99 Q45 Code 1320

[jr92591]

My 99 Q45 motor seems to misfire at low RPMs while in drive. The TCS and SLIP lights come on and the engine seems to be laboring like one or more cylinders are not firing. When put on a diagnosis machine, code 1320 comes up. The rough running only lasts a few minutes and goes away when RPMs increase. This has happened three times but the one code that comes up does not give the mechanic any help to find the problem. Its a great car with 80K miles. I bought it new and it has had all the scheduled services/maintenance. Anyone got an idea on this? jr92591

[96Qowner]

You likely have one or more marginal coils. That's an Ignition Signal code.

This is a VERY common problem for older Y33s. If you can somehow isolate the faulty coil(s) you can just replace it. Unfortunately, the code doesn't tell you which cylinder it is.

[jr92591]

I took your advice and my mechanic changed four of the ignition coils with new Hitachi coils($145. ea) with the plan to use the four that was removed for the other bank of four if the problem persists. After replacing the four on the right side, the chief mechanic at the Infiniti dealer told my mechanic that with 80,000 miles it would be much better if we replace all of the coils rather than use four old and four new. He said that I might get oxygen sensor problems since the coils performance could be different with the 80K miles on the old coils. The advice seems reasonable so we are picking up four new Hitachi coils Monday to do the left side. My mechanic was told that the Hitachi coils are original equipment for Infiniti. I did not want to use after market parts that may be inferior. Are the Hitachi coils used as original equipment? I am now driving the car with four of the new coils installed and the only performance change is that it seems to start easier and quicker than before and no misfires so far. As soon as I change the other four and check out the results, I will update this post. I really appreciate the fact that this forum exists and that folks are so willing to help each other. jr92591

[paranoidjack]

You likely have one or more marginal coils. That's an Ignition Signal code.

This is a VERY common problem for older Y33s. If you can somehow isolate the faulty coil(s) you can just replace it. Unfortunately, the code doesn't tell you which cylinder it is.

I can't help but feel lucky. I've had no coil issues at all, and I have 140k now. BG44k right before every other oil change, change all fluids as scheduled...

crossing my fingers, just changed my spark plugs and had each injector in my hand yesterday.

[maxnix]

Very unusual that all 8 coilpacks go bad at once.

Dealer standard procedure is to replace all 8 so customer can understand the amount of the bill, rather than spending close to as much for diagnosing which ones have failed if the technician is experienced, or even more if he is not.

Doubtful if more than one or two of yours is actually bad.

[bullittandy]

I took your advice and my mechanic changed four of the ignition coils with new Hitachi coils($145. ea) with the plan to use the four that was removed for the other bank of four if the problem persists. After replacing the four on the right side, the chief mechanic at the Infiniti dealer told my mechanic that with 80,000 miles it would be much better if we replace all of the coils rather than use four old and four new. He said that I might get oxygen sensor problems since the coils performance could be different with the 80K miles on the old coils. The advice seems reasonable so we are picking up four new Hitachi coils Monday to do the left side. My mechanic was told that the Hitachi coils are original equipment for Infiniti. I did not want to use after market parts that may be inferior. Are the Hitachi coils used as original equipment? I am now driving the car with four of the new coils installed and the only performance change is that it seems to start easier and quicker than before and no misfires so far. As soon as I change the other four and check out the results, I will update this post. I really appreciate the fact that this forum exists and that folks are so willing to help each other. jr92591

This was my plan as well (replace 4 and see what happens) and this idea above also makes sense.

However I don't think that they lose some ability to energize the spark plug. I don't know-but I think that modern coils either work-or do not.Anybody else know? I've also wondered if there is one/two coils that are failing on these cars-maybe some weird temp region in the engine bay?

[RAP]

This was my plan as well (replace 4 and see what happens) and this idea above also makes sense.

However I don't think that they lose some ability to energize the spark plug. I don't know-but I think that modern coils either work-or do not.Anybody else know? I've also wondered if there is one/two coils that are failing on these cars-maybe some weird temp region in the engine bay?

Looking in the FSM - 2000 Q45 page EC406 has a simple resistance test for coils.

Check terminals 2 & 3 The answer: Resistance Not O ohms OK O ohms NG

What does this mean?

I guessing that any measurement above O is good, and no measurement, O, is no good.

In any event if this info is to be believed it doesn't appear too difficult to ascertain that a coil is good, or, no good. No mention of Consults or elaborate engine analysis systems.

Jack

[bullittandy]

This will work for a coil that has stopped working entirely-but the problem appears to be inconsistent failure at idle.

If you had a coil that has failed entirely then you can find it by plling the electrical connection on each coil-like you use to do with plug wires.