2004 2.0 JTS 156 - Motor Control System Failure - Fixed!!!

[Sportscar Nut]

Thanks Craig - might do some shopping.

Col, my Toyota has not had a problem with the coil packs - have thrown a big end but no coil pack problems!

Paul

[bonno]

Found this post via the search function, which relates to diagnosing a faulty coil pack on the Alfa 156 JTS engine. My 2005 156 JTS has been experiencing symptoms applicable to a faulty coil pack (Engine misfire/hesitation under load and low rpm, with EMS light coming on momentarily).
The difficulty with such a diagnosis is identifying which cylinder is causing the problem and is it the coil pack or spark plug. Please note that the simple balance test of each cylinder as shown on several Youtube clips will not pinpoint the cylinder misfire because you are unable to replicate faulty condition. For such a situation, the cheaper diagnostic tool that has I/M readiness status when  switched to ON will be able to identify the cylinder at fault when symptom is replicated. As in my case P0303 identified cylinder 3 to be at fault. Now to determine whether the spark plug or coil pack was at fault and save myself some money, swap the coil pack to say cylinder number 4. If the coil pack is at fault the code will now be P0304 or if it is still P0303 then spark plug is at fault. As in my case, the coil pack was faulty and new one purchased through e-bay (refer to link below). The car has been driven for several days without any further problem.
https://www.ebay.com.au/itm/NEW-GENUINE-BOSCH-IGNITION-COIL-ALFA-ROMEO-156-GTV-SPIDER-JTS-937A1-0221604103/301940621302?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
Cheers
bonno

[Citroënbender]

Hi Bonno, I'm watching this to see if your "paired" coil pack (#2) goes soon after your replacement of #3.

[bonno]

Hi CB
The car has been running fine since the coil pack was replaced and I guess that it is only a matter of time that the others will start showing signs of failure (it's just a matter of when). I could have gone out and replaced all 4 at a cost of $500, but I see no sense in wasting money as it is quite a simple job to diagnose, identify and replace. A two day turn around on supply of new coil pack is not a worry and I do have a spare in the boot just in case a COMPLETE coil pack failure is experienced which I consider unlikely (low RISK).
cheers
bonno