Ignition Coils Keep Breaking Within 2 Weeks.

BlinkyBill · October 29, 2015

Hello

I have an Is200 Automatic Petrol X reg(year 2000 or so)

Every two weeks now the engine begins to grumble and vibrate when the car is idle, along with losing power.

When I buy new Denso Ignition Coils and replace them, the car works fine, all power is back and the car runs smooth.

However over the period of 2 weeks, these begin to feel like they are degrading too fast, the car engine temperature begins to get hotter over the course of these 2 weeks as it begins to lose power and as they begin to feel they are degrading.

What could be the cause of this? I have now brought 3 sets of 6 Denso Ignition Coils, all are now pretty much dead.

Before replacing all of these Ignition Coils I replaced the Spark Plugs with a brand new set, so I dont think its the Spark Plugs.

Also the engine symbol is illuminated on the dash board along with the TRAC OFF flashing every 4 seconds.

I dont have any engine codes as I dont have a machine to check it.

seems to me somthing is destroying the ignition coils

ROYT · October 29, 2015

wild guess, check the ignition leads........

andyk134 · October 29, 2015

or it maybe worth taking it to someone who has a machine to check error codes? will save you money in the end I expect.

steve2006 · October 29, 2015

As above get the fault codes read before doing anything else, guessing is the most expensive way to diagnose a fault.

Did you fit the correct type of plugs?

steve2006 · October 29, 2015

wild guess, check the ignition leads...

No leads Roy,they are coil over plug.

ColinBarber · October 29, 2015

wild guess, check the ignition leads........

it doesn't have any ;)

ColinBarber · October 29, 2015

The coil packs are driven directly from the ECU so if they really are being damaged then maybe the ECU is at fault or an electrical issue. I'm not so sure the coil packs are failing though - worth getting the error code(s) as a first step and checking the Battery voltage with and without the engine running.

When you are replacing the coils are you doing anything else that could explain the change - e.g. disconnecting the Battery?

ROYT · October 29, 2015

That'll teach me not to guess, never seen under the bonnet of an IS !!

ColinBarber · October 29, 2015

That'll teach me not to guess, never seen under the bonnet of an IS !!

:D

It's no work of art, not like an early LS400

BlinkyBill · October 29, 2015

The coil packs are driven directly from the ECU so if they really are being damaged then maybe the ECU is at fault or an electrical issue. I'm not so sure the coil packs are failing though - worth getting the error code(s) as a first step and checking the battery voltage with and without the engine running.

When you are replacing the coils are you doing anything else that could explain the change - e.g. disconnecting the battery?

I do dissconnect the Battery when I change the ignition coils yes.

I still have all my old coils (Which I think are degraded).

Whenever I change coils the car does run very well, perhaps I should dissconnect the Battery for a while and see if it fixes the problem.

A mechanic has suggested that perhaps it is an eletrical issue and the coils are being over powered which is causing them to break.

ColinBarber · October 29, 2015

A mechanic has suggested that perhaps it is an eletrical issue and the coils are being over powered which is causing them to break.

If the coils are truly being damaged then yes I would agree. The voltage regulator on the alternator could be faulty which is supplying too much voltage - easy to check with a voltmeter and if it is that then you are lucky the ECU and other electric components haven't been affected.

The only other way that the coils could be damaged that I can think of is if they are being overheated, but you would probably notice if the engine was running that hot.

BlinkyBill · October 29, 2015

A mechanic has suggested that perhaps it is an eletrical issue and the coils are being over powered which is causing them to break.

If the coils are truly being damaged then yes I would agree. The voltage regulator on the alternator could be faulty which is supplying too much voltage - easy to check with a voltmeter and if it is that then you are lucky the ECU and other electric components haven't been affected.

The only other way that the coils could be damaged that I can think of is if they are being overheated, but you would probably notice if the engine was running that hot.

Under the bonnet gets Extremly hot, So hot that the temperature gauge reaches the very top, then drops all the way to zero as it no longer registers the heat.

Once the car is this hot it will never start, I have to wait 2 hours or so for it to cool down.

Seems to me the heat gets worse when the coils degrade, better coils = no so hot, badder coils = hotter.

ColinBarber · October 29, 2015

If it is getting that hot then you really shouldn't be using it, you could cause serious damage to the engine.

