Non Starter, Possible Ignition Amp Problem? Help!

[BamBamGTI 0]

Hey guys,

 

Recently, after the recent bout of rain and onset of crappy winter weather I found my battery keeps going dead after a few days. I thought I might have a short somewhere. Charged up the battery and tried out the car. She took a few seconds to start up and was rough for a few seconds but that then went away so I shot down the A3 to Guildford (about a 50 minute drive) and back to make sure she's charged up and ok to leave for a day so I had time to see where the short is. Half a mile from my house she just dies... battery light comes up on dash, can't restart. She turns over but doesn't start.

 

After looking for similar problems on the forum, I tested the usual things, made sure I had fuel (loosened the top filter hose, turned on ignition, fuel pump is working). Spark plug testers off the plugs and the king lead show no spark. The coil is ok, (tested out of the car) + to - virtually no resistance and + to king lead connection is 7000 ohms. I also tested to see if I get 12v at the + and - terminals of the coil with the ignition on and I don't. I do get 12v if I put the neg lead of my multimeter to the aluminium plate on which the ignition amp is mounted though. Does this mean I have a bad amp or there is a bad earth somewhere? Surely the amp would ground there?

 

Also the source of the ground (I think) is my radio. It powers on but no sound. I had my back passenger foot well fill up with rainwater and I'm guessing a speaker or something has shorted out down there.

 

Any ideas chaps? I don't like the bus

[Anthony 1,003]

Check the condition of the dizzy timing/signal cable and for moisture in the 3-pin plug on the end of it.

 

Could be the coil or amp, but worth checking the above as that cable/connector can cause non-starts in cold, damp conditions. Cleaning up the pins and a squirt of WD40 works wonders.

 

The coil is grounded by the ignition amp to charge and fire it - with the ignition on and engine not running/turning, you'll only see +12v to it and not a ground. Ignition amp should have both +12v and a ground though on the appropriate pins.

[BamBamGTI 0]

Check the condition of the dizzy timing/signal cable and for moisture in the 3-pin plug on the end of it.

 

Could be the coil or amp, but worth checking the above as that cable/connector can cause non-starts in cold, damp conditions. Cleaning up the pins and a squirt of WD40 works wonders.

 

The coil is grounded by the ignition amp to charge and fire it - with the ignition on and engine not running/turning, you'll only see +12v to it and not a ground. Ignition amp should have both +12v and a ground though on the appropriate pins.

 

Shouldn't I get 12v between the terminals of the coil when the ignition is on? If the amp gives the coil the 12v it needs then that suggests the amp isn't working right?

 

I'll just go and check the 3 pin plug...

[jackherer 543]

The coil gets a + supply permanently when the ignition is on. The - is rapidly pulsed by the ignition amp which is what makes the spark actually happen.

 

The ignition amp will only supply the - pulses when it gets a signal from the distributor via the small signal wire plugged in the side of it.

[BamBamGTI 0]

The coil gets a + supply permanently when the ignition is on. The - is rapidly pulsed by the ignition amp which is what makes the spark actually happen.

 

The ignition amp will only supply the - pulses when it gets a signal from the distributor via the small signal wire plugged in the side of it.

 

I see... I've checked the 3 pin plug, all good, everything nice and shiny. I don't really know what to take from this, electrics is definitely not my strong point. Are there any other checks I could do to check individual components or with the multimeter? I've put everything back in and checked the battery again, 12.33v. Tried to start and starter turning very slowly and no start. I've seen on another forum that the battery should be at 12.66v to have a full charge, and it's not holding that. I'm going to swap out the battery as it's under guarantee and see what happens.

[Anthony 1,003]

A healthy charged battery should be around 12.7v give or take.

 

At 12.3v it's fairly discharged and not surprising that it's turning over slowly, but you should still get a spark and the engine start.

[DamirGTI 342]

Checked alternator ? if the batt. light comes on the dash instruments ... could be bad voltage regulator .

 

But yes , i agree with Anthony , while 12.3V is a tad low it should still start up ..

 

D

[BamBamGTI 0]

I replaced the battery anyway (it was under 5 year guarantee) for new. Halfords guy tested it and the cold start amps were way down at 120v. New battery in and the car almost started once then conked out.

 

Replaced the Ignition module for a brand new Bosch (£70 off eBay), and thermal paste from Maplin, started first time.

 

If anyone buys a module from eBay AVOID The Green Spark Plug Co. Item never arrived after two weeks of waiting and they did eff all to sort it out. I had to go to eBay for a refund.

 

Bought from The Parts Factor and module arrived after two days. The beast is back on the road...

Thanks for the help guys