does, it would short out the coil and it would eventually overheat the coil.

All the module does is amplify the hall sensor so the coil can be triggered.

As for Meyle, do not waste your money on their products.
 
#5 ·
Yeah, ICM, control module, amp, ECU, they are all used to identify that item.

One thing for certain, when you diagnose properly, you have test results. Using those test results allows you to make a logical decision on what is wrong. Once the bad part is replaced, then you can confirm you are correct because the test results will be different [as in better]. Meyle parts are not reliable at all. In the automotive business that I'm in, it's something you do not want to stand behind. It does not matter if it is their rubber, plastic, and for certain their electrical parts. Just because you put in a Meyle part does not mean it will work. To be fair, new does not mean it works either.
 
#7 · (Edited)
I like using a test light to test the coil. Hook up one end of the light to the neg side and touch the other end of the to the pos side of the coil. When the engine is cranking, the test light should flicker. If it does not, use your test light to determine if there is power to the pos side [key on of course]. If there is, then take the light and test the neg side. If the engine is not cranking [key on] the test light should also come on [slightly dimmer]. If it does not, the control module may be shorted. The module should not provide ground when the key is on, engine off. If it does, it would short out the coil and it would eventually overheat the coil.

All the module does is amplify the hall sensor so the coil can be triggered.

As for Meyle, do not waste your money on their products.
hi fella's,
i am wits end. only thing i can suspect and this is a long shot now, is ignition switch?

i changed the ICU with another VW original brand off another car from salvage yard. I unfortunately cannot assume its good or bad. but behaves similar to the meyle unit but with more voltage. 5V vs 3.5V-ish
I checked the coil + and - and the voltages are about 5Vdc when cranking. when not cranking and ignition switch is turned to "ON" the voltage will jump to 4.8V and then go down to almost zero.
I changed the coil temporarily (to a brand new Oil filled NGk coil) and the results were same. removed coil because i had to use another primary wire and jury-rig it to fit the center electrode on the NGK. the NGK electrode was too thick in diam. anyway this was not the main issue.

I went through all the bentley items i could including temporarily grounding pin 12 of the knock control unit to see voltage jump as per bently. everything checks out OK!

i also connected the batt+ straight to the coil + and with meyle ICU plugged in (in case i fry something i'd rather the meyle ICU). still nothing. but when I did do this i heard the ISV valve turn on and i think the fuel priming.

I also connected the LED test light to both coil + and - and went through what Butcher said and checked out OK.

i have no clue what else to look for. i checked wires and fraying, but nothing popped out at me.
i also checked the center electrode carbon like another poster had said. looks fine. spark plug wires check out OK. plugs are fairly new.

I want to keep the car, i really enjoy it. ..the only thing i can go off of was back to beginnning when this happened it was sudden and on the highway while under power. just suddenly lost all power. so something like a fusible link maybe? ignition switch is a long shot i think b/c it was not moving obviuosly on the highway.

i could use any help here please. thanks guys..
 
#11 ·
Garryt, i tried with a light lead (should have used heavy but did not have at the time) from batt(+) to coil (+). did not connect the (-) of coil to batt(-). But it still did not work. But i tried it with the Meyle ICU b/c i was afraid of messing up the VW ICU that I just bought from salvage (no guarantee that works either) but did not want to burn it out by chance.

I do not know how the system works exactly. can you please help me understand?
I am not sure if the coil + and coil - have to be at 12V at all times while the engine is running. Is this a true statement? I would think they are always ON and the primary wire going from coil to distributor is always HOT (voltage speaking). and the rotor takes that center pin (carbon spring-loaded) and distributes it to each of the contacts (which go to each spark plug) while it rotates.

so then I am not sure what does the ICU (ignition control module) do? I know it is supposed to get triggered by the hall-effect from the center pin of the plug that is on the side of the distributor and then it in-turn triggers the coil (+) or (-)? but i dont understand why does it need to trigger anything if the coil is always at +12V across + and - ?

so if i get a heavy set of leads and connect straight from batt + and - to coil + and - and then try to start the motor using the ignition key would that cause any harm on any component? if it starts, then what should i look at as being the problem? coil itself or wires going to coil i guess?

thanks very much for any detailed info. i want to get my car back on the road.
 