Difficult to tell remotely what is causing the overheating issue. Is it faulty coils causing the engine to run lean and getting hot, or is something else causing the engine to get hot (air lock, faulty thermostat, radiator fans, fuel injector issue causing lean running, restricted exhaust from cats breaking up) which then causes the coils to fail.

A Toyota engine will very rarely go above the middle on the temperature gauge if everything is working correctly, normally sits just below the mid point.

BlinkyBill · October 29, 2015

If it is getting that hot then you really shouldn't be using it, you could cause serious damage to the engine.

Difficult to tell remotely what is causing the overheating issue. Is it faulty coils causing the engine to run lean and getting hot, or is something else causing the engine to get hot (air lock, faulty thermostat, radiator fans, fuel injector issue causing lean running, restricted exhaust from cats breaking up) which then causes the coils to fail.

A Toyota engine will very rarely go above the middle on the temperature gauge if everything is working correctly, normally sits just below the mid point.

Going to d/c the Battery, will post back in 30 mins or so the outcome.

Regarding the heat, When I buy brand new coils and install, the engine doesnt get that hot, gradually as the coils degrade, the engine gets hotter, perhaps as the coils begin to not work, the engine gets hotter because only parts of it are working due to only some of the coils starting those cylinders?

BlinkyBill · October 30, 2015

So I dissconnected the Battery for around 15 Minutes, unplugged one ignition coil.

The problem still exists.

The temp gauge is at the halfway point for around 10 minutes of general car usage, after this 10 minutes it goes right to the very top. At this point the engine becomes very bumpy and not much power when trying to accelerate after a brief stop.

I do think if I was to go and buy a 4th set of Ignition Coils this would completly get rid of this problem, but these coils would probably degrade pretty fast like the current ones have.

BlinkyBill · October 30, 2015

Taking into account my most recent post above this, Does anybody know what the problem could be?

ColinBarber · October 31, 2015

You need to eliminate some things first as previously stated. Get the voltage checked out first.

BlinkyBill · October 31, 2015

Took it to the garage, apparently the tests shows ECU error numbers, coil pack numbers, air filter number and some others, Gona just scrap the car, had enough of it.

Thanks for the help guys.

steve2006 · October 31, 2015

Shame but there you go, re reading the posts I would have 1st checked the thermostat and then waterpump. Car is normal temperature for 10 minutes as engine warms up, if the stat pr wp are faulty the engine will then overheat which in turn due to the heat transfer will take out the coil packs.

BlinkyBill · November 2, 2015

Shame but there you go, re reading the posts I would have 1st checked the thermostat and then waterpump. Car is normal temperature for 10 minutes as engine warms up, if the stat pr wp are faulty the engine will then overheat which in turn due to the heat transfer will take out the coil packs.

I am going to try to check these myself(lost logbook so cant scrap yet).

Another thing I noticed is that many months ago the engine fans would come on, they havnt came on for months, I am assuming the fans are to cool the engine down, can this be the cause of the over heat problem?

steve2006 · November 2, 2015

Yep they sure do, there should be a thermostatic switch located on or near the radiator which kicks the fans in when the engine temperature rises above a set level. You can short it out to see if the fans then kick in.

BlinkyBill · November 3, 2015

I had a look under the hood, I also noticed a fuse/relay type box which had fan 1, fan 2, and fan 3 written on the underside of the lid, each fan had a corresponding socket with a relay plug in it, is it possible that one/all of these are broken? If they are broke cud they cause the fan to not work?

BlinkyBill · November 3, 2015

When turning on my AC I can see that the Radiator Fans do turn on, I guess this rules out the possibility of broken relays and broken fans right?

However it still doesnt make sense that when the engine is overheating the fans do not come on at all. Shouldnt they be on during this time?

ColinBarber · November 3, 2015

The fans operate at two speeds, slow when the AC is turned on and full speed when the water temperature reaches a certain temperature in the radiator. Therefore even though they work with the AC it doesn't mean they are functioning correctly.

BlinkyBill · November 4, 2015

The fans operate at two speeds, slow when the AC is turned on and full speed when the water temperature reaches a certain temperature in the radiator. Therefore even though they work with the AC it doesn't mean they are functioning correctly.

They havnt entered that high speed mode for months, What broken components could stop the Fan from receiving the signal to turn on when the engine is too hot?