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Discussion Starter #1
Hi everybody
Infinity fx35 Y2004
My FX35 start burning coils since 2 months I had to change and it 10 coils the service shop checked the car on the computer and it shows all OK. 2 weeks ago the car start trembling and finally stopped. It doesn't restart. The technician tells me that I have to replace the ECU. The ECU is marked U2 and has a number MEC35-430 C3 4128. I am no car technician but I doubt that the ECU burns the coils. I reside Dominican Republic and things are not easy when it comes to car diagnosis. Anybody can help? Thank You.

Giancarlo ::?
 

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Sounds like you have some other kinds of issues. I'm not sure what could cause this, but I havent heard many cases of coils going bad (except for high mileage FXs).
 

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well the vehicle has 56,240 miles and last year I had to replace one coil on cylinder 2, besides I replaced all the spark plugs even though they were looking good. I think you are right it is something else going on because to burn a coil that means that primary is getting a higher voltage, but which mod is supplying the voltage impulse to the coil?
this morning the technician brought ab ECU marked K3, mine is marked U2, he tried to start it but as you know the imovilizer wouldn't allow it as it don't match the key code, however he said that he will reprogram the eprom! Just keeping my fingers crossed.
 

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Check your alternator output. The voltage regulator should keep it below 14v or so. If its higher it'll fry anything. Ive seen it many times.
 

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ya you might be right will try to suggest this to the engineer even though they don't like client's suggestions. Tell me how the voltage gets to the coil, is thru the ECU or the ECU is triggering a distributor mod where the voltage is dropped down to coil primary?
 

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coil on plug design. each individual coil is triggered by the ecm. primary ignition voltage is generated by each individual coil.
check for faulty engine grounds and/or faulty ground at the coil/coils. tends to be the problem about 85% of the time if the ecu is not faulty.
 

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Thanks everyone who is contributing to shade light on my problem. If I well understand the ECM sends the impulse to the coil (12 volts or less) and the coils itself generates the high voltage which is amplified thru a power transistor as I can see from a coil diagram. Hence if the alternator is outputting more that 13.8 V this may burn either the primary coil or the transistor, when I look to the coil cap I can see a bulge. Now which are the best coils, any suggestion? When I replace a coil this last for a while and withing 3 days another one burns and so on. 3 weeks ago I was driving the car and boys the car was flying you could feel the g force and I was telling my son look it performs better than ever, those were the last famous words, when I enter the home garage, after setting the parking brake the car suddenly jumped without I ever press the accelerator and I was fast to press the brakes otherwise I would have crashed into the wall soon after it start jerking. Mistery of misteries.

Today another engineer is due to inspect the car. Hope he can find the remedy. Will keep you posted I a solution is found.
 

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Today the engineer checked the connectors of each coil besides the ECM unit. The ECM is damaged on pin 17 and 18 thus not allowing two coils to receive the impulse. He found that the ground was faulty hence he suggested to set an 6AWG wire to connect the negative pole of the battery to the engine body to allow a stable grounding. He explained that the 2 burned coils in shortening have returned a high voltage to the ECM IC. He found this kind of problems on other FX models and on the Maxima. Ok next week hope to get the new ECM unit properly coded for my key. will keep informed.
 

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Yeh some have had an issue with the body or engine ground.

Keep us posted.
 

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Theres was a couple of other cases that I read on other sites. I dont recall what the issue turned out to be......sorry I cant help anymore.
 

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Ebay
 

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hi everybody

Finally yesterday the car is back on the road. So replaced the ECM, new coils, and the alternator this last was the culprit of the problem, besides reviewing each ground connections and installing two AWG6 wires, one to ground the negative pole of the battery to the engine and the other engine to body frame. Lucky I have been to meet an excellent electrical engineer, a dominican who was trained in the US besides he attended a course in Japan at Nissan's. Thank you everybody for helping. By the way you can believe that, a gentleman had to replace 70 coils in 2 months so I directed him to the same engineer who detected that his car had the same problem as mine. It is amazing that some technicians just replace the coils and do not examine the reasons for that behaviour. So long friends let me enjoy the smooth driving of my FX35.
 

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Ah ha it was the alternator. Well good news then now youre all fixed up!

Now get to enjoying your FX!
 

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Grats on finding the fix BEFORE having to replace 70 coils in 2 months... :)
 

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Hello,

my wife's 2005 FX35 was diagnosed with this problem and we have some questions, but let me start from the beginning:

In November 2010 my wife had roadside trouble and the AAA guy replaced the battery, but not without warning her that the alternator looked bad and advising to bring the car in for service.

In January 2011, she took the car to the Infiniti dealer, with a note from the AAA mechanic describing the issue. The dealer checked and serviced the car, and found everything okay. The invoice details reflect this.

In June 2011, she took the car in again, this time because another mechanic had noticed the left axle was bad. She had ageneral ipsection performed as well, and the car was given a clean bill of health.

Two weeks ago, the car failed on us. We had it towed to the dealer and were told that there was a multiple misfire. Upon further inspection, it turned out three ignition coils had gone bad. Possibly because of bad battery cables, as those were bad as well.

What's more, upon replacing the three ignition coils, the dealer found that the engine computer had been fried and needs to be replaced as well. We're gonna be out $1100 for the three coils and $1400 for the computer.

Somehow we feel something does not add up. Reading this thread makes me feel that the January 2011 inspection should have averted this problem. Do we have a case or is this just something that happens to cars, as the dealer says?

Thanks.
 

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So we got our car back two weeks ago, ponied up $2500+ for the repairs: $600 for 4 ignition coils, $500 for labor and $1400 for a new ECM.

Last week the "service engine soon" light came and stayed on. We took the car back to Infiniti yesterday, and it was diagnosed with a dying catalytic converter. Thank God it will be replaced under warranty.
 

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This dealer may have saved your engine. Others have simply reset the code, more than once, only to find a dead engine in a matter of weeks. Sucks you've had so many issues but at least this time you got some good service.
 

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zeph said:
Last week the "service engine soon" light came and stayed on. We took the car back to Infiniti yesterday, and it was diagnosed with a dying catalytic converter. Thank God it will be replaced under warranty.
Yeah... there have been more than 1 story where someone found they had a dead CAT... only to find out later that something caused their engine to die... coincidence? Only if it happens once but there have been 3 or more similar stories...

Hope you get to keep your FX trouble free for many years to come!
 

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I had a serious problem with a miss, they replaced all the spark plugs, and it ran fine - for a while. Then it did it again, and the plug wasn't enough. I replaced the cylinder 3 coil as well, since this was my problem child. It fired the coil. I went to Infiniti yesterday and they showed me a service bulletin that says if you don't REPLACE (not clean) the grounding wires and the battery cables, along with the screws, this is going to happen. I got the parts for about $150, and they wanted 2 hours of labor, so at $135/hr, I'm doing that part myself as well. I hope this helps some others save the frustration of not knowing why the right fix fails.

2003 FX35 149,000 miles and still like a baby...
 
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