#12 ·
Older ignitions system all work the same. In the old days there were points. Once the points opened, there was spark. The points would open at the right time and the spark would be delivered to the spark plug thru the distributor. The points were also inside the distributor so they would open and close at the right time.

As time marches on, the points were replaced [since it was a wear item and the timing would go off as the points wore]. They were replaced with electronic parts but those electronic parts do exactly the same thing as points. So hook up the test light to each side of the coil. One on the + side and the other at the - side. None should be installed on the battery! When the key is turned on, the electrical system sound NOT apply ground to the coil so the test light should be be lit. Now crank over the engine. The test light should flicker. Do it? If not, you are missing + or -.

So with the key off, hook up the test light to the ground side of the battery and the other side to the + side of the coil. Turn on the key. Is the light on? If not, you have no power to the coil. You need power for the coil to make power. That needs to be fixed.

If you do have power, then that means you are missing the ground signal. The distributor makes a small signal that acts like a set of points. Since that part cannot handle the load of a coil, there is a amplifier that will make that signal stronger. That is what you are calling the ICU. Like all electrical parts, you need power for it to work. So you must have at least 2 wires [power and ground]. You should have power when the key is on and ground all the time. A test light may help here, but a volt meter would be better. If you do have a good power/ground, then you need to test that distributor signal to make certain it's making it to the ICU.

This is where you need to put your big boy pants on and find out what that signal is. Many Hall Effect sensors run on 12v. When the distributor is turning, the signal will bounce from power to ground [square wave]. Not all run on 12V, some run on 5V. Most Hall Effect sensors have three wires. Power, Ground, and the signal wire [that goes to the ICU]. The ICU may provide that power and ground to the Hall Effect sensor but you'll have to look at the wiring diagram to see what the facts are.

If the + and - are working correctly [the test light is flickering] and you have no spark, the coil is probably faulty.

Again, ignition system are still working the same in the most part, even on today's cars. Just more fancy electronics and more precision. So if you get confused, just think of old school points. When the points open, the power in the coil must go somewhere so it makes a spark to go to the spark plug. When the ground is present, the coil is filling up with all the power.

I hope that is simple enough. If not Google it. There is a YouTube video out there somewhere. Most if not all ignition systems work very similar.
 
#14 · (Edited)
tested mine today. you should be getting battery voltage to coil + with ignition on. and charging voltage with engine running. now if iirc, there is an earth wire from the icm to the battery - might want to check that connection is good. quick and easy to do:thumbup:
thanks guys, i've been on a trip. i went ahead and ordered a new bosch coil (just in case), and will get back to trying to fix this hopefully soon. i am thinking to run a heavy gauge wire direct to the coil +15term from batt +. previously i only ran a finer wire to it just to check and made no difference. woul you recommend i run a neg to the -1 term. of coil also?
Garryt: thanks for checking on yours. I definitly dont remember getting full batt voltage at that terminal. are you checking between pin 1 and 15 of coil or between body(neg) and pin15 of coil?> when you measured it? (not sure right now if pin1 and body is same potential i'd have to check.) this is making me think the ICU's i've been subbing might also be bad? one was a meyle new unit and another from a salvage unit. unknown good.
 
#13 ·
tested mine today. you should be getting battery voltage to coil + with ignition on. and charging voltage with engine running. now if iirc, there is an earth wire from the icm to the battery - might want to check that connection is good. quick and easy to do:thumbup:
 
#15 ·
I checked between + of coil and battery post-. done another check yesterday. with the icm and the hall sender unplugged I'm still getting 12v to the coil. so it's unlikely to be either of them at fault. you need to start from the + feed to the coil and work your way back.
 
#16 · (Edited)
got it. i mean there is some voltage, as i had stated about +5Vdc, but not 12V. so wire is not broken, if it was i wouldn't see anything when cranking. but something must be pulling the voltage down..coil? maybe, but when i tried the NGK coil made no difference..will check everything again fresh.....thanks.
 
#18 ·
Garryt I replaced the ign. Switch. It’s the same. I tried cranking with coil 1- and 15+ unplugged I get 12v while cranking. So as soon as I put a new coil on or the old one then that voltage drops to about 5v whilst cranking. If I run lines to +15 and -1 from battery directly then that voltage while cranking goes to about 10v. But engine still doesn’t fire or even try to fire. Any help anybody?? I’m stuck. Tried another icm and was same result.


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