P1320 Code - Aftermarket Coil Packs?

[plundccre]

Hello All:

2001 QX4 w/ 113,XXX miles

I hadn't been driving the QX4 for about a year. I needed to get a smog Cert to be able to register. I started her up and she was running rough and would die on idle. Hooked up the code reader and got a misfiring #2 cylinder.

I figured that it was probably either old plugs or faulty coil(s) so I ordered new NGK plugs and a full set of aftermarket coils.

In taking things apart, I found that mice had chewed through the wires to the #2 fuel injector so that was probably my problem. I spliced in new wires and had the injector hooked back up. Since I already bought them I decided to install the new plugs and coils.

Now I am receiving a Pending 1320 Ignition code. Can't pass smog with that. In doing some reading, I am seeing that several people claim that installing aftermarket coils will cause it to throw the 1320 code. Can anyone verify that this is a true condition? Since my prior problem was probably the chewed wires, and not a coil pack, I could install the old ones back in but I don't want to go through all of that work if its something else. I also have seen that the same code could be caused by a bad ignition condenser. Its not an expensive part but I don't want to go around replacing parts that aren't the problem.

Anyone have first hand knowledge about aftermarket coils throwing codes? If that's the case, why do they even sell them if they are such a problem?

Thanks for the help. I want to get her back on the road.

[mdmellott]

The condenser is a possible cause and the power transistor built into the coils is also a possible cause. I would focus on the new coils first since those aftermarket coils may be suspect. Testing them for this possible transistor issue is simple enough with a multimeter to probe their connector pins for resistance. (see page EC-509 for the FSM https://www.nicoclub.com/service-manual ... System.pdf ) Open or shorted harness or connector issues is also a possibility, especially since you already discovered rodent damage to another wire. Pages EC-499 through EC-509 covers everything you can check regarding this P1320 ignition signal circuit fault code without having to remove the coils. Additionally, some aftermarket components can have flakey connections to the stock harness connectors if the flat connector pins on the coils, for instance, are made a bit too thin to make a solid contact to their connectors. If that is the case, giving the pins an ever so slight twist, using a needle nose pliers, will better assure a good contact when they are plugged in.

[plundccre]

Thanks for the response. My first guess would not be additional harness issues (even though I did have the injector wire chewed through) as I was not seeing this code until after I replaced the coils so thy seem like the most likely suspect,

The engine seems to run fine, leading me to believe that the aftermarket coils are working but maybe the aftermarket ones have a difference resistance from the OEM that is just enough to cause a error code but still function sufficiently. There are several posts and even some YouTube videos about the aftermarket ones not working properly though no one gives a reason for it. Just that they throw codes.

[VStar650CL]

The ECM is basically looking at the pattern of current being drawn by each coil during charging and firing, including the back-EMF "kick" in the line from the coil primary during discharge. So wrong spark plugs can cause it in addition to a bad condenser or aftermarket coils with weak power transistors. There are bulletins regarding P1320 from wrong plugs for several older Nissan models.

[plundccre]

New plugs are NGK G-Power LFR5AGP. NGK states that they are a correct plug for the 2001 QX4.

[plundccre]

I removed the new aftermarket coil pack and reinstalled the old OEM ones and the code went away. Of course now there is something new. In park and at idle, the engine rev's between 1200 - 2000 rpm. no codes yet on this issue. I ordered a new TPS and am checking the hoses for vacuum leaks. Any other suggestions on what to check?

[mdmellott]

Before you replace the TPS, did check to see if the TPS was adjusted properly and then perform the IACV relearn process?

[plundccre]

No. No Idea what that is. Just read that a faulty TPS could cause those issues.

[mdmellott]

Reading through the Infinity factory service manual for your '01 QX4 will help you to understand how things work and what to do to diagnose and correct issues that will save you a great deal of time and money that can be wasted on unreliable sources guessing what the issue is and buying parts you do not need.

Pages EC-109 through EC-111 will walk you through the steps to check and adjust your TPS. Pages EC-57 through EC-58 will instruct you on how to perform the idle air volume learning procedure. https://www.nicoclub.com/service-manual ... System.pdf

Read through this information thoroughly and follow the steps precisely. You will need a digital multimeter and feeler gauges. Aside from these, no other special tools are required. Good luck.